JP3344802B2 - Planar antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar antenna,
In particular, the present invention relates to a planar antenna using a waveguide.

[0002]

2. Description of the Related Art Conventionally, as an antenna using a waveguide, for example, there is a slot array antenna as shown in FIG. This is because a large number of rectangular radiation waveguides 4 are arranged in the lateral direction of one rectangular feed waveguide 2, and each rectangular radiation waveguide 4 has:
A number of slots 6 for emitting radio waves are formed.

Radio waves transmitted from the feeding waveguide 2 to the radiation waveguides 4 are sequentially radiated from the slots 6, 6,... Arranged in series. The phase relationship is determined by the guide wavelength in the waveguide and the interval between the slots 6, and the directivity is determined according to the phase relationship.

Therefore, if the frequency changes, the directivity is inclined, which leads to a decrease in gain in communication with a fixed point, and it is not possible to widen the frequency bandwidth. If an attempt is made to increase the gain, the tendency is further increased because the beam width is reduced. FIG. 10 shows a gain-frequency characteristic diagram of such an antenna. In this case, 35d
The frequency bandwidth of 1dB down near Bi is about 190M
Hz, which is very narrow.

[0005] In addition, there is a radial line type antenna as shown in FIG. This is a configuration in which two parallel circular conductor plates 8a and 8b are arranged at an interval in the vertical direction, and power is supplied axially symmetrically from the center of the lower conductor plate 8b via a coaxial cable 10. The plate 1a has a slot 1
2 are formed.

[0006] In this radial line type antenna,
The slots 12 in the circumferential direction are fed in parallel, but are fed in series in the radial direction. Therefore, this method cannot increase the frequency bandwidth.

[0007]

In the near future, satellite broadcasting and satellite communication in the 21 GHz band with a higher use frequency are planned. In order to receive such broadcasts and communications,
For example, the gain is 37 dBi and the frequency bandwidth is 600 MHz
Antenna is required. However, the slot array antenna and the radial line antenna as described above have a narrow frequency bandwidth, and cannot be used at all for the 21 GHz band satellite broadcasting and satellite communication as described above.

In general, flat antennas for satellite broadcasting and satellite communication reception are shifting from microstrip line antennas and triplate-type antennas to antennas using a waveguide with a small transmission loss as a feed circuit. In such an antenna using a waveguide as a feeding circuit, it is desirable to feed a plurality of radiating elements in parallel by the waveguide in order to widen the frequency band. However, in that case, the spacing between the radiating elements should be 1
It must be below the wavelength, which is almost impossible by construction. As a result, a grating lobe is generated in the directivity characteristic, and the power is transmitted by the grating lobe, so that the gain is reduced, the efficiency is reduced, and the frequency bandwidth is narrowed.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and comprises a power supply waveguide section and a power supply waveguide section disposed on both sides of the power supply waveguide section . at least one pair radiating waveguide portion of the one end of which is a radiating aperture, between the waveguide section and the respective radiating waveguide portion for the feed, they state that electrically connects respectively provided, one end to the respective radiating waveguide portion, guide for the feeding
The other end is positioned in the wave tube side, less both ends are a probe
Each of the radiating waveguide sections includes a pair of suspended triplate lines, and a dielectric loaded on the radiation aperture of each of the radiation waveguide sections. Also, a plurality of such planar antennas can be arranged at intervals larger than the guide wavelength of the radio wave radiated from the radiation waveguide section.

