JPS6319086B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a waveguide slot array antenna having a small opening area, which is formed by forming a slot in a rectangular waveguide.

FIG. 1 shows a perspective view of the structure of a conventional waveguide slot array antenna. In the figure, 1 is a rectangular waveguide, 2 is a shorting plate, and 3a and 3d are slots. Here, a normal waveguide type slot array antenna requires a power feeding waveguide to feed power in a specific phase relationship to each rectangular waveguide 1, but this is omitted for the sake of brevity. There is.

This conventional waveguide slot array antenna will be briefly explained below.

In a conventional waveguide slot array antenna, a plurality of rectangular waveguides 1 are arranged so that their H planes are on the same plane, and each rectangular waveguide 1 has a plurality of rectangular waveguides 1 arranged on the H plane at predetermined intervals in the tube axis direction. This was realized by forming slots 3a and 3b. Here, the above-mentioned predetermined interval means that the short circuit plates 2 are formed at both ends of the rectangular waveguide 1 to generate a standing wave in the rectangular waveguide 1, and that the standing waves are connected to the slots 3a, 3.
In the case of a waveguide type slot array antenna formed by connecting the waveguides b, the wavelength is half the wavelength within the rectangular waveguide 1. In this case, the rectangular waveguide 1 with short-circuit plates 2 attached to both ends acts as a kind of resonator, and when trying to form n slots 3a and 3b, a length of (tube wavelength x n)/2 is required. It is. As described above, the disadvantage of the conventional waveguide slot array antenna is that the mutual spacing between the slots 3a and 3b formed in each rectangular waveguide 1 is limited, and the number of slots 3a and 3b is limited. This becomes a big problem especially when it comes to antennas with a small area, and becomes a big constraint when trying to improve the antenna gain and antenna pattern by increasing the number of slots 3a and 3b even by one. Here, the slot 3 mentioned above
I would like to add some additional information regarding the mutual spacing between a and 3b. First, before providing supplementary explanations, for convenience of explanation, we will define the following.

The tube axis direction of the rectangular waveguide 1 is called the X direction, and the direction in which the rectangular waveguides 1 are lined up is called the Y direction.

Returning to the explanation, slots 3a and 3b in the X direction
The mutual spacing between the slots 3a and 3b in the Y direction is determined by the internal wavelength of each rectangular waveguide 1, and the mutual spacing between the slots 3a and 3b in the Y direction is determined by the physical dimension of each rectangular waveguide 1, that is, the horizontal dimension of the H plane of each rectangular waveguide 1. It's decided. Therefore, if an attempt is made to reduce the H-plane dimension of each rectangular waveguide 1 and increase the number of slots 3a and 3b in the Y direction, the internal wavelength of each rectangular waveguide 1 will become longer and the number of slots 3 in the X direction will increase.
When the number of a and 3b decreases, and the area and frequency of the antenna as a whole are determined, slot 3
The numbers of a and 3b are almost fixed.

The waveguide slot array antenna of the present invention eliminates the above-mentioned drawbacks, and its purpose is to improve performance.

FIG. 2 is a perspective view showing an embodiment of the waveguide slot array antenna of the present invention. In the figure, 1 is a rectangular waveguide, 2 is a short circuit plate, and 3 is a rectangular waveguide.
a and 3b are slots, and 4 is an inductive iris. Here, a normal waveguide type slot array antenna requires a power feeding waveguide to feed power in a specific phase relationship to each rectangular waveguide 1, but this is omitted for the sake of brevity. There is.

The waveguide slot array antenna according to the present invention will be explained below. In the waveguide slot array antenna according to the present invention, a plurality of rectangular waveguides 1 are arranged so that their H planes are on the same plane, and a plurality of slots 3a, 3b are formed in the H plane of each rectangular waveguide 1. This is realized by forming an inductive iris 4 inside the rectangular waveguide 1 on both sides of the slot 3b that is not adjacent to the shorting plate 2.

By adopting such a configuration, the number of slots 3a and 3b can be increased to some extent without being limited by the area and frequency of the antenna as in the prior art, and the gain and antenna pattern of the antenna can be improved.

For convenience, before going into this explanation, we will define the following.

The tube axis direction of the rectangular waveguide 1 is called the X direction, and the direction in which the rectangular waveguides 1 are lined up is called the Y direction.

