The present application is a divisional application of an invention patent application having an application date of 1997, 11/15, application number 97126073.7 and an invention name of "multi-beam antenna".
Background
Recently, many geostationary broadcast satellites and geostationary communication satellites have been transmitted. This increases the need to receive microwaves from, for example, two adjacent satellites by using a single antenna and selectively use one of the received microwaves.
Generally, a multibeam antenna receiving microwaves from a plurality of satellites is configured so that the microwaves from the plurality of satellites are reflected and focused by a single parabolic reflector and focused satellite signals enter different primary radiators, respectively.
A horn-type primary radiator (or feed horn) is used as the primary radiator. When receiving two satellite microwaves, for example, two horn-type primary radiators are supported by one support so as to be disposed at the reflection and focusing positions of the parabolic reflector. The elevation angles of the satellites to the ground are different from each other. In addition, the angle difference of the elevation angle varies with the reception area. Thus, for each receiving area, the inclination of the horn-shaped configuration of the primary radiator with respect to an axis parallel to the ground must be adjusted.
The inclination of the horn-shaped configuration of the primary radiator with respect to an axis parallel to the ground is referred to hereinafter as the tilt angle.
In the case where the received satellite signal is linearly polarized, the tilt of each incident microwave relative to the ground varies with the satellite and the reception area. Therefore, the reception polarization angle of each primary radiator must be adjusted for each reception area.
Therefore, when the direction of a conventional multibeam antenna for linearly polarized waves is to be adjusted, it is necessary to adjust the set inclination angle of the horn of the primary radiator with respect to each satellite, and the reception polarization angle of the primary radiator, according to the reception area. This causes problems of complicating the structure of the angle adjusting mechanism and of making the adjustment work heavy.
Generally, a funnel horn type primary radiator is often used as a primary radiator of a satellite broadcasting antenna. Even when the parabolic reflector has a small diameter, for example, 45cm phi, it is possible to make the arrangement distance between the primary radiators large enough until adjacent satellites from which microwaves are received are separated from each other by a pitch angle of about 8 degrees. Thus, the funnel-shaped horn bodies of the primary radiators can be adjacently disposed without interfering with each other. In contrast, in the case where adjacent satellites from which microwaves are received are separated from each other by a small pitch angle of 4 degrees, the distance provided between the primary radiators can be as small as about 25 mm. Therefore, when such funnel horn type primary radiators are used, the radiator horns interfere with or contact each other, and thus it is impossible to construct a multibeam antenna, thereby causing a problem in that a plurality of antennas must be installed separately for satellites from which microwaves are received.
As described above, in a primary radiator of a 45cm 22 dual beam antenna system receiving microwaves of a 12GHz band from two satellites at 4 degrees separation, for example, the horn spacing is about 25 mm. When the primary radiator of such an antenna is constituted by a general funnel-shaped horn as shown in fig. 22A and 22B, the aperture diameter is about 30 mm. Therefore, the antenna cannot be constructed structurally. To realize such an antenna system, it is required to set the aperture diameter of the primary radiator to 25mm or less. In a circular waveguide designated as WCI-120 of EIAJ (japan electronics industry association standard), the inner diameter of the waveguide is 17.475 mm. Therefore, when such a waveguide is used, the horn has an opening angle of approximately 0 degree in consideration of the production process of an actual product. In other words, the horn has a circular waveguide cross-sectional aperture as shown in fig. 23A and 23B.
Fig. 22A is a front view of a conventional funnel horn type primary radiator, and fig. 22B is a sectional view taken along line a-a' of fig. 22A. Fig. 23A is a front view of a conventional circular waveguide type primary radiator, and fig. 23B is a sectional view taken along line a-a' of fig. 23A.
In fig. 22A and 22B, 131 shows a funnel-shaped waveguide disposed on a substrate 132. The feeding point 133 is formed by a printed circuit on the substrate 132 so as to be located at the center of the bottom surface of the funnel-shaped waveguide 131.
The circular waveguide type primary radiator shown in fig. 23A and 23B is a circular waveguide 135 in place of the funnel-shaped waveguide 131. Other components are constructed in the same manner as other components of the funnel horn type primary radiator of fig. 22A.
Fig. 24 shows a radiation pattern of a circular waveguide type primary radiator. The radiation angle of the primary radiator is about 40 degrees with the reflector offset. In the pattern of fig. 24, the leakage power is large in the reflector radiation, and the nonuniformity of the electric field in the reflector radiation range is large. Thus, the antenna gain is reduced.
