JPH02288708A - Slot array antenna - Google Patents

Abstract

PURPOSE:To obtain a high performance antenna with a desired characteristic without complicated structure by setting a power radiation slot formed with a metallic plate along a direction in which a traveling wave propagates while the size and mutual interval are sequentially changed. CONSTITUTION:Square metallic plates 1, 2 are arranged in this antenna so that they are opposed to each other while being parted with each other, and lots of power radiation slots 1a are arranged to the square metallic plate 1 longitudinally and laterally. Then a metal-made surrounding wall 3 to connect the surrounding ridge of the square metallic plates 1, 2 is provided. The size of the power radiation slots 1a is gradually increased toward the propagation direction for each array to obtain uniform power aperture distribution in the slot array and intervals Sy1, Sy2, Sy3,... among the slot arrays in the propagation direction are gradually decreased. That is, the said coupling rate is adjusted by varying sequentially the size of the slots so that the aperture distribution of the amplitude and phase of the radiation power is a desired distribution and the deviation of the phase caused by adjusting the coupling rate is compensated by gradually varying the interval among the slots.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a slot array antenna used for communication antennas, broadcasting antennas, etc., and particularly relates to the shape of the slot array on the radiation surface of these antennas.

[Conventional technology]

In the conventional waveguide slot array antenna, as shown in the perspective view of FIG. It is configured as an antenna with a leaky waveform that is radiated to the outside when passing through point b, and its power density exhibits characteristics as shown in FIG.

[Problem to be solved by the invention]

However, in the conventional slot array antenna as described above, the ratio (coupling rate) of the slot b to the propagating power is constant, so as shown in the power density characteristic in Figure 13, the propagating power decreases exponentially each time it passes through slot b). That is, slot 11
The power radiated from the antenna also decreases as it advances further, and with such characteristics where the aperture distribution of amplitude becomes non-uniform, there is a problem that the side lobe level increases and the gain decreases.

The present invention attempts to solve these problems, and aims to provide a slot array antenna with a desired amplitude-phase aperture distribution.

[Means to solve the problem]

Therefore, in the slot 7 ray antenna of the present invention, a traveling wave traveling on the back side of the radiation surface of a metal plate in which a large number of power radiation slots are formed combines with the above-mentioned sub-o7), and radio waves are emitted from the slot. In the slot array antenna, the power radiation slots formed in the metal plate constitute a slot array set by sequentially changing the size and mutual spacing along the direction in which the forward and downward waves advance. It is characterized by

[For production]

In the above-mentioned slot array antenna of the present invention, the coupling ratio is increased to 81g by sequentially changing the size of the slots so that the aperture distribution of the amplitude phase of the radiated power becomes a desired distribution. Furthermore, the phase shift caused by adjusting the coupling ratio can be compensated for by gradually changing the spacing between the slots.

〔Example〕

Hereinafter, embodiments of the present invention will be explained with reference to the drawings.
Pt51-8 show a slot array antenna as an fjSl top embodiment of the present invention, FIG. 1 is a perspective view thereof, FIG. 2 is a plan view showing the slot array, and FIG. 3 is its propagation. A perspective view showing the mode, FIG. 4 is a graph showing the relationship between the size of the slot and impedance,
FIG. 5 is a graph showing the relationship between the slot size and the coupling rate, FIG. 6 is a graph showing the relationship between the slot size and slow wave rate, and FIG. 7 is a slot array antenna as a modified example of ttSl. FIG. 8 is a perspective view of a slot 7 ray antenna as a second modification thereof,
9 to 11 show a slot array antenna as a second embodiment of the present invention, in which FIG. 9 is a central vertical perspective view of the antenna, FIG. 10 is a perspective view of the slot arrangement, and FIG.
Figure 1 is a graph showing the power density characteristics.

First, a slot array antenna as a first embodiment of the present invention will be explained. As shown in FIG. 1, this rectangular waveguide antenna consists of rectangular metal plates 1. are arranged, and one rectangular metal plate 1 has a large number of power radiation slots (la) arranged in rows and columns.

