Abstract: A high density electronic switching matrix (ESM) includes several splitting modules (200) arranged along a first axis, each including a signal input (202) and several splitter outputs (204). The ESM (500, 600) further includes several switching modules (400) arranged along a second axis perpendicular to the first axis. Each switching module (400) includes switching inputs (402) coupled individually to an output of each of the splitting modules (200). The ESM (500, 600) is further characterized by couplings between the splitter modules and the switching modules. The couplings are formed by mating male and female connectors (300) integrated into the splitting modules and the switching modules. The couplings support extremely high frequency operation. The splitting modules (200) and the switching modules (400) may thus be coupled closely together to form a dense, high frequency, switching matrix, and may be stacked upon one another.

Abstract: A phased antenna array (60) for use on a satellite, that employs a density tapering technique for positioning the antenna elements (62) in the array (60) to reduce co-channel interference between adjacent cells. Particularly, the spatial position of the various antenna elements (62) in the array (60) are spread out so that the center portion of the array (60) has the highest density of elements (62), and the outer portion of the array (60) has the lowest density of elements (62). Predetermined schemes are used to set the density of the elements (62) in the array (60). By providing fewer antenna elements (62) at the outer portion of the array (60), the beam side lobes are reduced.

Abstract: A digital audio radio service (DARS) antenna system is provided. The DARS antenna system includes a broadcast antenna mounted on a spacecraft. The broadcast antenna includes a slotted waveguide direct radiating array (SWDRA). The DARS antenna system also includes a mobile user receive antenna having a quadrifilar helix antenna (QHA). The DARS antenna system further includes a parallel plate polarizer arranged on the broadcast antenna for generating circular polarization. In an embodiment, the polarizer has a plurality of thin plates arranged perpendicular to the SWDRA surface. Broadcast antenna is optimized for overall system performance and is capable of high RF power and beam shaping. The DARS antenna system is also highly reliable and easily deployed from a spacecraft. An embodiment of the DARS antenna system of the present invention further includes "universal" model and "regional" model mobile antennas to easily accommodate personal travel and commuter needs.

Abstract: A steerable feeder link antenna is formed of a steerable reflector and a stationary feed horn assembly. A novel feed horn assembly allows dual mode transmit and receive functions for circularly polarized microwaves. The feed horn assembly includes a four arm turnstile junction coupled to a feed horn through the feed horn's side wall to couple transmit frequencies and an axially coupled transmission line for the receive frequencies. Each turnstile junction arm incorporates chokes for the receive frequencies. The transmission line's cut off frequency is above the transmit frequency to prevent transmit signals from interfering with receive signal receivers.

Abstract: A multiple beam antenna system (10) for use in satellite communications. The system (10) includes a feed array (20) containing multiple feed elements (22) which operate in connection with communications beams. In a transmitter application, the feed elements (22) are driven by feed signals delivered thereto from a beam forming network (14). The beam forming network includes multiple beam ports (16) which receive as inputs composite beam signals. The beam forming network includes feed ports (18) as outputs which deliver feed signals to the feed array (20). The beam forming network (14) includes a divider circuit trace (48) and a combiner circuit trace (46) aligned along substantially parallel planes. Combiners (111-117) within the combiner circuit trace (46) are arranged in clusters (92), such that each combiner (111-117) within a cluster (92) operates in conjunction with a common feed signal.

Abstract: An antenna system 10 for a communications satellite which transmits and receives communications from ground based devices. The system includes an antenna array 16 containing a plurality of feed elements 18 which cooperate to receive or transmit coverage beams arranged in a circular layout at a coverage area in a far-field region proximate the surface of the earth. The feed elements 18 are arranged in a non-circular layout within the antenna array 16. This system further includes a beam forming network 14 for mapping coverage beam signals onto feed signals which drive the antenna array 16. The beam forming network 14 includes a beam forming matrix 28 and a beam connecting network 30. The beam connecting network 30 separates each coverage beam signal into a plurality of component signals weighted to have differing amplitudes from one another.