JP4713292B2 - Multi-beam feed horn - Google Patents

Description

  The present invention provides a multi-beam feed horn provided in a single parabolic reflector and used to receive radio waves from a plurality of transmission sources, for example, a plurality of geostationary satellites, and an integral power supply including the multi-beam feed horn. The present invention relates to a parabolic antenna provided with a unit and the integral feeding unit.

  In recent years, a plurality of geostationary satellites, for example, communication satellites are approaching and launched on the same geostationary orbit. Radio waves from these close communication satellites are received by an antenna having one reflector and a plurality of horns. An example of this antenna is disclosed in Patent Document 1.

  In the technique of Patent Document 1, a multi-beam feed horn is disposed in the vicinity of the focal position of the reflecting mirror. In this multi-beam feed horn, two waveguides are arranged in parallel, and a horn is attached to the tip of each of the waveguides. These horns are integrally formed and configured to be detachable from the waveguide. There are two types of integrated horns, one for large calibers and one for small calibers, corresponding to reflectors with different calibers.

  In general, the aperture of the reflecting mirror is related to the gain of the antenna using the reflecting mirror. When a large gain is required, a reflecting mirror having a large aperture is used. When the apertures of the reflecting mirrors are different, even when the same radio waves are received, the positions where the radio waves are reflected by the reflecting mirrors are different, and the distances between these convergence positions are also different. In order to cope with this, in Patent Document 1, two types of horns are prepared in order to increase the number of components that can be used in common even in reflectors having different calibers, and either one is selected according to the caliber of the reflector. The horn is used.

JP 2002-124820 A

  In the technique of Patent Document 1, a waveguide can be used in common for different reflecting mirrors, but the horn needs to be prepared for reflecting mirrors having different apertures. When horns are prepared for reflectors having different calibers as described above, a mold must be prepared for each horn, resulting in an increase in cost.

  An object of the present invention is to provide a multi-beam feed horn that can be used for a reflector having a different aperture while using a horn prepared for a reflector having a specific aperture. Another object of the present invention is to provide an integrated power feeding unit including the multi-beam feed horn as described above. Another object of the present invention is to provide a multi-beam antenna provided with the multi-beam feed horn or the integral feeding portion as described above.

When the multi-beam feed horn according to the present invention is arranged in the vicinity of the focal position of the parabolic reflector having a predetermined aperture, the radio wave transmitted from at least two geostationary satellites arranged adjacent to each other on the geostationary orbit enters. Thus, it has at least two horns provided corresponding to these geostationary satellites . Three or more horns may be arranged close to each other. In this case, it is desirable to arrange each horn in a straight line. A waveguide is connected to each of the at least two horns. A fidome is detachably provided on the at least two horns. This fidome covers the front of these horns. When the at least two horns are disposed in the vicinity of the focal position of another parabolic reflector having a larger diameter than the parabolic reflector having the predetermined diameter, the at least two horns are positioned between the at least two horns. A radio wave refraction protrusion is provided on the inner surface of the fidome so that the radio wave from the geostationary satellite is refracted and incident on the corresponding at least two horns.

  In the multi-beam horn configured as described above, the radio wave traveling straight toward the radio wave refracting projection is refracted, and the radio wave arrives at the inner side of the position where there is no refracting projection in any horn. It becomes like this. As a result, radio waves from at least two transmission sources that are originally difficult to enter the horn enter each horn satisfactorily. Moreover, only one protrusion provided on the fidome is required for this purpose.

  Further, it is desirable that the radio wave refraction protrusion is located substantially at the center of a line segment connecting the central axes of the at least two horns. By providing at this position, radio waves corresponding to these horns can be incident on each of at least two horns.

A frequency converter that converts the frequency of the signals received by these multi-beam feed horns may be provided integrally with any of the multi-beam feed horns as described above to constitute an integrated power feeding unit. In addition, a parabolic antenna can be configured by arranging the integrated power feeding unit in the vicinity of the focal position of the other parabolic reflector.

  As described above, according to the present invention, by replacing the fidome that forms a part of the multi-beam feed horn, the multi-beam feed horn other than the fidome can be used in common for the reflectors having different apertures. Thus, a multi-beam feed horn, an integrated feed unit, and a parabolic antenna can be configured at low cost.

  As shown in FIG. 3, the multi-beam feed horn 2 according to an embodiment of the present invention is arranged near the focal position of a reflector of a parabolic antenna, for example, an offset parabolic reflector 4. Can be used in common for a plurality of different reflectors, for example, the first and second reflecting mirrors. The first reflecting mirror has a diameter D of 40 cm, for example, and the second reflecting mirror has a diameter D of 45 cm, for example.