Such a method can be used as a means for solving the above-described problems. For example, reduction of the aperture diameter of a horn, use of a helical antenna by supplying power through a coaxial system, and use of a traveling-wave antenna such as a circular waveguide feed dielectric rod antenna as a primary radiator. In addition, in the conventional multibeam antenna, a reception signal cable extending from a frequency converter of the primary radiator is connected to an external switching device, and a satellite broadcast program to be received is selected by controlling a switching operation of the switching device. Such a configuration has a problem that the user must purchase such an external switching device, and wiring and the like are required.
When a complete frequency converter is constructed by using a plurality of primary radiators, a substrate-printed probe 202 is formed on a single substrate 201 as shown in fig. 29, and all other circuits are also provided on the substrate 201. Each substrate print detector 202 includes a horizontally polarized wave probe 202a and a vertically polarized wave probe 202 b. The substrate printing detectors 202 are respectively disposed at power supply portions of a plurality of (e.g., two) primary radiator apertures 203. Signals output from the horizontal polarized wave probe 202a and the vertical polarized wave probe 202b are amplified by the high frequency amplifiers 203a and 203b, and then selected by the horizontal/vertical changeover switches 204a and 204 b. The signals selected by the horizontal/vertical switches 204a and 204b are then further selected by the satellite switch 205. The selected signal is amplified by the high frequency amplifier 206 and then supplied to the frequency converter 207. The oscillation output of the local oscillator 208 is supplied to the frequency converter 207. The frequency converter 207 outputs a signal having a frequency equal to the difference in frequency between the signal from the high-frequency amplifier 206 and the signal from the local oscillator 208 as an intermediate frequency signal. The signal output from the frequency converter 207 is amplified by an intermediate frequency amplifier 209. The amplified signal is output to the outside through the terminal 210.
The conventional multibeam antenna has a problem in that the set inclination angles of the primary radiators must be adjusted separately, and the reception polarization angles of the primary radiators must be adjusted separately.
The conventional multibeam antenna has a problem in that, in the case where satellites from which microwaves are to be received are spaced apart from each other by a small distance, for example, 4 degrees, the funnel-shaped horn-shaped primary radiators arranged adjacently contact or interfere with each other, and thus a multibeam antenna cannot be constructed.
The conventional multibeam antenna has a problem in that an external switching device, wiring of the device, etc. are required to selectively receive a desired satellite broadcasting program.
In addition, in the conventional primary radiator, a current supplied from a feeding point is shunted to a rear side through an edge portion of a horn-shaped radiator aperture or an edge portion of a ground plane of a helical antenna, so that the primary radiator has a radiation pattern in which radiation is large in addition to radiation to a reflector. Thus, the antenna gain is reduced.
When the microwaves from a plurality of satellites are received by a conventional frequency converter for receiving the microwaves from the satellites, the substrate-printed probe 202 is set so that an axis parallel to the ground, an orbital inclination of the target satellite, and a polarization angle of the satellite coincide with each other in each area. In this case, the frequency converter is used only for the satellite from which the microwaves are received. Therefore, when the frequency converters corresponding to all satellites are produced, the frequency converters cannot share the substrate completely, with the result that productivity is lowered, thereby increasing the production cost of the frequency converters.
