JP7173851B2 - Dual-polarized planar antenna - Google Patents

Description

The present invention relates to a dual-polarized planar antenna capable of transmitting and receiving two polarized signals orthogonal to each other.

Satellite communications generally adopt a method of performing communications by changing the frequency and polarization between uplink and downlink. In addition, users on the ground aim for mobile communication, and since the direction of the antenna changes, circularly polarized waves are used to cope with this change. That is, the frequency is changed between transmission and reception, and two circularly polarized waves, a right-handed circularly-polarized wave and a left-handed circularly-polarized wave, are used.

In order to transmit and receive circularly polarized waves, for example, it is conceivable to arrange a right-handed circularly polarized wave antenna and a left-handed circularly polarized wave antenna side by side. Occupied area becomes larger. Therefore, circularly polarized antennas that can be made smaller and lighter are known (see, for example, Patent Document 1, etc.). This circularly polarized planar antenna is an antenna in which two microstrip array antennas are stacked such that their planes of polarization are orthogonal to each other. As shown in FIG. 2 lamination part 120, the 3rd lamination part 130, and the 4th lamination part 140 are laminated.

The first laminated portion 110 has an upper layer slot plate 111 and a foam sheet 112 laminated in order from the top, and the second laminated portion 120 has an upper feeding element substrate 121 and a foam sheet 122 laminated in order from the top. . Here, the upper feeding element substrate 121 is an FPC (flexible printed circuit board) in which feeding elements for transmitting polarized signals are arranged in a matrix. The third laminated portion 130 has a middle layer slot plate 131 and a foam sheet 132 laminated in this order from the top. Laminated. Here, the lower feeding element substrate 141 is an FPC in which feeding elements for receiving polarized signals are arranged in a matrix.

JP-A-2004-88185

In such a circularly-polarized dual-wave planar antenna, the return loss band depends on the coupling of the elements, and in order to widen the return loss band, lamination of parasitic element substrates is generally adopted. However, there have been cases where the return loss cannot be widened to a desired band only by laminating parasitic element substrates.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a dual-polarized planar antenna capable of widening the return loss characteristic.

In order to solve the above-mentioned problems, the invention according to claim 1 provides a transmission substrate in which a plurality of feeding elements for transmitting polarized signals are arranged in a matrix, and a plurality of feeding elements for receiving the polarized signals. a receiving substrate having feeding elements arranged at the same position as the feeding elements of the transmitting substrate, the receiving substrate being stacked under the transmitting substrate, and polarized waves for transmitting and receiving two polarized signals orthogonal to each other. In the shared planar antenna, a parasitic element substrate having a plurality of parasitic elements arranged at the same position as the feeding elements is laminated on the transmission substrate, and a plurality of openings are formed on the lower side of the reception substrate. A slot plate arranged at the same position as the feeding element is laminated , and a bridge for adjusting a frequency band of return loss is provided in the opening .

The invention according to claim 2 is the dual-polarized planar antenna according to claim 1, wherein the parasitic element substrate is an upper parasitic element that narrows the beam width of the receiving substrate to improve the front gain. and a lower parasitic element substrate that narrows the beam width of the transmission substrate to improve the front gain, wherein the lower parasitic element substrate is laminated below the upper parasitic element substrate , It is characterized by

According to the first aspect of the invention, since the slot plate in which a plurality of apertures are arranged is laminated on the lower side of the receiving substrate, the return loss characteristics of reception are widened (return loss is reduced over a wide band). ) becomes possible. That is, by providing an opening (hole) under the feed element of the receiving substrate, an effect equivalent to that of increasing the thickness of the receiving substrate can be obtained, and the substantial dielectric constant of the receiving substrate decreases and the Q value is reduced, and the return loss characteristic is widened. For this reason, in general, increasing the substrate thickness of the receiving substrate can increase the bandwidth, but it is possible to increase the bandwidth of the return loss characteristics while maintaining the desired thickness without increasing the substrate thickness. Furthermore, since the opening of the slot plate is provided with a bridge, it is possible to adjust the return loss band to a desired band.