[0010]

In general, it is difficult to feed a radiating element in parallel with an element spacing of one wavelength or less by using only a waveguide circuit. To do this, the branching of the waveguide is indispensable. If the branching into a T-shape is made by an E branch having a relatively small occupied area in the plane including the branching direction, the two-way bidirectional phase difference is opposite since the phase, the waveguides as radiating elements in both ends, connecting the side surface of the waveguide, the direction of the radiation electric field, since the direction of the electric field in the connecting portion, both of the radiation field is reversed Become a phase. It is easy to arrange the two branched waveguides once so as to be parallel and feed them at the same distance. However, it is difficult to obtain a waveguide circuit in which a large number of elements are arranged in a plane to obtain an in-phase radiation electric field. Therefore, in the present invention, 1 / from the end of the feeding waveguide.
Using the end of the suspended triplate line as a probe at the wavelength inside the four waveguides, insert it from both sides of the side wall along the direction of the electric field to form a T-shaped branch and branch into at least one pair of radiation waveguides. Power is inserted into the side wall from the opposite direction or from the opposite side. In this case, the signals are branched in opposite phases. However, since the direction of the radiated electric field from the radiation waveguide is in the direction of the suspended triplate line, both radiated electric fields have the same phase. The distance between the radiation waveguide portions can be reduced. However, even in this case, grating lobes occur in the directional characteristics, and high gain, high efficiency, and wide
The frequency bandwidth was disturbed. Therefore, by providing a dielectric material in the radiation aperture, the grating lobe is suppressed to achieve high gain , high efficiency, and a wide frequency bandwidth.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment is shown in FIGS. This embodiment has, as shown in FIG. 1, conductor plates 14 and 16 which are arranged one above the other. A rectangular groove 18a having an open upper portion is formed in the conductive plate 14, and a rectangular groove 18b having an open lower portion is formed at a position of the conductive plate 16 corresponding to the groove 18a. In a state where the conductor plates 14 and 16 are overlapped, the rectangular feeding waveguide portion 18 is formed by the grooves 18a and 18b.

On both sides of the groove 18a in the conductor plate 14,
Circular holes 20a, 20a whose upper parts are open at intervals are formed. Conductor plate 1 corresponding to holes 20a, 20a
In the position of No. 6, circular holes 20b, 20b opened up and down
Is formed. Superposed state in the conductive plates 14 and 16, holes 20a, 20a, hole 20b, the circular waveguide 20, 20 for the radiation are formed by 20b.

The grooves 22a, 22a shallower than the groove 18a are provided between the groove 18a and the hole 20a so as to connect them.
Is formed. The conductor plate 16 also has grooves 22a, 22a
A shallow groove 22b is formed at a position corresponding to the groove so as to connect the groove 18b and the hole 20b. Conductor plates 14, 16
Are overlapped with each other, a space 22 for forming a triplate feeding circuit is formed by the grooves 22a and 22b.

With the conductor plates 14 and 16 superposed,
A thin film substrate 24 is inserted between these so as to straddle the holes 20a and 20b. Conductive plates 26, 26 are formed on the film substrate 24 such that one end is located on the groove 18a side, the halfway passes through the groove 22a, and the other end is located on the hole 20a side. These conductor plates 26
And a space 22 form a suspended triplate feed circuit. Note that each of the above suspenders
Both ends of the dead triplate circuit are placed inside the feed waveguide,
Probe with approximately 1/4 line wavelength inserted into launching waveguide
Functions as 28. Various shapes as shown in FIGS. 3A to 3D are used as the shape of the probe 28, for example. The radiating waveguides 20, 20 are fed in parallel in-phase by the suspended triplate feed circuit.

FIG. 4 (a) shows such a planar antenna, in which the diameter of the radiation waveguide 20 is 17 mm, and these are spaced apart in the direction of the E plane by a 1.375 in-tube wavelength interval (one wavelength is 24 wavelengths).
mm), that is, the distance between the centers of the radiation waveguides 20 is 33 m.
It represents a directivity characteristic diagram of E-plane direction in the case of a m, about
A large grating lobe 30 occurs in the direction of 50 degrees . This is because the interval between the radiation waveguides 20 is larger than one guide wavelength. Therefore, the gain versus frequency characteristic of this planar antenna is as shown by reference numeral 32 in FIG. 5, the maximum gain is only about 10 dBi, and the frequency bandwidth of 1 dB down is narrow.

