JPH036685B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an antenna device capable of transmitting and receiving circularly polarized waves, and particularly to one capable of transmitting and receiving both right-handed circularly polarized waves and left-handed circularly polarized waves.

[Prior art]

Conventionally, there has been a circularly polarized antenna device as shown in FIG. 6 that can transmit and receive both right-handed circularly polarized waves and left-handed circularly polarized waves. This includes a reflecting mirror 2 and a primary radiator 4 provided at the focal point of the reflecting mirror 2, and this primary radiator 4 is connected to a horn part 6 and a circular to straight line as shown in FIG. It consists of a polarization conversion section 8 and a branching section 10 for orthogonal polarization separation. For example, when this antenna device is used for reception, right-handed circularly polarized waves and left-handed circularly polarized waves input from the horn section 6 are converted into two orthogonal linearly polarized waves by the circular-linear converter 8, The polarized wave separating section 10 separates the right-handed circularly polarized wave into a linearly polarized wave and the left-handed circularly polarized wave into a linearly polarized wave.

[Problem that the invention seeks to solve]

However, in the above antenna device, the circular-linear polarization conversion section 8 has a complicated waveguide structure in which a dielectric material or a metal piece is inserted, and the orthogonal polarization separation branching section 1
0 also had a similarly complex structure. Therefore,
This circularly polarized antenna device has problems in that it has a complicated structure and is expensive.

[Means for solving problems]

The means for solving the problem includes a reflecting mirror and a primary radiator provided at the focal point of the reflecting mirror, as in the conventional one, but the structure and composition of this primary radiator are different. . That is, this primary radiator includes a dielectric plate, and this dielectric plate has a first surface facing the reflecting mirror side and a second surface opposite to the reflecting mirror side. A ground conductor is provided on this second surface, and a small number of crank-type microstripline antennas are provided on the first surface. First and second stripline isolators are provided at both ends of the microstripline.

[Effect]

When this problem-solving means is considered as a receiving antenna, for example, right-handed circularly polarized waves and left-handed circularly polarized radio waves reflected by a reflecting mirror are collected at a primary radiator provided at a focal point. At one end of the microstrip line of the primary radiator, one of two orthogonal linearly polarized wave components obtained by converting the right-handed circularly polarized wave and the left-handed circularly polarized wave is generated, and at the other end, two orthogonal straight lines are generated. The other polarization component is generated. These two orthogonal linearly polarized components are each extracted via an isolator. At this time, both isolators prevent reflected waves from being transmitted to the microstripline side, and also function as a so-called matching load.

〔Example〕

This embodiment has an offset parabolic reflecting mirror 12 as shown in FIG. 2, and a primary radiator 14 is provided at the focal point of this reflecting mirror 12.

This primary radiator 14 has a rectangular dielectric plate 16 as shown in FIG. This dielectric plate 16
A ground conductor 18 is provided over the entire surface opposite to the reflecting mirror 12.

A microstrip line antenna 20 is provided at the center of the surface of the dielectric plate 16 facing the reflecting mirror 12 . This microstripline antenna 20 has two elements 22, 2 connected in parallel.
Consists of 4. The element 22, as shown in FIG.
It has a crank shape, and the horizontal parts at both ends each have a length of λg/4, the horizontal part in the center has a length of λg, and the vertical part each has a length of λg/4. However, λg is the wavelength of the center frequency signal of the signal to be received. The element 24 also has a crank shape, with horizontal portions at both ends being λg/2, and a horizontal portion in the center also being λg/2.
2. Both vertical parts each have a length dimension of λg/4. λg is the same as in the case of element 22.

A stripline isolator 2 is provided at each end of the microstripline antenna 20.
6 and 28 are provided. These stripline isolators 26 and 28 have main lines 30a and 30b extending horizontally from connection points 27a and 27b of both elements 22 and 24 of microstripline antenna 20, respectively. These main lines 3
Short-circuit branch lines 32a, 32b and open branch lines 34a, 34b intersect at right angles to 0a, 30b.
is provided. Short circuit branch lines 32a, 32
The ends of the line b are connected to the ground conductor 18 and short-circuited, and the ends of the open branch lines 34a and 34b are open. Ferrites 36a and 36b are provided at the intersections of these branch lines and the main line.

Next, the operation of this embodiment will be explained.
First, it will be explained that the microstripline antenna 20 can radiate right-handed circularly polarized waves and left-handed circularly polarized waves. This type of microstripline antenna radiates electromagnetic waves from the corners of each element 22, 24, but it can be thought that this is equivalently radiated from a high-frequency current source flowing on the stripline. can. Now, when a high frequency current is supplied from one connection end 27a of the elements 22, 24 as shown in FIGS. 4a and 4b, the direction of the current flowing through each part of each element 22, 24 at a certain instant is shown as follows. The direction of the current is reversed every λg/2.

The microstripline antenna 20 emits electromagnetic waves in the same direction as the high-frequency current of each part of each element 22, 24 and proportional to the size thereof. Therefore, when observed from an infinite distance, the combined electric field E of the electromagnetic waves radiated from each part of each element 22, 24 will be in the direction shown in parentheses in FIGS. 4a and 4b at a certain time t=0. Next, when 1/4f of time t has elapsed, the direction of the instantaneous current is as shown in parentheses in FIGS. 4a and 4b. However, f is the frequency used. At this time, the combined electric field E〓 rotates counterclockwise toward the antenna as shown in the figure. The case where further time has elapsed is shown in (), (), and () of Fig. 4a and b. Eventually, the direction of the combined electric field E〓 of the electromagnetic waves radiated from the elements 22 and 24 rotates counterclockwise when viewed toward the antenna as time passes, and rotates once every 1/f, creating a right-handed circularly polarized wave. is emitted.