Drawings
Objects, advantages and features of the present invention will become more apparent from the detailed description of the invention with reference to the drawings, in which:
fig. 1A, 1B and 1C are side, front and top views of an external configuration of a multi-beam antenna as an embodiment of the present invention;
figures 2A, 2B and 2C are front, right and rear views of an external arrangement for mounting a primary radiator and a frequency converter on a radiator support arm of a multi-beam antenna;
fig. 3 is a schematic view showing the installation angle of the probes of the first and second primary radiators integrally provided with the frequency converter of the multibeam antenna, as viewed from the rear side of the frequency converter;
fig. 4 is a partial cross-sectional view showing a configuration in which one polarizer is implemented by a circular waveguide aperture horn and inserted into each primary radiator of a multibeam antenna;
fig. 5 is a sectional side view showing a funnel-shaped aperture horn-type primary radiator;
FIG. 6 is a sectional side view showing a circular waveguide aperture horn type primary radiator;
fig. 7 is a schematic view showing the structure of a dielectric lens used as a horn-shaped cover portion of a circular waveguide aperture horn-type primary radiator;
fig. 8A shows three side views of a dielectric rod structure connected to a circular waveguide aperture horn primary radiator; 8B is a partial sectional view showing a state where the lever is connected;
fig. 9A is a front view of a primary radiator of an antenna for receiving microwaves from a satellite as a second embodiment of the present invention; FIG. 9B is a cross-sectional view taken along line A-A' of FIG. 9A;
fig. 10 is a schematic view showing a radiation pattern of the primary radiator of the embodiment;
fig. 11 is a front view showing an application example of the primary radiator of the embodiment;
fig. 12 is a front view of a primary radiator of an antenna for receiving microwaves from a satellite as a third embodiment of the present invention;
fig. 13 is a front view of a primary radiator of an antenna for receiving microwaves from a satellite as a fourth embodiment of the present invention;
fig. 14 is a front view showing an application example of the primary radiator of the embodiment;
fig. 15 is a front view showing another application example of the primary radiator of the embodiment;
fig. 16 is a front view of a primary radiator of an antenna for receiving microwaves from a satellite as a fifth embodiment of the present invention;
fig. 17 is a front view showing an application example of the primary radiator of the embodiment;
fig. 18 is a front view showing another application example of the primary radiator of the embodiment;
fig. 19A is a front view of a primary radiator of an antenna for receiving microwaves from a satellite as a sixth embodiment of the present invention; and FIG. 19B is a cross-sectional view taken along line A-A' of FIG. 19A;
fig. 20A is a front view of a primary radiator of an antenna for receiving microwaves from a satellite as a seventh embodiment of the present invention; and FIG. 20B is a cross-sectional view taken along line A-A' of FIG. 20A;
fig. 21A is a front view of a frequency converter that receives microwaves from a satellite according to an eighth embodiment of the present invention; and FIG. 21B is a side view of the frequency converter;
fig. 22A is a front view of a conventional funnel horn-type primary radiator; and FIG. 22B is a cross-sectional view taken along line A-A' of FIG. 22A;
fig. 23A is a front view of a conventional circular waveguide type primary radiator; and FIG. 23B is a cross-sectional view taken along line A-A' of FIG. 23A;
fig. 24 is a schematic view showing a radiation pattern of a conventional primary radiator;
fig. 25A is a front view showing an external structure of a frequency converter for receiving microwaves from a satellite according to the present invention; and FIG. 25B is a side view of the frequency converter;
fig. 26A is a front view of a primary radiator of a frequency converter receiving microwaves from a satellite according to the present invention; and FIG. 26B is a cross-sectional view taken along line A-A' of FIG. 26A;
fig. 27 is a schematic diagram showing a circuit configuration of a frequency converter for receiving microwaves from a satellite as a ninth embodiment of the present invention;
fig. 28 is a schematic diagram showing a circuit configuration of a frequency converter for receiving microwaves from a satellite as a tenth embodiment of the present invention; and
fig. 29 is a schematic circuit diagram showing a conventional frequency converter for receiving microwaves from a satellite.
Detailed Description
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Fig. 1A to 1C show an external structure of a multibeam antenna as one embodiment of the present invention.
In fig. 1, 11 denotes a reflector, 12 denotes an antenna carrier, 13 denotes a radiator support arm, 14 denotes a frequency converter, and 15a and 15b denote horn-type primary radiators that respectively receive different satellite signals.
Each of the horn-type primary radiators 15a and 15b includes a circular waveguide aperture horn. Both the first and second primary radiators 15a and 15b are integrally connected to the primary frequency converter 14.
The two satellite microwaves reflected and focused by the reflector 11 enter the first and second primary radiators 15a and 15b, respectively, independently, and are then coupled and received by the respective radiator detectors. The received microwaves are converted into electrical signals and amplified by a frequency conversion circuit included in the frequency converter 14, and then guided to a reception tuner through output connection plugs 16a and 16b by a cable.
Fig. 2A to 2C show an external structure of mounting the primary radiators 15a and 15b and the frequency converter 14 to a radiator support arm in the multibeam antenna. Fig. 2A is a side front view, 2B is a right side view, and 2C is a rear view of the primary radiator.
The frequency converter 14 is connected to the radiator support arm 13 via a turning mechanism 17.
The rotating mechanism 17 includes: an angle indicating plate 17a capable of adjustably rotating the entire frequency converter 14 in a clockwise direction around the first primary radiator 15a within a fixed angle range and as seen from the front as the frequency converter 14; and fixing screws 19a and 19b which pass through the long and short holes 18a and 18b of the angle indicating plate 17a, respectively, and are then fixed. For example, in the case of receiving linearly polarized waves reflected and focused by the reflector 11 having a small diameter of 45cm Φ from two satellites located at a small distance above the equator at a height of approximately 36000km or at 124 degrees and 128 degrees east longitude, the arrangement pitch between the primary radiators 15a and 15b on the frequency converter 14 is set to 25mm, and the rotating mechanism 17 is constituted so that the arrangement inclination angles of the first and second primary radiators 15a and 15b with respect to an axis parallel to the ground can be rotationally adjusted from 0 to 20 degrees.
