JP2719592B2 - Array antenna with dielectric loading - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an array antenna loaded with a dielectric.

2. Description of the Related Art In recent years, so-called planar antennas have been widely used.
This planar antenna has a configuration in which a conductor serving as a wave source is laid on one surface of an electrically insulating substrate, and a ground conductor is arranged on the other surface. Various micro strip lines and various patch antennas are used as the wave source. When the patch antenna is used, for example, a large number of rectangular plate-shaped metal pieces (patches) are formed on a substrate to form an array antenna, and an AC voltage is supplied to these via a feed line to oscillate.

Problems to be Solved by the Invention It is known that when an oscillation or reception operation is performed by an array antenna using such a patch antenna, side ropes are significantly generated. An example is shown in FIG. FIG. 7 is a graph showing the directivity with the circular polarization rate as the observation target. That is, the transmission standard antenna that emits the linearly polarized radiation wave is directly opposed to the reception antenna whose characteristics are to be observed. The transmitting antenna is rotationally driven around an imaginary line toward the receiving antenna. In the direction in which the directivity of the receiving antenna is strong, the radiated wave is received in a state equivalent to a circularly polarized wave, and a high level as shown by waveforms P1, P2, and P3 in FIG. 7 is detected. The remaining states in FIG.
The level of the received wave oscillates due to the situation where the linearly polarized radiated wave whose direction of polarization is rotated from the transmitting antenna is received with different component levels in the directions orthogonal to each other. It shows a state where it disappears.

In the characteristics of the patch array antenna observed in such an experiment, large side lobes are observed as shown in FIG. It is known that in order to prevent such side lobes, it is necessary to increase the configuration density of patch antennas constituting an array antenna. When the configuration density is improved in this way, although side lobes can be reduced, much more precise fine processing technology is required when forming a patch antenna, and the number of steps increases. Further, since the length of the power supply line also increases, the loss of the excitation power in the power supply line increases unnecessarily, and there is a problem that the efficiency as an antenna is greatly reduced.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned technical problems and to provide a small and highly efficient dielectric loaded array antenna.

Means for Solving the Problems According to the present invention, a pair of crank-shaped micro strip lines 6 and 7 are formed on one surface 3 of a wiring board 2, and one of the micro strip lines 6 has a first length. 2a
And a plurality of first cranks having a height b extending in a direction approaching the other microstrip line 7 from the portion of the first length 2a, and having a total length L. A first straight line portion 8 having a length λg is interposed near the strip line, and the other micro strip line 7 has a second length c and a portion of the second length c from the one micro strip line 6. A plurality of second cranks of the height b extending in a direction approaching the length L are formed with the total length L. Between the second cranks, a second straight line of the length λg near the one microstrip line 6 is provided. When part 9 is interposed and λ0 is the excitation spatial wavelength, λg = 0.683λ0, and further, a = 7λg / 16, b = 3λg / 8, c = 3λg / 8, and L = 10λg / 8 are selected. On each of the first and second cranks. Gatsute rectangular parallelepiped dielectrics are dielectric loaded antenna array, characterized in that arranged, respectively.

According to the present invention, an array antenna is arranged on a wiring board made of an electrically insulating material. By arranging a dielectric equivalent on each unit antenna constituting the array antenna, the aperture efficiency of each unit antenna is increased. Thereby, the arrangement density of the unit antennas constituting the array antenna can be reduced, and the power loss in the unit antenna and the configuration for feeding power to each unit antenna can be remarkably reduced. Furthermore, by appropriately selecting the arrangement density of the unit antennas, the overall efficiency can be significantly improved.

