JPS5936443B2 - Folded horn reflector antenna device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bent horn reflector antenna device used for a radio relay line in an ultra-high frequency band.
More specifically, the present invention relates to a bent horn reflector device that transmits and receives two radio waves having different polarization planes in common in multiple frequency bands.

Conventionally, horn reflector antennas have been used as antennas that have good impedance characteristics over a wide frequency band, excellent wide-angle radiation patterns, and are capable of frequency sharing and polarization sharing, and are especially used as antennas for broadband relay type micro-circuits and space communications. There is.

However, this antenna has disadvantages such as being tall and therefore requiring a lot of installation space in practical use, and especially when installing the antenna on a steel tower, it is necessary to strengthen the tower or pillar. There is.

Therefore, in view of the above drawbacks, the present invention proposes a method of constructing an antenna that is relatively small, can share multiple frequency bands and polarizations, and has a good radiation pattern.

As an embodiment of the present invention, a bent horn reflector antenna that is bent twice will be described.

FIG. 1 shows a case where a radio wave absorber is not attached to the outer periphery of the radio wave path between the quadratic curved mirrors of the sub-reflector portion of the bent horn reflector antenna 1.

In FIG. 1, the main reflecting mirror part 2 is a part of a paraboloid of revolution with a focal point at point A, and the sub-reflecting mirror part 3 is a part of a hyperboloid of revolution with a focal point at point A and a fish eye. It consists of a hyperboloid reflector 4 and a plane reflector 5, each of which is attached to a shield plate 6 to maintain its relative position. It is fixed to the reflecting mirror part 2 so that their relative positions are maintained, and the main reflecting mirror part 2 is fixed to the pedestal 7.

Point C is a point of symmetry for the fish-eye plane reflector 5, and is the focal point of the antenna.

The primary radiator 8 is mounted so that its phase center substantially coincides with the focal point C of the antenna.

This antenna will be described below as a transmitting antenna that radiates radio waves.

After being reflected by the plane reflector 5, the spherical wave emitted from the primary radiator 8 is reflected by the hyperboloid reflector 5, like a spherical wave radiated from a symmetrical point aperture about the plane reflector 5 at the apparent focal point C.
heading to

The spherical wave reflected by the hyperboloid reflector 4 propagates like a spherical wave radiated from the focal point A, is further changed into a plane wave by the main reflector 2, and is radiated in a desired direction.

However, among the radio waves emitted from the primary radiator 8, reflected by the plane reflector 5, and directed towards the hyperboloid reflector 4, some of the so-called unnecessary radiation waves emitted in directions other than the predetermined direction have an adverse effect on the radiation pattern. effect.

These phenomena will be explained using FIG. 2.

FIG. 2 shows a schematic diagram of the bent horn reflector antenna according to the present invention, in which a is a front view, b is a side view, and c is a cross-sectional view in a horizontal plane.

The following will be explained in terms of geometrical optics to facilitate understanding.

In Fig. 2, the mirror image of the primary radiator 8 is formed by the flat reflecting mirror 5 (hereinafter, the mirror image formed by the flat reflecting mirror and the shield plate of the primary radiator will be simply referred to as a mirror image), and the second radiator of the mirror image 8'
The mirror image by the shield plate 6°6' shown in Figure C is 8", 8"
', and the mirror images 8", 8" of Fig. 2a are Fig. 2b v
This corresponds to the mirror images 8" and 8"' in FIG. 2a, and the mirror image of the shield 6" in FIG.

By the way, since it is the shield plates 6, 6' that have an adverse effect on the radiation pattern in the horizontal plane, the mirror images 8'', 8''' can be regarded as wave sources that have an adverse effect.

That is, in FIG. 2C, when considering that a spherical wave is radiated from the mirror image 8'', the angle of incidence on the shield plate 6 is θ, and the law of reflection at the hyperboloid reflector 4 and the main reflector 2 is expressed as follows: If the radio waves are tracked satisfactorily, the radio waves will be emitted in the Φ degree direction with respect to the principal axis, which will have a negative effect on the radiation pattern.

