JP2573768B2 - Leaky wave dielectric line - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leakage wave dielectric line used as a feed line, an antenna element or a circuit element in a microwave or millimeter wave band.

[0002]

2. Description of the Related Art Conventionally, for example, a microstrip line, a triplate line, a metal waveguide, a coaxial line, and the like are used as a feed line used for a high-frequency antenna.
However, when microwaves or millimeter waves having higher frequencies are used, conductor loss increases, which hinders improvement in antenna efficiency.

[0003]

Therefore, a dielectric line or a leaky wave dielectric line is used as a feed line for obtaining an antenna with low loss and high efficiency even in a high frequency centimeter wave or millimeter wave band. Used . The dielectric line is
Nonradiative Dielectric W
aveguide (NRD Waveguide)
Called, a line with a dielectric bar sandwiched between two parallel metal plates
This is a line that transmits radio waves without radiation. Leaky wave dielectric
The body line has an asymmetric structure such as a dielectric rod of a dielectric line.
To generate radiated radio waves between two parallel metal plates
I do. Since the conventional leaky wave dielectric line has a radiation direction only forward of the transmission direction with respect to the leaky wave dielectric line, for example, the radiation direction of the leaky wave is a direction perpendicular to the line or a backward inclination direction. There is a problem that the degree of freedom of design cannot be increased as a direction other than the front of the track.

[0004] The present invention has been made in view of the above problems,
Even in the microwave and millimeter wave bands, the radiation direction of leaky waves can be set to a direction other than the front of the line without generating grating lobes with large amplitude, and the design flexibility of antennas and circuit elements can be improved. It is an object of the present invention to provide a leaky wave dielectric line.

[0005]

That is, the leaky wave dielectric line according to the present invention is sandwiched and disposed between two vertically parallel metal plates, and is supplied with power at one end to be excited by the dielectric. A line and two lines which are provided at the same period and are shifted from each other by a half period corresponding to the length direction of the dielectric line, and the excitation power transmitted to the dielectric line is radiated as a leaky wave at each period. And a periodic structure of the above.

[0006]

In other words, when two systems of periodic perturbations having the same period and shifted by half a period are given to the dielectric line, a part of the transmission line wave is radiated as a leaky wave along the line.

For example, when the period length is one wavelength, radiation waves from two systems of periodic perturbations are superimposed in phase, and the radiation direction is perpendicular to the leaky dielectric line without grating lobes. Will be obtained.

[0008]

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

FIG. 1 shows the structure of a leaky wave dielectric line, in which an upper metal plate 1 and a lower metal plate 2 are arranged at an interval a of less than half a wavelength.
Are arranged in parallel, and one leaky-wave dielectric line 4 is inserted between them.

The leakage wave dielectric line 4 has a cross-sectional dimension a ×
Notch rows 5a and 5b having the same period t are formed on the upper and lower portions of the dielectric strip b, respectively, and the notch periods t are shifted from each other by a half period t / 2.

That is, the power supplied from the center conductor 7 of the coaxial line 6 excites the leaky wave dielectric line 4 and radiates a leaky wave corresponding to the notch rows 5a and 5b while transmitting.

As a result, the electric field parallel to the upper and lower metal plates 1 and 2 is transmitted as a transmission wave through the leaky wave dielectric line 4 in the z-axis direction of the coordinate axis in the drawing, and the notch trains 5a and 5b are used to transmit the electric wave. Some of them are radiated as leaky waves.

Here, the arrangement period t of the notch rows 5a, 5b
Is one wavelength, the electric field distributions of the leaky wave from the upper notch row 5a and the leaky wave from the lower notch row 5b have opposite phases.

