JPH0682977B2 - Wide directional microstrip antenna - Google Patents

Description

The present invention relates to a patch antenna that receives radio waves from a satellite or the like from a wide angle, and in particular has a perimeter that is open.

[Conventional technology]

Since radio waves broadcast from satellites use circular polarization,
For receiving radio waves from satellites, helical antennas and spiral type antennas are used as antennas to provide wide directivity. These antennas have the advantage of being able to easily realize a hemispherical omnidirectional antenna having a wide-angle directivity, but they have a complicated shape, and many manual operations are likely to occur during manufacture, which makes them expensive. Become.

[Problems to be Solved by the Invention]

Recently, the microstrip antenna is thin, lightweight, easy to manufacture, and low in cost, so that it is beginning to be used in a high frequency band.

The patch-type microstrip antenna is a dielectric substrate having a conductive bottom plate on the bottom of which a rectangular or circular conductor (patch) is arranged, and electrically forms a resonant element whose peripheral edge is open. In the case of a square patch, as an antenna, it resonates in a resonance mode with a long edge of λ / 2,
Radio waves are radiated from the open end. This radiated electric field is said to be equivalent to two magnetic dipoles placed around the patch at corresponding positions separated by a length of λ / 2. Therefore, in the linearly polarized wave, the electric field (E) plane and the magnetic field (H)
Since the directivity is narrowed on both sides, it was difficult to realize a hemispherical omnidirectional antenna with a patch-type microstrip antenna.

An object of the present invention is to eliminate the drawback that the patch type microstrip antenna has a narrow directivity, and to provide a microstrip antenna having a wide directivity when operated for linear polarization and further for circular polarization. To do.

[Means for Solving the Problems]

The present invention relates to a rectangular or circular patch-type microstrip antenna that generates linearly polarized waves, and is perpendicular to the main radiation axis of the antenna and orthogonal to each other.
On the P-axis, one or more linear or strip-shaped non-exciting elements are provided close to the outside of the periphery of the patch in the direction of the axis of the axis and the Q-axis, and the direction of the resonance mode of the patch is the P-axis. The non-exciting element provided in the direction of is the element perpendicular to the dielectric substrate, and the non-exciting element provided in the direction of the Q-axis is parallel to the dielectric substrate surface and is separated from the dielectric substrate surface by P. A horizontal element extending in the axial direction or a T-type element in which the center of the horizontal element is grounded to the surface of the dielectric substrate is used.

In a circularly polarized microstrip antenna, resonance modes orthogonal to each other are formed by patches of the microstrip antenna to form circularly polarized waves, and each resonance mode is set to the P
A non-excitation element for each resonance mode is provided as an axis. In this case, multiple patches or one common patch
Circular polarization can be formed by individual patches. In addition, as a means to further improve the directivity of the circularly polarized microstrip antenna, the non-exciting elements are arranged at 90 ° to each other and perpendicular to the dielectric substrate in the direction of each orthogonal resonance mode of circularly polarized waves. It is effective to dispose such non-exciting elements and provide horizontal non-exciting elements on the dielectric substrate in the intermediate direction between the vertical elements.

The shape of the patch is a square or a circle, but the circle here is not limited to a perfect circle, and includes an ellipse and an ellipse.

[Action]

The parasitic element has a length of λ / 2 or less (in the case of grounding, λ /
If it is 4), it operates as a wave director. If a vertical element is arranged on the E plane and a horizontal element is arranged on the H plane, the directivity of the radio wave in each direction is improved. By using the vertical and horizontal elements together, an antenna with good directivity can be obtained.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

(1) First Example As a first example, FIGS. 1 to 4 show a linearly polarized antenna. FIG. 1 is a perspective view, FIGS. 2 and 3 are side views, and FIG. 4 is a plan view. A patch with diagonal lines
10 is formed of copper foil on the dielectric substrate 1. The back surface of the dielectric substrate 1 is a base plate 2 to which a copper foil is attached. patch
The power supply to 10 is done from the back side by the connector. This feeding point 11 is related to the patch 10 as X in this example.
Since it is deviated from the center in the direction and located at the center in the Y direction, the resonance current flows in the X direction. That is, in this case, the P-axis direction indicating the direction of the resonance mode is the X direction. Then, the electromagnetic field is obtained assuming that there is a magnetic current at the edges l, l of the patch 10. P along the electric field (E) plane
By arranging the non-exciting elements 20 and 21 vertically on the axis (X direction) close to the patch 10 and vertically from the dielectric substrate 1, the directivity in this direction can be improved. The lengths of the non-excitation elements 20 and 21 are close to λ / 4 if they are grounded, and may be slightly shorter than this. Further, in the plane H of the magnetic field orthogonal to the plane of the electric field (E), the horizontal non-exciting elements 22 and 23 are arranged in parallel with the X direction on the line of the Q axis (Y direction) so as to float from the dielectric substrate 1. , The directivity in this direction can be improved. The element length is λ
It is close to / 2 and slightly smaller than this. Horizontal parasitic element
22 and 23 need to be supported by an insulator by some method in order to float from the dielectric substrate 1, but the center of the horizontal element may be grounded as shown by the dotted line in the figure. In this case, it is electrically the same as floating.