A metal fi91FFI"!! 3 is provided to connect the peripheral edges of these rectangular metal plates 1.2, and a rectangular waveguide space is formed inside of these rectangular metal plates 1.2 and the metal peripheral wall 3. A horn-shaped waveguide 4 as a power feeding means is connected to a power feeding opening 3a provided between the rectangular waveguides 2.A dielectric radio wave is formed inside the horn-shaped waveguide 4. A lens 5a is disposed, and this lens 5a functions to correct the spherical wave propagating inside the horn-shaped waveguide 4 into a plane wave and guide it to the waveguide space S. A dielectric slow wave circuit 5b is arranged inside,
The grating lobes are suppressed.

Note that a terminating resistor 6 is provided at the end of the waveguide.

In such an antenna, the slot 7 ray is arranged such that the size of the power radiation slot (la) gradually increases row by row in the propagation direction, as shown in FIG. 2, in order to obtain a −-like power aperture distribution. is formed. Furthermore, this slot array has three slot rows in the propagation direction.
The distance S)'+*5FzvSF3t... is formed so as to gradually decrease.

According to the configuration described above, in the ff1l embodiment of the present invention, the power supplied by the horn-shaped waveguide 4 is transferred to the rectangular waveguide cavity +1
118 in the fundamental mode shown in FIG. 3, each power radiator is gradually radiated into free space. Although Figure 3 is drawn ignoring the size ratio in order to make the mode easier to understand, it actually has a very flat and wide structure with a ratio of width to height of several tens of pairs.
Several tens of slots can be provided laterally on one mode.

By the way, in order to make the power radiated from each slot the same in an array with one row of slots and to ultimately radiate the total power, the total power must be P. Then, the radiation amount of each row should be P, /n, and the slot coupling ratio for the waveguide space internal power of each row should be set so that the radiation amount of each row is all P, /n. good.

For example, if the slot coupling rate of the kth column is α, and the internal power after passing through the slot of the second column is PK, then α, Po=α2P, =α, ■)2 ='''' = aK PK-1 = ・ ・ e=Po
/nAlso, P, -(1-1/n)Po P2=(1-2/n)P.

PK=(1k/n)P,) Therefore, α1= 1/port α2=Po/nP1=1/(n-1) αy = 1/(+1 to n->), and the connection of the k-th slot It is sufficient to set the rate αK to 1/(+1 to n-).

Figure 4 shows the relationship between the size of the slot 1a and the impedance in the vicinity of half a wavelength when the frequency is constant.From the graph in 2, when the size of the slot 1a is gradually increased from 0, It can be seen that both the resistance component R and the reactance component X increase, and when the wavelength reaches around half a wavelength, the reactance component X rapidly decreases, resulting in a resonance state. Furthermore, it can be seen that as the size of the slot is increased, the actance X continues to rapidly decrease and increases again after reaching a negative peak, while the resistance R decreases.

The relationship between the slot size and the coupling rate α due to this effect is shown in Figure 5. The coupling rate α peaks when the slot size is around half a wavelength, and decreases when the slot size becomes larger or smaller than half a wavelength. . Therefore, the size of the thrower )la to obtain the desired coupling ratio can be determined.

In the first embodiment of the invention, the slot 1 is smaller than the resonance length.
As shown in Figure 2.5, the size of slot 1a is such that the first column is α1, the second column is α2, and the k column is α. 11112I゛°°
Since it is designed to gradually increase in the conjugate of glK+..., the radiated power becomes uniform. The terminating resistor 6 can be omitted if it radiates as much power as possible so that the adverse effects of reflection from the outer wall can be ignored.

Further, as shown in FIG. 4, the phase of the radio waves radiated from the slots leads or lags the phase inside the rectangular waveguide due to the influence of the actance X.

If the ratio of the tube wavelength equation 8 and the free space wavelength λ considering the delayed phase and advanced phase is called the slow wave rate, then the relationship between the slot size and the slow wave rate is as shown in FIG. The slow wave factor ζ decreases when the slot size is less than half a wavelength, rapidly increases around the half wavelength, and decreases again when the slot size further increases. In this way, by correcting the spacing between slot rows to match the slow wave factor ζ that changes depending on the size of the slot, radio waves of the same phase can be emitted from each row.

