JP6082260B2 - Dual polarized patch antenna - Google Patents

Description

  The present invention relates to a two-polarized patch antenna provided with a director.

  In recent years, patch antennas are becoming popular as small and thin circularly polarized antennas (see, for example, Patent Documents 1 and 2). As this type of patch antenna, a two-polarized patch antenna having a director (parasitic element) has been conventionally considered.

  FIG. 9 is a perspective view showing a configuration example of a conventional dual-polarized patch antenna including a square parasitic element. In FIG. 9, 11 is an antenna substrate formed of a dielectric material (synthetic resin), for example, in a disk shape with a thickness of t1, and a ground plate 12 formed of a conductor is provided on the entire bottom surface thereof. In the center of the upper surface of the antenna substrate 11, a square patch element 13 having a side length L1 is provided. In the center of one side of the patch element 13, a main polarization feeding portion 14 is provided, and a central portion of the tip is a main polarization feeding point 15. Further, the patch element 13 is provided with a reverse polarization power supply portion 16 at the center of the side adjacent to the main polarization power supply portion 14, and a central portion of the tip is a reverse polarization power supply point 17. The main polarization feeder 14 and the reverse polarization feeder 16 have an impedance conversion function for adjusting the feeding impedance according to the line width.

  Further, on the upper surface of the antenna substrate 11, an element substrate 18 for a parasitic element formed by a dielectric (synthetic resin) in a square shape having a thickness t2 and a side length L2 is disposed. The element substrate 18 is provided at a predetermined height on the antenna substrate 11 by support columns 19a to 19d made of, for example, insulators provided at four corners. In the center of the upper surface of the element substrate 18, a parasitic element 21 formed in a square having a side length L <b> 3 by a conductor is provided so as to face the patch element 13 at a predetermined height h <b> 1.

  In the two-polarized patch antenna configured as described above, two different orthogonal modes are excited independently by feeding a predetermined high-frequency signal to the main polarization feed point 15 and the reverse polarization feed point 17. Can do.

In the two-polarized patch antenna, the diameter D, the thickness t1, the relative permittivity εr, the length L2 of one side of the element substrate 18, the thickness t2, and the length L3 of one side of the parasitic element 21 are, for example, D: 120mm as shown below
t1: 1.6 mm
εr: 2.3
L1: 41 mm
L2: 80 mm
t2: 1.6 mm
L3: 44 mm
FIG. 10 shows the VSWR of the main polarization and FIG. 11 shows the gain characteristics of the main polarization when the 2.3 GHz band dual polarization patch antenna is set. In FIG. 10, the horizontal axis represents frequency [GHz] and the vertical axis represents VSWR. FIG. 11 shows the frequency [GHz] on the horizontal axis and the gain [dBi] on the vertical axis. As described above, in the two-polarized patch antenna, both VSWR and gain characteristics are good. Note that the VSWR and gain characteristics are substantially the same as the characteristics of the main polarization and the reverse polarization, and therefore, only the characteristics of the main polarization are shown in FIGS.

  FIG. 12 shows the directivity pattern at 2.35 GHz of the two-polarized patch antenna, where (a) shows the main polarization directivity and (b) shows the reverse polarization directivity. In FIG. 12A, the solid line a1 is the directivity of the main polarization magnetic field surface, the broken line b1 is the directivity of the main polarization electric field surface, the magnetic field surface half width is 90 °, and the electric field surface half width is 97 °. Yes. In FIG. 12B, the solid line a2 is the directivity of the reverse polarization magnetic field surface, the broken line b2 is the directivity of the reverse polarization electric field surface, the magnetic field surface half width is 90 °, and the electric field surface half width is 96 °. is there.

  In the two-polarized patch antenna, as shown in FIG. 12, there is a difference in the directivity half-value width in both the electric field surface and the magnetic field surface in the main polarization directivity and the reverse polarization directivity. The difference is about 6-7 °.

