JPS587084B2 - Emhenpa antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a circularly polarized antenna that transmits and receives circularly polarized microwaves using a Hehat type parabolic antenna.

Satellite broadcasting using geostationary satellites is expected to be put into practical use in Europe, America, Japan, and other countries around the world in the near future, but since geostationary satellites are limited to only one orbit, if multiple broadcasting satellites are used, There is a risk of interference between broadcast waves from broadcast satellites.

In order to avoid such mutual interference of broadcast waves, it is necessary to utilize the cross-polarization discrimination of the satellite broadcast receiving antenna.

Therefore, when receiving terrestrial broadcast radio waves, it is not possible to make the radio waves horizontally or vertically linearly polarized, match the polarization plane of the receiving antenna to the polarization plane of the broadcast radio waves, and use cross-polarization discrimination. Although it is not very difficult, when receiving radio waves from broadcasting satellites, there is a shift in the plane of polarization due to disturbances such as the ionosphere in the radio wave propagation path and the angle of incidence of the radio waves at the receiving point, so the polarization as described above occurs. It is extremely difficult to match the wavefronts.

Figure 1 shows the direction of the polarization plane of broadcasting satellite radio waves on the earth's surface, and shows a great circle cut by a rectangular coordinate plane around a spherical surface centered at the position T of the broadcasting satellite. If AB, BC, and CA respectively, then the straight lines TA, TB,
The TCs are mutually orthogonal.

If R on the above spherical surface is the receiving point, then from the broadcasting satellite T to T
The polarization plane at the receiving point R of a radio wave transmitted with a polarization plane Ex in the A direction is Em in the tangential direction of the great circle AR at the point R, and the polarization plane E in the TC direction perpendicular to the polarization plane Ex.
The plane of polarization at the receiving point R of the radio wave transmitted with y is Ec in the tangential direction of the great circle CR at the point R.

That is, polarization planes EX and E that are orthogonal to each other from the broadcasting satellite T
When the radio waves sent out with y reach the receiving point R, their respective polarization planes Em and Ec will not be orthogonal to each other, and the angle of intersection will differ depending on the position of the receiving point.

Therefore, it is found that it is extremely difficult for ordinary viewers to simultaneously adjust the pointing direction of the receiving antenna and the prepared wave surface for the orthogonally polarized broadcast radio waves when receiving satellite broadcasting. .

Frequency allocation to multiple broadcasting satellites is considered to be done taking into consideration the degree of polarization plane discrimination from the point of view of effective use of satellite broadcasting frequency bands. Since the quality of the polarization plane adjustment of the antenna directly determines the level of interference between broadcast channels, it is not expected to obtain a high degree of cross-polarization discrimination when broadcast satellite radio waves are linearly polarized waves.

However, when broadcasting satellite radio waves are circularly polarized waves, it is easy to identify them by the direction of rotation of the circularly polarized waves, regardless of the deviation of the plane of polarization as described above, so that general viewers' receiving antennas All you have to do is adjust the pointing direction to direct it to the desired broadcasting satellite, and there is no need to adjust the plane of polarization, so it is much easier to adjust the receiving antenna than when linearly polarized waves are used. It is possible to obtain polarization discrimination as designed.

From the above, it is expected that future satellite broadcasting systems will use circularly polarized waves for broadcasting satellite radio waves.

On the other hand, conventional circularly polarized antennas include those that use a conical horn, those that combine two dipoles at right angles, and parabolic antennas that use these antennas as primary radiators. However, both have complicated structures, are large, and have high manufacturing costs, so 12 GHz
It is not suitable for receiving antennas for general viewers that receive satellite broadcasting radio waves using high frequency microwaves.

On the other hand, as a small and lightweight microwave antenna with an extremely simple structure, a rectangular waveguide extends in the axial direction from the center of a parabolic reflector, and its tip is curved so that the opening end surface is at the focal point of the parabola. There is a so-called Bee-hut type parabolic antenna which faces a parabolic reflector and uses this as a primary radiator, and is often used in microwave antennas for mobile relays, etc. However, conventional Bee-hut type parabolic antennas are As mentioned above, a rectangular waveguide is used to transmit and receive linearly polarized waves, and cannot be used for circularly polarized waves.

SUMMARY OF THE INVENTION An object of the present invention is to improve the conventional Hehat-type parabolic antenna and to provide a solar polarized antenna with simple structure, small size, and light weight.

Another object of the present invention is to provide an extremely small circularly polarized wave radiator that has a simple structure and good radiation characteristics and is suitable for use as a primary radiator for a sun-polarized parabolic antenna.

