Multiple beam antenna for satellite communications and LOS communications

This multiband, multfunction antenna uses a patented size reduction feature to minimize antenna size while providing multiple directional satellite communications beams. Combined with a Satellite Tracking System it provides a Self-Steering SATCOM Antenna. It can be adapted to commercial or military applications and frequency bands, most recently to UHF SATCOM.

This dual-polarized antenna covers multiple functions: it provides circularly polarized beams for satellite communications over a full one octave (2:1) frequency band; and a second RF port provides a vertically polarized omni beam over multiple frequency octaves for low-angle communications. The antenna can be connected to two radios to provide simultaneous SATCOM and vertically polarized modes, or with a coaxial switch a single radio can operate in any of these bands.

Improved low-angle SATCOM coverage can be obtained by using all five circularly polarized directional beams. The best beam is selected automatically while on-the-move when using a Satellite Tracking Unit. This is done electronically; no mechanically moving parts are used. All SATCOM beams have instantaneous bandwidth of 225 to 400 MHz (the antenna can also be scaled to cover a much higher band). It is a very efficient antenna since no resistive loading or impedance matching or tuning is needed to obtain this bandwidth. The directional SATCOM beams provide about 2 dB more passive gain than an omni SATCOM antenna, which helps maintain the link. The directional beams also reduce interference, noise, and multipath, resulting in better G/T. Amplifiers could be also added to increase gain.

The antenna uses a patented feature to reduce the antenna diameter and height to 0.23 wavelengths (less than ¼ wavelength) at the lowest frequency. For UHF SATCOM (225-400 MHz) the antenna is one cubic foot in size (12"x12"x12"). For other bands the size would be scaled accordingly. The photo shows the antenna under a radome. The following tables describe antenna features and specifications.

BENEFIT

Uninterrupted satellite communications while in motion

Reduces all the following: number of antennas required, space, visibility, pattern blockage, cosite EMI, switching, holes in platform, logistics

Low-loss use over ultra-wide frequency bands.

Offers satellite communications and also vertically polarized modes

On-the-move communications from fast-moving platforms

Greater gain than omni; More reliable link; Less interference.

Makes room for other equipment

Can use in rough terrain

Latitude, longitude, altitude, heading, tilt, and time can be available.

ADVANTAGE

No need to stop and manually point antenna or gyro-stabilize platform

Can use over multiple frequency bands and modes.

No need to tune or load the antenna; or to trade-off gain for bandwidth.

Transmits and receives both polarizations with high efficiency.

Rapid tracking of satellites, faster than mechanical tracking

Directional beam has higher gain and picks up less external noise than omni antennas.

Less space required

Withstands bumps, knocks, shocks

Provides GPS data (L1)

FEATURE

On-the-move coverage of the entire sky.

Extremely wide instantaneous frequency bandwidth: Low-loss and 2:1 VSWR:Circular Polarization over octave band satellite communications; and vertical polarization over multiple octaves.

Dual-Polarized: circular and vertical polarizations

Electronic beam steering

Circular polarized antenna is a directional multiple beam antenna

Small footprint antenna size

Mechanically strong and rugged

GPS antenna can be included in it