  In the conventional two-polarized patch antenna shown in FIG. 9, good characteristics are obtained in both VSWR and gain characteristics.

  However, the patch antenna does not have a symmetric shape with respect to the polarization direction when the feed structure is included, or by using a dielectric substrate, the half width of the magnetic field plane and the electric field plane is about 6 to 10 °. There is a difference. In order to eliminate this difference, in the case of using a single polarized wave, it is possible to adjust by making the radiating element and the parasitic element rectangular, or using a shape having different lengths on the top, bottom, left and right of the reflector. However, if it is desired to keep the half-width of the magnetic field plane and the electric field plane while maintaining the two half-polarized electric field planes and the magnetic field planes at the same half-value width, a parasitic element as described above should be used. This is not possible with the rectangular method. This is because, with respect to the polarization direction, one appears to be a parasitic element that is long vertically, and the other appears to be a parasitic element that is long to the left and right.

  FIGS. 13A to 13C show changes in directivity at the time of adjusting the half-value width of the magnetic field surface and the electric field surface of the conventional dual-polarized patch antenna, and FIG. 13A shows the directivity before the half-value width adjustment. b) shows the directivity of one polarization after half-width adjustment, and (c) shows the directivity of the other polarization after half-width adjustment. In FIG. 13, solid lines a, a1, and a2 indicate the directivity of the magnetic field surface, and broken lines b, b1, and b2 indicate the directivity of the electric field surface.

  As shown in FIG. 13B, when the half-value width of the magnetic field plane and the electric field plane of the two-polarized patch antenna is different as shown in FIG. If adjustment is made so that the magnetic field plane directivity a1 and the electric field plane directivity b1 in one polarization are aligned, the appearance of the parasitic element differs depending on the polarization direction, so the other polarization as shown in FIG. The difference between the half-value widths of the magnetic field surface directivity a2 and the electric field surface directivity b2 becomes larger than before the adjustment. For this reason, it has been very difficult to adjust the directivity of two orthogonally polarized waves in a two-polarized patch antenna.

JP 2006-237904 A JP 2006-25035 A

  As described above, in patch antennas, when the half-width of the magnetic field plane and the electric field plane is to be equalized, when using single polarization, the radiating element and parasitic element are rectangular, or the reflector plate has a length at the top, bottom, left and right. Can be adjusted by using a different shape. However, in the case where it is desired to keep the half-width of the magnetic field plane and the electric field plane while keeping the orthogonal two polarized magnetic field planes and the electric field planes at the same half-value width, the conventional adjustment method can change the parasitic element depending on the polarization direction. Therefore, it is very difficult to adjust the directivity of two orthogonal polarizations to be uniform.

  The present invention has been made in order to solve the above-mentioned problems, and while maintaining the same half-value width between two orthogonally polarized magnetic field surfaces and between electric field surfaces, the half-width of the magnetic field surface and the electric field surface can be easily increased. An object of the present invention is to provide a dual-polarized patch antenna that can be adjusted.

According to a first aspect of the present invention, there is provided an antenna substrate, a ground plate provided on a lower surface of the antenna substrate, a patch element having two orthogonally polarized feed points provided on an upper surface of the antenna substrate, and a relative to the patch element And a parasitic element provided with a parasitic element provided at a predetermined height, the parasitic element is provided with a dielectric material at four corners or upper, lower, left and right central portions with reference to the polarization direction. And a degenerate portion is formed by the shape and arrangement of the dielectric material, and the degenerate portion is configured to be able to adjust the half-width of the magnetic field plane and the half-width of the electric field plane in each polarization plane.

According to the present invention, the dual polarization patch antenna with a waveguide, four smear Rui provided parasitic element which constitutes the degeneration part in the center of the vertical and horizontal by the shape and arrangement of the dielectric material, the By using a parasitic element as a director, the half-width of the magnetic field plane and the electric field plane can be easily adjusted according to the purpose while keeping the two half-polarized magnetic field planes and the electric field planes at the same half-width. can do.

