JPS5951764B2 - Electronically scanned aperture antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronically scanned aperture antenna that uses an electronically scanned array antenna as a primary radiator of a reflecting mirror or lens and scans a beam within one radiation plane. In the above electronically scanned array antenna,
The feature is that an appropriate number of fixed phase shifters are combined along the array axis of each element antenna in the direction perpendicular to the radiation surface on which beam scanning is performed, and its purpose is to reduce the shift in the phase distribution on the aperture surface of the aperture antenna. It's about making it smaller.

FIG. 1 shows an embodiment of the present invention, in which 1 is a parabolic reflector whose mirror surface is a part of a paraboloid of revolution, 2 is an electronic scanning array antenna composed of a plurality of element antennas, and the vertical plane The beam is electronically scanned within the plane, that is, within the plane including the straight line 3.

4 is a straight line that is perpendicular to the straight line 3 and fits within the aperture plane of the electronic scanning array antenna 2, and is shown for convenience.

Specifically, FIG. 1 shows an offset-type parabolic reflector antenna using an electronic scanning array antenna 2 as a primary radiator.

FIG. 2 is a schematic diagram of the electronic scanning array antenna 2, in which 5 is an element antenna, 6 is a fixed phase shifter, 7 is a variable phase shifter, 8 is a power source, and 9 is a feed line.

□The signal from the power source 8 is subjected to an appropriate phase change by the variable phase shifter 7 and the fixed phase shifter 6, and then radiated from each element anti≠5.

□By electronically controlling the variable phase shifter 7, the radiation beam of the electronic scanning array antenna 2 is shifted within the radiation plane including the straight line 3 as shown in FIG. 2, that is, within the vertical plane in FIG. Can be scanned.

The primary radiation wave from the electronic scanning array antenna 2 hits the parabolic reflector 1 and is reflected, and at the same time, due to the properties of the parabolic reflector 1, the spherical wavefront is converted into a plane wavefront and radiated far away.

On the other hand, the element antennas 5 along the array axis in the direction of the straight line 4 perpendicular to the vertical plane which is the beam scanning plane are two element antennas 5 located symmetrically about the straight line 3 as shown in the second diagram. form one set and undergo the same phase change.

That is, a fixed phase shifter 6 provides a phase difference between a set of element antennas 5 close to the straight line 3 at the center of FIG. 2 and a set of element antennas 5 far from the straight line 3 in FIG.

Therefore, the spherical phase distribution of the electronic scanning array antenna 2 as a primary radiator, which is originally necessary in the horizontal direction, that is, in the direction of the straight line 4, is realized by the above phase difference, and this is achieved by the parabolic reflector 1. This has the effect of reducing the deviation (error) from the uniform phase distribution on the aperture surface after reflection.

It is true that the above-mentioned spherical phase distribution required in the four straight directions changes as the beam scans in the vertical plane, but this change does not occur when the beam scanning angle range in the vertical plane is narrow. Even if a fixed phase distribution by a fixed phase shifter 6 as shown in FIG. 2 is used, the effect of reducing the phase error in the aperture plane is large.

In theory, if a variable phase shifter is used instead of a fixed phase shifter, a more accurate phase difference can be given for each beam scan, but it is usually preferable to use a digital phase shifter as the variable phase shifter. However, the quantization phase error is always present, and furthermore, using a variable phase shifter, which is much more expensive than a fixed phase shifter, reduces cost/performance.
This is a big problem in terms of performance.

Therefore, in practice, it can be said that a method using a fixed phase shifter as shown in FIG. 2 is sufficient.

FIG. 3 is a schematic configuration diagram of another embodiment of the present invention, with 10
is a lens, and the lens 10 is the delivery element antenna 1.
1. It is constructed by arranging lens elements 14 consisting of a fixed phase shifter 12 and a transmitting element antenna 13.

2 is the same electronic scanning array antenna as shown in FIG. 2, and is also used as the primary radiator of the lens 10.

It is clear that in the case of FIG. 3, compared to the case of FIG. 1, except for the difference between reflection and transmission, the robot operates in the same way as the case of FIG. 1, and the same effects of the invention can be obtained.

Note that, although the above was a case of transmission, the present invention can be similarly implemented in the case of reception.

Furthermore, the configuration of the electronically scanned array antenna 2 is not limited to that shown in FIG.
A square arrangement may be used, and the method of grouping (grouping) of element antennas in four straight directions is not limited to two elements; 1. 3.
You are free to use four elements each.

As the fixed phase shifter 6, any fixed phase shifter such as one using a feed line length can be used.

The mirror surface of the reflecting mirror 1 is not limited to a parabolic surface, but may be a hyperbolic surface, a spherical surface, or the like.

Further, instead of the lens 10, any lens structure such as a metal plate lens, a waveguide lens, or a dielectric lens can be used.

As described above, according to the present invention, the phase distribution in the direction perpendicular to the beam-scanning radiation surface can be more accurately realized on the aperture surface, so that the electronic scanning aperture surface has excellent radiation characteristics such as gain and side lobes. The antenna can be realized,
When this is used for radar antennas and communication antennas, the effect is extremely large.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment of the present invention, FIG. 2 is a schematic diagram of the electronic scanning array antenna of FIG. 1, and FIG. 3 is a schematic diagram of another embodiment of the invention. In the figure, 1 is a parabolic reflector, 2 is an electronic scanning array antenna, 5 is an element antenna, 6 is a fixed phase shifter, 10 is a lens, and 14 is a lens element. In the drawings, the same or corresponding parts are designated by the same reference numerals.

Claims (1)

[Scope of Claims] 1. An electronically scanned aperture antenna consisting of a reflecting mirror or a lens, and an electronically scanned array antenna that faces the above-mentioned anti-constant mirror or mirror and is composed of a plurality of element antennas, The electronically scanned array antenna is configured to electronically scan a beam within one radiation surface, and the element antenna surface is arranged on the array aperture surface of the electronically scanned array antenna in a direction perpendicular to the radiation surface. In order to have a fixed relative phase distribution, some of the element antennas are equipped with a fixed phase shifter, thereby reducing the deviation of the phase distribution on the aperture surface of the reflecting mirror or lens from a uniform phase distribution.・Electronic scanning aperture antenna characterized by combing. ::′.