JP7565791B2 - High frequency board and antenna module - Google Patents

Description

The present invention relates to a high-frequency substrate that is made up of alternating dielectric layers and conductor layers, forming a log-periodic antenna.

Log periodic antennas have been known for some time as antennas that can expand the usable frequency band. For example, Patent Document 1 discloses an antenna device in which a log periodic antenna is configured using a conductor pattern on the surface of a dielectric substrate. Log periodic antennas generally require a large layout area to accommodate a large number of radiating elements, so Patent Document 1, for example, shows a method for reducing the layout area of a log periodic antenna by forming radiating elements in a meandering or V-shape.

Japanese Patent Application Publication No. 11-168323

In recent years, in order to accommodate various wireless communication standards, it is common to adopt a configuration in which a large number of antenna elements are arranged in an array. In addition, from the perspective of reducing the size and weight of antenna devices, it has been proposed to arrange multiple antenna elements using a dielectric substrate. However, assuming the use of a log periodic antenna to share different frequency bands, a structure such as that of Patent Document 1 mentioned above increases the arrangement area required to form a complex antenna shape, making it inevitable that the antenna device will become larger. In addition, in recent years, there has been a demand for antenna devices that can share horizontal and vertical polarizations as different polarizations, but it is difficult to realize an antenna device that can accommodate different polarizations with a planar configuration such as that of Patent Document 1.

The present invention has been made to solve the above problems, and realizes a high-frequency board that has a log-periodic antenna inside it, and that can be made smaller by suppressing an increase in the layout area while maintaining good antenna characteristics.

In order to solve the above problems, the high-frequency substrate of the present invention is a high-frequency substrate formed by alternately laminating dielectric layers and conductor layers, and is characterized in that it is provided with one or more log-periodic antennas configured using a plurality of conductor patterns formed on the conductor layers and a plurality of via conductors penetrating the dielectric layers, and the one or more log-periodic antennas are embedded inside the high-frequency substrate.

According to the high frequency board of the present invention, one or more log periodic antennas are embedded inside the high frequency board and are configured using multiple conductor patterns and multiple via conductors. This allows the log periodic antenna to be configured compactly due to the wavelength shortening effect of the surrounding dielectric layer, and by utilizing the conductor patterns in the planar direction and the via conductors in the thickness direction, it is possible to realize log periodic antennas having not only planar shapes but also a variety of three-dimensional shapes.

In the present invention, in addition to one or more log periodic antennas, one or more layers of ground conductors can be provided in an area that does not overlap with the area in which the one or more log periodic antennas are arranged in a plan view from the thickness direction of the high frequency substrate. Also, a power supply structure can be provided that supplies high frequency signals to each of the one or more log periodic antennas.

The multiple log periodic antennas of the present invention may be configured with a log periodic antenna for horizontal polarization and a log periodic antenna for vertical polarization, and may be arranged in a first direction perpendicular to the thickness direction of the high frequency substrate. In this way, when realizing a high frequency substrate capable of both horizontal and vertical polarization, a complex three-dimensional shape can be easily configured by appropriately combining conductor patterns and via conductors according to the extension direction, and the wavelength shortening effect also enables miniaturization.

In the present invention, the number of horizontally polarized logarithmic periodic antennas and the number of vertically polarized logarithmic periodic antennas may be the same, and two or more of each may be provided. In this case, the high-frequency board further includes one or more ground conductors arranged in an area that does not overlap with the area in which the multiple logarithmic periodic antennas are arranged in a plan view from the thickness direction of the high-frequency board, an opening capable of accommodating an electronic component in the central area in a plan view from the thickness direction, and a multiple power supply path included in the power supply structure and electrically connecting the electronic component and each of the multiple logarithmic periodic antennas, and only the horizontally polarized logarithmic periodic antenna can be arranged in an area that overlaps with the opening in a plan view from the thickness direction. Furthermore, the multiple logarithmic periodic antennas can be arranged in a symmetrical arrangement with respect to the central position in the first direction. With the above arrangement, the vertically polarized logarithmic periodic antenna, which requires a size in the thickness direction, can be prevented from overlapping with the opening or the electronic component, and the space of the high-frequency board can be effectively utilized while maintaining good antenna performance.