Lens type dielectric covers 20a and 20b are connected to the horn-shaped cover portions of the primary radiators 15a and 15b, respectively.
Fig. 3 is a view showing the probe 21a of the first and second primary radiators 15a and 15b integrally provided with the frequency converter 14 of the multibeam antenna as seen from the rear side of the frequency converter 141，21a2，21b1And 21b2Schematic diagram of the setting angle of (1).
The detector 21a of the first primary radiator 15a is set in a state that the arrangement inclination angle of the first and second primary radiators 15a and 15b is set to 0 degree or parallel to the ground1And 21a2Set parallel and perpendicular to the ground, respectively, and the detector 21b of the second primary radiator 15b1And 21b2Respectively set as detectors 21a with respect to the first primary radiator 15a1And 21a25 degrees off.
The detectors 21a of the first and second primary radiators 15a and 15b are switched according to the difference between the polarization angles of one satellite and the other1、21a2、21b1And 21b2The set angle difference therebetween is set to 5 degrees.
Specifically, when the frequency converter 14 of the constructed multibeam antenna is rotated using the rotating mechanism 17, the arrangement inclination angles of the two primary radiators 15a and 15b with respect to the axis parallel to the ground can be adjusted within the range of 0 to 20 degrees. In addition, the detector 21a of the primary radiators 15a and 15b can be adjusted within a range of 0 to 20 degrees1、21a2、21b1And 21b2While maintaining an angle difference of 5 degrees.
Therefore, according to the multibeam antenna having the above-described configuration, the arrangement inclination angles of the primary radiators 15a and 15b for respectively receiving signals from two satellites and the reception polarization angles in the primary radiators 15a and 15b can be easily adjusted simultaneously by rotating the frequency converter 14 using the rotating mechanism 17.
Further, according to the multibeam antenna having the above-described structure, circular waveguide aperture horn-shaped radiators are used as the primary radiators 15a and 15 b. Therefore, even when the arrangement interval in the frequency converter 14 is as small as, for example, 25mm, it is possible to integrally connect the primary radiator to the frequency converter without causing the horn radiators to contact or interfere with each other. Furthermore, it is possible to implement a multibeam antenna for satellites that are separated from each other by a small distance, e.g., 4 degrees.
In this case, since the lens-type dielectric covers 20a and 20b are respectively fixed to the horn cover portions of the primary radiators 15a and 15b implemented by circular waveguide aperture horns, it is possible to prevent deterioration of antenna performance, such as a decrease in antenna efficiency caused by leakage power of the reflector 11, and a drop-out deterioration in radiation pattern.
In this embodiment, primary radiators 15a and 15b for receiving two reflected satellite microwaves are provided and integrally fixed to the primary frequency converter 14. When a switching device for switching a satellite from which microwaves are received according to a satellite selection signal from a tuner is added to a primary transducer substrate for receiving and amplifying two satellite broadcast signals, two satellite programs can be selectively received using the output of one single cable without the need for an external switching device or the like.
Fig. 4 is a partial sectional view showing a structure in which a polarizer 22 is inserted into each of the primary radiators 15a and 15b of the multibeam antenna and the polarizer is implemented by a circular waveguide aperture horn.
A polarizer 22 is inserted into each of the primary radiators 15a and 15b so thatThe reception polarization angle can be arbitrarily adjusted without performing the detector 21a of the primary radiators 15a and 15b1、21a2、21b1And 21b2And (4) angle adjustment.
Fig. 5 is a side sectional view showing the funnel-shaped aperture horn-type primary radiator 23.
Fig. 6 is a side sectional view showing the circular waveguide aperture horn type primary radiator 24.
Fig. 7 is a schematic view showing the structure of a dielectric lens 25 serving as a horn-shaped cover portion of the circular waveguide aperture horn-shaped primary radiator 24;
fig. 8A and 8B show the structure of the dielectric rod 26 connected to the circular waveguide aperture horn type primary radiator 24. Fig. 8A shows three side views of the rod, and 8B is a partial sectional view showing a state where the rod is connected.