It is a figure for demonstrating the basic composition of the two polarization patch antenna which concerns on one Embodiment of this invention. In the dual-polarized patch antenna according to the same embodiment, it is a diagram showing a current distribution required on the parasitic element when it is desired to make the magnetic field planes or the electric field planes wider. It is a figure which shows the electric current distribution on the parasitic element in the two polarization patch antenna which concerns on the same embodiment. It is a figure which shows the electric current distribution on the parasitic element which contributes to radiation | emission in the two polarization patch antenna which concerns on the same embodiment. It is a perspective view which shows the specific structural example of the dual polarization patch antenna which concerns on Example 1 of this invention. It is a figure which shows the main polarization directivity and reverse polarization directivity of the dual polarization patch antenna which concerns on the Example 1. FIG. It is a perspective view which shows the specific structural example of the two polarization patch antenna which concerns on the Example 2. FIG. It is a figure which shows the main polarization directivity and reverse polarization directivity of the two-polarization patch antenna based on the Example 2. FIG. It is a perspective view which shows the structural example of the conventional 2 polarized-wave patch antenna. It is a figure which shows the VSWR characteristic of the conventional 2 polarized wave patch antenna based on the Example of this invention. It is a figure which shows the gain characteristic of the 2 polarized-wave patch antenna which concerns on the prior art and the Example of this invention. It is a figure which shows the main polarization directivity and reverse polarization directivity of the conventional 2 polarization patch antenna. It is a figure which shows the directivity at the time of the half value width adjustment of the magnetic field surface and electric field surface of the conventional 2 polarized-wave patch antenna.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First, a basic configuration of a two-polarized patch antenna according to an embodiment of the present invention will be described. The present invention shows a two-polarized patch antenna having a director, as shown in FIG. 1A, for example, with respect to a square parasitic element 30 whose polarization direction is vertical, as shown in FIG. As shown in the figure, for example, four corners are cut into squares to provide the contracted portions 31a to 31d, or as shown in FIG. 3C, the upper, lower, left and right central portions are cut into a square to provide the contracted portions 32a to 32d. As shown in FIG. 1 (b), the parasitic element 30A is provided with the degenerate portions 31a to 31d at the four corners, and as shown in FIG. 1 (c), the degenerate portions 32a to 32d are provided at the upper, lower, left and right central portions. By using the feed element 30B as a director, the increase / decrease in the magnetic field surface half-value width and the electric field surface half-value width are inversely correlated, and the half-value width of the magnetic field surface and the electric field surface in each polarization plane is adjusted to a desired difference.

  Next, with respect to the half-value width adjusting action of the parasitic element 30A in which the degenerate portions 31a to 31d are provided at the four corners and the parasitic element 30B in which the degenerate portions 32a to 32d are provided in the central portions of the upper, lower, left, and right sides, FIG. This will be described with reference to FIG.

  FIG. 2A shows a current distribution required on the parasitic element 30 when it is desired to make the magnetic field surface half width wider than the electric field surface half width, and the arrow line 41 and the arrow line 42 are different polarizations. Directional excitation current is shown. One excitation current 41 flows in a horizontal direction on the parasitic element 30, and the other excitation current 42 flows in a direction orthogonal to the excitation current 41, and intersects at a central portion on the parasitic element 30.

  FIG. 2B shows a current distribution required on the parasitic element 30 when it is desired to make the electric field surface half-width wider than the magnetic field surface half-width, and the arrow line 43 and the arrow line 44 are different polarizations. Directional excitation current is shown. The excitation current 43 of one polarized wave flows in the same direction, for example, in the right direction in the central portion of the upper edge and the lower edge of the parasitic element 30, and the other excitation current 44 is the center of the left and right side edges of the parasitic element 30. The current flows in a direction different from the excitation current 43 by 90 °, for example, upward. The excitation current indicated by the arrow line in FIG. 2 indicates the position, and does not indicate the magnitude.

