JP6108158B2 - Pseudo multipole antenna - Google Patents

Description

  The present invention relates to an antenna having an extremely large effective aperture diameter, and relates to an antenna using an electric / magnetic multipole based on a novel principle completely different from the conventional one.

  Electric power transmission far away by electromagnetic waves (hereinafter referred to as “wireless power transmission”) has the potential to solve a number of major problems. For example, in one of the power transmission systems as infrastructure, a power plant using huge sunlight is created in outer space, and power is transmitted from there to a ground rectenna (antenna with rectifier) using microwaves. "Space Solar Power Station" (Space Solar Power Station = SPS) concept (see Non-Patent Document 1). In the atmosphere, there is also a concept in which a solar power generator is provided on a flying mother ship, and power is transmitted from there to another working airship or an antenna on the ground using a large antenna. The former contributes to the stable supply of power, and the latter contributes to the regeneration of mountain forestry (unmanned airship forestry) and the supply of power to communication base stations during disasters.

  In addition, by providing a power receiving antenna at a terminal of the mobile communication system, electromagnetic waves flying around the surrounding space can be secured as a power source.

Shinohara Shingo, Hisada Yasumasa, JAXA SSPS WG4 Team, "Current Status and Issues of Microwave Power Transmission Phased Array", IEICE Publishing, IEICE Technical Report 2006-06

  In order to transmit power with electromagnetic waves to a distant place, it is necessary to increase transmission efficiency as much as possible. As will be described later, for this purpose, it is necessary to increase directivity (narrow the beam width) using an antenna having a large aperture surface with respect to the wavelength. Although microwaves are suitable for power transmission, mechanical strength, weight, installation location, and the like become major issues when applying an antenna with a large aperture to an artificial satellite or airship as described above. Therefore, there is a demand for an antenna having a large electrical aperture area with small hardware.

  However, in the antenna based on the conventional principle, if the mechanical aperture area and the distribution thereof are determined, the directivity gain is almost determined, and the mechanical aperture area and the electrical aperture area coincide. That is, there is a trade-off between antenna miniaturization and beam width reduction.

  Further, since wireless power transmission is a spatial transmission of large electric energy, it is necessary to suppress sidelobe radiation as much as possible in order to avoid interference with other communication systems and ensure safety. That is, an antenna having almost no side lobe is required.

  However, for example, in the structure of a conventional array antenna, side lobes (grating lobes) are generated according to the array pitch. There is a limit to the optimization design method for suppressing side lobes. To obtain low side lobe characteristics, a parabolic antenna or a patch antenna placed on a parabolic curved surface is effective. However, in order to avoid the edge effect at the periphery of the parabolic, the aperture distribution is Gaussian or Taylor type. As a result, there is a problem that the aperture efficiency is lowered. In other words, there was a trade-off between beam width reduction and sidelobe suppression.

  Here, when the aperture diameter of the aperture antenna is represented by Dm, the gain by G, and the beam width by θ, these are represented by the following relationship.

  Thus, the beam width Θ is inversely proportional to the aperture diameter Dm of the antenna.

  In the antenna based on the conventional principle, it is constrained by the relationship of the formula (1.1), and an antenna having an electrical opening area exceeding the mechanical opening area cannot be configured. An object of the present invention is to provide an antenna that is based on a principle that is completely different from the conventional principle, and that has a large electrical opening area with respect to a mechanical opening area and does not generate side lobes.

  The pseudo multipole antenna of the present invention is configured as follows.

(A) Electromagnetic radiation is performed by an electromagnetic field equivalent to a directional electromagnetic beam produced by one or both of a TM wave using an electric multipole as a wave source and a TE wave using a magnetic multipole as a wave source. Features.

(B) A spherical electromagnetic wave corresponding to each order (l, m = 1) of the spherical harmonic function which is an element of the solution of the Maxwell equation in the spherical coordinate system is one of the TM wave and the TE wave from l = 1 to l = L. Alternatively, by superimposing both of them as a set, the (l-1) side lobes of each order of electric multipole radiation and magnetic multipole radiation are canceled.

  When the electromagnetic beam is formed in the half space by the set of the TE wave and the TM wave using the electric multipole and the magnetic multipole as wave sources, side lobes of the order of l−1 of the spherical harmonic function are generated. However, the side lobes are canceled by superimposing the spherical electromagnetic wave from l = 1 to l = L with the TE wave and TM wave as a set. If L is made infinite, the side lobe is completely canceled, but even if it is finite L, it is sufficiently canceled.

(C) The wave source is configured on a spheroid having a radius smaller than the effective aperture radius of the aperture antenna given by the directivity gain of the electromagnetic beam, and an electric multipole and a magnetic multiplex are formed at the center of the spheroid. Preferably, there are a plurality of radiation sources that produce an electromagnetic field equivalent to the presence of a pole.

(D) The unit antenna is preferably a dielectric resonator.

(E) The dielectric resonator is preferably a spherical dielectric resonator that resonates in one or both of the TE ₁₁ dual mode and the TM ₁₁ dual mode.

(F) In the above (e), the spherical dielectric resonator is one of a TM mode that generates an electromagnetic field equivalent to the electric multipole and a TE mode that generates an electromagnetic field equivalent to the magnetic multipole or A multilayer spherical dielectric resonator having a core and a shell that resonates at both is preferred.

(G) In the above (e), it is preferable that the spherical dielectric resonator has a dielectric constant different between a core portion and an outer shell portion, and a TE mode and a TM mode are degenerated.

(H) It is preferable that the spherical dielectric resonator has a core portion made of metal and an outer shell portion made of a dielectric, and a TE mode and a TM mode are degenerated.

(I) In the above (a) or (b), the wave source generates a spherical electromagnetic wave equivalent to the electric multipole, respectively, and causes a TM electromagnetic resonance and a spherical electromagnetic wave equivalent to the magnetic multipole. A (multilayer) spherical dielectric resonator having a plurality of dielectric layers, each of which degenerates from resonance in the TE mode, is preferable.

(J) In the above (i), the multilayer spherical dielectric resonator preferably has different dielectric constants in the radial direction and the circumferential direction in the dielectric layer, and therefore a slit extending in the radial direction is formed. It is preferable that

  According to the present invention, the electrical opening area with respect to the mechanical opening area can be greatly increased without increasing the size, the beam width is sharpened forward, and directivity with almost no side lobe can be obtained.

