RU2636259C1 - Dual-polarized dipole antenna - Google Patents

Abstract

FIELD: radio engineering, communication.SUBSTANCE: two-polarized dipole antenna comprises a radiator of two orthogonal dipoles located in a plane parallel to the reflector. Each arm of the dipoles is formed by a pair of conductors symmetrically bent relative to the longitudinal axis of the dipole, closed around each other at the feed point with one end and having a gap between the second ends which forms a rupture of the arm contour. The initial portion of each conductor adjacent to the feed point is rectilinear and parallel to the initial portion of the adjacent second dipole conductor and to the end portion of the second conductor portion of the pair adjacent to the gap. The essence of the solution lies in the fact that the initial portions of conductors are made with a length L = (0.07-0.15)⋅λ, where λis the wavelength corresponding to the midfrequency of the frequency range, wherein the initial and end portions of each conductor are interconnected by an intermediate portion. The intermediate portion can be made rectilinear or in an arc.EFFECT: improved matching of the dipoles with the supply cable and expanded operating frequency band.5 cl, 19 dwg

Description

FIELD OF THE INVENTION

The invention relates to antenna technology and can be used in an operational deployment radio communication system for multi-stream data transmission (MIMO).

State of the art

Known group of cross-polarized antennas, manufactured by KATHREIN. The XPol antennas mentioned are composed of two independent dipole systems symmetrically located along a reflective screen. Power distribution between dipoles and impedance transformation are provided by low-loss cabling. A high level of isolation between the system inputs, at least 35 dB, allows the aforementioned antennas to operate in duplex mode, where the permissible minimum isolation is 30 dB.

Known bipolarization dipole antennas manufactured by the aforementioned company, operating in the 450 MHz band and intended for use in cellular communication systems. The advantage of these antennas over traditional panels is that on the basis of each such antenna it is possible to realize not only reception and transmission, but also diversity reception, so that one such antenna can replace up to three traditional panel antennas.

One of such antennas, the design of which is disclosed in patent US 6313809, IPC: H01Q 21/26, publ. November 6, 2001, adopted as the closest analogue to the proposed technical solution.

The closest analogue is characterized by the following features, similar to the essential features of the proposed antenna, namely: the presence of a reflector and a radiating part, then a radiator, consisting of two centrally symmetric orthogonal dipoles lying in a plane parallel to the reflector. The shoulders of the dipoles are each formed by a pair of conductors symmetrically bent relative to the longitudinal axis of the dipole. The conductors are closed to each other at one end at the power point and have a gap between the second ends, forming a gap in the contour of the shoulder. The initial, adjacent to the supply point, the section of each conductor of the pair is made rectilinear and parallel to the adjacent initial section of the conductor of the second dipole and the terminal section of the second conductor of the pair adjacent to the gap.

In the known construction, each shoulder is a square contour oriented to the center of the dipole of one of its peaks, to which the power is connected, and made with a gap in the corner opposite the power point. The reflector, made in the form of a continuous aluminum sheet, is a supporting structure for the radiating part, completely covered from above with a radiolucent plastic fairing.

The closest analogue is characterized by a high level of isolation between the inputs of the system, both in the case of using a single emitter, and in the case of using an array of emitters.

A significant drawback of the closest analogue is the relatively narrow operating range of 430-580 MHz. The disadvantages should also include the large weight and windage of the antenna, due to the design of the reflector.

The technical problem to which the claimed invention is directed is to expand the working band, otherwise the antenna bandwidth, while maintaining a high level of isolation between the dipole inputs.

Disclosure of invention

The problem is solved thanks to improvements in the well-known bipolarization dipole antenna containing an emitter of two orthogonal dipoles placed in a plane parallel to the reflector, the shoulders of which (dipoles) are formed, each, by a pair of conductors symmetrically bent relative to the longitudinal axis of the dipole, closed to each other at the power point by one end and having a gap between the second ends, forming a gap in the contour of the shoulder, while the initial, adjacent to the supply point, the section of each conductor of the pair it is full of rectilinear and parallel to the initial section of the conductor of the second dipole adjacent to it and the terminal section of the second conductor of the pair adjacent to the gap.

The mentioned improvements of the known antenna according to the claimed invention consist in the fact that the initial sections of the conductors are made with a length L = (0.07-0.15) ⋅λcр, where λav is the wavelength corresponding to the average frequency of the frequency range, while the initial and end sections of each conductor are interconnected by an intermediate section.

The intermediate section can be made rectilinear or arched.

The frequency range and its average frequency are set initially when designing the antenna.

By the frequency range is meant the selected frequency region in which the antenna should operate.

Because Since the invention is aimed at improving the performance of a known antenna, the operating range of the antenna, the closest analogue, is adopted as a given frequency range.

The frequency range and its average frequency are largely determined by the geometry of the emitter and its limiting dimensions (dimensions), which correspond to the amplitude of the shoulders of the dipoles, their longitudinal dimensions (along the axis of the dipole).