  The multi-beam feed horn 2 reflects radio waves from a plurality of satellites, for example, two geostationary satellites launched close to a geostationary orbit in outer space by a reflecting mirror 4 as shown in FIG. , For receiving. The two geostationary satellites include, for example, communication satellites launched at 124 degrees east longitude and 128 degrees east longitude with an interval of 4 degrees. The received radio wave is in the GHz band, for example, the 12 GHz band. The multi-beam feed horn 2 is originally designed for use with a reflector having a diameter of, for example, 40 cm.

  The multi-beam feed horn 2 has two waveguides 6 and 8 as shown in FIGS. These two waveguides 6 and 8 are configured as circular waveguides, for example, and they are arranged close to each other so that their central axes are parallel to each other. The rear ends of these waveguides 6 and 8 are closed. On the side of these waveguides, although not shown, a frequency converter that converts the frequency of the microwave in the GHz band received by the multi-beam feed horn 2 into, for example, an intermediate frequency signal in the 1 GHz band is provided integrally. It has been. Microwaves are supplied to the frequency converter from a probe provided in the vicinity of the rear ends of the waveguides 6 and 8, and the frequency conversion is performed by the frequency converter.

  The leading ends of the waveguides 6 and 8 are both open, and the horns 10 and 12 are integrally formed in these openings. The horns 10 and 12 have the same symmetrical shape, and are formed in a truncated cone shape having a front end portion and a rear end portion, for example, a truncated cone shape. These horns 10 and 12 have circular openings on the front end side on the same surface, and circular openings on the rear end side are also on the same surface (tip surfaces of the waveguides 6 and 8). The circular opening on the front end side has a larger diameter than the circular opening on the rear end side, and the center of the circular opening on the rear end side is located on the central axis of the waveguides 6 and 8. The center of the circular opening on the distal end side is located somewhat outside the central axis of the waveguides 6 and 8.

  The two are combined so as to substantially cover the periphery of the horns 10 and 12, and the planar shape is substantially oval, and corrugates 14 and 16 each having substantially the same shape are formed. These corrugates 14 and 16 have their openings located on the same plane as the openings on the distal ends of the horns 10 and 12. A boundary portion 20 of the horns 10 and 12 is located on an extension line of the boundary portions 18a and 18b between the corrugations 14 and 16.

  Recesses 22a and 22b having the same shape are formed outside the corrugations 14 and 16 so as to be substantially perpendicular to the boundary portions 18a, 18b and 20. These recesses 22a and 22b are both formed in an arc shape.

  For example, the opening on the front end side of the horns 10 and 12 is formed with a diameter of about 25 mm, the opening of the rear end is formed with a diameter of about 19.6 mm, and the distance d1 between the centers of the openings is formed at 22 mm. . When these feed horns 10 and 12 are arranged in the vicinity of the focal position of the reflector having a diameter of 40 cm as described above, the radio waves from the communication satellite of 124 degrees east longitude are transmitted to the horn 10 and from the communication satellite of 128 degrees east longitude. The above dimensions are set so that the radio wave enters the horn 12.

  A fidome 24 is detachably attached to the periphery of the horns 10 and 12 so as to cover the periphery of the horns 10 and 12 and the opening on the front end side. The fidome 24 is made of, for example, a synthetic resin, specifically, an ABS resin, and has a flat portion 24a that is located at a predetermined distance from the distal end side openings of the horns 10 and 12.

  The radio wave refraction protrusion 26 faces the horn 10, 12 side so that it is located at the center on the inner surface side of the flat portion 24 a of the fidome 24, that is, the center of the boundary portion 20 of the horns 10, 12, and the flat portion 24 a It is integrally formed. The radio wave refraction protrusion 26 is also made of the same ABS resin as the fidome 26.

  At the center of the inner surface of the flat portion 24a of the fidome 24, that is, the center of the boundary 20 of the horns 10 and 12, in other words, the position corresponding to the center of the straight line connecting the centers of the horns 10 and 12, the radio wave refraction protrusion 26 is provided. , Provided. The protrusion 26 is formed in a columnar shape, for example, a cylindrical shape, and is provided perpendicular to the flat surface portion 24a so that the tip of the cylinder faces the horns 10 and 12 side. As the protrusions 26, for example, those having an outer diameter of 12 mm, an inner diameter of 7 mm, and a height of 10 mm are used. Accordingly, the outer diameter is about ½ wavelength of the center frequency of the used frequency band, the inner diameter is about 0.3 wavelength, and the height is about 0.4 wavelength.