When such a funnel-shaped aperture horn-type primary radiator 23 as shown in fig. 5 is used as the primary radiator provided on and integrally adjoining the primary transducer 14 so as to constitute a multibeam antenna for two satellites spaced at a small distance, the arrangement interval between the two radiators 23 is also reduced, whereby the radiators contact or interfere with each other, with the result that the radiators cannot be connected to the transducer. In this connection, such a circular waveguide aperture horn-type primary radiator 24 as shown in fig. 6 is used so that a multibeam antenna for two satellites spaced apart by a small distance can be constructed without bringing the primary radiators into contact with each other even in the case of a small arrangement pitch.
In this case, a dielectric lens 25 such as shown in fig. 7, or a dielectric rod 26 such as shown in fig. 8 may be connected to the circular waveguide aperture horn type primary radiator 24. According to this structure, it is possible to realize a multibeam antenna with a high-efficiency low-noise frequency converter.
Fig. 9A is a front view of a primary radiator of a small-diameter multi-beam antenna for receiving microwaves from a satellite as a second embodiment of the present invention, and fig. 9B is a sectional view taken along line a-a' of fig. 9A.
In fig. 9A and 9B, 101a and 101B show circular waveguides having a predetermined length and integrally arranged while maintaining a spacing of several millimeters. The circular waveguides 101a and 101b form apertures of the primary radiators. A first choke coil 102a composed of a groove having a wavelength depth of about 1/4 is formed on the periphery of the circular waveguides 101a and 101 b. A second choke coil 102b, which is configured in a similar manner to the first choke coil 102a, is formed at the periphery of the first choke coil. The circular waveguides 101a and 101b, and the chokes 102a and 102b constitute a primary radiator 103. The substrate 104 is disposed at the bottom of the circular waveguides 101a and 101 b. The feeding point 105 is constituted by a printed circuit formed on the substrate 104 so as to be located at the center of the bottom of the circular waveguides 101a and 101 b. A terminal portion 106 is formed on the bottom surface of the primary radiator 103. For example, the primary radiator 103 and the terminal portion 106 may be composed of aluminum or the like.
For example, when the primary radiator 103 is used as a primary radiator of a 45 cm-phi dual-beam antenna system that receives microwaves of a 12GHz band from two satellites spaced 4 degrees apart, the circular waveguides 101a and 101b are set to have an inner diameter of 17.475mm and their center distances are set to about 25 mm.
When the chokes 102a and 102b are formed around the circular waveguides 101a and 101b as described above, the edge portion of the aperture surface formed by the circular waveguides 101a and 101b theoretically has infinite impedance, and therefore the current flowing backward from the edge portion of the aperture surface can be suppressed, thereby preventing the occurrence of radiation to the rear side of the primary radiator 103. As a result, the amount of power leakage from the reflector is reduced, and it is possible to obtain an antenna gain substantially equal to that in the case where a usual funnel-shaped horn is used.
Fig. 10 shows the radiation pattern of the primary radiator.
The leakage power and the nonuniformity of the electric field in the radiation range of the reflector are improved as compared with the conventional radiation pattern shown in fig. 24. The antenna gain of this embodiment is substantially equal to the antenna gain in the case of using a funnel horn.
As shown in fig. 11, the first choke coil 102a may be sometimes configured adjacent to the circular waveguides 101a and 101b so that the boundary wall between the choke coil and the circular waveguides 101a and 101b is made lower than the wall between the first and second choke coils 102a and 102b for impedance matching.
In this embodiment, the same effect can be obtained even if a horn with a small opening angle is used instead of the circular waveguides 101a and 101 b.
A third embodiment of the present invention will be described. Fig. 12 is a front view of a primary radiator 103 as a second embodiment of the present invention.
The third embodiment is constituted by modifying the primary radiator 103 of the second embodiment so as to remove the second choke coil 102 b. In the primary radiator 103 of the second embodiment, the radiation pattern is not raised to the energy level of the radiation pattern of the second embodiment shown in fig. 10, but the antenna efficiency is raised by the order of about 60%.
Fig. 13, 14 and 15 are front views of a primary radiator 103 as a fourth embodiment of the present invention. The primary radiator 103 of the fourth embodiment is constructed in order to prevent the radiation pattern of fig. 10 from becoming laterally asymmetrical, so that the shape of the choke coil 102(102a, 102 b. -) is constructed by a circle located at the center of each circular waveguide and the intersection of the circles is removed.