A significant difference of the proposed antenna from the closest analogue is the changed shape of the dipole arms. If in the closest analogue the contour of the shoulder of the dipole is a square, then in the proposed design, the angles (vertices) of the contour of the shoulder located between the feed point and the gap are cut or rounded by introducing intermediate sections of the conductors. The mentioned changes made it possible to preserve the basic geometry of the antenna and the dimensions of the emitter, namely, the longitudinal dimensions of the dipoles, while ensuring a decrease in the length of parallel adjacent (adjacent) sections of the shoulders of the dipoles and a significant improvement in matching the dipoles with the power cable.

The studies (see examples below) confirm that within the specified limits of the length of parallel adjacent sections of the dipole arms corresponding to (0.07-0.15) ⋅λav, where λcr is the wavelength at the middle frequency of the range, the matching of the dipoles with the supply cable and extension of the working frequency band.

Thus, the aforementioned set of distinctive features made it possible to maintain the basic geometry of the antenna and the high level of isolation, and at the same time obtain a new technical result, which consists in improving the coordination of dipoles with the power cable and expanding the working frequency band.

Under the working band, otherwise the bandwidth, refers to the frequency range (within the selected range) at which the antenna operates efficiently.

The dipoles are powered by coaxial cables through short-circuited balancing devices.

In a preferred embodiment, the design of the proposed antenna is characterized in that the power points of the dipoles and balancing devices are hermetically sealed by a dielectric casing. Due to the fact that the dielectric body does not cover the entire radiating part, but only its most vulnerable elements, which are most affected by atmospheric precipitation and mechanical stress, it is possible to make the reflector from a wire mesh fixed to the power frame. In this design, a significant reduction in windage and antenna weight is achieved.

The possibility of industrial feasibility of the proposed technical solution and the achievement of the above technical results is confirmed by the following examples and drawings, which depict:

in FIG. 1 is an example of an antenna made according to the invention;

in FIG. 2 - the antenna emitter of FIG. one;

in FIG. 3 - shows two possible options for the execution of the shoulders of the dipoles: with a rectilinear intermediate section (a), and with an arched intermediate section (c).

in FIG. 4 - four-element antenna array made using the present invention;

in FIG. 5 is a view A from FIG. four;

in FIG. 6 - shows a table of values of SWR for antennas with a rectilinear intermediate section;

in FIG. 7 - a table of SWR values for antennas with an arched intermediate section;

in FIG. 8, 10, 12, 14, 16, 18 are examples of antennas whose test data are shown in the tables of FIG. 6-7, and in FIG. Figures 9, 11, 13, 15, 17, 19 show frequency diagrams of SWR dependencies corresponding to examples.

The implementation of the invention

The bipolarization dipole antenna contains (see Fig. 1) a radiator consisting of two identical centrally symmetric orthogonal dipoles 1 and 2, placed in one conditional plane parallel to the reflector 3 made of a conductive wire mesh fixed to the power frame 4.

Each dipole, otherwise a symmetric vibrator, (see Fig. 2) has two arms symmetrically located relative to the center of the structure: 5 and 6 (dipole 1), 7 and 8 (dipole 2).

Each arm 5, 6, 7, 8 consists (see Fig. 3) of two conductors 9 and 10, symmetrically bent relative to the longitudinal axis of the dipole (shown by the axial line in Fig. 2 and 3). The conductors 9 and 10 are closed to each other at one end at the power point 11, and a gap 12 is formed between the second ends of the conductors, forming a gap in the contour of the shoulder.

Each conductor (9, 10) can be conditionally divided into three sections: the initial section 13 adjacent to the supply point 11, the final section 14 adjacent to the gap 12 and connecting their intermediate (middle) section 15.

Sections 13 and 14 of the conductors 9 and 10 are made rectilinear. In this case, the portion 13 of the conductor 9 is parallel to the portion 14 of the conductor 10, and the portion 13 of the conductor 10 is parallel to the portion 14 of the conductor 9.

In fact, the shape of the shoulder corresponds to the shape of a square with cut-off (see Fig. 3a) or rounded corners (see Fig. 3c). In the first case, the intermediate section 15 (Fig. 3a) is made straightforward, in the second case (Fig. 3c), the section 15 is made in an arc.

However, the initial sections 13 of the conductors 9 and 10 of each arm (5 and 6) of the first dipole are parallel to adjacent sections of the conductors of the arms 7 and 8 of the second dipole (see Fig. 1, 2). The length L of the parallel initial sections 13 is (0.07-0.15) ⋅λcр, where λcr is the wavelength corresponding to the average frequency of the range.

Dipoles (1, 2) are fed from coaxial cables through short-circuited balancing devices (not shown in the drawings).

The power points 11 of the dipoles and balancing devices, as the most susceptible to atmospheric precipitation and mechanical stress, are hermetically sealed by dielectric housings 16, for example, as shown in FIG. 4-5, where an example of the implementation of a four-element antenna array based on the proposed antenna.