For example, if there is no deviation of half a cycle t / 2 between the upper and lower notch rows 5a and 5b and the notches are formed at the same cross-sectional position, they cancel each other out and no leaky wave is generated. As shown by the two-system periodic structure in (1), if the periods t of the notch rows 5a and 5b are equal to the transmission wavelength and are arranged at positions shifted by a half period t / 2, respectively, the leakage wave dielectric line 4 and On the parallel lines, in-phase leaky waves are generated. In this case, even if there is a reflected wave at the end of the leaky wave dielectric line 4, the occurrence of the leaky wave is not affected. This notch
The arrangement was explained with the upper and lower notches, but arranged at right angles,
Alternatively, they may be arranged at different angles.

FIG. 2 shows the xy plane electric field distribution characteristics of the leaky wave dielectric line. In this case, the dimensions of the leaky wave dielectric line 4 are height a = 5.9 mm and width b = b. 5.4mm,
At the measurement frequency f = 23.9 GHz, the structure of the notch rows 5a and 5b has a width w = 2 mm, a depth d = 2 mm, and a period t = 23 mm. In the figure, the horizontal electric field component Ex as a transmission wave is indicated by a black circle, and the vertical electric field component Ey of a leaky wave is indicated by a white circle.

That is, the horizontal electric field component Ex has its electric field concentrated near the leaky wave dielectric line 4,
Decreases sharply when moving away from. Also, the vertical electric field component Ey
Is weak near the center of the leaky wave dielectric line 4, increases sharply away from the center, shows a maximum value near the end of the line, and gradually decreases thereafter. That is, this is radiated as a leaky wave. Note that the phases of the leaky waves on the left and right are opposite to each other.

FIG. 3 shows the yz plane electric field intensity distribution characteristics of the horizontal electric field component Ex in the leaky wave dielectric line. The line length of the leaky wave dielectric line 4 in this case is 195 m.
m and the number of notches are 18 in total in the upper and lower directions, and other specifications are the same as those shown in FIG. In the upper part of the figure, the schematic structure of the leaky wave dielectric line 4 is shown corresponding to the horizontal axis z.

That is, the peak of the horizontal electric field component Ex coincides with the position where the notch rows 5a and 5b are formed. After a mountain is formed, it becomes weak rapidly.
By configuring such a structure of the notch rows 5a and 5b as asymmetric on the track, a leak wave can be easily generated.

FIG. 4 shows radiation directivity characteristics when the above-mentioned leaky wave dielectric line is applied to an antenna. The radiation is radiated from between the upper metal plate 1 and the lower metal plate 2 in FIG. The case where the horizontal direction is the θ direction in the plane and the vertical axis is the electric field strength Ey is shown.

According to this radiation directivity characteristic, the maximum electric field strength Ey at θ = 90 ° perpendicular to the leaky wave dielectric line 4
The half width is 4.3 ° and the sub-lobe
The level is -12.5 dB, and no grating lobe is generated.

That is, when two systems of periodic perturbations having the same period are given to the dielectric line, a part of the transmission line wave is radiated as a leaky wave along the line. The radiation waves from the periodic perturbations are superimposed in phase. For example, when the period length is one wavelength, the radiated wave is radiated in a direction perpendicular to the leaky wave dielectric line 4 without a crating lobe.

Therefore, when the leaky-wave dielectric line 4 is used for an antenna which radiates to the broad side, it is not necessary to match the ends of the line, so that the loss is extremely small, and the efficiency is high. A standing wave antenna can be realized.

Further, the leaky wave dielectric line 4 can be used as a traveling wave type antenna, and even in this case, an arbitrary radiation direction can be obtained without a grating lobe.

Here, the propagation speed and the attenuation constant of the leaky wave dielectric line 4 can be easily controlled by changing parameters of the width w, the depth d and the period t of the notch rows 5a and 5b. it can.

Therefore, according to the leaky wave dielectric line having the above-described structure, two periodic structures having the same period, each including the notch rows 5a and 5b, are formed along the dielectric strip of the leaky wave dielectric line 4. Are formed so as to be shifted from each other by a half cycle t / 2, and are arranged between the upper metal plate 1 and the lower metal plate 2 so that various types of leakage waves can be obtained without any grating lobe in any radiation direction. Can be generated, and various antennas and circuit elements can be configured by coupling the antenna radiating element to the antenna radiating element.