Therefore, in this embodiment, the radiation waveguide 2
Above the 0-opening surface, columnar dielectrics 34, 34 having a small loss and a low dielectric constant are loaded. This dielectric 34
For example, one having a diameter of 28 mm and a height of 26 mm is used. This dielectric 34 is used for the radiation waveguide 20.
Can be arranged directly on the opening surface of the substrate, or can be arranged with a space or through a spacer 36 having a low dielectric constant such as a foam material. Instead of providing the spacer 36, a leg may be provided on the outer periphery of the lower surface of the dielectric 34.

FIG. 4B shows a directional pattern of the plane antenna in which the dielectric material 34 is added in the E-plane direction. As is clear from this, the grating lobe in the direction of about 50 degrees has disappeared due to the loading of the dielectric 34,
The grating lobe 37 remains in the direction of about 30 degrees.
However , this is the same as the size of the side lobe that can be obtained even when the element spacing is small, and is very small as is clear from the comparison of the grating lobes 30 and 37 in FIGS. Accordingly, the gain versus frequency characteristic when the dielectric 34 is loaded is as shown by reference numeral 38 in FIG. 5, and the maximum gain is 17.4 dBi. FIG.
Reference numeral 40 designates 1 when the dielectric 34 is loaded.
It is a level of dB down, and its frequency bandwidth is about 1
About 1.15 from 1.9 GHz to about 13.05 GHz
There is also GHz.

The area of the antenna must be between the two radiating waveguides.
When calculated as twice the square of the interval , the aperture efficiency is up to 1
Over 20%. Since the aperture efficiency of the electromagnetic horn having the same gain is about 80%, it can be seen that this planar antenna has a very high efficiency. There is also about 1.15 GHz from 9 GHz to about 13.05 GHz.

FIGS. 6A and 6B show a second embodiment. This embodiment is for supplying in-phase power to four radiation waveguides 20, and a triplate line 26 which forms a part of a triplate power supply circuit provided on both sides of the power supply waveguide 18.
1 splits into two near the feeding waveguide 18 and feeds the radiation waveguide 20. Reference numeral 221 denotes a space for forming a suspended triplate feed circuit, 281 denotes a probe provided at the tip of the triplate line 261, and 241 denotes a thin film substrate on which the triplate line 261 is formed. It is exaggerated. Other parts are the same as those of the first embodiment. As is clear from the drawing, the power supply waveguide 18, the radiation waveguide 20, and the space 221 for the suspended triplate power supply circuit configuration.
Are divided into upper and lower parts. Arrows shown in FIG. 3A indicate the direction of the electric field.

FIGS. 7A and 7B show a third embodiment. This embodiment is also for supplying in-phase power to the four radiation waveguides 20, and a triplate line 26 which is a part of a triplate power supply circuit provided on both sides of the power supply waveguide 18 is provided.
2 branches off at a position distant from the feeding waveguide 18, and feeds the radiation waveguide 20 from the opposite side of the second embodiment. Reference numeral 222 denotes a space for forming a suspended triplate feed circuit; 282, a probe provided at the tip of the triplate line 262; 242, a thin film substrate on which the triplate line 262 is formed; It is exaggerated. Other parts are the same as those of the first embodiment. As is clear from the figure, the power supply waveguide 18, the radiation waveguide 20, and the space 222 for forming the suspended triplate power supply circuit are formed vertically. Also in FIG. 3A, the arrows indicate the direction of the electric field.

FIG. 8 shows a fourth embodiment. In this embodiment, four radiation waveguides 20 are used as one set, and four sets, that is, a total of 16 waveguides are used. Even between adjacent sets of radiation waveguides 20, each has a 1.5 guide wavelength (one guide wavelength is, for example, 24 mm).

The feeding waveguide 18 for feeding the four waveguides 20 in the same set includes an upper waveguide portion 181 and a lower waveguide at almost the center of the four radiation waveguides 20. 2 in the wave tube section 182
The upper waveguide 181 and the lower waveguide 182 in FIG.
Only different.