Fig. 13 shows an example in which only the first choke 102a is provided, fig. 14 shows an example in which the first and second chokes 102a and 102b are provided, and fig. 15 shows an example in which the first, second, and third chokes 102a, 102b, and 102c are provided. In the example shown in fig. 14, the second choke coil 102b disposed on the outside has a shape similar to that of the choke coil of the second embodiment. In other words, the second chokes may be formed on the circles whose centers are located on the circular waveguide, respectively, in the same manner as the first chokes 102 a.
Fig. 16, 17 and 18 are front views of a primary radiator 103 as a fifth embodiment of the present invention. In the fifth embodiment, the primary radiator 103 is configured to receive microwaves from three satellites.
Fig. 16 shows an example in which the choke coil 102a is disposed outside the circular waveguides 101a, 101b, and 101 c.
Fig. 17 shows an example in which a choke coil 102a is provided outside circular waveguides 101a, 101b, and 101c and the circular waveguides 101a, 101b, and 101c are arranged in an "angular" shape according to the difference in the elevation angle of the satellite. For example, the aperture is arranged to be "angled" using an extension of the two circular waveguides 101a and 101b to correspond to the elevation angle of the satellite.
Fig. 18 shows an example in which two chokes 102a and 102b are provided outside circular waveguides 101a, 101b, and 101c and the circular waveguides 101a, 101b, and 101c are arranged in an "angular" shape according to the difference in the satellite elevation angle.
Fig. 19A is a front view of a primary radiator as a sixth embodiment of the present invention, and fig. 19B is a sectional view taken along line a-a' of fig. 19A.
In the sixth embodiment, to focus a beam, a dielectric member 110 is loaded to each of the circular waveguides 101a and 101 b. In this example, a choke coil 102a is provided.
Fig. 20A is a front view of a primary radiator as a seventh embodiment of the present invention, and fig. 20B is a sectional view taken along line a-a' of fig. 20A.
In the seventh embodiment, a helical antenna 112 such as a dipole antenna, a helical antenna, or a meander antenna is connected to the ground plane 111. Specifically, the ground plane 111 is formed using aluminum or a similar metal, and a plurality of (e.g., two) circular apertures 113a and 113b are disposed at intervals of several millimeters on the ground plane. The helical antenna 112 is disposed in the central portions of the apertures 113a and 113b, respectively. A power supply to the helical antenna 112 is introduced from the feeding point 105 provided at the ground plane 111. A choke coil 102a having a wavelength depth of about 1/4 is formed at the periphery of the apertures 113a and 113 b.
Also in the case where the helical antenna 112 is provided as shown in the seventh embodiment, it is possible to obtain the same effects as those of the above-described embodiments.
In the seventh embodiment, a single choke 102 is provided. A plurality of chokes may of course be provided in the same manner as in the above-described embodiment.
Fig. 21A and 21B show a case constituting a frequency converter 120 for receiving microwaves from a satellite using a primary radiator 103 according to the present invention. Fig. 21A is a front view of a frequency converter 120 receiving microwaves from a satellite according to an eighth embodiment, and fig. 21B is a side view of the frequency converter.
In fig. 21A and 21B, 121 represents a housing accommodating the main unit of the frequency converter and connected to a reflector (not shown) via a bracket 122. The angle adjusting mechanism 123 is provided at the inverter supporting portion by the bracket 122. The connection angle of the frequency converter 120 can be adjusted using the elongated hole 124 and the screw 125. The primary radiator 103 in the embodiment described is connected to one surface of the frequency converter housing 121, i.e. the surface opposite the reflector.
The structure of the frequency converter 120 in which the frequency converter is combined with the primary radiator 103 to receive microwaves from a satellite as described above makes it possible to receive microwaves from a plurality of satellites by a single frequency converter 120 and to miniaturize the antenna system.
Fig. 25A and 25B show the overall structure of a frequency converter that receives microwaves from a satellite as one embodiment of the present invention. Fig. 25A is a front view of the frequency converter, and fig. 25B is a side view of the frequency converter.
In fig. 25A and 25B, 211 denotes a housing that accommodates the main unit of the frequency converter and is connected to a reflector (not shown) via a bracket 212. The angle adjusting mechanism 213 is provided to the inverter supporting portion using a bracket 212. The connection angle of the inverter 220 can be adjusted using the long hole 214 and the tilt angle adjusting screw 215. The primary radiator 216 is connected to one surface of the frequency converter case 21, i.e., the surface opposite to the reflector.
