JPS5820164B2 - lens antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an antenna having an aperture that can be used simultaneously for a plurality of high frequency bands such as microwave bands.

A conventional example of such an antenna is a horn reflector type antenna device as shown in FIG.

That is, in the same figure, 1 is the antenna aperture, 2 is the antenna aperture, and 3 is the antenna aperture.
It is a parabolic reflector with a focal point of .

4 is a waveguide path that gradually becomes smaller in the direction of the focal point 3, but this does not necessarily have to be continuous; in this case, the waveguide 4 becomes a radiator.

Now let's consider the case where this antenna is used on the receiving side.

In the figure, 5 represents the course of microwave band radio waves (hereinafter referred to as fl), for example, from 4 to 6 GHz, and 6 represents, for example, from 17 to 30.
This is the path of radio waves in the GHz millimeter wave band (hereinafter referred to as fH).

As shown in the figure, the radio waves fL and fH incident on the aperture 1 are reflected by the parabolic reflector 2, propagate within the waveguide 4, and are focused on the focal point 3.

The focused radio waves are transferred to a second waveguide 7 connected to the waveguide 4.
proceed within.

A branch waveguide 9 is attached to this waveguide 7 so as to be coupled through a coupling hole 8, and the radio waves fL j fH inside this waveguide 7 are connected to the coupling hole 8 and the branch waveguide 9. By appropriately designing the waveguides 7 and 9, the waveguides 7 and 9 can be separated.

However, it is not desirable to separate broadband radio waves that simultaneously include microwaves (eg, 4 to 6 GHz) and millimeter waves (eg, 17 to 30 GHz) as described above because of the following drawbacks.

First, the waveguide 7, through which fL and fH, which have frequencies 4 to 5 times different, are simultaneously transmitted, is oversized with respect to fH, so a large number of unnecessary higher-order modes are generated at the coupling hole 8. occurs, degrading transmission quality.

Second, inside the waveguide 7, both fL and fH have the same energy distribution as y, and the coupling hole 8 portion is fL.

To isolate fH, the coupling must be made longer, which increases losses.

Particularly when such an antenna is used for satellite communication, the loss caused by the waveguide remains unchanged to the gain/noise temperature (normally G
/T), so it must be made as small as possible.

An object of the present invention is to propose an antenna that can easily separate or combine radio waves of relatively widely different frequency bands without mutual loss or coupling.

In this invention, an antenna having an opening is used, and a radio wave lens such as a dielectric lens, an artificial dielectric lens, or a metal lens is provided in the opening.

This lens focuses only one of the radio waves fL and fH, and a dedicated primary radiator for this is provided at the focusing position.

The lens has no lens effect on the other radio wave, and a primary radiator dedicated to the other radio wave is provided at a different position from the primary radiator for the one radio wave.

FIG. 2 shows an embodiment of the present invention, in which a concave metal lens 4
A dielectric rod 47 is disposed at the center of each of the metal tube passages 6 along the extending direction thereof.

However, contrary to the metal lens 46, the dielectric rod 47 is longer at the center and shorter at the periphery, so that its overall shape forms the lens surface of a convex dielectric lens. done to.

In such a case, the fundamental mode of radio wave energy is concentrated at the center in each metal tube passage of the metal lens 46, so that the dielectric rod 47 as a whole constitutes a convex dielectric lens 47'.

Near the focal point 3 of this lens 47', the end of the inner groove wave tube 49 of the double waveguide 48 is positioned so as to protrude from the open sea wave tube 50 as a primary radiator exclusively for fH.

Further, a focal point 3' of the metal lens 46 is located at a different position from the focal point 3, that is, at a position further away from the lens 46 than the focal point 3 in the figure, and a double waveguide is installed near this as a primary radiator exclusively for fL. 48 open sea wave tube 50 ends are provided.

The operation of this lens antenna will be explained below.

Both fL and fH are lenses 46 placed at the antenna aperture.
.

On the other hand, f near the focal point 3 due to the dielectric lens 47'
The degree of convergence of L is small, and the size of the inner groove wave tube 49 is a cutoff region for fL, so fL is smaller than the inner groove wave tube 4.
Do not pass within 9.

Since most of the energy of fL is focused on the focal point 31, the energy transmitted into the inner groove wave tube 49 is minute.

However, the inner groove wave tube 49 is large enough to transmit fH, and the dielectric lens 47' focuses fH on the focal point 3' and is transmitted within the inner groove wave tube 49.

Since fH is hardly focused on the focal point 31, the energy transmitted into the outer groove wave tube 50 is minute.

If a band rejection filter that blocks only fH is added to the outer groove wave tube 50 as necessary, the amount of interference of fH with fL can be further reduced.

In this way, fH and fL can be separated from each other without loss.

The lens antenna of the present invention can be designed to have no polarization characteristics, and can be used for both linearly polarized waves and circularly polarized waves.

Further, as the dielectric lens, an artificial dielectric lens loaded with a capacitance using a metal piece may be used.

Although it was used as a receiving antenna in the above embodiment, it can also be used as a transmitting antenna, or it may be configured to transmit in one frequency band and receive in the other frequency band.

As described above, according to the antenna of the present invention, multiple frequency bands can be separated or combined without loss or coupling, and a small and simple antenna can be obtained without requiring anything such as a coupling hole in the feeding section. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an antenna device equipped with a conventional demultiplexing device, and FIG. 2 is a sectional view showing an example of the lens antenna of the present invention. 46: Metal lens, 47th dielectric lens, 49: Internal groove wave tube as a primary radiator exclusively for fH, 50: Open sea wave tube as a primary radiator exclusively for fL.

Claims (1)

[Claims] 1. A concave first radio wave lens formed by a plurality of metal tube passages, and a convex second radio wave lens formed by a dielectric element inserted into all or part of the plurality of metal tube passages, provided near the focal point of the first radio wave lens,
a first primary radiator for a first frequency band that exhibits a lens action with respect to this lens; , a second primary radiator for a second frequency band that exhibits a lens effect with respect to the second radio wave lens.