Moreover, since it is only necessary to provide the slot plate on the lower side of the receiving substrate, it is possible to broaden the band of return loss characteristics at low cost without affecting other characteristics. On the other hand, since the parasitic element substrate is laminated on the upper side of the transmission substrate, the directivity of the main beam is narrowed and the gain is increased. By laminating the slot plate and the parasitic element substrate in this way, it is possible to increase the gain while broadening the return loss characteristics.

According to the second aspect of the invention, the upper parasitic element substrate for narrowing the beam width of the receiving substrate to improve the front gain and the upper parasitic element substrate for improving the front gain by narrowing the beam width of the transmission substrate are provided above the transmission substrate. Since the lower parasitic element substrate to be improved is laminated, the main beam can be narrowed in directivity and the gain can be increased.

1 is an exploded perspective view showing a laminated structure of a dual-polarization planar antenna according to an embodiment of the present invention; FIG. 2 is a graph showing return loss characteristics in reception of the dual-polarized planar antenna of FIG. 1; FIG. 11 is an exploded perspective view showing a laminated structure of another dual-polarized planar antenna according to an embodiment of the present invention; FIG. 2 is an exploded perspective view showing a laminated structure of a conventional dual-polarized planar antenna;

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on the illustrated embodiments.

FIG. 1 is an exploded perspective view showing a laminated structure of a dual-polarized planar antenna 1 according to an embodiment of the invention. This dual-polarized planar antenna 1 is a dual-linearly polarized planar antenna that transmits and receives two mutually orthogonal linearly polarized signals in satellite communications in the microwave band. A lower feeding element substrate (receiving substrate) 81 is laminated on the substrate. By stacking a circular polarization converter on the dual-polarization planar antenna 1, a dual-polarization planar antenna capable of transmitting and receiving two circularly polarized signals is configured.

The dual-polarization planar antenna 1 includes, from the top, a first lamination section 2, a second lamination section 3, a third lamination section 4, a fourth lamination section 5, a fifth lamination section 6, and a sixth lamination section. A laminated portion 7, a seventh laminated portion 8 and an eighth laminated portion 9 are laminated.

In the first laminated portion 2, an upper cover 21, a foam sheet (dielectric) 22, an intermediate cover 23, and a foam sheet 24 are laminated in this order from the top. The foam sheets 22 and 24 are sheet materials of foamed polyethylene or foamed polypropylene, and the same applies to other foam sheets to be described later.

In the second laminated portion 3, an upper parasitic element substrate (parasitic element substrate) 31 and a foam sheet 32 are laminated in this order from the top. The upper parasitic element substrate 31 is a substrate in which a plurality of parasitic elements are arranged in a matrix. It has a plurality of upper-layer parasitic patches (parasitic elements) 31b of conductive foil arranged and arranged at the same position in a substantially rhombic shape. The upper layer parasitic element substrate 31 is arranged at a height position where the lower layer foam sheet 32 affects the lower layer feeding element substrate 81 for reception. Furthermore, the shape of the upper parasitic patch 31b extending along the excitation direction of the lower feeder element substrate 81 and the foam sheet 32 affect the directivity of the lower feeder element substrate 81. To improve the front gain by narrowing the beam width.

In the third laminated portion 4, a lower parasitic element substrate (parasitic element substrate) 41 and a foam sheet 42 are laminated in this order from the top. The lower parasitic element substrate 41 is a substrate in which a plurality of parasitic elements are arranged in a matrix. It is provided with a plurality of lower-layer parasitic patches (parasitic elements) 41b of conductive foil which are rectangular (substantially square) and arranged at the same position. This lower layer parasitic element substrate 41 is arranged at a height position that affects the directivity of the upper layer feeding element substrate 61 for transmission by the foam sheet 42 of the lower layer, and the beam width of the upper layer feeding element substrate 61 is adjusted. It is narrowed to improve frontal gain.

The fourth laminated portion 5 has an upper layer slot plate 51 and a foam sheet 52 laminated in this order from the top. The upper layer slot plate 51 is provided with a rectangular opening (hole) 51a at a position facing (the same position as) an upper layer power supply patch 61b, which will be described later. The upper layer slot plate 51 is a shielding plate for shielding and is made of a conductive thin plate such as an aluminum plate.