The horizontally polarized log periodic antenna of the present invention is configured to include multiple pairs of horizontal radiating elements that are paired on the signal side and the ground side, and the multiple pairs of horizontal radiating elements are configured using multiple conductor patterns and are arranged side by side in a second direction perpendicular to the first thickness direction, while the vertically polarized log periodic antenna of the present invention is configured to include multiple pairs of vertical radiating elements that are paired on the signal side and the ground side, and the multiple pairs of vertical radiating elements are configured using multiple via conductors and are arranged side by side in the second direction. Both structures are three-dimensional structures that combine multiple conductor patterns and multiple via conductors, and can be easily embedded inside a high-frequency substrate.

In the present invention, each of the at least two horizontally polarized logarithmic periodic antennas may be arranged so that the extension direction from the base end of the multiple pairs of horizontal radiating elements to each tip on the signal side and ground side coincides with the first direction. In this case, each of the at least two horizontally polarized logarithmic periodic antennas near the center position in the first direction may be arranged so that the extension direction is inclined from the first direction in the plane of the conductor layer in a direction in which each tip moves away from the ground conductor. This suppresses the influence of interference with the surroundings near the center and outer edges of the multiple horizontally polarized logarithmic periodic antennas, and is effective in improving antenna gain.

In the present invention, each of at least two vertically polarized logarithmic periodic antennas may have a thickness direction in which the extension direction of each of the pairs of vertical radiation elements is the thickness direction, and the signal side via conductors and ground side via conductors constituting each of the pairs of vertical radiation elements may be arranged opposite to each other in a first direction, and the respective arrangement directions may be aligned in a second direction. In this case, each of at least two vertically polarized logarithmic periodic antennas near the central position may have a thickness direction in which the extension direction of the pairs of vertical radiation elements is aligned, and the signal side via conductors and ground side via conductors may be arranged opposite to each other in a first direction, and the respective arrangement directions may be inclined from the second direction to the opposite via conductors as they approach the ground conductor. This suppresses the influence of interference with the surroundings near the center and the outer edges of the multiple vertically polarized logarithmic periodic antennas, and is effective in improving the antenna gain.

The high frequency substrate of the present invention can have an electronic component placed in the opening. An example of the electronic component placed in the opening is an IC chip. For example, power can be fed from a specific terminal of the IC chip to the log periodic antenna via a power feed path formed in the conductor layer of the high frequency substrate.

According to the present invention, one or more log periodic antennas are embedded inside a high frequency board, and a complex log periodic antenna shape can be formed using multiple conductor patterns and multiple via conductors. This allows the high frequency board to be miniaturized without increasing the layout area due to the wavelength shortening effect, and the frequency band can be expanded to easily accommodate different polarizations, resulting in a high frequency board that provides good antenna performance.

FIG. 1 is a plan view of the entire high-frequency substrate 10 of the first embodiment, viewed from above in the Z direction. 2 is a schematic cross-sectional view of the high-frequency substrate 10 of FIG. 1 as viewed in the direction of arrow A along the X direction; 2 is a schematic cross-sectional view of the high-frequency substrate 10 of FIG. 1 as seen in the direction of arrow B along the Y direction. 1 is a perspective view showing a structure of a horizontally polarized log periodic antenna 41 configured on a high-frequency substrate 10. FIG. 5 is a cross-sectional view showing the structure of the horizontally polarized log periodic antenna 41 of FIG. 4. 1 is a perspective view showing a structure of a vertically polarized log periodic antenna 31 formed on a high-frequency substrate 10. FIG. FIG. 7 is a cross-sectional view showing the structure of the vertically polarized log periodic antenna 31 of FIG. 6. FIG. 11 is a plan view of the entire high-frequency substrate 10 according to the second embodiment, viewed from above in the Z direction. 9 is an enlarged view showing the planar shape of the horizontally polarized log periodic antenna 42a of FIG. 8. 9 is an enlarged view showing the planar shape of the vertically polarized log periodic antenna 32a of FIG. 8.

Below, preferred embodiments of the present invention will be described with reference to the drawings. In the following description, two embodiments in which the antenna shapes configured on the high frequency substrate are different will be described as examples of forms in which the technical concept of the present invention is applied.