FIG. 1 is a visual representation of the far field of radiated power associated with electrical multipole radiation. FIG. 2 is a visual representation of the far field of radiated power when electrical multipole radiation and magnetic multipole radiation are combined. FIG. 3 is a diagram showing a magnetic field vector on a spherical surface at kr = 1 in octupole radiation. FIG. 4 is a diagram showing the magnetic field intensity on the spherical surface at kr = 1 when E wave and H wave are combined. FIG. 5 is a visual representation of the far field of radiated power when electric multipole radiation and magnetic multipole radiation are combined, and shows the relationship between the order of the multipole and the beam width. FIG. 6 is a diagram showing the directivity when spherical waves obtained by combining electric multipole radiation and magnetic multipole radiation are superposed from the order l = 1 to l = L. FIG. 7 is a diagram showing a beam in the near field when spherical waves obtained by combining electric multipole radiation and magnetic multipole radiation are superposed from orders l = 1 to l = 50. It is a figure which shows the directivity of a spherical wave when the maximum order is 10. FIG. 9A is a diagram showing the relationship between the maximum order of the spherical wave and the half-value angle, and FIG. 9B is a diagram showing the relationship between the maximum order of the spherical wave and the effective aperture radius. FIG. 10 is a diagram showing the relationship between the highest order L of spherical waves to be superimposed and the directivity (beam width). FIG. 11A is a diagram showing the distribution of the electric field strength in the near field when the spherical waves of the electrical multipoles and magnetic multipoles of each order from 1 to 10 are superimposed. FIG. 11B shows the electric field strength on the z axis when x = 0, and FIG. 11C shows the electric field strength on the circumference of r = 2λ in the xz plane. FIG. 12A is a diagram showing the distribution of the electric field strength in the near field when the spherical waves of the electrical multipoles and magnetic multipoles of the respective orders 1 to 10 are superposed. FIG. 12B shows the electric field strength on the circumference of r = 1.6λ in the xz plane, and FIG. 12C shows the electric field strength on the circumference of r = 3λ in the xz plane. It is. FIG. 13 is a diagram in which the motion of the electric field intensity distribution in the near field shown in FIGS. 11 (A) and 12 (A) is time-lapsed for one period. FIG. 14A is a diagram showing the concept of multipole radiation, and FIG. 14B is a diagram showing the concept of pseudo-multipole equivalent to multipole radiation according to the first embodiment. FIG. 15 is a diagram showing the contents shown in FIG. 14 in relation to the evanescent electromagnetic field region. FIG. 16 is a conceptual diagram showing the state of energy flow entering and exiting on a spherical surface in a resonant electromagnetic field. FIG. 17 is a conceptual diagram showing a state of radiation and absorption in a large number of unit antennas arranged on a spherical surface. FIG. 18 is a block diagram of one of the receiving antenna power networks. FIG. 19 is a plan view seen from the z-axis of the antenna spherical surface on which the unit antennas are arranged. FIG. 20 is a plan view of the antenna spherical surface on which the unit antenna is disposed as viewed from the −z axis. FIG. 21 is a perspective view of an antenna spherical surface on which unit antennas are arranged. It is a figure which shows the analysis result of the polarization plane of the electric field of a unit antenna, and a magnetic field in the north pole P001 of FIG. It is a figure which shows the analysis result of the polarization plane of the electric field of a unit antenna, and a magnetic field in the north pole P100 of FIG. It is a figure which shows the analysis result of the polarization plane of the electric field of a unit antenna, and a magnetic field in the north pole P110 of FIG. It is a figure which shows the analysis result of the polarization plane of the electric field of a unit antenna, and a magnetic field in the north pole P010 of FIG. FIG. 26 is a diagram showing a plurality of resonance modes of the unit antenna. Figure 27 is a magnetic dipole radiation is performed in a resonant mode TE ₁₁ ^xy0 by ^{_{(TE 11 X + jTE 11 Y}} ), the electric dipole radiator is performed in the resonance mode of the TM ₁₁ ^0YZ by ^{_{(TM 11 Z + jTM 11 Y}} ) FIG. FIG. 28A and FIG. 28B are block diagrams showing the structure of a power feeding circuit for the spherical dielectric resonator. FIG. 29 shows the internal structure of the antenna spherical surface. FIGS. 30A and 30B are diagrams showing the electromagnetic field and angular momentum of each resonance mode of the spherical dielectric resonator. FIG. 31 is a diagram showing a resonance electromagnetic field and energy flow formed by a number of spherical dielectric resonators on the antenna spherical surface. FIG. 32 is a diagram according to the second embodiment, and shows a directivity when spherical waves generated by electric multipole radiation are superimposed from the order l = 1 to l = L (the far field of the radiated power is shown). It is a visual representation). FIG. 33 is a cross-sectional view taken along a plane passing through the center of the multilayer spherical dielectric resonator 101 according to the third embodiment. FIG. 34 is a configuration diagram of the power feeding unit 200 for the multilayer spherical dielectric resonator 101. FIG. 35A is a cross-sectional view taken along a plane passing through the center of the multilayer spherical dielectric resonator 102 according to the fourth embodiment, and FIG. 35B is an external view. FIG. 36 is a diagram illustrating the resonance frequencies of the TE11 mode and the TM11 mode when the radius ratio (a / b), which is the ratio of the diameter of the core portion 30 to the diameter of the dielectric layer 31, is changed. FIG. 37 is a diagram showing the state of the electric field vector in each mode of the multilayer spherical dielectric resonator 102. In FIG. FIG. 38 is a diagram illustrating a configuration example of a power feeding unit for the multilayer dielectric resonator 102.

  First, multipole radiation generated by plane wave spherical wave expansion is considered as an element of plane waves. The electric field and magnetic field of each multipole radiation (spherical wave) are given as analytical solutions by the spherical wave expansion of the plane wave. In addition, since each multipole radiation (spherical wave) has orthogonality, an electromagnetic field obtained by superimposing multipole radiation can be directly obtained by adding each electric field and magnetic field. Each analysis result shown below used Mathematica (Mathematical processing system of Wolfram Research).

  FIG. 1 is a visual representation of the far field of radiated power associated with electrical multipole radiation. FIG. 1A is a representation of each order (l, m = 1) of a spherical harmonic function, which is an element of a solution of Maxwell's equations in a spherical coordinate system, and is represented by [l = 1, m = 1]. It represents the directivity of radiated power by bipolar radiation. Similarly, FIG. 1B shows the directivity of the radiated power due to [l = 2, m = 1], that is, electric quadrupole radiation, and FIG. 1C shows [l = 6, m = 1], that is, electric 12-fold. The directivity of radiated power by polar radiation is shown respectively.

Here, the power dP _watt radiated in the range of the small solid angle dΩ is expressed by the following relationship.

^{_{dP watt = [E E (l}} , m) × H E (l, m)] · e r R 2 ∞ dΩ
As described above, if the radiation is generated only by the electric multipole, the main beam of the radiation wave is generated in the ± z directions. In addition, when the order of the multipole is expressed by 2 × l (el), l−1 side lobes are generated.

  FIG. 2 is a visual representation of the far field of radiated power when electrical multipole radiation and magnetic multipole radiation are combined. FIG. 2A shows [1 = 1, m = 1], that is, the radiation power directivity by a combination of electric dipole radiation and magnetic dipole radiation. FIG. 2 (B) shows [l = 2, m = 1], that is, directivity of radiated power by a combination of electric quadrupole radiation and magnetic quadrupole radiation, and FIG. 2 (C) shows [l = 3, m = 1] That is, directivity of radiated power by a combination of electric hexapole radiation and magnetic hexapole radiation is shown.

  FIG. 3 is a diagram showing a magnetic field vector on a spherical surface at a position of kr = 1 (radius r = λ / 2π) in octupole radiation. 3A is the real part of the E wave, FIG. 3B is the imaginary part of the E wave, FIG. 3C is the real part of the H wave, and FIG. 3D is the imaginary part of the H wave. Represents. The horizontal axis is the angle θ around the x axis, and the vertical axis is the angle φ around the z axis. The right end of the horizontal axis is the pole in the + z direction (north pole), and the left end of the horizontal axis is the pole in the -z direction (south pole). Thus, since it is octupole radiation, the order l is 4 and the node of l-1 = 3 arises.

  FIG. 4 is a diagram showing the magnetic field intensity on the spherical surface at the position of kr = 1 when the TM wave and the TE wave are combined. That is, FIG. 4A shows the real part of (E wave + H wave), which is a combination of FIG. 3A and FIG. 4B is an imaginary part of (E wave + H wave), and is a combination of FIG. 3B and FIG. 3D.

  In this way, when electric multipoles and magnetic multipoles are used as wave sources, and TM waves and TE waves are combined, they are emitted only in the + z direction. That is, electromagnetic radiation is performed in the half space. Utilizing this principle is one of the features of the present invention. In order to make the bidirectional directivity radiating in the ± z directions shown in FIG. 1 unidirectional directivity, a reflector is disposed behind the conventional technology. ) Is required, and the antenna cannot be downsized. In the present invention, unidirectional directivity can be obtained without using a reflector. As will be described later, the electromagnetic radiation in the backward direction (−z direction) does not cause a loss, but contributes to the radiation in the forward direction (z direction).

  FIG. 5 is a visual representation of the far field of radiated power when electric multipole radiation and magnetic multipole radiation are combined, and shows the relationship between the order of the multipole and the beam width. FIG. 5A shows the directivity of the radiated power due to [l = 6, m = 1], that is, 12-pole radiation. FIG. 5B shows the directivity of the radiated power by [l = 10, m = 1], that is, 20-pole radiation.

  Thus, the beam width becomes narrower as the order increases. However, even if the order is increased, as described above, when the order of the multipole is expressed by 2 × l (el), l−1 side lobes are generated. If such a large side lobe occurs, it cannot be used as an antenna for power transmission.

  FIG. 6 is a diagram showing the directivity when spherical waves obtained by combining electric multipole radiation and magnetic multipole radiation are superposed from the order l = 1 to l = L. FIG. 6A shows a superposition of spherical waves by a combination of three different orders of electric multipole radiation and magnetic multipole radiation from [l = 1, m = 1] to [l = 3, m = 1]. The combined radiation power directivity, FIG. 6B shows six different orders of electrical multipole radiation and magnetic multipole from [l = 1, m = 1] to [l = 6, m = 1]. Directivity of radiated power superposed by spherical waves by a combination of radiation, FIG. 6C shows 10 different orders from [l = 1, m = 1] to [l = 10, m = 1]. The directivity of the radiated power obtained by superimposing spherical waves by a combination of electric multipole radiation and magnetic multipole radiation is shown.