In the fifth laminated portion 6, an upper feeding element substrate 61 and a foam sheet 62 are laminated in this order from the top. The upper feeding element substrate 61 is a substrate in which feeding elements for transmitting polarized signals are arranged in a matrix. It includes a plurality of rectangular upper-layer power supply patches (power-supply elements) 61b arranged at intervals, and an upper-layer power supply line 61c for supplying power to the upper-layer power supply patches 61b. The upper-layer power supply patch 61b and the upper-layer power supply line 61c are made of conductive foil such as copper, aluminum, and gold.

The sixth laminated portion 7 has a middle layer slot plate 71 and a foam sheet 72 laminated in this order from the top. The intermediate layer slot plate 71 is provided with a rectangular opening 71a at a position facing a lower layer power supply patch 81b, which will be described later. A bridge portion 71b is provided in the opening 71a so as to cross the diagonal direction. The bridge portion 71b is provided parallel to the transmission excitation direction of the upper layer power supply patch 61b (in a direction different from the reception excitation direction by 90°), and exerts a strong influence on the excitation when power is supplied to the upper layer power supply patch 61b. to improve antenna characteristics such as directivity. In addition, since it is orthogonal to the excitation direction of the lower layer feeding patch 81b and its width is sufficiently narrower than that of the lower layer feeding patch 81b, it has almost no effect and does not degrade other antenna characteristics.

In the seventh laminated portion 8, a lower feed element substrate 81 and a foam sheet 82 are laminated in this order from the top. The lower feeding element substrate 81 is a substrate in which feeding elements for receiving polarized signals are arranged in a matrix. It includes a plurality of rectangular lower layer power supply patches (power supply elements) 81b arranged and arranged at the same positions as the power supply patches 61b, and a lower layer power supply line 81c for supplying power to the lower layer power supply patches 81b. The lower layer power supply patch 81b and the lower layer power supply line 81c are formed of the same conductive foil as the upper layer power supply patch 61b.

Here, when the lower layer feeding element substrate 81 receives a polarized signal in a frequency band lower than that of the upper layer feeding element substrate 61, the size of the lower layer feeding patch 81b is set larger than that of the upper layer feeding patch 61b. Further, in this embodiment, the lower feeding element substrate 81 receives a polarized wave signal whose plane is parallel to the receiving polarization plane and perpendicular to the plane of the drawing. Therefore, the excitation direction of the lower feeding element substrate 81 is also the direction of this reception polarization plane. Similarly, the upper feeding element substrate 61 transmits a polarized signal whose plane is parallel to the transmission polarization plane and perpendicular to the plane of the paper. Therefore, the excitation direction of the upper feeding element substrate 61 is also the direction of this transmission polarization plane.

The eighth laminated portion 9 has a lower layer slot plate (slot plate) 91, a ground plate 92, a foam sheet 93, a base plate 94 and a lower cover 95 laminated in this order from the top. The lower layer slot plate 91 is provided with a plurality of rectangular openings 91a at positions (the same positions) facing the lower layer power supply patch 81b. In addition, a bridge portion 91b is provided in the opening 91a so as to traverse the diagonal direction, thereby adjusting the frequency band of the return loss. That is, the bridge portion 91b is provided so as to obtain a desired return loss in a desired frequency band. Further, the bridge portion 91b is provided in the same direction as the bridge portion 71b of the intermediate layer slot plate 71, so that an effect equivalent to that of the bridge portion 71b described above can be obtained.

According to the dual-polarized planar antenna 1 having such a configuration, the lower layer slot plate 91 in which the plurality of openings 91a are arranged is laminated below the lower layer feeding element substrate 81, so that the return loss characteristic of reception is broadband. become possible. That is, by providing the opening (hole) 91a below the lower layer power supply patch 81b of the lower layer power supply element substrate 81, an effect equivalent to that of increasing the thickness of the lower layer power supply substrate 81a of the lower layer power supply element substrate 81 can be obtained. , the substantive dielectric constant of the lower-layer feeding substrate 81a is lowered, the Q value is lowered, and the return loss characteristic is widened. For this reason, in general, increasing the thickness of the lower-layer feeding substrate 81a can achieve a broader bandwidth, but without increasing the thickness, the return loss characteristics can be broadened while maintaining a desired thickness (after suppressing reflection). It becomes possible to

