A relatively low cost, easy to install and aesthetically pleasing digital video broadcast from satellite (DVBS) elliptical horn antenna designed as part of a reflector antenna system to receive satellite television broadcast signals with circular polarity. This type antenna may be implemented with a single antenna feed horn with multiple feed horns that may be arranged separately or in one or more integral feed horn blocks. The antennas may be designed to achieve acceptable circular polarity performance over broad and multiple frequency bands through the use of oppositely sloped differential phase differential sections.

Circular polarity elliptical horn antenna

A unique single offset reflector antenna has been designed which provides as much as +or-30 degrees of scanning in azimuth while maintaining a much higher aperture efficiency than a torus antenna. Like a torus antenna, different portions of the reflector are illuminated for each scanned beam. The reflector profile curve in the plane of scan is found by least squares to minimize the error for the beams with the greatest scan angle, and then polynomial terms of up to sixth order which minimize nonplanar phase errors are added to produce a three-dimensional reflector surface. Numerical simulation indicates very good results for all 0.5 degrees beams in the +or-30 degrees azimuth field of view, with peak gain no more than 0.3 dB below ideal and highest side-lobe levels no worse than 13.3 dB below the peak gain. Additionally, comparable performance can be extended to the elevation plane out to 15 degrees /-30 degrees , although full azimuth performance becomes compromised at extreme elevation scan angles. By using an offset design, there is no blockage of the outgoing beam by the feed array assembly for azimuth scanning. With better feed performance than comparably sized paraboloids, and being more compact than similar torus reflectors, this novel antenna should find numerous uses in spacecraft and terrestrial applications. >

A high aperture efficiency, wide-angle scanning offset reflector antenna

The present invention provides a feed horn for use in an antenna assembly having a non-circular reflector. The feed horn is capable of transmitting and receiving circularly polarized signals. The feed horn includes a circular waveguide section for connection to a transmitter and receiver of the antenna assembly. A conical waveguide section is connected to an opposed end of the circular waveguide section for creating a smooth transition from the circular waveguide section to a non-circular corrugated waveguide section. The corrugated waveguide section includes a plurality of corrugations that transition for a circular shape adjacent to the conical waveguide section to an increasing non-circular shape at an end proximal to the reflector of the antenna assembly. The corrugations have individuals depths defined in the inner wall of the corrugated waveguide section. These depths compensate circularly polarized signals propagating in the feed horn for distortions due to the non-circular reflector.

Circularly polarized receive/transmit elliptic feed horn assembly for satellite communications

A feed assembly for an antenna having a non-circular reflector, in which the feed assembly includes a feed horn capable of correcting the distortions of circularly polarized signals caused by the non-circular reflector profile, and wherein the feed horn is coupled with a polarizer that is field-switchable between linear and circular polarization modes of operation. The feed assembly can include a second receive-only feed located in close proximity to the feed horn for communication with adjacent satellites.

Feed assembly for multi-beam antenna with non-circular reflector, and such an assembly that is field-switchable between linear and circular polarization modes

For future direct broadcasting satellites in Japan, precisely contoured beam antennas will be required for onboard antennas. Single shaped-reflector antennas are suitable for that purpose, since they do not need complex feed networks. However, in a previous study, discontinuities in the reflector surface were observed. The problem of the discontinuity was circumvented in this work and the shaped reflectors were successfully designed to produce contoured beams for covering the Japanese islands for the downlink and feederlink antennas. The downlink antenna was fabricated, and the radiation pattern was verified by measurement. The radiation pattern meets the radio regulations imposed on the onboard antenna, such as sidelobe and cross-polarization characteristics. >

Single shaped reflector antennas for broadcasting satellites

A corrugated elliptical waveguide medium comprises a corrugated hybrid mode excitation member having an elliptical transverse cross-section for propagating electromagnetic energy therethrough. The excitation member is provided with longitudinally spaced apart parallel corrugations with the teeth of the corrugations defining an inner ellipse and the grooves of the corrugations defining an outer ellipse. The depths of the corrugation grooves on the major and minor axes of the ellipsis are dimensioned such that the tangential electric and magnetic field components of the energy in a circumferential direction are zero on the inner ellipse.