  Separately from the fidome 24 provided with the projection 26, a fidome having the same shape is prepared separately except that the projection 26 is not provided at the center position of the straight line connecting the horns 10, 12, and any one of the fidomes, Attached to the front of 12

  This multi-beam feed horn is launched at a position of 124 degrees east longitude and 128 degrees east longitude when placed near the focal position of an offset parabolic reflector having a diameter of 40 cm with a fidome not provided with a projection 26. It is designed so that radio waves from communication satellites are incident at a beam interval of 4.5 degrees. This beam interval of 4.5 degrees is a beam interval at which a radio wave from both the satellites can be satisfactorily received at a certain reception location in Japan.

  When this multi-beam feed horn is placed at the focal position of an offset parabolic reflector having a diameter of 45 cm with a fidome not provided with a projection 26, the radio wave from both communication satellites has a beam interval of about 4 degrees. Incident at. Therefore, when the fidome is replaced with the fidome 24 provided with the protrusions 26, the radio waves arriving from the horn 12 side as seen from the horn 10 as shown in FIG. It hardly enters the horn 10. However, when the fidome 24 provided with the projection 26 is used, the projection 26 is refracted as shown by the solid line, and the efficiency of entering the horn 10 is the best. Although not shown in the figure, the radio wave arriving from the horn 10 side is also refracted by the projection 26 and incident on the horn 12. The angle formed by these incident radio waves with respect to the normal line standing on the reflecting mirror is larger than the angle formed by the incident radio waves with respect to the normal line standing on the reflecting mirror when there is no projection 26. That is, the angle formed when radio waves that can be incident on the projection 26 are directed toward the reflecting mirror is larger than the angle formed when the incident radio wave is directed toward the reflecting mirror without the projection 26, and the beam interval is increased. Any of the 4.5 degree radio waves can be received by the horns 10 and 12.

  FIG. 5A shows the directivity when the multi-beam feed horn is arranged near the focal position of the offset parabolic reflector having a diameter of 45 cm and the vertically polarized 12.5 GHz radio wave is received by the horns 10 and 12, respectively. In the characteristic diagram, the peak-to-peak beam interval d in this case is 4.552 degrees. In FIG. 5B, the protrusion 26 is changed to an outer diameter of 12 mm, an inner diameter of 5 mm, and a height of 8 mm, and a multi-beam feed horn is arranged in the vicinity of the focal position of an offset parabolic reflector having a diameter of 45 cm. The directional characteristic diagram when the 12.5 GHz radio wave is received by the horns 10 and 12, respectively, and also in this case, the peak-to-peak beam interval d is 4.552 degrees.

  As shown in FIG. 6 (a), the projection 26 is formed in a truncated cone shape, the diameter of the lower base is 12 mm, the diameter of the upper base is 9.6 mm, the height is 10 mm, and the inner diameter is 3.4 mm. As described above, when the 12.5 GHz radio wave of vertical polarization is received by each of the horns 10 and 12 by being arranged near the focal position of the offset parabolic reflector having a diameter of 45 cm, the peak-to-peak beam interval is 4.74. It was a degree. When the projection 26 is formed in a truncated cone shape as shown in FIG. 4B, the diameter of the lower base is 12 mm, the diameter of the upper base is 10 mm, the height is 8 mm, and the inner diameter is 3.4 mm. The peak-to-peak beam interval was 4.673 degrees. When the projection 26 is formed in a truncated cone shape as shown in FIG. 6 (c), the diameter of the lower base is 12 mm, the diameter of the upper base is 10 mm, the height is 6 mm, and the inner diameter is 3.4 mm. The peak-to-peak beam spacing was 4.408 degrees. As shown in FIG. 4D, when the protrusion 26 is cylindrical, the outer diameter is 12 mm, the height is 8 mm, and the inner diameter is 5 mm, the peak-to-peak beam interval is 4.552 degrees. Also, as shown in FIG. 5E, when the projection 26 is cylindrical, the outer diameter is 12 mm, the height is 8 mm, and the inner diameter is 7 mm, the peak-to-peak beam interval is 4.432 degrees. It was. Further, when the protrusion 26 was formed in a columnar shape with a diameter of 13 mm and a height of 8 mm, the peak-to-peak beam interval was 4.923 degrees. Further, when the protrusion 26 was formed in a columnar shape with a diameter of 13 mm and a height of 6 mm, the peak-to-peak beam interval was 4.52 degrees.

  SKY PerfecTV TV using two communication satellites launched at 124 and 128 degrees east longitude! Is viewed using an offset parabolic reflector with a 45 cm aperture, the theoretical value of the peak-to-peak beam spacing of radio waves transmitted from both communication satellites is 4.42 degrees in Wakkanai and 4.61 in Okinawa. The average is 4.52 degrees. The deviation of the beam interval of about ± 0.3 degrees hardly affects the peak level and is within the allowable range. Therefore, when the design value is 4.5 degrees, if the projection 26 is made of ABS and is cylindrical, the reception is good if the outer diameter is 12 mm, the inner diameter is 5 to 7 mm, and the height is 8 to 10 mm. In the case of a truncated cone shape, reception can be satisfactorily performed when the cylindrical shape has a lower base of 12 mm, an upper base of about 10 mm, and a height of 8 to 10 mm.