[First embodiment]
A first embodiment, which is an example of a high frequency substrate of the present invention, will be described with reference to Figs. 1 to 7. For convenience of description, the X, Y, and Z directions, which are orthogonal to each other, are indicated by arrows in Figs. 1 to 7. Fig. 1 is a plan view of the entire high frequency substrate 10 of the first embodiment, viewed from above in the Z direction. Fig. 2 is a schematic cross-sectional view of the high frequency substrate 10 of Fig. 1 viewed from the direction of arrow A along the X direction, and Fig. 3 is a schematic cross-sectional view of the high frequency substrate 10 of Fig. 1 viewed from the direction of arrow B along the Y direction. Figs. 4 and 5 are perspective and cross-sectional views showing the structure of a horizontally polarized logarithmic periodic antenna 41 configured on the high frequency substrate 10, and Figs. 6 and 7 are perspective and side views showing the structure of a vertically polarized logarithmic periodic antenna 31 configured on the high frequency substrate 10.

The high-frequency substrate 10 of the first embodiment is a dielectric substrate made of a dielectric material having a predetermined dielectric constant, has a multi-layer structure in which dielectric layers and conductor layers are alternately stacked, and is a rectangular plate-shaped member having a short side along the X direction, a long side along the Y direction, and a predetermined thickness along the Z direction. In FIG. 1, the high-frequency substrate 10 is shown in its entirety in a plan view from above in the Z direction, and an RF region A1 including a multi-layer ground conductor 11 and a high-frequency circuit, and an antenna region A2 including multiple log periodic antennas 31-34, 41-44 are arranged. That is, the RF region A1 and the antenna region A2 are divided at a boundary position XB in the X direction (the second direction of the present invention) and face each other in the X direction.

In the antenna region A1, four vertically polarized logarithmic periodic antennas 31-34 and four horizontally polarized logarithmic periodic antennas 41-44 are embedded inside the dielectric substrate 10 and arranged side by side in the Y direction (the first direction of the present invention). Here, the logarithmic periodic antenna is an antenna that can ensure a wide frequency band and sharp radiation directivity by regularly arranging pairs of radiating elements with different lengths. The four vertically polarized logarithmic periodic antennas 31-34 each radiate vertically polarized waves, and the four horizontally polarized logarithmic periodic antennas 41-44 each radiate horizontally polarized waves. In the first embodiment, the number of vertically polarized logarithmic periodic antennas and the number of horizontally polarized logarithmic periodic antennas are four, but from the viewpoint of antenna characteristics, the number of both can be increased or decreased while keeping them the same. Note that, as described later, the structure may be such that at least one of the vertically polarized logarithmic periodic antennas or the horizontally polarized logarithmic periodic antennas is embedded inside the high frequency substrate 10.

As shown in FIG. 1, the eight log periodic antennas 31-34, 41-44 are arranged symmetrically with respect to the center position YC in the Y direction. That is, near the center position YC, the two horizontally polarized log periodic antennas 42, 43 are adjacent, and from there, the vertically polarized log periodic antennas 32, 33, the horizontally polarized log periodic antennas 41, 44, and the vertically polarized log periodic antennas 31, 34 are arranged in that order. The reason for adopting such an arrangement will be described later. In addition, in the first embodiment, the eight log periodic antennas 31-34, 41-44 are arranged at unequal intervals in the X direction. In general, when multiple antennas are arranged side by side, they are often set at equal intervals according to the wavelength used, but even if the antenna intervals in the arrangement of the first embodiment are set to a certain degree, it is possible to ensure antenna performance.

The cross-sectional structure of the high frequency board 10 in FIG. 1 will be described below with reference to FIG. 2 and FIG. 3. FIG. 2 is a cross-sectional view of the high frequency board 10 in FIG. 1 as viewed from the direction of the arrow A along the X direction, and FIG. 3 is a cross-sectional view of the high frequency board 10 in FIG. 1 as viewed from the direction of the arrow B along the Y direction. In FIG. 2 and FIG. 3, eight log periodic antennas 31 to 34 and 41 to 42 are omitted from the illustration in order to clarify the structure of the RF region A1. As shown in FIG. 2 and FIG. 3, the high frequency board 10 has a plurality of conductor layers L including a lower surface 10a and an upper surface 10b facing in the Z direction, and various conductor patterns are formed on each conductor layer L. In addition, the high frequency board 10 has a plurality of via conductors V extending through each dielectric layer in the Z direction, which is the thickness direction. The above-mentioned multi-layer ground conductors 11 (FIG. 1) are formed on the plurality of conductor layers L, and the ground conductors 11 facing in the Z direction are electrically connected to each other via the plurality of via conductors V.