In addition, microstripline antenna 20
When a high frequency current is supplied from the other connecting end 27b, left-handed circularly polarized waves can be emitted as shown in FIGS. 5a and 5b. Therefore, by supplying high frequency currents to both connection ends 27a and 27b of the microstripline antenna 20, it is possible to simultaneously radiate right-handed circularly polarized waves and left-handed circularly polarized waves.

Note that since the antenna is a reversible circuit, when it receives right-handed circularly polarized waves and left-handed circularly polarized waves at the same time, one connection end 27a receives the right-handed circularly polarized wave converted into a linearly polarized wave, and the other connection end 27a receives the right-handed circularly polarized wave and the left-handed circularly polarized wave. A left-handed circularly polarized wave converted into a linearly polarized wave is generated at the end 27b.

The linearly polarized waves generated at the connection ends 27a, 27b in this way are transmitted to the main lines 30a, 30b, the branch lines 3
2a, 34a, 32b, and 34b, a rotating magnetic field is generated at each intersection of the main line and the branch line. The rotation direction of this rotating magnetic field is reversed depending on the radio wave propagation direction, and the ferrites 36a and 36b
It absorbs reflected waves by using the resonance absorption phenomenon of
Therefore, only radio waves in the direction shown by the arrow in FIG. 1 pass through, and matching is achieved. Therefore, if the primary radiator 14 having such a configuration is provided at the focal position of the offset parabolic reflector 12, the right-handed circularly polarized wave and the left-handed circularly polarized wave reflected by the offset parabolic reflector 12 will be directed to the focal position. are collected in the primary radiator 14 located at
As described above, each of the waves is converted into a linearly polarized wave and taken out from the main lines 30a and 30b.

Note that the primary radiator 14 uses crank-type microstripline antennas 22 and 24, so if the frequency of the input circularly polarized wave deviates from the center frequency, it will be different from the case where it is incident from the right direction.
Although the tilt angle is in the opposite direction for the incident from the left direction, as is clear from the pattern diagram of the primary radiator 12 shown in FIG.
3dB) is as much as ±25 degrees, and the curve at 0 degrees is also very smooth. Also, satellite broadcasting
It is carried out in the 12GHz band, and its bandwidth is 300MHz,
The ratio of bandwidth to satellite frequency band is 2.5
It is only %. Therefore, even if the direction of this antenna is adjusted or fixed at the center frequency, the effect of decreasing the gain at other frequencies within the bandwidth is small. This is a microstripline antenna 22,2
The same holds true even when the number of 4s is slightly increased.

In the above embodiment, the isolator 26 was provided on one connection end 27a side for reception, and the isolator 28 was provided on the other connection end 27b side, but when used for transmission, the direction of the radio waves to be absorbed is reversed. Therefore, it is necessary to install the isolators 26 and 28 in opposite positions. In addition, the above embodiment has a reflector 1
2 is a parabolic antenna using an offset parabolic reflector, but the present invention can also be applied to other parabolic antennas, such as parabolic columnar antennas and rotating parabolic antennas, and also to antennas such as Cassegrain antennas. Can be implemented.

〔effect〕

As described above, according to the present invention, the microstripline antenna is used as the primary radiator of the antenna device that transmits and receives right-handed circularly polarized waves and left-handed circularly polarized waves, so the configuration is simplified and the Manufacturing becomes easier and manufacturing costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a primary radiator used in one embodiment of the circularly polarized antenna device according to the present invention;
The figure is a perspective view of the same embodiment, Figure 3 is a plan view of the microstripline antenna of the primary radiator of the same embodiment, and Figures 4a and b are right-handed circles from the primary radiator of the same embodiment. An explanatory diagram of the principle that can radiate polarized waves. Figures 5a and b are explanatory diagrams of the principle that left-handed circularly polarized waves can be radiated from the primary radiator of the same embodiment. Figure 6 is a conventional circularly polarized antenna device. FIG. 7 is a perspective view of a primary radiator used in a conventional circularly polarized antenna, and FIG. 8 is a pattern diagram of the primary radiator of this embodiment. 12...Reflector, 14...Primary radiator, 16...
...Dielectric plate, 18... Ground conductor, 20... Microstripline antenna, 26, 28... Stripline isolator.

Claims (1)

[Claims] 1 reflector and 1 provided at the focal point of this reflector
the primary radiator includes a dielectric plate having a first surface facing the reflecting mirror and a second surface opposite to the reflecting mirror; A ground conductor provided on the ground conductor, and a signal obtained by receiving the right-handed circularly polarized wave signal and the left-handed circularly polarized wave signal reflected by the reflecting mirror provided on the first surface and converting the right-handed circularly polarized wave signal into a linearly polarized wave signal at one end. a crank-type microstripline antenna that generates a signal obtained by converting the left-handed circularly polarized wave signal into a linearly polarized wave signal at the other end; and a strip that is provided at each end of the microstripline antenna and absorbs the reflected wave signal. A circularly polarized antenna device including a line isolator.