For example, as shown in FIG. 2, when the desired return loss value C is required from frequency F1 to frequency F2, as shown in the return loss characteristic curve L1, the return loss is lower than the C value in the entire band. It becomes possible to On the other hand, in the conventional dual-polarization planar antenna in which the lower layer slot plate 91 is not laminated, the return loss becomes a value larger than the C value in some frequency bands, as indicated by the return loss characteristic curve L2. Here, FIG. 2 shows the characteristics per element, and the same effect occurs even with a plurality of elements as shown in FIG. 1 (16 elements in FIG. 1).

Moreover, since the lower layer slot plate 91 only needs to be provided on the lower side of the lower layer feeding element substrate 81, it is possible to broaden the return loss characteristics at low cost without affecting other characteristics. . On the other hand, since the upper parasitic element substrate 31 and the lower parasitic element substrate 41 are laminated on the upper side of the upper feeding element substrate 61, the directivity of the main beam is narrowed and the gain is enhanced. By laminating the lower layer slot plate 91 and the parasitic element substrates 31 and 41 in this way, it is possible to widen the band of the return loss characteristics and increase the gain.

Further, since the bridge portion 91b is provided in the opening 91a of the lower layer slot plate 91, it is possible to adjust the return loss band to a desired band. For example, as shown in FIG. 2, it is possible to adjust the return loss value to be equal to or less than the desired return loss value C at frequencies F1 to F2.

Although the embodiments of the present invention have been described above, the specific configuration is not limited to the above-described embodiments. Included in the invention. For example, in the above embodiment, two parasitic element substrates 31 and 41 are provided for transmission and reception. It is also possible to obtain the same effect with one parasitic element substrate by arranging it at a height position that affects both. In addition, even if the parasitic element substrate is at a height that affects both the transmitting and receiving feed elements, by extending the patch shape of the parasitic element substrate along the excitation direction of the target feed element, the target It is also possible to have an effect on the feed element to be set.

By the way, in the above embodiment, the opening 91a of the lower layer slot plate 91 is provided with the bridge portion 91b. As shown, there is no need to provide a bridge portion 91b. The present invention may also be applied to a circularly polarized planar antenna in which circularly polarized wave converters composed of meander line polarizers and the like are stacked.

1 shared polarized plane antenna 31 upper layer parasitic element substrate (parasitic element substrate)
31b Upper parasitic patch (parasitic element)
41 lower parasitic element substrate (parasitic element substrate)
41b lower layer parasitic patch (parasitic element)
61 upper feeding element substrate (transmitting substrate)
61b Upper layer feeding patch (feeding element)
81 lower feed element substrate (receiving substrate)
81b Lower layer feeding patch (feeding element)
91 lower layer slot plate (slot plate)
91a opening 91b bridge portion

Claims (2)

A transmission board in which a plurality of feed elements for transmitting polarized signals are arranged in a matrix, and a reception board in which a plurality of feed elements for receiving polarized signals are arranged at the same position as the feed elements of the transmission board. a substrate, wherein the receiving substrate is laminated under the transmitting substrate, and a dual-polarized planar antenna for transmitting and receiving two polarized signals orthogonal to each other,
A parasitic element substrate in which a plurality of parasitic elements are arranged at the same positions as the feeding elements is stacked above the transmitting substrate, and a plurality of openings are formed at the same positions as the feeding elements under the receiving substrate. Aligned slot plates are laminated ,
The aperture is provided with a bridge for adjusting the frequency band of return loss .
A dual-polarized planar antenna characterized by: The parasitic element substrates include an upper parasitic element substrate that narrows the beam width of the receiving substrate to improve front gain, and a lower parasitic element substrate that narrows the beam width of the transmitting substrate to improve front gain. , wherein the lower parasitic element substrate is laminated on the lower side of the upper parasitic element substrate ,
2. The dual-polarized planar antenna according to claim 1, wherein:

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