Embodiment FIG. 1 is a perspective view showing a configuration of a dielectric loaded array antenna (hereinafter abbreviated as an antenna) 1 having a configuration which is a premise of the present invention. The antenna 1 will be described with reference to FIG. In the antenna 1 of this configuration, a large number of patches 4 made of, for example, a rectangular plate-shaped metal copper are formed on one surface 3 of a wiring board 2 made of an electrically insulating material such as a synthetic resin material. Each patch 4 has, for example, a square shape in plan view, and an interval L1 between them of 1.6, for example.
λ0 (λ0 is the excitation spatial wavelength), and the overall size of the antenna 1 is selected to be, for example, 320 mm × 320 mm. The present inventor conducted an experiment in which, for example, 64 elements of such a patch 4 were formed on the wiring board 2 and were excited at a frequency f0 (11.25 GHz). Such an experimental result is the result of FIG. 7 referred to in the section of the prior art.

On the other hand, the present inventor has conceived of disposing a dielectric 5 as indicated by a two-dot chain line on the patch 4 shown in FIG. Such a dielectric 5 is formed in a rectangular parallelepiped shape as an example,
W1 (1.25λ0), vertical D1 (1.25λ0), height H1 (1.42λ
0), and the distance D2 of the gap between the one surface 3 and the dielectric 5 was selected to be, for example, 0.08λ0.

The results of observing the frequency characteristics using such an antenna 1 are shown in the graph of FIG. For the standard transmission antenna having linear polarization described as a configuration for obtaining the result of FIG. 7 in the section of the prior art, the case where the polarization direction is parallel to the vertical direction and the case where the polarization direction is parallel to the horizontal direction The frequency characteristics of the antenna 1 of the present invention were observed. Line 1 in FIG. 2 is the case of vertical polarization, and line l2
Is the case of horizontal polarization. As is clear from FIG. 2, the antenna 1 of the present configuration obtained a result that the frequency bands f1 to f2 can be used centering on the used frequency of 12 GHz. As shown in the experimental example, a frequency band of 0.5 GHz was obtained within a range of 1 dB from the peak state of the radiated power. It is understood that such a measurement result has a significantly expanded frequency band as compared with the frequency characteristics of the standard electromagnetic horn shown in FIG.

The directivity diagram of such an antenna 1 is shown in FIG. The measuring method for obtaining FIG. 4 is the same as that described in the section of the prior art as the configuration for obtaining the result of FIG. In this configuration, it is understood that side lobes such as waveforms P1 and P3 shown in FIG. 7 are eliminated, and directivity is realized only in the front direction as shown by waveform P2.

FIG. 5 is a graph showing the relative radiated power of the antenna 11 according to this configuration. In performing the measurement shown in FIG.
In the antenna 1 having the configuration shown in FIG.
L1 is 1.19λ0, patch 4 is 16 elements, the whole size of the antenna 1 is 12cm × 12cm (4.74λ0 × 4.74λ0), and the size of the dielectric 5 is 1.0λ0 for the horizontal W1 and 1.0λ0 for the vertical D1. Height H1
Was set to 1.2λ0, and the interval D2 was set to 0.08λ0. In FIG. 5, line 13 is the relative radiated power of the antenna 1 of this configuration, and line 14 is the relative radiated power of the standard electromagnetic horn antenna.

The present inventor has proposed an antenna 11 having the dimensions described with reference to FIG. 1 and an antenna 1 having the dimensions described above with reference to FIG.
For both, the aperture efficiency and power were measured. According to this, the aperture efficiency of 35% and the gain of 28.6 dB were obtained in the configuration of 64 elements shown in FIG. 1, and the aperture efficiency of 77.1% and the gain of 23.4 dB were obtained in the configuration of 16 elements. These results show that the relative radiated power is more than doubled to several times in view of the fact that the gain of the standard electromagnetic horn is usually 22.6 to 22.9 dB.

As described above, in the antenna 1 of this configuration, by providing the dielectric 5 on the patch 4, the aperture efficiency and the gain can be significantly increased, whereby the arrangement density of the patch 4 on the wiring board 2 can be increased. Can be significantly reduced. This makes Patch 4
In this embodiment, for example, the power consumption loss in the power supply line can be reduced to half. Also, the overall efficiency can be improved.