2 and 3, an opening 10c is formed in the central region on the surface 10a of the high frequency substrate 10, and an IC chip 20 is placed in the opening 10c. The IC chip 20 has a plurality of terminals 20a, each of which is connected to a plurality of pads (not shown) on a predetermined conductor layer L facing the opening 10c. The IC chip 20 has a role of feeding power from the eight predetermined terminals 20a to each of the eight log periodic antennas 31 to 34, 41 to 44 via power feeding paths (not shown) formed on the plurality of conductor layers L. In addition, an RF circuit required for the operation of the IC chip 20 is configured in the RF region A1 near the IC chip 20. In addition, as shown in FIG. 3, a reflector 12 is disposed on the upper part of the IC chip 20 in the antenna region A2. The reflector 12 is connected to the ground conductor 11 and functions as a shield plate that prevents interference between the IC chip 20 and the eight log periodic antennas 31 to 34, 41 to 44. As can be seen from FIG. 1, the reflector 12 is placed directly below a pair of horizontally polarized log-periodic antennas 42 and 43.

Next, the structure of the horizontally polarized log periodic antenna 41 will be described with reference to Figures 4 and 5. The other horizontally polarized log periodic antennas 42 to 44 have the same basic structure as the horizontally polarized log periodic antenna 41. As shown in Figure 4, the horizontally polarized log periodic antenna 41 is configured with signal side connecting conductors 50a, 50b and ground side connecting conductors 60a, 60b, signal side and ground side via conductors Va, Vb, three horizontal radiating elements 51, 52, 53 on the signal side, and three horizontal radiating elements 61, 62, 63 on the ground side. Figure 4 shows the boundary position XB (see Figure 1), and only shows the structure of the horizontally polarized log periodic antenna 41 in the antenna area A2.

In the above configuration, a pair of signal side connecting conductors 50a and ground side connecting conductors 60a are formed on the same conductor layer La (FIG. 5) and extend in the X direction from their respective ends Ea and Eb. The signal side connecting conductor 50b is formed on the conductor layer Lb (FIG. 5) directly below, is connected to the signal side connecting conductor 50a through the via conductor Va, and extends in the opposite direction to the signal side connecting conductor 50a in the X direction. The ground side connecting conductor 60b is formed on the conductor layer Lc (FIG. 5) directly above, is connected to the ground side connecting conductor 60a through the via conductor Vb, and extends in the opposite direction to the ground side connecting conductor 60a in the X direction. Therefore, as shown in FIG. 5, the signal side connecting conductor 50b is arranged at the bottom and the ground side connecting conductor 60b is arranged at the top, sandwiching the pair of signal side connecting conductors 50a and ground side connecting conductor 60a arranged on the central conductor layer La of the three consecutive conductor layers La, Lb, and Lc. Although not shown in FIG. 4, the end Ea of the signal side connecting conductor 50a is connected to a power supply path 13 (FIG. 5) that leads to a specified terminal 20a of the IC chip 20, and the end Eb of the ground side connecting conductor 50b is connected to a specified ground conductor 11.

A pair of horizontal radiating elements 51, 61, a pair of horizontal radiating elements 52, 62, and a pair of horizontal radiating elements 53, 63 are connected to the signal side connecting conductor 50b and the ground side connecting conductor 60b, which make up a total of three pairs on the signal side and ground side, and extend from their base ends to their tips on both sides in the Y direction. The pair of horizontal radiating elements 51, 61, the pair of horizontal radiating elements 52, 62, and the pair of horizontal radiating elements 53, 63 arranged side by side in the X direction have longer lengths in the Y direction as they approach the boundary position XB, and the extension directions in the Y direction are staggered along the arrangement direction. Furthermore, the positions in the Y direction of each pair on the signal side and the ground side are common, but as explained in Figure 5, the positions in the Z direction are different on the signal side and the ground side.