To increase the rigidity of the structure, the shoulders of the dipoles at the vertices opposite to the supply points can be supported on the reflector 3 through dielectric posts 17.

The antenna works as follows. Each dipole 1 and 2 is excited by a signal from its own radio transmitter and, in conjunction with reflector 3, creates a directional electromagnetic field. Due to the fact that the antenna consists of two dipoles rotated 90 ° relative to each other, two fields with mutually perpendicular polarization are formed in space. Dipole 2 emits a horizontally polarized wave. Dipole 3 emits a vertically polarized wave.

The changes in the shape of the shoulders of the dipoles made it possible to maintain a high level of isolation and to achieve a significant improvement in matching the dipoles with the power cable, which allowed us to expand the passband mainly in the high-frequency region.

In practice, the bandwidth is usually determined by the level of the SWR - the standing wave coefficient, which characterizes the quality of matching the antenna with the transmission line.

Permissible values of SWR in the operating frequency band for various devices are regulated in GOSTs and technical conditions. Acceptable values of SWR are in the range from 1.0 to 2.0. In microwave technology, an SWR of 1.6 ÷ 1.8 is preferred.

Tables 1 and 2 (see Fig. 6-7) show the experimentally obtained data of the SWR values for antennas with different lengths L of the initial sections 13 of the conductors 9 and 10.

Table 1 shows the test data of antennas with rectilinear intermediate sections of 15 conductors, and table 2 shows the test data of antennas with intermediate sections 15 made in an arc.

In FIG. 8, 10, 12, 14, 16, 18 show examples of test antennas, and in FIG. 9, 11, 13, 15, 17, 19 — frequency graphs of the SWR dependencies corresponding to examples.

The measurements were carried out at lower F _n , average F _cp and upper F _{in the} frequencies of the working range with subsequent determination of the average value of the coefficient of SWR.

The first lines of tables 1 and 2 (example 1) show the test antenna data of the prototype, where the intermediate section 15 is missing.

As can be seen from tables 1 and 2, for both cases of the execution of the emitters, the permissible level of SWR ≤2 is obtained within the limits of lengths L = (0.07-0.15) ⋅λav.

As the tests showed, the proposed shape of the emitters made it possible to maintain a high level of isolation between the signals and to achieve a significant expansion of the passband.

The passband can be characterized by the overlap coefficient, which, according to GOST 24375-80, represents the ratio of the highest operating frequency to the lowest operating frequency.

For the proposed antenna, the overlap coefficient in terms of SWR ≤1.6 is 1.65, which is significantly higher than in the closest analogue, where the said coefficient is 1.35.

All of the above is true both for antennas with a single emitter, and for antenna arrays (see Fig. 4-5) containing many emitters made according to the invention.

In the above examples, the emitter is made of a metal tubular profile, however, this does not exclude the possibility of using a different profile, as well as the possibility of manufacturing the emitter using planar technology.

In the examples shown in the drawings, the dipoles of the emitters are oriented for receiving and emitting vertical and horizontal polarized waves. However, the proposed solution can be used for receiving and emitting obliquely polarized waves, with the corresponding installation of the antenna with the dipole axes at an angle of + 45 ° and -45 °.

Based on the proposed antenna, it is possible to realize reception and transmission of signals, as well as diversity reception. The antenna allows you to replace up to three traditional panel antennas, which allows you to save seats on the antenna masts and increase the number of channels at the base station without renting additional antenna structures.

The implementation of the reflector 3 of the mesh conductive mesh can reduce the windage of the antenna and its weight. The cell size and the diameter of the wire mesh are determined based on the required backward radiation in the operating frequency range, according to well-known graphical dependencies (see Prince G.Z. Aizenberg. Antennas for ultrashort waves. Svyazizdat, 1957, p. 555).

Claims (5)

1. A bipolarization dipole antenna containing an emitter of two orthogonal dipoles placed in a plane parallel to the reflector, the dipole arms are each formed by a pair of conductors symmetrically bent relative to the longitudinal axis of the dipole, closed to each other at the supply point by one end and having a gap between the second ends forming a gap in the contour of the shoulder, while the initial, adjacent to the supply point, the section of each conductor of the pair is made rectilinear and parallel to the initial section of the adjacent wire arrester terminal and the second dipole, adjacent to the gap portion of the second conductor pair, characterized in that the initial parts are made of conductors with a length L = (0,07-0,15) ⋅λ _cp where _cp λ - wavelength corresponding to the mean frequency frequency range, while the initial and end sections of each conductor are interconnected by an intermediate section. 2. The antenna according to claim 1, characterized in that the intermediate section is made rectilinear. 3. The antenna according to claim 1, characterized in that the intermediate section is made along an arc. 4. The antenna according to claim 1, characterized in that the dipoles are powered from coaxial cables through short-circuited balancing devices. 5. The antenna according to claim 4, characterized in that the power points of the dipoles and the balancing devices are hermetically sealed by a dielectric casing, while the reflector is made of a conductive wire mesh fixed to the power frame.

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