FIG. 6 is a drawing showing a plan view of the antenna 11 according to one embodiment of the present invention. In the above-described configuration, the patches 4 are arranged on the wiring board 2 and the dielectrics 5 are arranged thereon. In this embodiment, for example, the crank-shaped micro strip lines 6 and 7 are used. I made it. In the microstrip line 6, a crank having a length 2a and a height b has a total length L, and a straight portion 8 having a length λg (λg is a line wavelength) is interposed between them.

In the microstrip line 7, a crank having a length c and a height b is arranged with a total length L, and a straight portion 9 also having a length λg is interposed between them. Such a configuration including the portion of the length L in the microstrip lines 6 and 7 and the linear portions 8 and 9 is repeated at a period L1.

The micro strip line 6, shown in FIG.
The dielectric is disposed on a portion having a length L of 7 and over both of the portions 6 and 7. That is, a gap having a length λg is provided between the dielectrics. In this embodiment, λg = 0.68
3λ0, b = 3λg / 8, a = 7λg / 16, c = 3λg / 8, L
= 10λg / 8 and L1 = 18λg / 8. Here, the length L1 is selected as follows: L1 = 2a + 2b + c (= 2λg) (1) L1 = L + λg (= 3λg) (2)

It has been verified that the use frequency band of the antenna 11 having such a configuration is improved by 3L / 2 (L + λg) times as compared with the case of the standard electromagnetic horn. It was also confirmed that results similar to those of the above-described embodiment were obtained for the aperture efficiency and the gain.

In the antenna 11 of the present embodiment, in addition to the effects of the above-described configuration, by providing the linear portions 8 and 9 having the length λg,
The overall length of the microstrip lines 6 and 7 in the antenna 11 can be made relatively short, which can significantly reduce the phase shift that occurs as the antenna 11 moves away from the excitation side during excitation. Can be used.

Effect of the Invention As described above, according to the present invention, the aperture efficiency of each unit antenna is increased. Thereby, the arrangement density of the unit antennas constituting the array antenna can be reduced, and the power loss in the unit antenna and the configuration for feeding power to each unit antenna can be remarkably reduced. Furthermore, by appropriately selecting the arrangement density of the unit antennas, the overall efficiency can be significantly improved.

Further, according to the present invention, it is possible to shorten the entire length of the pair of microstrip lines 6,7.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a basic configuration of an antenna 1 having a configuration as a premise of the present invention, FIG. 2 is a graph illustrating a frequency band used in the configuration, and FIG. 3 is a diagram illustrating frequency characteristics of a standard electromagnetic horn. FIG. 4 is a graph illustrating the directivity of the antenna 1, FIG. 5 is a graph illustrating the gain of the antenna 1, FIG. 6 is a plan view illustrating the configuration of the antenna 11 according to one embodiment of the present invention, and FIG. FIG. 7 is a graph showing the directivity of a typical prior art antenna. DESCRIPTION OF SYMBOLS 1 ... Antenna, 2 ... Wiring board, 4 ... Patch, 5 ... Dielectric, 6, 7 ... Micro strip line, 8, 9 ... Straight line part

Claims (1)

(57) [Claims] 1. A pair of crank-shaped microstrip lines 6, 7 are formed on one surface 3 of a wiring board 2, and one of the microstrip lines 6 has a first length 2a and a first length. A plurality of first cranks having a height b extending from the portion 2a in a direction approaching the other microstrip line 7 are formed with a total length L, and between the first cranks, a portion close to the other microstrip line is provided. A first linear portion 8 having a length λg is interposed, and the other microstrip line 7 extends from the portion having the second length c and the second length c in a direction approaching the one microstrip line 6. The second of the height b
A plurality of cranks having the total length L are provided, and a second linear portion 9 having the length λg is interposed between the second cranks near the one microstrip line 6, and λ0 is defined as the excitation spatial wavelength. Then, λg = 0.683λ0, and a = 7λg / 16, b = 3λg / 8, c = 3λg / 8, L = 10λg / 8, and on each of the first and second cranks, A dielectric-loaded array antenna, wherein rectangular parallelepiped dielectrics are respectively arranged.