The horizontally polarized log periodic antenna 41, which has three horizontal radiating elements of different lengths as described above, can radiate horizontally polarized radio waves in a wide frequency band mainly along the X direction. However, due to the presence of multiple ground conductors 11, the radiation directivity of the horizontally polarized log periodic antenna 41 is strong along the X direction mainly toward the side of the antenna region A2 of the high frequency board 10, and is relatively weak in the direction toward the RF region A1. In addition, the overall radiation directivity of horizontally polarized waves from the high frequency board 10 is determined by the combined directivity of the four horizontally polarized log periodic antennas 41 to 44.

Next, the structure of the vertically polarized log periodic antenna 31 will be described with reference to Figures 6 and 7. The other vertically polarized log periodic antennas 32 to 34 have the same basic structure as the vertically polarized log periodic antenna 31. As shown in Figure 6, the vertically polarized log periodic antenna 31 is configured with signal side connecting conductors 70a, 70b and ground side connecting conductors 80a, 80b, four vertical radiating elements 71, 72, 73, 74 on the signal side, and four horizontal radiating elements 81, 82, 83, 84 on the ground side. Figure 6 also shows only the structure of the vertically polarized log periodic antenna 31 in the antenna region A2 on one side of the boundary position XB.

In the above configuration, the pair of signal side connecting conductors 70a and ground side connecting conductors 80a extend in the X direction from their respective ends Ed and Ee, and then fold back at the opposite ends to form the pair of signal side connecting conductors 70b and ground side connecting conductors 80b that extend in the opposite direction in the X direction. In this case, the signal side connecting conductors 70a and 70b are formed on the conductor layer Ld (FIG. 5), and the ground side connecting conductors 80a and 80b are formed on the conductor layer Le (FIG. 5) slightly below the conductor layer Ld. Note that the pair of signal side connecting conductors 70a and ground side connecting conductors 80a are arranged opposite each other in the Z direction, but the pair of signal side connecting conductors 70b and ground side connecting conductors 80b are also arranged opposite each other in the Z direction with a gap in the Y direction. Although not shown in FIG. 6, the end Ed of the signal-side connecting conductor 70a is connected to a power supply path 13 (FIG. 7) that leads to a specified terminal 20a of the IC chip 20, and the end Ee of the ground-side connecting conductor 80b is connected to a specified ground conductor 11.

A pair of vertical radiating elements 71, 81, a pair of vertical radiating elements 72, 82, a pair of vertical radiating elements 73, 83, and a pair of vertical radiating elements 74, 84 are connected to the signal side connecting conductor 70b and the ground side connecting conductor 80b on the folded side, which make up a total of four pairs on the signal side and ground side, and extend up and down in the Z direction from their base ends to their tips. The pair of vertical radiating elements 71, 81, the pair of vertical radiating elements 72, 82, the pair of vertical radiating elements 73, 83, and the pair of vertical radiating elements 74, 84 arranged side by side in the X direction have longer lengths in the Z direction as they approach the boundary position XB, and the extension directions in the Z direction are staggered along the line-up direction. Furthermore, the positions in the X direction of each pair on the signal side and the ground side are common, but as mentioned above, the positions in the Y direction are different on the signal side and the ground side.

The vertically polarized log periodic antenna 31, which has three types of vertical radiating elements with different lengths as described above, can radiate vertically polarized radio waves in a wide frequency band mainly along the X direction. However, due to the presence of multiple ground conductors 11, the vertically polarized log periodic antenna 31 also has radiation directivity along the X direction with the same tendency as the horizontally polarized log periodic antenna 41 described above. In addition, the overall vertically polarized radiation directivity of the high frequency board 10 is determined by the combined directivity of the four vertically polarized log periodic antennas 31 to 34.

Returning to FIG. 1, the arrangement order of the eight log periodic antennas 31-34, 41-44 in the Y direction is mainly due to the arrangement in the Z direction described in FIG. 5 and FIG. 7. Originally, when horizontal polarization and vertical polarization are to be shared, it is common to arrange the number of horizontally polarized log periodic antennas and the number of vertically polarized log periodic antennas to be the same and alternately arranged from the viewpoint of antenna characteristics. However, since the IC chip 20 in the opening 10c and the reflector 12 (FIG. 1) above it are present immediately below the vicinity of the central position YC, it is difficult to arrange the vertically polarized log periodic antennas 31-34 that extend on both sides in the Z direction as shown in FIG. 7. Therefore, in this embodiment, by arranging the two horizontally polarized log periodic antennas 42, 43, which can be made sufficiently thin in the Z direction, in the vicinity of the central position YC as shown in FIG. 5, it is possible to avoid interfering with the arrangement of the IC chip 20 and the reflector 12. On the other hand, the horizontally polarized log periodic antennas 41-44 and the vertically polarized log periodic antennas 31-34 are arranged symmetrically on the left and right sides of FIG. 1 with respect to the center position YC, and the number of each is kept the same, making it possible to maintain good antenna performance while effectively utilizing space without increasing the size of the high frequency board 10.