  In this way, l−1 side lobes generated by a 2 × l multipole are canceled by superimposing spherical waves by multipole radiation from the order l = 1 to l = L (L: lmax). . According to this method, the side lobe gradually approaches 0 by increasing the order l. Utilizing this principle is one of the features of the present invention.

  FIG. 7 is a diagram showing a beam in the near field when spherical waves obtained by combining electric multipole radiation and magnetic multipole radiation are superposed from orders l = 1 to l = 50. Here, the expansion coefficient inherent to the plane wave was used as the overlay weight. It is not a weight optimized with a finite order. FIG. 7A shows the intensity (dB scale) of the power P in terms of concentration over a range of distance r = 2 to 40λ. FIG. 7B is a detailed view of the fan-shaped region in FIG.

  In this way, the spherical wave radiated in the −z direction is forward by the combination of the TM wave and the TE wave, and the superposition of each order of the electric multipole and the magnetic multipole. It can be seen that no side lobe is generated.

  Next, the gain of the aperture antenna is considered from another viewpoint.

  The directivity of spherical waves is expressed using the directivity index in antenna theory. The directivity gain Gd in antenna theory is

As given. Here, E (θ, φ) is the electric field directivity obtained by normalizing the radiated electric field with the maximum intensity. The effective opening area Ae and the effective opening radius a are given as follows.

Further, the half-value angle θ ₀ is an angle at which the electric field strength is lowered by 1 / √2 from the peak. Here, the r direction dependency of the electric field and magnetic field of the spherical wave is given by a spherical Hankel function, so the r direction dependency of the radiated power density is r ⁻² . In addition, the total radiated power of the spherical wave of the maximum order l _max is calculated using the expansion coefficient of the TM wave and TE wave of each order,

And given.

  From this, the directivity gain is calculated using the complex pointing vector P

Can be calculated without performing spherical integration. Here, e _r represents a unit vector in the r direction, and r _f is a sufficiently large radius. FIG. 8 is a diagram showing the directivity of a spherical wave of l _max = 10 obtained by the equation (2.22). However, it is a graph in the case of φ = 0. FIG. 8 shows that (l _max −1) side lobes exist on one side. Also, the -3dB line is plotted together. By finding the intersection of the directivity function and the -3dB straight line, the half-value angle of the spherical wave is obtained.

  Next, the same calculation is performed by changing the maximum order of the spherical wave, and the relationship between the maximum order of the spherical wave, the half-value angle, and the effective aperture radius is shown. FIG. 9A is a diagram showing the relationship between the maximum order of the spherical wave and the half-value angle, and FIG. 9B is a diagram showing the relationship between the maximum order of the spherical wave and the effective aperture radius. Thus, it can be seen that the half-value angle decreases in inverse proportion to the maximum order of the spherical wave. It can also be seen that the effective aperture radius increases in proportion to the maximum order of the spherical wave.

  It is considered that the energy high density region in the spherical wave is mathematically due to the spherical Neumann function. Therefore, the intersection of the spherical wave maximum order spherical Bessel function and the spherical Neumann function is defined as the boundary point, and the inside of the boundary point is defined as the energy high density region, and the radiated electromagnetic field outside the boundary point. Distinguish from the area. FIG. 9B also shows the radius of this energy high density region. From FIG. 9B, it can be seen that the radius of the energy high density region is approximately the same as the effective aperture radius.

  The relationship between the maximum order of the spherical wave and the directivity described above cannot be explained by the conventional aperture antenna equation that expresses the relationship between the size of the aperture area of the antenna and the directivity. Therefore, the expression of the aperture antenna is re-examined from the standpoint of the uncertainty relationship, and the directivity of the spherical wave is examined using the uncertainty relationship.

  If the width of the wave function in the de Broglie wave position space is Δx, Δy, and the width of the wave function in the momentum space is Δpx, Δpy, the uncertainty relation between the position and the momentum is given as follows.

Here, h` (H) is a converted Planck constant obtained by dividing the Planck constant h by 2π. Equations (2.23) and (2.24) are equivalent when they are Gaussian wave packets. At this time, p <sub>x, y</sub> = k <sub>x, y</sub> h`, so if we assume a Gaussian wave packet, multiplying (2.23) and (2.24)

Holds. Assuming a square aperture with width a and length b, Δx = a / 2π and Δy = b / 2π. At this time, if the wave number of the radiated electromagnetic wave is k ₀ , θ _{x, y} / 2 = Δk _{x, y} / k ₀ ,

It becomes. Furthermore, assuming that the effective opening area is S, θx · θy = ΔΩ, k ₀ = 2π / λ, so equation (2.26) is

Can be transformed. Here, using the definition formula of Gd ≡ 4π / ΔΩ,

It becomes. This is a relational expression between the area of the aperture antenna and the directivity gain. From the above, the equation of directivity gain in the aperture antenna can be derived from the definition of Δx, Δy and the uncertainty relationship between the position and momentum when the electromagnetic field distribution of the beam on the aperture surface is Gaussian.

  There are three uncertainties: position and momentum, angle and angular momentum, and time and energy. Of these, we investigated the directivity of spherical waves using the uncertainty relation between angle and angular momentum. Similar to the uncertainty relationship between position and momentum, the uncertainty relationship between angle and angular momentum is given as follows.

Here, when the equality is true, the equation (2.29) and the equation (2.30) are squared and added.

Holds.

Spherical harmonics representing a spherical wave according to the quantum mechanics it is well known that eigenvalues with the square of the eigenfunctions of the total angular momentum is ^{l (l + 1) h` 2} . Even in an electromagnetic field with zero mass, energy, momentum, and angular momentum are defined in the same manner as in the particle system. Assuming that each order of the electromagnetic spherical wave has an eigenvalue of angular momentum, the following relationship is obtained.

Lt ² = Lx ² + Ly ² + Lz ²
ΔLz = 0
And
If Δθx = Δθy = θ ₀ / 2π (θ ₀ is half-value angle),

It can be expressed. Arranging both sides and taking a positive square root,

It becomes. Where Δ√ {l (l + 1)} = √ {lmax (lmax + 1)}

It becomes. Thus, the relational expression between the half-value angle and the maximum order can be derived from the uncertainty relation between the angle and the angular momentum. The straight line shown in FIG. 9A is a theoretical value according to this relational expression. From FIG. 9A, it can be seen that the formula obtained from the uncertainty relationship well explains the directivity of the spherical wave.

Furthermore, the relationship between the maximum order and the effective aperture radius is derived. Assuming that ΔΩ = θ ₀ ² , equation (2.34) can be modified as follows.

Here, using Gd = 4π / ΔΩ and equations (2.19) and (2.20),

It becomes. The straight line shown in FIG. 9B is a theoretical value based on this relational expression.

  FIG. 10 is a diagram showing the relationship between the highest order L of spherical waves to be superimposed and the directivity (beam width).

Here a directional gain Gd, the effective opening area Ae, the effective aperture radius a, the half angle of the beam width is represented by theta _0,
If the highest order L = 10,
Gd = 21.7dBi
Ae = 11.96λ ²
a = 1.95λ
θ ₀ = 16.1deg
If the highest order L = 20,
Gd = 27.4dBi
Ae = 43.89λ ²
a = 3.74λ
θ ₀ = 8.44deg
If the highest order L = 30,
Gd = 30.5dBi
Ae = 89.54λ ²
a = 5.34λ
θ ₀ = 5.72deg
It becomes.

  Thus, the directivity increases according to the highest order L of l to be superimposed. The effective aperture radius a = 5.34λ when the maximum order L = 30 is an aperture diameter corresponding to a diameter of 10λ. In this way, a sharp beam equivalent to a diameter of 10λ can be generated with only one radiation source.

  In this way, the maximum order L required to obtain the desired half-value angle is obtained, and the spherical waves of the electrical multipoles and magnetic multipoles of the respective orders from 1 to L may be superimposed.