  Moreover, when this multi-beam feed horn is used together with an offset parabolic reflector having a diameter of 40 cm, if the fidome is changed to one that does not have the projections 26, the skyperfec TV! Can be received well. Therefore, the parts other than the fidome of one type of multi-beam feed horn can be used in common for two types of offset parabolic reflectors, and it is necessary to manufacture a dedicated multi-beam feed book for each of the reflectors with different apertures. The cost can be reduced.

  As a material of the fidome 24, polypropylene (PP) may be used in addition to the ABS described above. The relative dielectric constant of PP and ABS resin is different. For example, ABS resin is 2.44 to 3.11 (1 MHz), and PP is 2.0 to 2.1 (1 MHz). Therefore, when the cylindrical protrusion 26 having an outer diameter of 12 mm, an inner diameter of 7 mm, and a height of 10 mm is integrally formed with the fidome 24 with PP, the beam interval, which was 4.552 degrees made of ABS resin, is 4.39 degrees. . Moreover, when a cylindrical projection having an outer diameter of 12 mm, an inner diameter of 5 mm, and a height of 8 mm was integrally formed with the fidome 24 with PP, the beam interval, which was made of ABS resin and was 4.552 degrees, became 4.42 degrees. That is, the beam interval is reduced due to the difference in relative permittivity.

  Therefore, by increasing the outer diameter of the protrusion 26 such that the outer diameter is 15 mm, the inner diameter is 7 mm, and the height is 10 mm, the beam interval of 4.39 degrees is restored to 4.538 degrees. The antenna gain also satisfied 33.8 dB (standard) required for a 45 cm antenna.

  Thus, in a multi-beam feed horn, when a projection is provided on the fidome and the beam interval is manipulated, the beam deflection angle (the refraction effect of radio waves) is a factor of the relative permittivity and the outer diameter of the projection material. Dominate.

  In the above-described embodiment, when the projection having the above-described dimensions was used, the reception was most favorable. However, the present invention is not limited to this, and for example, the same SkyPerfect TV! Even if the diameter of the tip opening of the horns 10 and 12 is different from that of the above embodiment, it is necessary to use projections having different dimensions, and reflections other than 40 cm and 45 cm. When using with a mirror, it is necessary to use projections of different sizes, and it is also necessary to use projections of different sizes even when the angles of two geostationary satellites launched adjacently are different. In the above-described embodiment, the projections are cylindrical or frustoconical. However, the present invention is not limited to these, and for example, a prismatic or truncated pyramid can be used. . In the above embodiment, the case where radio waves from two communication satellites are received has been described, but radio waves from three geostationary satellites may be received. In this case, three horns are arranged in a line, but a protrusion may be provided at each of the boundary portions of two adjacent horns.

It is a vertical side view of the multi-beam feed horn of one embodiment of the present invention. It is a top view of the multi-beam feed horn of FIG. It is a schematic block diagram which shows the use condition of the multi-beam feed horn of FIG. It is the schematic which shows the refraction | bending state of the electromagnetic wave in the multi-beam feed horn of FIG. It is a directional characteristic figure at the time of using a different protrusion in the multi-beam feed horn of FIG. It is a longitudinal cross-sectional view of each protrusion used in the multi-beam feed horn of FIG.

Explanation of symbols

2 Multi-beam feed horn 4 Reflector 10 12 Horn 24 Fidome 26 Protrusion for radio wave refraction

Claims (4)

Corresponding to these geostationary satellites so that radio waves transmitted from at least two geostationary satellites placed adjacent to each other on geostationary orbit are incident when placed near the focal position of a parabolic reflector with a predetermined aperture And at least two horns,
A fidome detachably provided on the at least two horns so as to cover the front surfaces of these horns;
When the at least two horns are arranged in the vicinity of the focal position of another parabolic reflector having a larger aperture than the reflector having the predetermined aperture, the at least two horns are positioned between the at least two horns. A radio wave refraction protrusion provided on the inner surface of the fidome so that radio waves from the geostationary satellites are refracted and incident on the corresponding at least two horns ,
Multi-beam feed horn provided. 2. The multi-beam feed horn according to claim 1 , wherein the radio wave refraction protrusion is located at substantially the center of a line segment connecting the central axes of the at least two horns. An integrated power feeding unit provided with a frequency conversion unit for frequency-converting signals received by the multi-beam feed horn integrally with the multi-beam feed horn according to claim 1 or 2 . A parabolic antenna in which the integrated power feeding unit according to claim 3 is disposed in the vicinity of a focal position of the another parabolic reflector .

Images