FIG. 5 shows a configuration in which the leaky wave dielectric line of the present invention is applied to a power distribution circuit. This power distribution circuit is composed of two leaky wave dielectric lines 11 and 12, The metal blocks 13 and 14 are arranged on both sides of the wave dielectric lines 11 and 12 which are parallel to and correspond to the notch rows 11a, 11b, 12a and 12b, respectively, serving as leak wave generating portions.

That is, the power supplied from the terminal T 1 of the first leaky-wave dielectric line 11 is radiated as a leak wave from the notch trains 11 a and 11 b of the line 11, and the notch of the second leaky-wave dielectric line 12 is It is coupled to columns 12a, 12b. Then, the electric power is output from the terminals T2 and T3 of the second leaky dielectric line 12 with equal power.

On the other hand, each of the above-mentioned leaky wave dielectric lines 11 and 12
The leakage wave radiated in the direction opposite to the opposing side surface is not reflected by the metal blocks 13 and 14 and does not propagate to the outside. Further, there is no variation due to the arrangement interval of the leakage wave dielectric lines 11 and 12. In addition, it is possible to realize a power distribution circuit which can easily obtain a stable coupling operation.

If the embodiment shown in FIG. 1 is applied, an antenna or a circuit element can be constituted by using one leaky wave dielectric line. It can be used as an antenna by coupling with a radiating element that has been used, or for coupling between other circuits.

The leaky wave dielectric line in each of the above embodiments is constructed based on various dielectric lines such as an NRD guide, an image guide, an insulator guide, a gobo line, and an inverse dielectric strip. For feeding power to the dielectric line, a dielectric line, a strip line, a Rechel line, a coaxial line, a waveguide, or the like is used.

[0031]

As described above, according to the present invention, a dielectric line which is sandwiched and disposed between two vertically parallel metal plates, one end of which is supplied with power and is excited, Corresponding to the length direction, the two periodic structures are provided at the same period and shifted from each other by a half period, and the excitation power transmitted to the dielectric line is radiated as a leakage wave at each period. In microwave and millimeter wave bands,
Without the occurrence of grating lobes with large amplitude, the radiation direction of the leaky wave is set to a direction other than the front of the line,
The degree of freedom in designing antennas and circuit elements can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a leaky wave dielectric line according to one embodiment of the present invention.

FIG. 2 is a view showing an xy plane electric field intensity distribution characteristic of the leaky wave dielectric line.

FIG. 3 shows a horizontal electric field component E in the leaky wave dielectric line.
The figure which shows the yz-plane electric field intensity distribution characteristic of x.

FIG. 4 is a diagram showing radiation directivity characteristics when the leaky wave dielectric line is applied to an antenna.

FIG. 5 is a diagram showing a configuration when the leaky wave dielectric line of the present invention is applied to a power distribution circuit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Upper metal plate, 2 ... Lower metal plate, 4, 11, 12 ... Leaky wave dielectric line, 5a, 5b, 11a, 11b, 12
a, 12b: Notch row, 6: Coaxial line, 7: Central conductor,
13, 14 ... metal block.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Toshihiko Agatsuma 4-16-20 Tsurugaoka, Izumi-ku, Sendai, Miyagi Prefecture (56) References Special Table Sho-63-500698 (JP, A) Real Open Showa 50-91784 (JP) , U) Proceedings of the 1991 Autumn Meeting of the Institute of Electronics, Information and Communication Engineers B-70 Transactions of the Institute of Electronics, Information and Communication Engineers, VOL. J73-CI, NO. 3, PP. 87−94

Claims (1)

(57) [Claims] (1)Sandwiched between two vertically parallel metal plates
Dielectric line that is provided and excited at one end
When, On the different surface corresponding to the length direction of this dielectric line, the same
Are shifted from each other by half a cycle, and the
The excitation power transmitted to the dielectric line is radiated as a leakage wave.
Two periodic structures, Characterized by having Leaky wave dielectric line.