  FIG. 3A shows a rough current distribution on the parasitic element 30B in which the degenerate portions 31a to 31d are provided at the central portions of the top, bottom, left, and right as shown in FIG. 1C. ) Shows a rough current distribution on the parasitic element 30A in which the degenerate portions 31a to 31d are provided at the four corners as shown in FIG.

  As shown in FIG. 3A, in the parasitic element 30B in which the degenerate portions 32a to 32d are provided in the upper, lower, left and right central portions, the excitation current 51 of one polarized wave flowing in the horizontal direction is generated in the upper and lower central portions. It flows in a curved manner along the provided degenerate portions 32a and 32c. In addition, the excitation current 52 of the other polarization that flows upward flows in a curved manner along the degenerate portions 32b and 32d provided in the left and right central portions.

  In addition, in the parasitic element 30A in which the degenerate portions 31a to 31d are provided at the four corners as shown in FIG. 3B, the excitation current 53 of one polarization flowing in the horizontal direction is applied to the degenerate portions 31a to 31d. The flow has a shape curved in the outer direction (vertical direction) in the center portion that is not present. Further, the excitation current 54 of the other polarized wave that flows in the upward direction becomes a flow having a curved shape in the left and right outer directions at the central portion without the degenerate portions 31a to 31d.

  In the excitation currents 51 and 52 flowing through the parasitic element 30B and the excitation currents 53 and 54 flowing through the parasitic element 30A, the current value is large in the vicinity of the center of the distribution curve. Is as shown in FIG.

  Excitation currents 51 and 52 that contribute to radiation in the parasitic element 30B are curved along the inside of the degenerate portions 32a to 32d as shown in FIG. 4A, and current distribution intersects at the center of the parasitic element 30B. It becomes. This current distribution is close to the current distribution in the case where it is desired to make the magnetic field surface half width shown in FIG. 2A wider than the electric field surface half width. As a result, in the parasitic element 30B in which the contracted portions 32a to 32d are provided at the center portions of the upper, lower, left, and right sides, the magnetic field surface half width can be adjusted by adjusting the size of the contracted portions 32a to 32d.

  In addition, the excitation currents 53 and 54 that contribute to radiation in the parasitic element 30A have a current distribution that is curved outward in the center portion where the degenerate portions 31a to 31d are not present as shown in FIG. This current distribution is close to the current distribution in the case where it is desired to make the electric field surface half width shown in FIG. 2B wider than the magnetic field surface half width. As a result, in the parasitic element 30A in which the degenerate portions 31a to 31d are provided at the four corners, it is possible to adjust the electric field surface half width by adjusting the size of the degenerate portions 31a to 31d.

  Next, a specific configuration example of a two-polarized patch antenna using the parasitic element 30A or the parasitic element 30B will be described.

  FIG. 5 is a perspective view showing a specific configuration example of the dual polarization patch antenna according to the first embodiment of the present invention. In this Example 1, the example at the time of using the parasitic element 30A in which the compression parts 31a-31d were provided in the four corners is shown. The two-polarized patch antenna according to the first embodiment is different from the conventional two-polarized patch antenna shown in FIG. 9 only in the configuration of the parasitic element 30A. A detailed description is omitted with reference numerals.

  The parasitic element 30A is provided at the center of the upper surface of the element substrate 18 and is formed into a square having a side length L3 by a conductor, and is opposed to the patch element 13 on the antenna substrate 11 at a predetermined height h1. It is provided as follows. The parasitic element 30 </ b> A includes degenerate portions 31 a to 31 d formed by cutting four corners into squares with lengths of d <b> 1 and d <b> 2. The lengths d1 and d2 of the contracting portions 31a to 31d are set to about 4 mm, for example.