That is, in the circularly polarized antenna of the present invention, a waveguide extends in the axial direction of the parabolic reflector by penetrating the reflecting surface of the reflector at the center of the parabolic reflector. At least the tip of the circular waveguide is configured with a circular waveguide, and a set of four slots spaced apart by 90 degrees from each other is inserted into the wall of the circular waveguide in the vicinity of the focal point of the parabolic reflector. It is characterized in that two sets of circular waveguides are arranged at a predetermined interval in the axial direction of the tube, and the end faces of the circular waveguides are short-circuited.

The present invention will be described in detail below with reference to the drawings.

FIG. 2 shows a schematic configuration of a Hehat type circularly polarized parabolic antenna according to the present invention, which is provided with a circularly polarized primary radiator 2 extending in the axial direction at the center of a parabolic reflector 1. The figure is shown schematically when it is installed.

FIG. 3 shows an example of the configuration of the circularly polarized primary radiator 2 in the circularly polarized parabolic antenna according to the present invention shown in FIG.

In the configuration example shown in Figure 3, the configuration of the primary radiator 2 is shown when feeding power to the circularly polarized antenna of the present invention using a WRJ-1120 standard rectangular waveguide, which is often used for the transmission of microwaves in the 12 GHz band. A rectangular waveguide 5 equipped with an unsightly mounting part 4 is connected to a rectangular waveguide 5 through a rectangular-to-circular converting part 6, and a dielectric block of an appropriate shape and size is provided inside the circular waveguide, and the inside of the pipe is changed by the direction of the high-frequency electric field. It is connected to the circularly polarized wave generator 7 so as to selectively delay the phase of the propagating radio waves to generate solar polarized waves, and is further connected to the circular waveguide via the tapered portion 8 to form a circular waveguide with a reduced diameter. A circularly polarized wave radiating section 11 is provided with a plurality of slots 9 on the tube wall so as to be located near the focal point of the parabolic reflector 1, and the end face is short-circuited by a matching plate 10.
Connect to.

The circularly polarized wave radiating section 11 having the above-mentioned configuration is constructed by filling the inside with a dielectric block 13 formed in an appropriate shape and size to shorten the internal wavelength and reduce the dimensions of each part, and consisting of a combination of a plurality of slots. Parabolic reflector 1 for the slot radiation part
It is desirable to be able to arrange the radiation centrally near the focal point of the radiation beam to facilitate formation of an appropriate radiation pattern.

FIGS. 4a and 4b show an example of the configuration of the circularly polarized wave radiating section 11, with symbols indicating the dimensions of each part.

In the circularly polarized wave radiating section 11 shown in FIG. 4, four slots A each having a length m are spaced at equal intervals of 90 degrees, as shown in FIG. . D' are provided, and the end faces of the circular waveguides are short-circuited by matching plates 10 at a distance of 12 from the centers of these slots.

In the circularly polarized wave radiating section 11 having such a configuration, the pipe diameter d is reduced as much as possible as described above, and the slot interval t1 and the slot lengths m and n of each set are appropriately set, and as described below. In addition to obtaining an appropriate radiation pattern, the short-circuit distance l2 of the waveguide is appropriately set to cancel out the reactance of the slot radiation part, and the slot radiation part is matched to obtain high radiation efficiency. Do it like this.

FIG. 5 shows the operation of the slot radiator having the above-described configuration.

In the circularly polarized wave generating section 7 shown in FIG. 3, depending on the arrangement position of the dielectric block 12 provided inside, the linearly polarized wave propagating within the rectangular waveguide 5 is converted into a right-handed or left-handed circularly polarized wave. When the radio wave converted into is guided into the elliptical waveguide with the inner diameter d reduced through the tapered part 8, the inner wavelength λg of the radio wave is determined by the inner diameter d of the waveguide and the dielectric of the dielectric block 13 filled in the pipe. It is shortened to a value determined by the rate.

The above two sets of slots A, B, C, D and A',
When B', C', and D' are excited by circularly polarized waves, high-frequency electric fields EA, EB, Ec, and E are generated in these slots at the same time in the directions shown by the arrows in FIG.
D and EA', EB', Ea', ED'
is applied, and furthermore, high frequency electric fields EA and Ea, EB and ED1 and EA' are applied to the mutually opposing slots.
and Ea', EB' and ED' are each in phase, and the high frequency electric fields applied to adjacent slots, for example, EA and EB, or EA/ and EB', have a phase difference of 90 degrees from each other. .