The primary radiator 216 is constructed in the manner shown in fig. 26A and 26B. Fig. 26A is a front view of the primary radiator 216, and fig. 26B is a sectional view taken along line a-a' of fig. 26A.
In fig. 26A and 26B, 221a and 221B show circular waveguides having a predetermined depth and integrally arranged while maintaining a spacing of several millimeters. Circular waveguides 221a and 221b form the aperture of the primary radiator. A first choke coil 222a composed of a groove having a wavelength depth of about 1/4 is formed on the periphery of the circular waveguides 221a and 221 b. A second choke coil 222b, which is configured in a similar manner to the first choke coil 222a, is formed at the periphery of the first choke coil. The substrate 223 is disposed at the bottom of the circular waveguides 221a and 221 b. A feeding point 224 composed of a printed circuit is formed on the substrate 223 so as to be located at the bottom center of the circular waveguides 221a and 221 b. A terminal portion 225 is formed at the lower surface of the primary radiator 216. For example, the circular waveguides 221a and 221b and the terminal portion 225 are formed of aluminum or the like.
For example, when the primary radiator 216 is used as a primary radiator of a 45 cm-phi dual-beam antenna system that receives microwaves of a 12GHz band from two satellites spaced 4 degrees apart, the circular waveguides 221a and 221b are provided to have an inner diameter of 17.475mm and their center-to-center distances are set to about 25 mm.
The inverter circuit portion shown in fig. 27 is formed on a substrate 223.
At the substrate 223, portions corresponding to the circular waveguides 221a and 221b, that is, primary radiator apertures are cut out in a substantially circular shape to form the notch portions 230a and 230b, and substantially circular substrate print detector substrates 231a and 231b are rotatably provided at the notch portions 230a and 230b, respectively. For example, at each substrate. In the printed probe substrates 231a and 231b, upper portions are protruded outward, and arc-shaped grooves 232a or 232b are formed at the convex portions. In the groove 232a or 232b, the substrate-printed probe substrate 231a or 231b is fixed to the substrate 223 by the screw 233a or 233b in such a manner that the substrate-printed probe substrate 231a or 231b can be maximally laterally rotated by an angle corresponding to the length of the groove 232a or 232b when the screw 233a or 233b is loosened. After adjusting the rotation angle of the substrate printing probe substrate 231a or 231b, the substrate is fixed by the screw 233a or 233 b.
In each of the substrate-printed probe substrates 231a and 231b, the substrate-printed probe 202 is formed at the feeding point of the circular waveguide 221a or 221 b. Each substrate print detector 202 includes a horizontally polarized wave probe 202a and a vertically polarized wave probe 202 b. These probes are connected to a printed circuit formed on substrate 223 via leads 234a and 234 b. For example, in this case, the wiring pattern on the substrate 223 may be formed in an arc shape so as to extend along the outer edges of the substrate-printed probe substrates 231a and 231b, and the leads 234a and 234b may be connected to the positions of the wiring pattern on the substrate 223 that are closest to the horizontal polarized wave probe 202a and the vertical polarized wave probe 202 b. According to this structure, the leads 234a and 234b can be shortened and the circuit characteristics can be improved. In other words, the wiring patterns of the horizontally polarized wave probe 202a and the vertically polarized wave probe 202b can be brought into close contact with the wiring patterns on the substrate 223 so as to be connected to each other.
Signals output from the horizontal polarized wave probe 202a and the vertical polarized wave probe 202b are amplified by the high frequency amplifiers 203a and 203b, and then selected by the horizontal/vertical changeover switches 204a and 204 b. The signal selected by the horizontal/vertical switches 204a and 204b is then further selected by the satellite switch 205. The high frequency amplifier 206 amplifies the selected signal and then supplies it to the frequency converter 207. The oscillation output of the local oscillator 208 is supplied to the frequency converter 207. The frequency converter 207 outputs a signal having a frequency equal to the difference in frequency between the signal from the high-frequency amplifier 206 and the signal from the local oscillator 208 as an intermediate frequency signal. The intermediate frequency amplifier 209 amplifies the signal output from the frequency converter 207. The amplified signal is supplied to the outside through the terminal 210.
Such a structure that the substrate-printed probe substrates 231a and 231b are independently provided in addition to the substrate 223 as described above and the rotation angle of the substrate-printed probe substrate can be arbitrarily adjusted enables the frequency converter to easily conform to the polarization angles of a plurality of satellites and the inclination angle which is the angular difference between the axis parallel to the ground and the axis of the satellite orbit. Therefore, even when the polarization angles of the adjacent two satellites are changed or when the satellite from which the microwaves are received is changed to another, it is possible to easily make the frequency converter coincide with the polarization angle. In addition, the use of a common circuit can reduce production costs.