  FIG. 11A is a diagram showing the distribution of the electric field strength in the near field when the spherical waves of the electrical multipoles and magnetic multipoles of each order from 1 to 10 are superimposed. FIG. 11B shows the electric field strength on the z axis when x = 0, and FIG. 11C shows the electric field strength on the circumference of r = 2λ in the xz plane.

  FIG. 12A is a diagram showing the distribution of the electric field strength in the near field when the spherical waves of the electrical multipoles and magnetic multipoles of the respective orders 1 to 10 are superposed. FIG. 12B shows the electric field strength on the circumference of r = 1.6λ in the xz plane, and FIG. 12C shows the electric field strength on the circumference of r = 3λ in the xz plane. It is. Thus, it can be seen that there is a strong electromagnetic field that does not radiate in the radial direction in the vicinity of the origin. In addition, comparing FIG. 12B and FIG. 12C, it can be seen that the energy radiated in directions other than θ = 0 decreases rapidly as the distance from the origin increases. That is, it can be seen that the side lobe is not generated, and is approaching a plane wave.

  FIG. 13 is a time-lapse view of the motion of the electric field intensity distribution in the near field for one period.

  Thus, it can be seen that there is a strong electromagnetic field around the multipole, and radiation is occurring.

  As is clear from FIGS. 11 and 13, the electromagnetic field radiated to -z (backward) or to the side causes an energy flow as indicated by arrows in the figure, and z (front) in the far field. Will be emitted.

  In FIG. 11A, 2a is the effective aperture diameter of a general antenna. However, in the present invention, the effective aperture diameter 2a can be secured while the multipole is disposed at the center.

<< First Embodiment >>
Next, hardware for realizing the above-described multipole will be described.

  If an antenna that performs multipole radiation is configured, a large number of poles exist in the same space, and unnecessary coupling between the antennas occurs. Therefore, a pseudo multipole is arranged in the near field (inside the effective aperture diameter) that is some distance away from the central source.

  FIG. 14A is a diagram showing the concept of multipole radiation, and FIG. 14B is a diagram showing the concept of pseudo multipole equivalent to multipole radiation. In FIG. 14A, there is a multipole at the center, and a resonant electromagnetic field is generated on a spherical surface around it (effective aperture diameter). A radiation electromagnetic field is generated from the region of the resonance electromagnetic field. In FIG. 14B, a magnetic field and an electric field indicate a magnetic field and an electric field on a spherical surface separated from the center by a certain radius. The pseudo multipole is a plurality of radiation sources that generate an electromagnetic field equivalent to an electric multipole and a magnetic multipole in the center. A pseudo multipole is used as a wave source, and it is treated as radiating from this wave source.

  FIG. 15 is a diagram showing the contents shown in FIG. 14 in relation to the evanescent electromagnetic field region. FIG. 15A is a diagram showing an evanescent electromagnetic field region. In the case of a receiving antenna, even if a spherical wave is incident toward the origin, it does not collect at the origin (one point). This is because the angular momentum of the spherical wave becomes apparent near the origin. In other words, energy is absorbed by the multipole at the origin while rotating. This is therefore not a normal evanescent wave. The expression that should be called a rotating traveling wave is appropriate. If attention is paid to the energy flow in the radius R direction, it can be said that a resonant electromagnetic field having a high Q exists in the space near the origin, and the multipole at the origin matches the inward spherical wave.

  FIG. 15B shows a sphere on which the pseudo multipole is arranged. Thus, when a sphere having an arbitrary radius centered on a multipole in rotational energy is considered, it is considered that the energy flow goes back and forth between the inside and outside of the sphere. However, since the law of conservation of energy holds, the energy flow to the inside is equal to the energy of the inward spherical wave when subtracted by the spherical surface.

  FIG. 16 is a conceptual diagram showing the state of energy flow entering and exiting the spherical surface in the resonance electromagnetic field. A specific method for calculating the energy flow subtraction on the spherical surface is expressed as follows.

  Electromagnetic fields having inward and outward energy flows on the spherical surface are combined to form a set of electric field vector and magnetic field vector. The surface integral of the vector product of these tangential components matches the input energy. This is expressed as follows.

  If this input energy is recovered by a spherical antenna, 100% of the energy of the inward spherical wave can be received.

  Next, let us consider radiation and absorption in a spherical antenna. FIG. 17 is a conceptual diagram showing a state of radiation and absorption in a large number of unit antennas arranged on a spherical surface. In the case of an antenna that receives a spherical wave propagating in the −z direction (receiving antenna), the unit antenna near the front direction needs to radiate energy rather. The underlying multipole model creates an electromagnetic field that absorbs while preserving both energy and angular momentum. An antenna on a sphere in the resonant electromagnetic field must mimic this electromagnetic field. In order to create the y-axis and x-axis angular momentum, energy is radiated from the z direction, and the power is synthesized in phase with the power to be received. Furthermore, it is necessary to create an energy flow around the x-axis or y-axis and suck it from the unit antenna behind the antenna. As a result, the receiving antenna can receive a moment (angular momentum). The amount of energy absorption / radiation depends on the location on the sphere where the unit antenna exists.

  Here, the angular momentum density is expressed by the following equation.

  Here, the product of x ′ and dv ′ is the angular momentum.

  Next, an example of a power network of a receiving antenna is shown. FIG. 18 is a block diagram of one of the receiving antenna power networks. In FIG. 18, the received power of the unit antennas U1 to U5 is phase-shifted by the phase shifters φ1 to φ5, and is combined by the RF power combiner. It is synthesized by this RF power synthesizer, and its RF output is converted into DC power.

  The reception antenna has been described above, but the same applies to the transmission (radiation) antenna based on the reciprocity theorem (time reversal symmetry).

  Next, a specific configuration example of the entire pseudo multipole antenna is shown. FIG. 19 is a plan view of the antenna spherical surface (see FIG. 17) on which the unit antenna is arranged as viewed from the z axis, and FIG. 20 is a plan view of the antenna spherical surface as viewed from the −z axis. FIG. 21 is a perspective view of the spherical surface of the antenna.

  In these drawings, a pair of crossed arrows represents an electric field vector and a magnetic field vector generated in the unit antenna. That is, the unit antenna is disposed at the position of the crossed arrow pair. However, in order to avoid complication of the drawings, in FIG. 19 to FIG. 21, all unit antennas are depicted sparsely. Here, a solid line arrow represents an electric field vector, and a broken line arrow represents a magnetic field vector. This example radiates in the z direction with x polarization.

  Assume that the z-axis passes through the north and south poles, and l + 1 unit antennas are arranged between the north pole and the south pole, and 2 × l unit antennas are arranged around the circumference. In addition, 2 × l unit antennas are arranged on the equator. For example, if the order is l = 2000, 4000 unit antennas are arranged on one circumference of the spherical surface. For example, on a spherical surface having a diameter of 10 m, they are arranged at equiangular intervals at a pitch of about 8 mm. As the latitude increases from north to south from the equator, the circumference at the same latitude becomes shorter. Therefore, the unit antennas adjacent to each other in the longitude direction are arranged in a number that does not overlap. In this example, the half-value angle is 0.05 degrees, the aperture diameter is 200 m, and the reception beam diameter at a transmission distance of 10 km is 17.5 m.

  As shown in FIG. 19, the direction of the electric field of each unit antenna faces the x direction and the magnetic field faces the y direction when viewed from the z-axis. Further, as shown in FIG. 20, the direction of the electric field of each unit antenna faces the −x direction and the magnetic field faces the −y direction as seen from the −z axis.

  When the north pole direction is the radiation direction, the unit antenna closer to the north pole has a larger electric field vector and magnetic field vector, and the unit antenna closer to the south pole has a smaller electric field vector and magnetic field vector. In addition, the unit antenna on the equator generates a circularly polarized electromagnetic field, the unit antenna near the North Pole generates a substantially linearly polarized electromagnetic field, and the mid-latitude unit antenna generates an elliptically polarized electromagnetic field. .

  22 to 25 are diagrams showing the analysis results of the polarization planes of the electric field and magnetic field at the representative points in FIG. The electric field of the spherical wave and the polarization of the magnetic field can be expressed by plotting 0 <t <2π as a parameter for each component of the electric field and the magnetic field. In these figures, arrows in the figures represent electric field and magnetic field vectors at t = 0, π / 12ω, π / 4ω. This represents the phase difference and the direction of polarization rotation. In the figure, “t0” represents the timing at t = 0, “t1” represents the timing at t = π / 12ω, and “t3” represents the timing at t = π / 4ω.