The distance between the parasitic elements 20 to 23 and the edge of the patch 10 is 0.05 to 0.
It was confirmed that a sufficient effect can be obtained by setting the height of 5λ and 22 to 23 on the dielectric substrate 1 to a height of 0.1 to 0.2λ. An example of the directivity of the above linearly polarized antenna is as shown in FIG. The directivity in the Y direction is the same. FIG. 8 shows the directivity of the patch antenna only, whereas the directivity of the angle θ with respect to the radiation main axis according to the present invention was clearly confirmed.

(2) Second Embodiment Next, as a second embodiment, FIGS. 5 and 6 show the case where the present invention is applied to the case of circular polarization. FIG. 5 is a side view and FIG. 6 is a plan view. In the case of circular polarization, 2 feeding points
It is also possible to supply resonance currents in the X direction and the Y direction, respectively, but by using one feed point 13 provided in the diagonal direction as shown in FIG. It is well known that orthogonal resonance modes M1 and M2 can be generated. The resonance modes M1 and M2 have different current path lengths by providing the slits K, and the respective resonance frequencies are different. Therefore, when excited from the feeding point 13 at an intermediate frequency, the phases of the two resonance modes differ by 90 °,
A circularly polarized electric field is generated.

Circularly polarized waves as electromagnetic waves have orthogonal electric fields corresponding to the orthogonal resonance modes generated in the patch. If the non-exciting element shown in the first embodiment is provided on the outer periphery of the patch for each orthogonal electric field of circular polarization, wide directivity for the case of circular polarization can be obtained. Therefore, as shown in Fig. 5 and Fig. 6, 24
2 ~ 30 and 33 corresponding to M2 mode shifted by ~ 27 and 90 °
Pairs are shown.

(3) Third Embodiment In the above-mentioned embodiment, one patch is shared as a patch and a slit is provided to shift the phase by 90 °, but as a patch for generating circular polarization, Of course, it can be generated by other methods. As shown in FIG. 7 as a third embodiment, four patches 14A to 14D are provided on the dielectric substrate 1, and all the patches are single-point feeding without slits, and the feeding points are located in the X direction or Y direction, respectively. Different so that a resonance current is generated in each direction. by this,
Since M1 and M2 resonance modes that are effectively orthogonal are generated,
As shown by the solid and dotted lines in the figure, two sets of non-exciting elements corresponding to each resonance mode may be provided. In this case, the power supply current needs to be supplied to the patches 14A to 14D in a time-divisional manner, but the directivity is the second patch using one patch.
It is similar to the embodiment.

(4) Fourth Embodiment As described above, wide-angle directivity can be obtained for both linearly polarized waves and circularly polarized waves by implementing the present invention. But,
Since the vertical element arranged on the E plane and the horizontal element arranged on the H plane as the non-exciting element are arranged orthogonally to the P-axis direction of the resonance mode and the Q-axis direction perpendicular to them, respectively, they are located between the P and Q axes. Therefore, the directivity in the φ direction is deteriorated. As a means for preventing the lowering of this portion, it is conceivable to arrange the horizontal element arranged on the H-plane not at a right angle to the E-plane but in the middle so as to be in the direction of about 45 °. As a fourth embodiment, specifically, FIG.
As shown in the side view and the plan view of FIG. 11, the vertical elements 40 to 43 are arranged corresponding to the respective sides of the patch 12, but the horizontal elements 44 to 47 are arranged.
Are placed so that they have an inclination of 45 ° with respect to each side.
Excite from 13. This makes it possible to reduce the decrease in directivity in the φ direction in the middle direction of the X and Y axes in the figure. In this case, each horizontal element 44-47 participates in both orthogonal resonant modes of the patch. Figure 12 shows the measured directivity in the φ direction when the directivity is viewed in the X and Y planes. In the case of the circularly polarized wave in the second embodiment, there is a tendency as shown by the dotted line in the intermediate direction of the X and Y axes, but in this embodiment, this directivity reduction can be improved as shown by the solid line. The resonance mode generated in the square patch is generated between the corresponding two sides, but as an excitation method by driving it and shifting the phase of the two resonance modes by 90 °, the patch as shown in Fig. 13 is used. It is also possible to provide a slit K'on the diagonal line of 15 and provide a feeding point 16 at the position shown in the figure. At this time, the arrangement corresponding to the patch 15 of the parasitic element is exactly the same.

(5) Fifth Embodiment As a fifth embodiment, FIG. 14 shows the same means as the fourth embodiment, but applied when the patch has a circular shape.

Since the patch 17 has a circular shape, a resonance mode slightly different from that in the case of a square is obtained, but in this example, the slit K ″ and the feeding point 18 are used to obtain two resonance modes orthogonal to each other. Circularly polarized waves can be obtained by exciting at a frequency intermediate between both resonance frequencies from the feeding point 18. In Fig. 14, the non-excitation element is arranged at the 12th position.
Similar to Fig. 13 and Fig. 13, 40 to 43 are vertical elements and 44 to 47 are horizontal elements.