Therefore, between two sets of slots having a center spacing t1, the high frequency electric field E applied to each slot is
A phase difference occurs between A, EB, Ec, ED and EA', EB'.

Therefore, by appropriately setting the center spacing t1 of the slot group, the radiation pattern of the radio waves emitted from the plurality of slots having such a dimension arrangement can be directed toward the parabolic reflector 1, as shown in FIG. 5a. The radiation energy can be maximized in the R direction and minimized in the opposite F direction.

In the above explanation, for convenience, the operation of the antenna of the present invention has been described in the case where linearly polarized waves are fed to the antenna of the present invention using a rectangular waveguide and the radio waves of the polarized wave of the present invention are radiated as a transmitting antenna. , by a process completely opposite to that described above, receives the incoming circularly polarized radio waves, distinguishes and separates the left and right sides of the circularly polarized waves, converts them into linearly polarized waves, and uses the scales as a receiving antenna. Of course.

Further, when a circularly polarized wave is transmitted from a transmitter connected to the circularly polarized antenna of the present invention, or when a circularly polarized wave can be supplied to a connected receiver, a rectangular waveguide 5 shown in the third figure, a rectangular A Hehat-type primary radiator is constructed by a circular waveguide with an appropriate pipe diameter without providing a circular converter 6, a circularly polarized wave generator 7, etc. By simply providing the diurnal polarization radiation section 11 similar to that in the example, a Hehat type circularly polarized parabolic antenna having an extremely simple configuration and structure can be obtained.

As is clear from the above description, according to the present invention, 12
A circularly polarized antenna with a simple configuration and structure for SHF microwave bands such as GHz can be obtained, and it can be used as a receiving antenna suitable for general viewers, so satellite broadcast radio waves can be circularly polarized. It can be done, and the effects are great.

In other words, if the satellite broadcast radio waves are circularly polarized waves, all that is needed is to adjust the direction of the antenna when receiving them.
It is possible to omit a difficult mechanism for adjusting the plane of polarization of the receiving antenna, which would be required in the case of linearly polarized waves.

However, since it is possible to allocate two channels of circularly polarized waves, right-handed and left-handed, to the satellite broadcast radio waves at the same frequency, mutual interference between the satellite broadcast radio waves at the receiving point on the ground can be reduced.

According to the present invention, it is possible to obtain a small circularly polarized parabolic antenna that is easy to manufacture with a simple configuration in which the primary radiator is configured in a Hehat shape, and the reflector and the primary radiator are made of a plastic material coated with a conductive layer. It is possible to obtain an extremely lightweight and inexpensive circularly polarized antenna suitable for receiving satellite broadcasts by general viewers.

In particular, when feeding circularly polarized radio waves to the circularly polarized antenna of the present invention using a circular waveguide, the Hehat type primary radiator in the antenna of the present invention is provided with a required slot radiating portion at the tip; Moreover, it can be configured with an extremely simple structure using only a circular waveguide with short-circuited end faces.

[Brief explanation of the drawing]

Fig. 1 is a vector diagram for explaining the shift in the plane of polarization at the ground receiving point of radio waves transmitted from a broadcasting satellite, and Fig. 2 schematically shows the schematic configuration of the Hehat type circularly polarized parabolic antenna according to the present invention. FIG. 3 is a perspective view showing an example of the configuration of the primary radiator in the antenna of the present invention shown in FIG. 2, and FIGS. FIGS. 5a and 5b are a side view and a sectional view showing the operation of the circularly polarized wave radiating section shown in FIG. 4, respectively. 1... Parabolic reflector, 2... Primary radiator, 3...
... Receiver, 4... Waveguide mounting section, 5... Rectangular waveguide, 6... Rectangular-to-circular conversion section, 7... Circularly polarized wave generating section, 8... Waveguide Part of pipe taber, 9...Slot, 10
... Matching plate, 11... Circularly polarized wave radiation section, 12.13.
...Dielectric block.

Claims (1)

[Claims] 1 A waveguide is extended in the axial direction of the parabolic reflector through the reflective surface of the reflector in the center of the parabolic reflector, and at least the tip of the waveguide is provided with a circular waveguide. a set of four slots spaced apart at 90 degrees from each other in the tube wall of the circular waveguide near the focal point of the parabolic reflector at a predetermined interval in the axial direction of the circular waveguide; 1. A circularly polarized wave antenna, characterized in that two sets of the circular waveguides are arranged at the same time, and the end faces of the circular waveguides are short-circuited.