In the dual-polarized patch antenna having the parasitic element 30A as described above, the antenna substrate 11 has a diameter D, a thickness t1, a relative permittivity εr, a length L2 of one side of the element substrate 18, a thickness t2, and a parasitic power. Similarly to the conventional two-polarized patch antenna shown in FIG.
D: 120 mm
t1: 1.6 mm
εr: 2.3
L1: 41 mm
L2: 80 mm
t2: 1.6 mm
L3: 44 mm
And the lengths d1 and d2 of the degenerate portions 31a to 31d in the parasitic element 30A are d1: 4 mm
d2: 4 mm
When a 2.3 GHz band dual polarization patch antenna is set, the same VSWR (see FIG. 10) and gain characteristics (see FIG. 11) as the conventional dual polarization patch antenna shown in FIG. 9 are obtained. It was. The dimensions of the above-described parts are merely examples, and can be arbitrarily changed according to specifications such as a frequency band to be used and directivity.

  FIG. 6 shows the directivity pattern at 2.35 GHz of the dual-polarized patch antenna according to the first embodiment, where (a) shows the main polarization directivity and (b) shows the reverse polarization directivity. In FIG. 6A, the solid line a1 is the directivity of the main polarization magnetic field surface, the broken line b1 is the directivity of the main polarization electric field surface, the magnetic field surface half width is 92 °, and the electric field surface half width is 103 °. Yes. In FIG. 6B, the solid line a2 is the directivity of the reverse polarization magnetic field surface, the broken line b2 is the directivity of the reverse polarization electric field surface, the magnetic field surface half width is 92 °, and the electric field surface half width is 102 °. is there.

  Example 1 shows an example in which a parasitic element 30A having degenerate portions 31a to 31d at four corners is used and the electric field surface half width is set wider than the magnetic field surface half width. Thus, the electric field surface half width could be increased by 10 ° to 11 ° with respect to the magnetic field surface half width.

  FIG. 7 is a perspective view showing a specific configuration example of the dual polarization patch antenna according to the second embodiment of the present invention. In the second embodiment, an example is shown in which a parasitic element 30 </ b> B in which the degenerate portions 32 a to 32 d are provided in the center portions of the upper, lower, left, and right sides is used.

  The two-polarized patch antenna according to the second embodiment is different from the conventional two-polarized patch antenna shown in FIG. 9 only in the configuration of the parasitic element 30B. A detailed description is omitted with reference numerals.

  The parasitic element 30 </ b> B includes degenerate portions 32 a to 32 d formed by notching the center portions of the top, bottom, left, and right with a width W <b> 1 and a depth d <b> 3. For example, the width W1 of the contracted portions 32a to 32d is set to about 2 mm, and the depth d3 is set to about 7 mm.

  In the dual-polarized patch antenna having the parasitic element 30B as described above, the antenna substrate 11 has a diameter D, a thickness t1, a relative permittivity εr, a length L2 of one side of the element substrate 18, a thickness t2, and a parasitic power. 1. The length L3 of one side of the element 21 is set to the same value as that of the conventional two-polarized patch antenna shown in FIG. 9, the width W1 of the parasitic element 30B is set to 2 mm, and the depth d3 is set to 7 mm. In the case of a 3 GHz band dual polarization patch antenna, the same VSWR (see FIG. 10) and gain characteristics (see FIG. 11) as those of the conventional dual polarization patch antenna shown in FIG. 9 were obtained.

  FIG. 8 shows the directivity pattern at 2.35 GHz of the dual-polarized patch antenna according to the second embodiment, where (a) shows the main polarization directivity and (b) shows the reverse polarization directivity. In FIG. 8A, the solid line a1 indicates the directivity of the main polarization magnetic field surface, the broken line b1 indicates the directivity of the main polarization electric field surface, the magnetic field surface half width is 88 °, and the electric field surface half width is 84 °. Yes. In FIG. 8B, the solid line a2 is the directivity of the reverse polarization magnetic field surface, the broken line b2 is the directivity of the reverse polarization electric field surface, the magnetic field surface half width is 88 °, and the electric field surface half width is 84 °. is there.