Further, it may be necessary to make both the dielectric substrate and the patch circular in order to downsize the device or design the entire device. At this time, as shown in FIG. 15, wide directivity can be maintained even if the horizontal elements are formed into arc shapes 44 'to 47'.

(6) Up to the fifth embodiment described above, the vertical element which is a non-excitation element is a vertical element whose length is slightly shorter than λ / 4, but as shown in FIG. 16 (corresponding to FIG. 13). In addition, even if an inverted L-shaped element in which the tip of the element having the above length is bent horizontally is used,
It was found that a similar effect can be obtained. The direction of the horizontal portion needs to be the direction of the resonance mode, but the direction of the tip thereof may be the direction of the patch or the opposite direction. Since it is an inverted L type, there is an advantage that a thin antenna can be realized.

〔The invention's effect〕

An object of the present invention is to obtain a wide angle hemispherical omnidirectional antenna using a patch type microstrip antenna. Therefore, in the present invention, the non-excited elements are arranged on the E plane and the H plane near the patch, which are generated when the patch is excited, and the element perpendicular to the dielectric substrate with respect to the E plane and the H plane with respect to the H plane. Wide-angle directivity could be obtained as an antenna for linear polarization by using a horizontal element and operating as a director. Further, as an antenna for circularly polarized waves, the arrangement of the non-excited elements for linearly polarized waves is combined with each other corresponding to two orthogonal resonance modes occurring in the patch.
This makes it possible to effectively deal with circularly polarized waves radiated from satellites and the like.

Furthermore, as an antenna for circularly polarized waves, an antenna in which the positional relationship between the vertical element group and the horizontal element group of the non-excited elements is shifted to improve the φ directivity in the plane (X, Y plane) including the dielectric substrate. Was presented.

[Brief description of drawings]

1 to 4 relate to a first embodiment of the present invention for an antenna for linearly polarized waves. FIG. 1 is a perspective view, FIGS. 2 and 3 are side views, FIG. 4 is a plan view, 5 and 6 are examples of the circularly polarized wave antenna of the second embodiment, and a side view and a plan view thereof are shown in FIG. 7, and FIG. 7 is a circularly polarized wave antenna using four patches of the third embodiment. FIG. 8 is a θ directivity characteristic diagram for the radiation main axis of the conventional example, and FIG. 9 is a θ directivity characteristic diagram for the first embodiment. 10 and 11 are a side view and a plan view of a fourth embodiment in which the φ directional characteristic is improved, FIG. 12 is a view showing an improvement in the φ directional characteristic according to the fourth embodiment, and FIG. 13 is a fourth embodiment. 14 and 15 show an example of the circular patch of the fifth embodiment, and FIG. 16 shows an example using an inverted L-type vertical element. 1 ... Dielectric substrate, 2 ... Ground plane, 10,12,15,17,14A to 14D ... Patch, 11,13,16,18 ... Feeding point, 20,21,24,25,30,31 , 40〜43 …… Vertical element, 22,23,26,27,32,33,44〜47,44′〜47 ′ …… Horizontal element.

Claims (6)

[Claims] 1. A rectangular or circular patch-type microstrip antenna for generating linearly polarized waves, in a direction perpendicular to the main radiation axis of the antenna and perpendicular to each other on the axes of P-axis and Q-axis. One or a plurality of line-shaped or band-shaped non-excited elements are provided in the vicinity of the outer periphery of the patch periphery, the direction of the resonance mode of the patch is the P axis, and the non-excited elements provided in the direction on the P axis are The non-excitation element which is an element perpendicular to the body substrate and which is provided in the direction on the Q axis is
A horizontal element arranged parallel to the dielectric substrate surface and separated from the dielectric substrate surface and extending in the P-axis direction, or a T-type element in which the center of the horizontal element is grounded to the dielectric substrate surface. Wide directional microstrip antenna characterized by. 2. A resonance mode orthogonal to each other is formed by a patch of four microstrip antennas so as to form a circularly polarized wave, and a non-excitation element for each resonance mode is provided with each resonance mode as the P axis. The wide directional microstrip antenna according to claim 1. 3. In order to form a circularly polarized wave, resonance modes orthogonal to each other are formed by a patch of one common microstrip antenna, and each resonance mode serves as the P axis, and a non-excitation element for each resonance mode is formed. The wide directional microstrip antenna according to claim 1, which is provided. 4. The microstrip antenna according to claim 3, wherein a non-exciting element perpendicular to the dielectric substrate is arranged in the direction of each orthogonal resonance mode of circular polarization, and a dielectric is provided in an intermediate direction between the vertical elements. A wide directional microstrip antenna with a horizontal parasitic element on the substrate surface. 5. The wide directional microstrip antenna according to claim 4, wherein both the patch and the dielectric substrate are circular, and the non-exciting element horizontal to the dielectric substrate is formed as an arc. 6. The wide directional microstrip antenna according to claim 1, wherein the non-exciting element perpendicular to the dielectric substrate is an inverted L-shape having a tip bent horizontally in the resonance direction of the patch.