  FIG. 22 is a diagram showing the analysis results of the polarization planes of the electric field and magnetic field of the unit antenna at the north pole P001 in FIG. It can be seen that the electric field is a linearly polarized wave having only the θ direction (angle around the x axis) component and the magnetic field only in the φ direction (angle around the z axis) component.

  FIG. 23 is a diagram showing the analysis results of the polarization planes of the electric field and magnetic field of the unit antenna at the point P100 in the x-axis direction of FIG. It can be seen that the electric field is elliptically polarized with a polarization plane in the r-θ plane, and the magnetic field is linearly polarized with only the φ direction component.

  FIG. 24 is a diagram showing the analysis result of the polarization plane of the electric field and magnetic field of the unit antenna at point P110 in FIG. It can be seen that both the electric and magnetic fields are elliptically polarized.

  FIG. 25 is a diagram showing an analysis result of the polarization plane of the electric field and magnetic field of the unit antenna at the point P010 in the y-axis direction of FIG. It can be seen that the electric field is a linearly polarized wave having only the φ direction component, and the magnetic field is an elliptically polarized wave having a polarization plane in the r-θ plane.

  As described above, the unit antenna needs to arbitrarily reproduce linearly polarized waves, circularly polarized waves, and elliptically polarized waves at each point. Here, a spherical dielectric resonator is used as a unit antenna to reproduce the polarization planes of electric and magnetic fields.

FIG. 26 is a diagram showing a plurality of resonance modes of the unit antenna. In this example, a spherical dielectric resonator is used as a unit antenna. FIG. 26A is a diagram showing an electromagnetic field distribution in the TE ₁₁ ^X mode. In this figure, the dot symbol and cross symbols a cross section of the electric flux of the TE ₁₁ ^X mode, thereby representing the electric field distribution of the TE ₁₁ ^X mode. The dashed line is a flux of TE ₁₁ ^X mode, thereby representing a magnetic field distribution of the TE ₁₁ ^X mode. FIG. 26B is a diagram showing an electromagnetic field distribution in the TE ₁₁ ^Y mode. In this figure, the dot symbol and the cross symbol are cross sections of the TE ₁₁ ^Y mode electric flux, thereby representing the TE ₁₁ ^Y mode electric field distribution. The dashed line is a flux of TE ₁₁ ^Y mode, thereby representing a magnetic field distribution of the TE ₁₁ ^Y mode. FIG. 26C is a diagram showing an electromagnetic field distribution in the TM ₁₁ ^Z mode. In this figure, the dot symbol and cross symbols are flux cross-section of a TM ₁₁ ^Z mode thereby representing a magnetic field distribution of the TM ₁₁ ^Z mode. The loop-shaped solid line is the electric flux of the TM ₁₁ ^Z mode, and this represents the electric field distribution of the TM ₁₁ ^Z mode. FIG. 26D is a diagram showing an electromagnetic field distribution in the TM ₁₁ ^Y mode. In this figure, the dot symbol and cross symbols are flux cross-section of a TM ₁₁ ^Y mode, thereby representing a magnetic field distribution of the TM ₁₁ ^Y mode. The loop-shaped solid line is the TM ₁₁ ^Y mode electric flux, which represents the TM ₁₁ ^Y mode electric field distribution.

  A spherical wave magnetic field is reproduced using a TE mode magnetic field of the dielectric resonator, and a spherical wave electric field is reproduced using a TM mode electric field. In each of the electric field and the magnetic field, circularly polarized waves and elliptically polarized waves having arbitrary polarization planes as well as linearly polarized waves can be excited individually, so that it is possible to reproduce a spherical wave electromagnetic field.

The unit antenna of this embodiment is used in a state where the TE ₁₁ mode and the TM ₁₁ mode of the spherical dielectric resonator are degenerated. However, because the TE ₁₁ mode and the TM ₁₁ mode have different resonance frequencies due to the difference in the size in which energy is confined, the TE ₁₁ mode and the TM ₁₁ mode are degenerated within the same spherical dielectric resonator. It ’s difficult. Therefore, a concentric double sphere structure having a core and an outer shell surrounding the periphery of the core is used, and the core is a conductor.

  If the relative permittivity εperi of the outer shell is 18, the degeneration between the TE mode and the TM mode occurs at about 8 GHz when the nuclear radius ratio Pres is in the range of 0.3 to 0.4. In addition, if the relative permittivity εperi of the outer shell was 40, the degeneration between the TE mode and the TM mode occurred at about 5.8 GHz with the nuclear radius ratio Pres ranging from 0.3 to 0.4.

Next, for the dielectric resonator with εperi of 40, the outer diameter r ₀ and the diameter ratio Pres were optimized so that the resonance frequency at the time of degeneration was 5.8 GHz. As a result, when r ₀ is 4.78 mm and Pres is 0.4, the resonance frequency of the TE ₁₁ ^Z mode rotationally symmetric with respect to the z axis is 5.97 GHz. The resonance frequency of TM ₁₁ ^Z mode, which is rotationally symmetric with respect to the z-axis, is 5.789 GHz. At this time, it was confirmed that the resonance frequencies of the TE ₁₁ ^Z mode and the TM ₁₁ ^Z mode almost coincided and the two modes degenerate.

FIG. 27A shows that a magnetic dipole moment is generated in the resonance mode of TE ₁₁ by (TE ₁₁ ^X + jTE ₁₁ ^Y ). FIG. 27B shows that an electric dipole moment is generated in the resonance mode of TM ₁₁ by (TM ₁₁ ^Z + jTM ₁₁ ^Y ). In this way, a strong induction magnetic field is generated from the spherical dielectric resonator by the magnetic dipole moment, and a strong induction electric field is generated by the electric dipole moment. The phase of the magnetic dipole moment and the electric dipole moment is determined so that a predetermined linearly polarized wave, circularly polarized wave, or elliptically polarized wave is radiated by the orthogonal induced magnetic field (Hx) and induced electric field (Ez). . In addition, since the electric (magnetic) dipole moment carries energy along the antenna spherical surface, the pointing vector, which is the product of the electric field vector and magnetic field vector, rotates along the longitude line from the south pole to the north pole along the antenna spherical surface. As if, the feeding phase to each spherical dielectric resonator is controlled.

A concentric double sphere structure including a core and an outer shell surrounding the outer periphery of the core may be used, and the core and the outer shell may have different dielectric constants. For example, a dielectric ceramic sphere with a dielectric constant of the core and outer shell is set so that the resonance frequency of the TM ₁₁ mode with high electric field strength near the center is relatively lowered to match the resonance frequency of the TE ₁₁ mode. Use.

  Next, a configuration for supplying power to a plurality of spherical dielectric resonators on the antenna spherical surface will be described.

FIG. 28 is a block diagram showing the structure of a power feeding circuit for the spherical dielectric resonator. In the example of FIG. 28A, a spherical dielectric resonator PR, a TE coupling probe 13, a TM coupling probe 14, a hybrid circuit 12, and an oscillator 11 coupled to the spherical dielectric resonator PR are provided on the origin side. For each spherical dielectric resonator (for each unit antenna) R, a cross coil 21, a phase / amplitude control circuit 22, a TE ₁₁ coupling probe 23 coupled to the TE ₁₁ mode of the spherical dielectric resonator R, and TM ₁₁ A TM ₁₁ coupling probe 24 that couples to the mode is provided. These circuits are arranged in a layer immediately below (inside) the spherical surface of the antenna where the spherical dielectric resonator R is arranged.

  The oscillator 11 oscillates at, for example, 5.8 GHz, and the hybrid circuit 12 gives a phase difference of 90 degrees to the feeding phase with respect to the TE coupling probe 13 and the TM coupling probe 14.

  The spherical dielectric resonator PR arranged at the origin is a multiple dielectric resonator in which the TE mode and the TM mode are degenerated. The spherical dielectric resonator PR generates a magnetic field Hφ that draws a magnetic field loop around the z-axis by the TM mode and a magnetic field Hθ that draws a magnetic field loop around the x-axis by the TE mode.

The TE11 coupled probe 23 excites the TE ₁₁ ^X resonance mode and the TE ₁₁ ^Y resonance mode with respect to the spherical dielectric resonator R. The TM11 coupling probe 24 excites the TM ₁₁ ^Z resonance mode and the TM ₁₁ ^Y resonance mode with respect to the spherical dielectric resonator R.