Corrugated elliptical waveguide or horn

Shuichi Miura Noboru ~oyama t (Satellite Program Department, NASDAI* Kenji Ohmaru Kazuyoshi Shogen (Science and Technical Research Laboratories, NHK)** Tomoki Obuchi Yoshihide Miyata (Space Development Division, NEC Corporation)*** This paper describes the electrical performance of the Shaped-beam antenna for the next phase Japanese broadcasting satellites (BS-3a, BS-3b) with analysis and some typical test results of both a bread board model (BBM) and an engineering one (EM). The BS-3a and BS-3b will be launched as successors of the BS-2 in 1990 and 1991 respectively by H-I launch vehicle. BS-3 antenna employs an elliptical offset parabolic reflector fed with a new type elliptical corrugated horn and a rectangular one. The major and minor axis lengths of the aperture are 1700 mm and 800 mm, which is somewhat smaller than that of the BS-2 antenna. The EM antenna has attained a gain of more than 39 dB for the major part of the Japan Islands, more than 36 dB for Okinawa and more than 28 dB for the remote islands. The sidelobe and crosspolar components radiated outside the service area are verified to satisfy the WARC-BS requirements on the basis of power flux density on the earth assuming 120 W output power of the transponder. It is found that BS-3 EM antevna has an efficiency of more than 70%.

Electrical performance of BS-3 shaped-beam antenna

PURPOSE:To obtain a circularly polarized horn with simple constitution by utilizing the phase difference in guide wave produced because of the difference from the guide wavelength between the major and minor axes of an elliptic horn so as to adjust the length of the horn and the direction of the excited electric field. CONSTITUTION:The length (l) of the horn 1 is adjusted so that the phase difference in guide wavelength of an electric field toward the major and minor axes caused due to the difference in the guide wavelength in the direction of the major axis and the guide wavelength in the minor axis of the horn 1 having an elliptic aperture is a phase difference of 90 deg. in the major and minor axis direction and an electric field is excited by an exciting probe 7 from an angle theta in a proper direction from one direction of the cross section of the ellipse. Thus, the electric field having a phase difference of 90 deg. in the major and minor axis direction at the aperture of the elliptic horn 1 is excited so as to omit a circularly polarized wave generator thereby irradiating a circularly polarized wave having a different beam width depending on the direction of the major and minor axes.

Circularly polarized horn

A study of highly shaped contoured beam antenna for Japanese DBS

This paper describes a study of contoured beam onboard a n t e n n a for f u t u r e Japanese direct broadcasting satellites (DBS) with pattern analysis and test results for the full-scale bread board model (BBM). The BS-3a and BS-3b were launched in 1990 and 1991, respectively, by the HI launch vehicle into a geo-synchronous orbit of 110 degrees east longitude. A follow-on DBS will be launched before the end of the BS-3's life (7 years). As the methods to realize the contoured-beam pattern for Japanese territory, the BS-3 antenna employs an elliptical offset parabolic reflector fed with a new type. \rJ of elliptical corrugated horn as well as a rectanylar horn. Thus, the contoured beam is based on an el ipse, and it is difficult to achieve the best fitting contour patterns for the Japanese territory. The antenna examined herein consists of a shaped reflector and a horn. This shaped reflector antenna has achieved a better shaped radiation pattern than the BS-3, and has attained a gain of more than 38 dBi for the major parts of Japan while, maintaining the RR.AP30* regulations for sidelobe and cross-polarization levels, theoretically and experimentally. In order to verify our shaped reflector antenna characteristic, a BBM antenna with 2.3m aperture was constructed and has shown good agreement with the analytical results. The authors propose this reflector antenna as a candidate for the next Japanese direct broadcasting satellite antenna system.

Noboru Toyama

Papers

Corrugated elliptical waveguide or horn

Electrical performance of BS-3 shaped-beam antenna

Circularly polarized horn

A study of highly shaped contoured beam antenna for Japanese DBS

A study of a contoured beam antenna for future Japanese DBS