The phase difference between the electric field supplied to the lower radiation waveguide 20 and the electric field supplied to the upper radiation waveguide 20 is set to 180 degrees, and the phase difference is inverted by the waveguide branch. This is because the phases become in-phase and linearly polarized waves are radiated. The other configuration is the same as that of the first embodiment. Therefore, the same reference numerals are given to the same parts, and the description is omitted.

Such a dielectric-loaded planar antenna has a gain of 17d depending on the size of the dielectric 34 when used alone.
Since the aperture efficiency can be set to about 200% near Bi, the grating lobe can be eliminated even if the interval between the radiation waveguides 20 is set to 1.5 wavelength or more. Accordingly, even if the interval between the radiation waveguides 20 is set to 1.5 in-wavelength as in this embodiment, a sufficiently wide frequency bandwidth, high efficiency, and high gain can be obtained.

[0025]

As described above, according to the present invention, the distance of the radiating waveguide portion is reduced to be as close to one wavelength as possible by using the suspended triplate line,
By loading the dielectric, the grating lobes are suppressed, and the power consumed by the grating lobes is directed toward the main surface, thereby improving the gain and achieving higher efficiency and wider frequency bandwidth. . In particular, this effect is remarkable when a plurality of such planar antennas are arranged and arranged at intervals equal to or longer than the guide wavelength. Therefore, it is possible to realize an antenna optimal for receiving 21 GHz band satellite broadcasting and satellite communication to be realized in the future.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a first embodiment of a planar antenna according to the present invention.

FIG. 2 is a plan view and a partially broken front view of the first embodiment.

FIG. 3 is a plan view of various conductor plates used in the first embodiment.

FIG. 4 is a directional characteristic diagram of the first embodiment and a state where a dielectric is removed therefrom.

FIG. 5 is a gain-frequency characteristic diagram of the first embodiment and a state where a dielectric is removed therefrom.

FIG. 6 is a plan view of the second embodiment and AA in the plan view.
It is sectional drawing which follows a line.

FIG. 7 is a plan view of the third embodiment and BB of the plan view.
It is sectional drawing which follows a line.

FIG. 8 is a plan view of the fourth embodiment.

FIG. 9 is a perspective view of a conventional slot array antenna.

10 is a gain-frequency characteristic diagram of the slot array antenna of FIG. 7;

FIG. 11 is a plan view and a vertical sectional front view of a conventional radial line antenna.

[Explanation of symbols]

18 Feeding Waveguide 20 Radiating Waveguide 22 Space for Triplate 26 Conductor Plate (Suspended Triplate Line) 34 Dielectric

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshio Makimoto 2-15-3 Shinsenri Nishimachi, Toyonaka City, Osaka (72) Inventor Yoshihiko Sugio 3-3-9, Okutenjincho, Takatsuki City, Osaka Prefecture (72) Inventor Tetsuo Tsugawa 13-1 Otsuki Yamato, Yawata-shi, Kyoto (72) Inventor Shunichi Makaku 2-15, Hamasaki-dori, Hyogo-ku, Kobe-shi, Hyogo Inside of Die-Tux antenna, Inc. 62-58706 (JP, A) JP-A-62-36905 (JP, A) JP-A-6-503930 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01Q 13/02 H01Q 21/06

Claims (1)

(57) [Claims] 1. A power feeding waveguide portion, at least one pair of radiation waveguide portions respectively disposed on both sides of the power feeding waveguide portion and having one end provided with a radiation opening, between the waveguide portion and each radiating waveguide section, these are provided respectively in a state of electrically connecting one end to the respective radiating waveguide portion side guide for the feeding
The other end is positioned in the wave tube side, less both ends are a probe
A planar antenna comprising : a pair of suspended triplate lines; and a dielectric loaded on the radiation aperture of each of the radiation waveguide sections.