The cross coil 21 is obtained by crossing a coil coupled to the magnetic field Hφ and a coil coupled to the magnetic field Hθ. The phase / amplitude control circuit 22 controls the phase of the signal (current) for the TE ₁₁ coupling probe 23 and the TM ₁₁ coupling probe 24. By this phase control, a predetermined electric (magnetic) dipole moment is generated from the spherical dielectric resonator R. Also, a spherical dielectric resonator so that this electric (magnetic) dipole moment carries energy along the antenna spherical surface (so that the pointing vector rotates on the longitude line from the south pole to the north pole along the antenna spherical surface). The phase control according to the position of is performed.

In the example of FIG. 28B, a spherical dielectric resonator having a slit-like groove facing in the 45-degree direction as the spherical dielectric resonator R, a TE11 coupling probe 23 coupled to the spherical dielectric resonator R, And a TM11 binding probe 24 is provided. The configuration on the origin side is the same as that in FIG. When two resonance modes having a degenerative relationship are generated by the slit-shaped grooves and the intermediate frequency is set as the power transmission frequency, both modes are excited. That is, in the spherical dielectric resonator R, the TE ₁₁ ^X resonance mode and the TE ₁₁ ^Y resonance mode are excited by one TE11 coupling probe 23, and the TM ₁₁ ^Z resonance mode and the TM ₁₁ ^Y resonance mode are excited by one TM11 coupling probe 24. Excited.

  Although a high positional accuracy is required at the location where such a groove is formed, there is an advantage that the no-load Q of the dielectric resonator is not lowered by the groove, and the circuit configuration can be simplified. Similarly, the spherical dielectric resonator PR may be a grooved spherical dielectric resonator.

FIG. 28C shows an example in which an oscillator is provided on the unit antenna side. For each spherical dielectric resonator R which is a unit antenna, an oscillator 25, a hybrid circuit 26, a phase / amplitude control circuit 22, a TE ₁₁ coupling probe 23 coupled to the TE ₁₁ mode of the spherical dielectric resonator R, and TM A TM ₁₁ coupling probe 24 that couples to ₁₁ modes is provided. These circuits are arranged in a layer immediately below (inside) the spherical surface of the antenna where the spherical dielectric resonator R is arranged.

  The oscillator 25 is synchronized with the synchronization signal and oscillates at a phase corresponding to the phase control signal, for example, at 5.8 GHz. The hybrid circuit 26 outputs two signals having a phase difference of 90 degrees. The phase / amplitude control circuit 22 controls the phase of the signal (current) for the TE11 coupling probe 23 and the TM11 coupling probe 24. By this phase control, a predetermined electric (magnetic) dipole moment is generated from the spherical dielectric resonator R. Similarly to the case of FIGS. 28A and 28B, phase control is performed according to the position of the spherical dielectric resonator.

  The synchronization signal is input from a reference signal generation circuit wirelessly or via a transmission line (network). Similarly, the phase control signal is input from the phase control signal generation circuit wirelessly or via a transmission line (network). The reference signal generation circuit and the phase control signal generation circuit are disposed at the origin position of the antenna spherical surface, for example.

  FIG. 29 shows the internal structure of the antenna spherical surface. As shown in FIG. 29, the antenna spherical surface (electromagnetic flow definition surface) is covered with a large number of spherical dielectric resonators. A power supply circuit board is provided below the layer formed by the large number of spherical dielectric resonators. A TE11 coupling probe, a TM11 coupling probe, and a circuit (see FIG. 28) connected to these coupling probes are provided on the power supply circuit board. Is formed. Each cross coil includes a TM mode coupling probe and a TE mode coupling probe. Each probe is arranged for each spherical dielectric resonator R, but FIG. 29 shows only some cross coils. The TE mode coupling probe is coupled to a TE mode magnetic field radiated from the spherical dielectric resonator PR disposed at the origin, and the TM mode coupled probe is radiated from the spherical dielectric resonator PR disposed at the origin. Couple to TM mode magnetic field.

  A large number of spherical dielectric resonators R are coupled to each other by adjacent spherical dielectric resonators R when the intervals are narrow. The spherical dielectric resonators R adjacent to each other along the longitude line are coupled in a state where the phases are substantially inverted. Since the spherical dielectric resonators R adjacent to each other along the latitude line have substantially the same phase, the coupling is weak.

FIG. 30 is a diagram showing the relationship between the electromagnetic field of a spherical dielectric resonator, which is a unit antenna, and the antenna spherical surface (electromagnetic current definition surface). FIG. 30A shows magnetic fields Hθ, Hr, and Hφ in the TE ₁₁ mode. Thereby, at the point on the + y axis (point P010 shown in FIG. 21), the angular momentum of Lφ is radiated by the circular polarization of the magnetic field around the equator. FIG. 30B shows electric fields Eθ, Er, Eφ in the TM ₁₁ mode. Thereby, at the point on the + x axis (point P100 shown in FIG. 21), the angular momentum of Lφ is radiated by the circular polarization of the electric field with the equator as the axis.

  With the above operation, a linearly polarized electromagnetic wave having an electric field in the x-axis direction and a magnetic field in the y-axis direction is radiated in the z direction from the pseudo multipole antenna shown in FIG.

  FIG. 31 is a diagram showing a resonance electromagnetic field and energy flow formed by a number of spherical dielectric resonators on the antenna spherical surface. With the antenna configuration as described above, the radiated power accumulates angular momentum by the resonant electromagnetic field, and is radiated with a sharp directivity in the z direction in the far field.

  In the example described above, a large number of unit antennas are arranged on the spherical surface. However, the unit antennas are not limited to the spherical surface, and may be arranged along the spheroid surface.

<< Second Embodiment >>
In the first embodiment, electromagnetic radiation is performed in a half space by an electromagnetic field equivalent to a directional electromagnetic beam generated by a TM wave and a TE wave using an electric multipole and a magnetic multipole as wave sources. On the other hand, in the second embodiment, an example is shown in which only the TM wave or the TE wave is used without degenerating the TM mode and the TE mode every degree l.

  FIG. 32 is a diagram showing the directivity when spherical waves generated by electric multipole radiation are superimposed from the order l = 1 to l = L (a visual representation of the far field of the radiated power). FIG. 32A shows the directivity of radiation power obtained by superposing spherical waves by three different orders of electric multipole radiation from [l = 1, m = 1] to [l = 3, m = 1]. FIG. 32B shows the directivity of radiation power in which spherical waves are superimposed by six different orders of electric multipole radiation from [l = 1, m = 1] to [l = 6, m = 1]. FIG. 32 (C) shows the radiation power of superposed spherical waves of 10 different orders of electric multipole radiation from [l = 1, m = 1] to [l = 10, m = 1]. Each represents directivity.

  In this way, the beam width is narrowed by superimposing spherical waves by electric multipole radiation to a high order. However, unlike the example shown in FIG. 6 in the first embodiment, the electromagnetic radiation is not radiated to the half space but is radiated to the rear to some extent. Some side lobes remain. Further, the directivity is flat (fan beam shape). When the spherical waves generated by the magnetic multipole radiation of each order are superimposed, the directivity shown in FIG. 32 becomes the directivity rotated by 90 degrees with respect to the main axis of radiation.

  In this way, electromagnetic radiation is performed by an electromagnetic field equivalent to a directional electromagnetic beam created by a TM wave using an electric multipole as a wave source according to the allowable back-radiation and allowable sidelobe intensity. It may be. Alternatively, electromagnetic radiation may be performed by an electromagnetic field equivalent to a directional electromagnetic beam generated by a TE wave using a magnetic multipole as a wave source.

When a plurality of spherical dielectric resonators shown in the first embodiment are used as a specific configuration example for generating a TM wave using an electric multipole as a wave source, the TM mode of these spherical dielectric resonators is used. Use only. Similarly, when generating a TE wave using a magnetic multipole as a wave source, it is only necessary to use the TE mode of the spherical dielectric resonator << Third Embodiment >>
The electromagnetic field outside the spherical dielectric resonator is exactly the same as the spherical wave radiated from the origin multipole. In the third embodiment, a multilayer spherical dielectric resonator used as an electric multipole or magnetic multipole wave source is shown.