  Example 2 above is an example in which a parasitic element 30B including degenerate portions 32a to 32d is used in the center portion of the upper, lower, left, and right sides, and the magnetic field surface half width is set to be wider than the electric field surface half width. The surface having a wide half-value width is reversed with respect to the conventional two-polarization patch antenna (see FIG. 9), and the half-width of the magnetic field plane of the main polarization directivity and the reverse polarization directivity is 88 °. The electric field surface half width is 84 °, and the magnetic field surface half width is 4 ° wider than the electric field surface half width.

  In the two-polarized patch antenna having a director as shown in the first and second embodiments, the parasitic element 30A in which the degenerate portions 31a to 31d are provided at the four corners, or the degenerate portions 32a to 32a By using the parasitic element 30B provided with 32d as a director, the half-width of the magnetic field plane and the electric field plane is maintained while maintaining the same half-width between the two polarized magnetic field surfaces and the electric field surfaces. It can be easily adjusted according to. Moreover, the half-value width of the magnetic field plane and the electric field plane can be adjusted more easily by using a parasitic element made of a printed circuit board. Furthermore, the axial ratio can be improved when designing a circularly polarized antenna.

  In addition, when a single-row multi-stage stack antenna with ± 45 ° polarization is designed as a patch antenna and a vertical beam tilt is formed, a change in the maximum radiation direction in the horizontal plane can be suppressed.

  In the above embodiment, the case where the parasitic elements are provided with the degenerate portions 31a to 31d and 32a to 32d has been described. However, the conductor shape of the parasitic element is left as it is, and a dielectric material is provided around the parasitic element. The half width of the magnetic field surface and the electric field surface can also be adjusted by making the dielectric material into a degenerated shape as in the above embodiment. That is, since the distribution of the dielectric material affects the current distribution on the conductor, the degenerate portion is configured by the shape and arrangement of the dielectric material provided around the parasitic element, so that the magnetic field surface and the electric field surface are The full width at half maximum can be adjusted.

  In the above-described embodiment, the case where the degenerate portions 31a to 31d and 32a to 32d are provided in the square parasitic element 30 has been described. Even if the degenerate portion is formed at the center portion of each, the half-value width of the magnetic field surface and the electric field surface in each polarization plane can be adjusted.

  Furthermore, although the case where the parasitic element 30A or 30B is provided on the upper surface of the element substrate 18 has been described in the above embodiment, the parasitic element 30A or 30B may be provided on the lower surface of the element substrate 18. In this case, the parasitic elements 30 </ b> A and 30 </ b> B are held at a predetermined height with respect to the patch element 13 on the antenna substrate 11.

  In the above-described embodiment, the case where the one-stage parasitic element (30A or 30B) is provided has been described, but it is needless to say that the parasitic element may be configured in multiple stages.

  Further, the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage.

  DESCRIPTION OF SYMBOLS 11 ... Antenna board, 12 ... Ground plate, 13 ... Patch element, 14 ... Main polarization feeding part, 15 ... Main polarization feeding point, 16 ... Inverse polarization feeding part, 17 ... Inverse polarization feeding point, 18 ... None Element substrate for power feeding elements, 19a to 19d ... posts, 21 ... parasitic elements, 30, 30A, 30B ... parasitic elements, 31a to 31d, 32a to 32d ... degenerate parts, 41 to 44, 51 to 54 ... excitation currents .

Claims (1)

An antenna substrate, a ground plate provided on the lower surface of the antenna substrate, a patch element having two orthogonally polarized feed points provided on the upper surface of the antenna substrate, and a predetermined height opposite to the patch element In the two-polarized patch antenna comprising a parasitic element provided in the antenna,
The parasitic element is provided with a dielectric material at the four corners or at the center of the top, bottom, left, and right with respect to the polarization direction, and a degenerate portion is formed by the shape and arrangement of the dielectric material. A dual polarized patch antenna characterized in that the interface half width and electric field half width can be adjusted.

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