Abstract: A self-contained four-dipole element provides a 360 degree phase-progressive-omnidirectional (PPO) circularly polarized antenna pattern. Via a single signal port, a PPO excitation network incorporated into the element excites the four dipoles at phases differing by successive 90 degree increments. The four-dipole element is adapted for efficiently reproducible fabrication using printed circuit techniques. Antennas employing a stack of the elements provide a hemispherical antenna pattern with PPO circular polarization and a sharp cutoff below horizontal. For GPS reception in Differential GPS aircraft landing applications, a 21 element antenna provides multipath suppression and a unitary phase center enabling avoidance of signal phase discrepancies. More or fewer elements may be employed in other applications.

Abstract: Cellular antenna systems are provided for airship-type support at a position in the stratosphere. A single antenna system (20) may provide cellular communication for earth-based users located anywhere within a circle 400 miles in diameter (10). By use of array assemblies (21a) each providing 12 side-by-side beam positions per quadrant, with higher and lower elevation beams (32a', 36a') at each beam position, coverage can be provided for 96 cells arranged side-by-side in inner and outer annular bands (10). A turnstile-type antenna (26) provides coverage for a 97th central circular cell. By allocation of available groups of cellular frequencies in repetitive patterns around the outer annular band (1-6, FIG. 1), with frequency reuse in offset positions around the inner annular band, 16 times frequency reuse is provided while maintaining acceptable co-channel interference levels.

Abstract: In a cellular type communication system a sector antenna 12 provides coverage of a sector with a relatively low receive gain. A multi-beam antenna 20 covers the same sector with a plurality of narrower beams 21', 22', 23' and 24' providing higher gain. A multi-beam antenna system 10 provides higher gain operation by selecting the one of the narrower beams 21', 22', 23' or 24' currently providing best reception of a signal transmitted by a user and coupling that selected beam to a system receiver 18. Beam selection is accomplished by sequentially coupling each narrow beam to a microprocessor based control unit 40 and storing samples of user signals as received in each narrow beam on a continuing repetitive basis. The stored samples are then analyzed in order to select the beam currently providing best reception.

Abstract: In a cellular type communication system a sector antenna 12 provides coverage of a sector with a relatively low receive gain. A multi-beam antenna 20 covers the same sector with a plurality of narrower beams 21', 22', 23' and 24' providing higher gain. A multi-beam antenna system 10 provides higher gain operation by selecting the one of the narrower beams 21', 22', 23' or 24' currently providing best reception of a signal transmitted by a user and coupling that selected beam to a system receiver 18. Beam selection is accomplished by sequentially coupling each narrow beam to a microprocessor based control unit 40 and storing samples of user signals as received in each narrow beam on a continuing repetitive basis. The stored samples are then analyzed in order to select the beam currently providing best reception.

Abstract: Thin panel antennas, suitable for mounting on the side of a building, display a graphic representation and coloration compatible with the surface form and coloration of the building. A graphic display structure functions as a radome covering the front of an antenna utilizing slot arrays or other radiating elements. The graphic representation positioned on such display structure provides an image and coloration which may simulate the surface form and coloration of the building, simulate a structural feature, or otherwise provide a compatible visual relationship with a building or other structure.

Abstract: In a communication system, two multi-beam antennas laterally spaced from each other each provide coverage of an azimuth sector for receiving signals from a system user. Each antenna provides lower gain performance at regions of crossover between its beams, as compared to peak gain along the center line of each beam. By aligning the two multi-beam antennas at different azimuths within the sector of interest, angular diversity is achieved. With the peak gain beam center lines of one multi-beam antenna aligned with regions of beam crossover of a similar antenna, a minimum gain improvement of 5 dB may typically be obtained with two four-beam antennas, as compared to coverage of the same sector by one or more antennas each having a single sector-wide beam. Systems and methods for achieving angular diversity/spaced diversity operation are described.