Returning to the explanation, the slots 3a and 3b in the Y direction
The mutual spacing is determined by the H-plane lateral dimension of each rectangular waveguide 1. If you want to increase the number of slots 3a, 3b in the Y direction, change the H-plane lateral dimension of the rectangular waveguide 1 (when the fundamental mode is cut-off). (under conditions where it does not occur).

Next, in this case, the slot 3a in the X direction,
Let's think about the 3b number. In the conventional waveguide type slot array antenna, since the inner wavelength of the rectangular waveguide 1 has become longer, the slots 3a in the X direction,
Although the number of slots 3b is reduced, in the waveguide slot array antenna according to the present invention, the inductive iris 4 allows the gap between the slots 3a and 3b in the X direction to be narrower, and the number of slots 3a and 3b in the X direction can be reduced. It can be increased.

Here, we will supplement the point that the above-mentioned inductive iris 4 allows the gap between the slots 3a and 3b in the X direction to be apparently narrower. FIG. 3a shows an equivalent circuit when two inductive irises 4 are formed in a rectangular waveguide 1 separated from each other. In the figure, 5 is a transmission line realized by a rectangular waveguide 1, and 6 is a susceptance realized by an inductive iris 4. FIG. 3b shows the resonance conditions of the equivalent circuit shown in FIG. 3a. In the figure, 7 is a characteristic curve showing the relationship between the length of the transmission line 5, that is, the resonator length, when the susceptance 6 is changed.

As can be seen from FIGS. 3a and 3b, by attaching the inductive susceptance 6 to the transmission line 5 at a distance l', the resonator length l' is shorter than when the shorting plate 2 is used (susceptance ∞). can be made smaller.

The waveguide slot array antenna according to the present invention utilizes the above-mentioned effect, and has inductive irises 4 on both sides of the slot 3b that are not adjacent to the shorting plate 2.
By forming the resonator, a resonator can be realized in a short section, and the interval between the slots 3a and 3b connected to the resonator can be narrowed. In this case, since the slot 3b sandwiched between the inductive iris 4 and the slot 3a adjacent to the other shorting plate 2 have different coupling conditions to the standing wave generated within the rectangular waveguide 1, each slot 3a, 3b
If the same phase is desired, the length of the slot 3b needs to be shorter than that of the slot 3a.

As described above, in the waveguide type slot array antenna according to the present invention, the inductive iris 4 formed on both sides of the slot 3b allows the slot 3a,
The number of slots 3b can be increased, and not only the gain of the antenna can be improved, but also the antenna aperture distribution can be controlled relatively continuously by increasing the number of slots 3a and 3b, so that a good antenna pattern can be obtained.

In addition, in the embodiment, the case where the slots 3a and 3b were formed on the H-plane of the rectangular waveguide 1 or the case where the inductive iris 4 was used was explained, but the present invention is not limited to this, and It can also be used when a slot is formed on the E side or when an inductive post is used.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a conventional waveguide slot array antenna, FIG. 2 is a perspective view of a waveguide slot array antenna according to an embodiment of the present invention, and FIG. 3a is a rectangular waveguide slot array antenna. An equivalent circuit diagram when two inductive irises are formed separately in a wave tube, and FIG. 3b is a diagram showing the resonance conditions of the equivalent circuit shown in FIG. 3a. In the figure, 1 is a rectangular waveguide. pipe, 2 is a shorting plate,
3a, 3b are slots, 4 is an inductive iris, 5
is a transmission line, 6 is a susceptance, and 7 is a characteristic curve. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

Claims (1)

[Claims] 1 A plurality of rectangular waveguides whose ends are short-circuited by short-circuit plates are arranged so that their H-planes are on the same plane, and a plurality of slots are formed in the H-plane of each rectangular waveguide. In the waveguide-type slot array antenna consisting of a rectangular waveguide, an inductive iris or an inductive post is provided on both sides of the slots that are not adjacent to the rectangular plate and within the rectangular waveguide between the slots formed in the same rectangular waveguide. Features a waveguide slot array antenna. 2. The waveguide slot array according to claim 1, characterized in that the length of the slot sandwiched between the inductive iris or the inductive post is shorter than the length of the slot adjacent to the shorting plate. antenna.