In the above first embodiment, an example in which eight log periodic antennas 31 to 34, 41 to 44 are configured on the high frequency substrate 10 has been described, but the present invention can be applied even when a configuration in which at least one log periodic antenna is embedded inside the high frequency substrate 10 is adopted. That is, in the conventional configuration, the main part of the planar log periodic antenna is generally arranged on the substrate surface (see, for example, Patent Document 1). In contrast, the high frequency substrate according to the present invention has a log periodic antenna configured by combining the conductor patterns of multiple conductor layers L and multiple via conductors V, and since a dielectric material with a relatively high dielectric constant exists around it, there is an advantage in that the log periodic antenna can be configured in a small size due to the wavelength shortening effect. In the conventional configuration, if a log periodic antenna having the same antenna characteristics as the present invention is configured, the substrate size will inevitably increase, so the effect of miniaturizing the high frequency substrate by applying the present invention is clear.

In the first embodiment, a structure in which an IC chip 20 is mounted in the opening 10c of the high frequency substrate 10 is shown, but various electronic components having a predetermined function can be mounted in the opening 10c instead of the IC chip 20. In addition, when feeding power to the eight log periodic antennas 31 to 34, 41 to 44 from the outside, a structure may be adopted in which only the respective power feeding terminals are provided, and no opening 10c or electronic components such as the IC chip 20 are provided. When using such a structure, it is necessary to form a power feeding structure that includes a power feeding path from the power feeding terminal provided on the exposed portion of the high frequency substrate 10 to the ends Ea, Eb, Ed, and Ee shown in Figures 4 to 7.

[Second embodiment]
Next, a second embodiment, which is an example of a high frequency substrate of the present invention, will be described with reference to Figures 8 to 10. In the second embodiment, many of the basic configurations and effects are common to the first embodiment, so the following mainly describes the differences from the first embodiment. Figure 8 is a plan view of the entire high frequency substrate 10 of the second embodiment as viewed from above in the Z direction, and corresponds to Figure 1 of the first embodiment. Note that each cross-sectional view of the high frequency substrate 10 in Figure 8 is similar to Figures 2 and 3.

The high frequency board 10 of the second embodiment differs from the first embodiment in that, as shown in FIG. 8, the two vertically polarized log periodic antennas 32, 33 and the two horizontally polarized log periodic antennas 42, 43 of FIG. 1 are replaced with two vertically polarized log periodic antennas 32a, 33a and two horizontally polarized log periodic antennas 42a, 43a, each of which has a different planar shape as viewed from the Z direction. Here, FIG. 9 and FIG. 10 are enlarged views showing the planar shapes of the horizontally polarized log periodic antenna 42a and the vertically polarized log periodic antenna 32a of FIG. 8. Note that, for the other horizontally polarized log periodic antenna 42b and vertically polarized log periodic antenna 32b, FIG. 9 and FIG. 10 can be considered as being arranged symmetrically with respect to the Y direction.

The horizontally polarized logarithmic periodic antenna 42a shown in FIG. 9 has a generally common three-dimensional structure with the components of the horizontally polarized logarithmic periodic antenna 42 described with reference to FIG. 4 and FIG. 5, but the number of horizontal radiating elements and the extension direction are different. That is, in the horizontally polarized logarithmic periodic antenna 42a, a total of eight horizontal radiating elements 51-54, 61-64 form four pairs on the signal side and ground side, and the extension direction from the base end to the tip of each element is inclined from the Y direction. Specifically, based on the positions of the signal side connecting conductor 50a and the ground side connecting conductor 60a, the tips of the eight horizontal radiating elements 51-54, 61-64 on both sides are inclined toward the direction away from the boundary position XB (the direction away from the ground conductor 11), and are arranged symmetrically on both sides. The changes in length and the alternating arrangement of the eight horizontal radiating elements 51-54, 61-64 are the same as in the first embodiment.