Next, a tenth embodiment of the present invention will be described.
Fig. 28 is a schematic diagram showing the configuration of a circuit part of a frequency converter in the tenth embodiment of the present invention.
In the above-described ninth embodiment, the substrate-printed probe substrates 231a and 231b corresponding to the circular waveguides 221a and 221b are rotatably provided, and the substrate-printed probe 202 is provided on the substrate-printed probe substrates 231a and 231b, respectively. In the tenth embodiment, a substrate-printed probe 202 for receiving microwaves from one satellite is provided on a substrate 223, and one or more other probes for receiving microwaves from a satellite are provided on a substrate-printed probe substrate 231 formed separately from the substrate 223.
In this embodiment, the substrate printing probe 202 fixedly disposed on the substrate 223 is adjusted by the angle adjusting mechanism 213 to receive the microwave of the target satellite, and the substrate printing probe 202 disposed on the substrate printing probe 231 is adjusted by rotating the substrate printing probe substrate 231 to receive the microwave of the target satellite.
Further, in the second embodiment, in the same manner as in the ninth embodiment, it is possible to use a common substrate even when receiving microwaves from a plurality of satellites, with the result that productivity is improved and production cost is reduced.
As described above, the multibeam antenna of the present invention includes: a reflector that reflects and focuses microwaves from a plurality of satellites; a plurality of horn-type primary radiators that respectively receive the plurality of satellite microwaves reflected and focused by the reflector; a plurality of horn-shaped primary radiators integrally connected adjacent to each other, and a frequency converter for frequency-converting and amplifying satellite signals received by the primary radiators, respectively; detectors for the primary radiators, respectively, the detectors being disposed with an angle difference corresponding to a difference in polarization angle between the satellites in a state where the plurality of primary radiators are connected to the frequency converter; a radiator support arm that supports the frequency converter so that a horn of the plurality of primary radiators faces a reflection direction of the reflector; and a rotation mechanism which is provided between the radiator support arm and the inverter and adjusts a rotation position of the inverter so that an arrangement inclination angle of the primary radiator with respect to an axis parallel to the ground, an arrangement inclination angle of the plurality of primary radiators, and a reception polarization angle of each radiator are simultaneously adjusted by the rotation mechanism. Therefore, the setting inclination angle and the reception polarization angle of the primary radiator can be easily adjusted.
In the multibeam antenna of the present invention, the primary radiator is a circular waveguide aperture horn, and the dielectric portion is connected to the aperture of the horn. Therefore, even in the case where satellites from which microwaves are received are separated from each other by a small pitch angle of 4 degrees, it is possible to configure a configuration for receiving multiple beams without causing horns of primary radiators to interfere with or contact each other.
In the multibeam antenna of the present invention, the antenna further comprises a reception satellite switching means for selecting one of the plurality of satellite signals received by the plurality of primary radiators according to an external instruction and outputting the selected signal. Therefore, a desired satellite broadcast program can be easily selected for reception without the need for providing an external switching device, wiring, and the like.
In addition, according to the invention, two or more horn radiators of a smaller opening angle or circular waveguide are integrated with each other, and one or more chokes having a wavelength of about 1/4 are arranged around the integrated structure. Therefore, the edge portion of the aperture surface theoretically has infinite impedance, and therefore, the current flowing backward from the edge portion of the aperture surface can be suppressed, thereby preventing radiation to the rear side of the primary radiator from occurring. Therefore, microwaves from a plurality of satellites can be efficiently received.
As described above in detail, according to the present invention, a plurality of substrate-printed probe substrates are independently provided from a substrate on which a frequency converter circuit portion is formed and configured, so that the rotation angle of each substrate-printed probe substrate can be arbitrarily adjusted. A substrate-printed probe for receiving microwaves from a satellite is provided on a substrate on which a frequency converter circuit portion is formed, and one or more other probes for receiving microwaves from a satellite are provided on a substrate-printed probe substrate formed separately from the above substrate. Therefore, the polarization angle of the frequency converter with respect to the plurality of satellites and the inclination angle, which is the difference in angle between the axis parallel to the ground and the axis of the satellite orbit, can be easily made to coincide. Therefore, even when the polarization angles of the adjacent two satellites are changed or when one satellite from which microwaves are received is changed to another, the converter can easily conform to the polarization angles. In addition, the use of a common circuit can reduce production costs.