In the example shown in the second embodiment, one dielectric resonator is configured to generate one spherical wave . However, in the third embodiment, one multilayer spherical dielectric resonator includes a plurality of spherical waves. Is generated.

  FIG. 33 is a cross-sectional view taken along a plane passing through the center of the multilayer spherical dielectric resonator. This multilayer spherical dielectric resonator 101 has a core 30 and a plurality of dielectric layers 31, 32, 33. The space between the dielectric layers is filled with air or other low dielectric constant dielectrics 61 and 62. Each of the dielectric layers 31, 32 and 33 has a spherical shell structure, and functions as a TM mode spherical shell dielectric resonator. Hereinafter, a resonator including the core 30 and the dielectric layer 31 is referred to as a “core resonator”, and a spherical shell-shaped dielectric resonator including the dielectric layers 32 and 33 is referred to as a “shell resonator”. The resonance frequencies of the resonators are substantially equal, and each resonator generates a spherical electromagnetic wave. Therefore, superposition of spherical waves is performed with the number of resonators corresponding to the number of the order l.

  For example, the core resonator uses the TM11 mode, the shell resonator based on the dielectric layer 32 uses the TM21 mode, and the shell resonator based on the dielectric layer 33 uses the TM31 mode. The dimensions and dielectric constant of each resonator are also determined so that the frequencies of these resonance modes are substantially equal.

  Similarly, each of the resonators may use their TE mode resonance. For example, the core resonator uses the TE11 mode, the shell resonator based on the dielectric layer 32 uses the TE21 mode, and the shell resonator based on the dielectric layer 33 uses the TE31 mode.

  Since a dielectric layer with a low dielectric constant is interposed between the dielectric layers, each resonator is not affected by another resonator adjacent to it and acts as an independent resonator. To do. In particular, the higher the outer shell is, the higher the resonance mode is used, so that it is less affected by other resonators located inside the outer shell.

  In the example shown in FIG. 33, three dielectric layers are provided in order to avoid complication of the drawing, but many dielectric layers can be provided in the same manner. If the L dielectric layers are provided, the layers are overlapped from the order l = 1 to l = L.

  The multilayer spherical dielectric resonator 101 is manufactured by, for example, a method in which the dielectric layer is sequentially coated on the core 30.

  Next, a configuration example of a power feeding unit for the multilayer dielectric resonator will be described. FIG. 34 is a configuration diagram of the power feeding unit 200 for the multilayer spherical dielectric resonator 101. The power feeding unit 200 includes a circular waveguide 50 and a circular dielectric line (dielectric waveguide having a circular cross section) 40. A tapered portion 42 is formed in the circular waveguide at the root of the circular dielectric line 40. A horn antenna 51 is formed at the tip of the circular waveguide 50. A fixing member 41 having a low dielectric constant is provided at a connection portion between the circular dielectric line and the multilayer spherical dielectric resonator 101. An excitation element such as a probe or a loop is provided in the circular waveguide 50, and a connector group 52 for each mode is provided outside the circular waveguide 50. The excitation element excites a propagation mode for exciting the multilayer spherical dielectric resonator 101 in each mode of TM11, TM21, TM31,. The connector group 52 is connected to an excitation element that excites these propagation modes. The same applies to the case where the multilayer spherical dielectric resonator 101 is excited in each mode of, for example, TE11, TE21, TE31. In this way, power can be supplied via the dielectric line. The circular dielectric line 40 is not limited to a tapered shape (conical truncated cone shape), and may be a cylindrical shape.

<< Fourth Embodiment >>
In the fourth embodiment, a multilayer spherical dielectric resonator used as an electric multipole and magnetic multipole wave source is shown.

  FIG. 35A is a cross-sectional view taken along a plane passing through the center of the multilayer spherical dielectric resonator 102 according to the fourth embodiment, and FIG. 35B is an external view.

  The multilayer spherical dielectric resonator 102 has a core 30 and a plurality of dielectric layers 31, 32, 33. The space between the dielectric layers is filled with a dielectric having a low dielectric constant. Similarly to the resonator shown in the third embodiment, each of the dielectric layers 31, 32, and 33 has a spherical shell structure, and the core resonator is configured by the core 30 and the dielectric layer 31, and the dielectric layer The body layers 32 and 33 constitute shell resonators. The structure described in detail later acts as a resonator in which the TM mode resonance and the TE mode resonance are degenerated. The resonance frequency of TM mode and TE mode of each resonator is almost equal. Each resonator generates a spherical electromagnetic wave equivalent to an electric multipole by resonance of the TM mode, and generates a spherical electromagnetic wave equivalent to a magnetic multipole by resonance of the TE mode. Therefore, superposition of spherical waves is performed with the number of resonators corresponding to the number of the order l.

  For example, the TM11 mode and the TE11 mode are degenerated in the core resonator formed by the core 30 and the dielectric layer 31. In the shell resonator formed of the dielectric layer 32, the TM21 mode and the TE21 mode are degenerated. In the shell resonator formed of the dielectric layer 33, the TM31 mode and the TE31 mode are degenerated. The dimensions and dielectric constant of each resonator are determined so that the frequencies of these resonance modes are substantially equal.

  Unlike the example shown in the third embodiment, the TM mode and the TE mode cannot be degenerated simply by setting the dimensions and dielectric constant of each resonator. In addition, since a low-order dielectric resonator is present inside the spherical shell-shaped dielectric resonator, the degeneration method by providing a conductor sphere inside cannot be used. Therefore, the dielectric constant in the radial direction and the dielectric constant in the circumferential direction of the dielectric layer are made different by the following structure. As shown in FIGS. 35A and 35B, the dielectric layers 32 and 33 are formed with a plurality of slits SLx, SLy, and SLz. The slit SLx is a slit along a conical surface with the x-axis as the central axis and the center point of the sphere as the apex. The slit SLy is a slit along a conical surface with the y-axis as the central axis and the center point of the sphere as the apex. Similarly, the slit SLz is a slit along a conical surface having the z-axis as the central axis and the center point of the sphere as the apex. In this way, slits extending radially from the center of the sphere are formed in each dielectric layer. However, in this example, no slit is formed in the dielectric layer closest to the nucleus as described later.

  The slit is a space or is filled with a dielectric having a lower dielectric constant than the dielectric of the dielectric layer. Therefore, the dielectric layers 32 and 33 have a dielectric anisotropy that the dielectric constant in the circumferential direction is lower than the dielectric constant in the radial direction. The TE mode electric field loop occurs around the circumferential direction of the dielectric layer, and the TM mode electric field mode passes along the radial direction of the dielectric layer, so the TE mode hardly changes the resonance frequency of the TM mode. The resonance frequency can be increased. As a result, the TE mode resonance frequency can be brought close to the TM mode resonance frequency and degenerated.

  Thus, by forming slits about three orthogonal axes, the rotational symmetry of the electromagnetic field can be maintained and the mode orthogonality of the spherical wave can be maintained.

  The multilayer spherical dielectric resonator 102 is manufactured by, for example, forming a multilayer by a method in which each dielectric layer is sequentially coated on the core 30 and forming a slit by laser processing. As another construction method, the multilayer spherical dielectric resonator 102 may be formed in a hemispherical state or in an equally divided shape, and finally joined.

  Note that the effective dielectric constant in the circumferential direction can be adjusted by the number of slits and the size of the gap.

  The spherical wave generated by the resonance of the TE11 mode and the TM11 mode by the dielectric layer 31 shown in FIG. 35A is the lowest-order spherical wave and needs special handling. In this example, the TE11 mode and the TM11 mode are degenerated by a resonator having the core 30 as a conductor sphere.

  If the radius of the conductor is a and the radius of the dielectric is b, the eigenvalue equation of order L is given by the following equation from the boundary condition.

  Equation (4.1) is an eigenvalue equation of TE mode, and Equation (4.2) is an eigenvalue equation of TM mode. Here, the function F and the function G are expressed by the following expressions.

  FIG. 36 shows the resonance frequencies of the TE11 mode and the TM11 mode when the radius ratio (a / b), which is the ratio of the diameter of the core portion 30 to the diameter of the dielectric layer 31, is changed. As an example, εr = 18 and b = 10. The curves in the figure are calculated from the equations (4.1) and (4.2), and the points in the figure are the results calculated by FEM. It can be seen that when the radius ratio (a / b) is small, the resonance frequency of the TM11 mode is higher, but is reversed when the radius ratio of the core (conductor sphere) 30 is increased. This suggests the existence of a point where the resonance frequencies of TM11 mode and TE11 mode match. The TM11 mode and the TE11 mode are degenerated by giving an appropriate radius ratio.