In addition, the vertically polarized logarithmic periodic antenna 32a shown in FIG. 10 has a generally common three-dimensional structure with the components of the vertically polarized logarithmic periodic antenna 32 described using FIG. 6 and FIG. 7, but the arrangement direction of the vertical radiation elements is different. That is, in the vertically polarized logarithmic periodic antenna 32a, the extension direction of the signal side connecting conductor 70b and the arrangement direction of the four vertical radiation elements 71 to 74 connected thereto are both inclined in a direction away from the central signal side connecting conductor 70a as they approach the boundary position XB (as they approach the ground conductor 11). Similarly, the extension direction of the ground side connecting conductor 80b and the arrangement direction of the four vertical radiation elements 81 to 84 connected thereto are both inclined in a direction away from the central ground side connecting conductor 80a as they approach the boundary position XB (as they approach the ground conductor 11). And, the central signal side connecting conductor 70a and the ground side connecting conductor 80a are arranged symmetrically on both sides. The changes in length in the Z direction and the staggered arrangement of the eight vertical radiating elements 71-74 and 81-84 are the same as in the first embodiment.

As shown in FIG. 8, the planar shapes shown in FIG. 9 and FIG. 10 are applied only to the two horizontally polarized log periodic antennas 42a, 43a sandwiching the center position in the Y direction and the two vertically polarized log periodic antennas 32a, 33a on both sides of them, and the other two horizontally polarized log periodic antennas 41, 44 and the two vertically polarized log periodic antennas 31, 34 have the same planar shapes as in the first embodiment. When multiple log periodic antennas are arranged side by side, the log periodic antennas closer to the center of the arrangement direction tend to be more susceptible to interference with surrounding log periodic antennas and ground than the log periodic antennas closer to the outer edges of the arrangement direction, and as a result, the antenna gain tends to be more likely to decrease. As a result of the inventors' verification, it was found that it is effective to adopt the configurations of FIG. 8 to FIG. 10 of the second embodiment in order to improve this point. As a result of the simulation, it was confirmed that by adopting the configuration of the second embodiment, an improvement of about 2 to 3 dB in antenna gain along the X direction was achieved for the horizontally polarized log periodic antennas 42a, 43a and the vertically polarized log periodic antennas 32a, 33a having the planar shapes shown in Figures 9 and 10.

Note that in Figures 8 to 10, the horizontally polarized log periodic antennas 42a and 43a have horizontal radiating elements 51-64 and 61-64 in the extension direction inclined by about 30° compared to the first embodiment, and the vertically polarized log periodic antennas 32a and 33a have vertical radiating elements 71-74 and 81-84 in the arrangement direction inclined by about 5° compared to the first embodiment, but the respective inclination angles can be changed as appropriate depending on the desired antenna performance.

When manufacturing the high-frequency substrate 10 of the first and second embodiments, for example, multiple ceramic green sheets for low-temperature firing formed by the doctor blade method are prepared, and multiple via holes are punched into each ceramic green sheet. Then, each via hole is filled with a conductive paste by screen printing to form multiple via conductors, and the conductive paste is applied to the surface of each ceramic green sheet by screen printing to form multiple conductor patterns. The multiple conductor patterns and multiple via conductors thus formed can form basic structures such as multiple log periodic antennas and ground conductors. Next, multiple ceramic green sheets are stacked in order and heated and pressed, and the resulting stack is degreased and fired to obtain the high-frequency substrate 10.

The present invention has been specifically described above based on the first and second embodiments, but the present invention is not limited to the above-mentioned embodiments and can be modified without departing from the spirit of the invention. In other words, the structure of the wiring board 10 described using Figures 1 to 10 can be widely applied to various wiring boards using other structures and materials as long as the effects of the present invention can be obtained. In particular, various changes can be made to the number and shape of the horizontally polarized log periodic antennas 41 to 44 and the vertically polarized log periodic antennas 31 to 34, the number and length of the radiating elements, other design details, or the arrangement and shape of the ground conductor 11, as long as the effects of the present invention can be obtained.