One possible way to remove this negative effect is to attach a radio wave absorber to the shield plate 6 to absorb unnecessary radiation waves, but the relatively thin radio wave absorbers currently available on the market have a good return loss for normal incidence. Even if the radio wave absorber has the following characteristics, if the incident angle is 50 to 60 degrees or more, sufficient return loss cannot be obtained.

Therefore, even if a radio wave absorber is attached parallel to the shield plate 6, a non-negligible amount of radio waves reflected by the radio wave absorber portion will be radiated through the above-mentioned path.

Therefore, in the present invention, one or
By attaching a plurality of radio wave absorbers and using the radio wave absorbers near the vertical incidence of the radio waves incident on the shield plate 6 to suppress any unnecessary radiated waves, it is possible to bend the waves with an excellent radiation pattern. The present invention provides a horn reflector antenna.

FIG. 3 shows one embodiment of the present invention.
Figure a shows a side view of the three radio wave absorbers 9 and a side view of the radio wave absorbers 9; is an arch-shaped radio wave absorber γ, and FIG. 3C is a radio wave absorber 9'' with a radio wave passage section hollowed out.

By attaching an arch-shaped radio wave absorber 9 or a radio wave absorber 9'' hollowed out in the radio wave passage, unnecessary radiation waves from the hyperboloid reflector 4 can be absorbed and reflected waves from the shield plate 6 can be suppressed. It is possible to ensure a good radiation pattern.

In the above embodiment, a bent horn reflector antenna constructed by bending twice using a quadratic curved mirror was shown, but a plurality of parts of a suitable quadratic curved mirror or a part of a non-quadratic curved mirror may be used. It is also applicable to a bent horn reflector antenna configured using the present invention.

Furthermore, as a similar antenna of this type, an offset cast-grain antenna (Japanese Patent Application No. 48-44699, filed 1973, 4.21) has been proposed. It is believed that the radiation pattern can be improved by attaching a radio wave absorber as in the present invention.

In the above embodiments, the bent horn reflector antenna has been described as an antenna that emits radio waves, but it goes without saying that it operates in exactly the same way as an antenna that receives radio waves, so a description thereof will be omitted.

By configuring as described above, it is possible to provide an antenna that is relatively small and has good performance.

[Brief explanation of the drawing]

Fig. 1 is a side view showing a schematic configuration diagram of a folded horn reflector antenna according to the present invention; Figs. 2a, b, and c are illustrations of the operating principle of the folded horn reflector antenna; Figure 2C is a horizontal sectional view, Figure 3a is a conceptual diagram showing the mounting position of the radio wave absorber according to the present invention, and Figures 3b and 3c are shape diagrams of the radio wave absorber according to the present invention. Yes, 2 is the main reflector part, 3 is the sub-reflector part,
8 is a primary radiator, and 95g' and 9'' are radio wave absorbers. In the figures, the same or corresponding parts are given the same reference numerals.

Claims (1)

[Claims] 1. Consisting of a main reflector, a sub-reflector, a primary radiator, a shield plate, and a pedestal to which these are attached, the main reflector fixed on the pedestal has one quadratic curved surface. The sub-reflector section is made of a mirror or a non-quadratic curved mirror and is fixed to the main reflector section via a shield plate. One or more pieces are set to maintain a predetermined positional relationship depending on the part, and one or more pieces are placed on the outer periphery of the radio wave path between the quadratic curved mirrors or non-quadratic curved mirrors of the sub-reflector part at an angle perpendicular to the axis. A bent horn reflector antenna device characterized by having a radio wave absorber attached thereto. 2. The bent horn reflector antenna device according to claim 1, which uses an arch shape as the radio wave absorber. 3. The bent horn reflector antenna device according to claim 1, which uses a hollowed-out radio wave passage portion as the radio wave absorber.