  Even if a conductor is used for the core, the dipole mode has a radiation Q value of 100 or less and is small, and therefore does not significantly affect the radiation efficiency.

  Here, a specific characteristic example is shown.

  A multilayer resonator in which the four modes of TE11, TM11, TE21, and TM21 are degenerated is designed using FEM. The core 30 has a diameter of 7 mm, the dielectric layer 31 has an outer diameter of 20 mm, the dielectric layer 31 has an inner diameter of 30 mm, the dielectric layer 31 has an outer diameter of 50 mm, and the dielectric layer 31 has a relative dielectric constant of 40. The relative dielectric constant of the layer 31 was 140. The number of slits formed in each dielectric layer was nine per half, and the slit width was 1 °. The resonance frequencies of the TE11, TM11, TE21, and TM21 modes at this time were 2.50 GHz, 2.44 GHz, 2.55 GHz, and 2.54 GHz, respectively, and could be degenerated within the range of 100 MHz. It can be expected that a high degree of degeneracy can be obtained by optimizing the structural parameters of each resonator.

  FIG. 37 is a diagram showing the state of the electric field vectors in the above four modes. The radiation Q values for each mode were 50, 19, 90, and 42, respectively. The effective dielectric constant of each mode of the multilayer spherical dielectric resonator designed from the resonator size and resonance frequency is obtained as 22, 36, 18, and 11, respectively. In this design example, the relative permittivity of the shell resonator is 140, which is larger than the relative permittivity of the core resonator, but the slit width should be set finer or anisotropic materials should be used. Therefore, it is considered that the dielectric constant of the shell resonator can be lowered. The effective aperture radius obtained from the directivity gain of the composite spherical wave with L = 1 and L = 2 is 54 mm. In contrast, the radius of the multi-layered spherical dielectric resonator designed this time is 25 mm. That is, when each mode was ideally synthesized, the cross-sectional area of the resonator was about 21% of the effective aperture area.

  FIG. 38 is a diagram showing a configuration example of a power feeding unit for the multilayer dielectric resonator. In this example, two power supply portions 200TE and 200TM that supply power to the multilayer spherical dielectric resonator 102 are provided. The configuration of the power feeding units 200TE and 200TM is the same as that shown in FIG. The excitation elements provided in the circular waveguide 50 of the power feeding unit 200TE excite the propagation modes for exciting the multilayer spherical dielectric resonator 102 in each mode of TE11, TE21, TE31. A connector group 52 for these modes is provided outside the circular waveguide 50 of the power feeding unit 200TE. Further, the excitation elements provided in the circular waveguide 50 of the power supply unit 200TM excite the propagation modes for exciting the multilayer spherical dielectric resonator 102 in the TM11, TM21, TM31... Modes, respectively. . A connector group 52 for these modes is provided outside the circular waveguide 50 of the power feeding unit 200TM. In this way, power can be supplied via the dielectric line.

P ... Spherical dielectric resonator PR ... Spherical dielectric resonator R ... Spherical dielectric resonator U1-U5 ... Unit antenna 11 ... Oscillator 12 ... Hybrid circuit 13 ... TE coupling probe 14 ... TM coupling probe 15 ... Probe 21 ... Cross Coil 22... Phase / amplitude control circuit 23... TE ₁₁ coupling probe 24... TM ₁₁ coupling probe 30... Core 31 to 33. Wave tube 51 ... Horn antenna 52 ... Connector group 101, 102 ... Multilayer spherical dielectric resonator 200, 200TE, 200TM ... Feeding section

Claims (15)

Equipped with a pseudo multipole that generates an electromagnetic field equivalent to a directional electromagnetic beam created by a TM wave using an electric multipole as a wave source,
The pseudo multipole superimposes the TM wave from l = 1 to l = L on the spherical electromagnetic wave corresponding to each order (l, m = 1) of the spherical harmonic function which is an element of the solution of the Maxwell equation in the spherical coordinate system. combined with electrical multipole radiation of each order (l-1) pieces of pseudo multipole antennas, wherein beat extinguishing Succoth sidelobes. The pseudo multipole is configured on a spheroid having a radius smaller than the effective aperture radius of the aperture antenna given by the directivity gain of the electromagnetic beam, and the electrical multipole is at the center of the spheroid. The pseudo multipole antenna according to claim 1, wherein the pseudo multipole antenna is a plurality of unit antennas that generate an equivalent electromagnetic field. The pseudo multipole causes the electric multipole equivalent electromagnetic field, respectively resonates in a TM mode, a multi-layered spherical dielectric resonator having a plurality of dielectric layers, the pseudo multi according to claim 1 Polar antenna. Equipped with a pseudo multipole that generates an electromagnetic field equivalent to a directional electromagnetic beam created by a TE wave using a magnetic multipole as a wave source,
The pseudo multipole superimposes the TE wave on the spherical electromagnetic wave corresponding to each order (l, m = 1) of the spherical harmonic function which is an element of the solution of the Maxwell equation in the spherical coordinate system from l = 1 to l = L. by combining, with magnetic multipole radiation of each order (l-1) pieces of pseudo multipole antennas, wherein beat extinguishing Succoth sidelobes. The pseudo multipole is configured on a spheroid having a radius smaller than the effective aperture radius of the aperture antenna given by the directivity gain of the electromagnetic beam, and the magnetic multipole is at the center of the spheroid. The pseudo multipole antenna according to claim 4, which is a plurality of unit antennas that generate an equivalent electromagnetic field. The pseudo multipole, the resulting magnetic multipole equivalent electromagnetic field, respectively resonate in a TE mode, a multi-layered spherical dielectric resonator having a plurality of dielectric layers, the pseudo multi according to claim 4 Polar antenna. Equipped with a pseudo multipole that emits electromagnetic radiation in a half space by an electromagnetic field equivalent to a directional electromagnetic beam created by a TM wave and a TE wave using an electric multipole and a magnetic multipole as a wave source,
Wherein the pseudo multipole, each order (l, m = 1) of the spherical harmonics is an element of the solutions of Maxwell's equations in spherical coordinates corresponding spherical waves from l = 1 to l = L the TE wave to the superimposed by a TM wave in the set, having electrical multipole radiation and magnetic multipole radiation of each order (l-1) pieces of pseudo multipole antennas, wherein beat extinguishing Succoth sidelobes. The pseudo multipole is configured on a spheroid having a radius smaller than the effective aperture radius of the aperture antenna given by the directivity gain of the electromagnetic beam, and an electric multipole and a magnetic multipole at the center of the spheroid. The pseudo multipole antenna according to claim 7 , wherein the antenna is a plurality of unit antennas that generate an electromagnetic field equivalent to the presence of the antenna. The unit antenna is a dielectric resonator multimode, pseudo multipole antenna according to claim 2, 5 or 8. The quasi-multipole antenna according to claim 9 , wherein the dielectric resonator is a spherical dielectric resonator that resonates in a TE ₁₁ dual mode and a TM ₁₁ dual mode. Before Ki誘 collector resonators have different dielectric constant between the core portion and the outer shell, a spherical dielectric resonator and the TE and TM modes are degenerate, pseudo multipole antenna according to claim 9. Before Ki誘 collector resonator, a core portion is metal, the outer shell is dielectric, a spherical dielectric resonator and the TE and TM modes are degenerate, pseudo multipole antenna according to claim 9 . The pseudo multipole generates a spherical electromagnetic wave equivalent to the electric multipole, each of a TM mode resonance and a spherical electromagnetic wave equivalent to the magnetic multipole, each of which degenerates a TE mode resonance. The quasi-multipole antenna according to claim 7, which is a multilayer spherical dielectric resonator having a plurality of dielectric layers. The pseudo multipole antenna according to claim 13 , wherein the dielectric layer of the multilayer spherical dielectric resonator has a dielectric constant different between a radial direction and a circumferential direction. The pseudo multipole antenna according to claim 14 , wherein a slit extending in a radial direction is formed in the dielectric layer, and the dielectric constant of the dielectric layer is different between the radial direction and the circumferential direction by the slit.