Therefore, in the case of this embodiment, it is sufficient to gradually reduce the slot interval.

In a specific example when such an antenna is designed to be used in the 1201+2 band, the size of metal plates 1 and 2 is 50.
At X30cm, the efficiency is 70%, which is approximately 33.2d B
The gain is obtained.

However, contrary to the first embodiment, if a slot larger than the resonance length is used, the length of the thrower (la) is gradually decreased and the interval is gradually increased.

Further, if the distance between the throwers (thrower) la is increased at a constant rate, the directivity will be tilted in the propagation direction, and if it is decreased, the directivity will be tilted in the opposite direction, so that the directivity can be easily tilted.

Next, in the antenna of the 11.2 modification shown in FIGS. 7 and 8, instead of the horn-shaped waveguide 4 as the power feeding section, a rectangular waveguide of approximately the conventional size with a power supply opening 9 formed therein is used. A wave tube 10 is provided. This increases the uniformity of the internal power, improves the aperture efficiency, and has the advantage of being more compact.

Also, when using the power feeding means of the first modified example, the antenna is tiled symmetrically with respect to the rectangular waveguide 10, as shown by the two-dot chain line in FIG. 7, similarly to the second example. can be achieved. As a result, even when the 1.1 wave number fluctuates and the directivity changes, the composite directivity on both sides is kept constant, so stable characteristics can be obtained over a wide band.

As for the power feeding method in C), a configuration in which a plurality of posts and slots are excited by a microstrip line can be adopted.

In the first embodiment of the present invention, the magnetic surface is used as the radiation surface as shown in FIG. tpJ3, but it is of course possible to configure the antenna so that the electric surface is a flat radiation surface.

Next, a second embodiment of the present invention will be described. This example is an example of a circular waveguide slot array antenna, and as shown in FIG. Disc-shaped metal plates 1 and 2 are arranged, and on one metal plate 1, throwers 1a are formed so as to be arranged on concentric circles or on a spiral trajectory.

Further, in the center of the other metal plate 2, a power feeding opening 3a is formed to be connected to a coaxial line 7 serving as a power feeding section. A metal peripheral wall 3 is provided that connects the peripheral edges of these metal plates 1.2, and a waveguide space S is formed inside of these metal plates 1.2 and metal peripheral wall 3. By the way, in this waveguide space S, an intermediate metal plate 8 parallel to the metal plate 1.2 is provided with a gap left between it and the surrounding wall 3 for detouring the power supply. , the waveguide space S is divided into two waveguide space sections S1.32.

Further, a coaxial line 7 is connected to the power feeding opening 3a of the metal plate 2.

In this example, in order to obtain a uniform distribution, the size of the power discharging thrower) la is formed so as to gradually decrease from row to row along the propagation direction.

In the antenna configured in this way, the lower waveguide space S
As shown by the arrow Pf, the power supplied to t passes through the lower waveguide space S1, bypasses the gap between the peripheral wall 3 and the intermediate metal plate 8, and reaches the upper waveguide space S2. It spreads towards the medium heat area. In this way, the coaxial line 7 and the intermediate metal plate 8 that forms the gap for detouring the feeding power between the peripheral wall 3 and the peripheral wall 3 can be used to create a circumference! ! 3 to the internal waveguide space S
A power supply that can concentrate the power supplied towards the center of the
An f-stage is constructed.

Then, when the feeding power passes through the upper waveguide air fi11 section S2, the power is radiated through the throat (thrower) la formed on the metal plate l.

Next, we will explain how to design the size of each station of the thrower) la and the Ill interval between V cycles in this example. lit! As shown in FIG. 1, consider a slot located on the radius of a circle with a radius nd, in which n rows of throwers) la are formed at equal fit intervals d. The power density before slot radiation in the row from the outer periphery is PK-〇, and the power density after radiation is PK. , the initial value of the power density is P, and the power radiated from each slot is C, then the power density of 6iS passing through the slot in column 0 is Pl-0=P.

, and the power density after passing is P1+. = P　o　−C becomes.