10...high frequency substrate 10a, 10b...surface 10c...opening 11...ground conductor 12...reflector 13...power supply path 20...IC chip 31, 32, 33, 34...vertical polarization log periodic antenna 41, 42, 43, 44...horizontal polarization log periodic antenna 51, 52, 53, 61, 62, 63...horizontal radiating element 71, 72, 73, 74, 81, 82, 83, 84...vertical radiating element 50a, 50b, 70a, 70b...signal side connecting conductor 60a, 60b, 80a, 80b...ground side connecting conductor L...conductor layer V...via conductor A1...RF region A2...antenna region

Claims (13)

A high-frequency substrate formed by alternately laminating dielectric layers and conductor layers,
one or more log periodic antennas configured using a plurality of conductor patterns formed on the conductor layer and a plurality of via conductors penetrating the dielectric layer;
A high frequency substrate, wherein the one or more log periodic antennas are embedded inside the high frequency substrate. The high frequency board according to claim 1, characterized in that one or more layers of ground conductors are provided in an area that does not overlap with an area in which the one or more log periodic antennas are arranged in a plan view from the thickness direction of the high frequency board. The high-frequency board according to claim 2, characterized in that a power supply structure is provided for supplying a high-frequency signal to each of the one or more log-periodic antennas. 4. The high frequency substrate according to claim 3, wherein the plurality of log periodic antennas are comprised of a horizontally polarized log periodic antenna and a vertically polarized log periodic antenna, and are arranged side by side in a first direction perpendicular to a thickness direction of the high frequency substrate. The high-frequency board according to claim 4, characterized in that the number of the horizontally polarized log-periodic antennas and the number of the vertically polarized log-periodic antennas are the same and are each 2 or more. one or more ground conductors arranged in a region that does not overlap a region in which the plurality of log periodic antennas are arranged in a plan view seen from a thickness direction of the high frequency substrate; and
an opening capable of accommodating an electronic component in a central region in a plan view seen from the thickness direction;
a plurality of power supply paths included in the power supply structure and electrically connecting the electronic component and each of the plurality of log periodic antennas;
Further comprising:
6. The high frequency board according to claim 5, wherein only the horizontally polarized log periodic antenna is disposed in a region overlapping with the opening in a plan view seen from the thickness direction. The high frequency board according to claim 6, characterized in that the plurality of log periodic antennas are arranged symmetrically with respect to a central position in the first direction. The horizontally polarized log periodic antenna includes a plurality of pairs of horizontal radiating elements on a signal side and a ground side,
The plurality of pairs of horizontal radiating elements are configured using the plurality of conductor patterns, and are arranged side by side in the thickness direction and a second direction perpendicular to the first direction,
The vertically polarized log periodic antenna includes a plurality of pairs of vertical radiating elements on a signal side and a ground side,
The plurality of pairs of vertical radiating elements are configured using the plurality of via conductors and are arranged side by side in the second direction.
8. The high frequency substrate according to claim 7. The high-frequency board according to claim 8, characterized in that each of the at least two horizontally polarized log-periodic antennas extends from the base ends of the multiple pairs of horizontal radiating elements to the respective tips on the signal side and ground side in the first direction. The high-frequency board according to claim 9, characterized in that the extension direction of each of at least two of the horizontally polarized log-periodic antennas near the center position in the first direction is inclined from the first direction in the plane of the conductor layer in a direction in which each tip is away from the ground conductor. The high-frequency board according to claim 8, characterized in that in each of the at least two vertically polarized log-periodic antennas, the extension direction of each of the pairs of vertical radiating elements is the thickness direction, the multiple signal-side via conductors and the multiple ground-side via conductors constituting each of the pairs of vertical radiating elements are arranged opposite to each other in the first direction, and the respective arrangement directions are the second direction. The high-frequency board according to claim 11, characterized in that, in each of at least two of the vertically polarized logarithmic periodic antennas near the central position, the extension direction of the pairs of vertical radiating elements is the thickness direction, the signal side via conductors and the ground side via conductors are arranged opposite each other in the first direction, and the respective arrangement directions are inclined from the second direction to the ground conductor as they approach the ground conductor, so that they move away from the opposite via conductors. An antenna module comprising a high-frequency substrate according to any one of claims 6 to 12, in which the electronic component is placed in the opening.

Images