Furthermore, the power that has passed through the slots in the first column is as follows just before reaching the slots in the second column, and the power density after passing through is as follows.

In this way, in order for the power density to become 0 after passing through the nth column slot, the following equation must hold true.

=0 nPo-%n+(n-1)+(n-2)+6+@
It is sufficient if +3+2+11C=0 power is radiated.

In addition, if we determine the coupling 4< a K such that the product of the coupling TlPa of the k-th slot and the internal power density PK-0 that reaches the second column is equal to the above C, then the radiation surface The amplitude distribution of the aperture surface of the metal plate 1 becomes uniform.

Furthermore, PK-ri is -0 to P = 1 (,, +2 cl to po-k-12n-
Since n-(k-1) 2 , it becomes.

By determining αK using the method described above, determining the size of slot 1a in the same manner as in the first embodiment, and correcting the spacing, radio waves with the same phase and approximately the same amplitude can be emitted. Become.

Note that, as mentioned above, the phase shift caused by changing the size of the slots (la) for each row can be corrected by the spacing between the slot rows, and the desired coupling rate can be set, so the binomial distribution and dollar 7 - Naebishi 7 distribution and tailor -
A high-performance antenna can be obtained with a desired [1110 distribution, etc.] distribution.

On the other hand, when the throws 2) 1a are arranged on a spiral locus, the internal electromagnetic field power per unit area on the circumference of radius r is the total supplied power P.

and the interval of the waveguide space is 11, then P −P o/
(2tr rX h ).

Also, the radiation power P at the position of radius r is p,=axp
==crxpJ2yrXh).

Therefore, the radiation power P ra+ from the 11th thron t counting from the outer circumference is: Prn=αII
It is sufficient to calculate aI+ for each slot as follows: (r, t: distance between the n@a slot and the center).

Furthermore, although in this second embodiment, the slot 1a uses a portion shorter than the resonance length, it is of course possible to use a longer portion.

〔Effect of the invention〕

As detailed above, according to the slot 7-ray antenna of the present invention, a desired aperture distribution can be obtained by changing the size of the slots and their mutual spacing along the direction in which the traveling wave travels. Since the antenna can be designed appropriately, a high-performance antenna with desired characteristics can be obtained without complicating the structure.

[Brief explanation of drawings]

1 to 8 show the slot array antenna as the ground side of the present invention, FIG. 1 is a perspective view thereof, FIG. 2 is a plan view showing the slot array, and FIG. The figure is a perspective view showing the propagation mode, and Figure 4 is a graph showing the relationship between the slot size and impedance.
Figure 55 is a graph showing the relationship between the slot size and the coupling rate, Figure 6 is a graph showing the relationship between the slot size and slow wave rate, and Figure PltJ7 is a pickpocket/door as the first modification. A perspective view of the ray antenna, Figure 8 is the second one.
19 to 11 are perspective views of a slot array antenna as a modified example, and FIGS. 19 to 11 show a slot 7-inch antenna as a second embodiment of the present invention. FIG. is a perspective view of the slot arrangement, and FIG. 11 is a graph showing its power density characteristics.
Figure 2.13 shows a conventional slot array 7 antenna, Figure @12 is its perspective view, and Figure 13 is a graph showing its power density characteristics. 1.2...Metal plate, 1a...Slot, 3...Metal peripheral wall, 3a...Power feeding opening, 4...Horn type waveguide, 5a...Conductor radio wave lens, 5b... Dielectric slow wave circuit, 6... Terminating resistor, 7... Coaxial line, 8
...Intermediate metal plate, 9...Power supply opening, 10...
・Rectangular waveguide, S... waveguide space, S F + t
S Y 21...Slot spacing. Agent Patent attorney Yoshihiko Iinuma Isao Adachi Department of the Department

Claims (1)

[Claims] In the slot array antenna, a traveling wave traveling on the back side of the radiation surface of a metal plate formed with a large number of power radiation slots is combined with the slots, and radio waves are radiated from the slots. A slot array antenna characterized in that the radiation slots constitute a slot array in which the size and mutual spacing are sequentially changed along the direction in which the traveling wave travels.