Project Title:

Switched Hemispherical Antenna

14.04-8080
Switched Hemispherical Antenna
Technical Research Associates, Inc.
410 Chipeta Way, Suite 222
Salt Lake City, UT 84108
Stephen Peterson  (801-582-8080)
JSC -- NAS9-17951

Abstract:

	 A switched hemispherical antenna was proposed for use on space transportation systems,
space stations, and satellites. The antenna, operating in the Ku band, would be able
to scan over 2 pi steradians, sample signal strength from a beacon, and route data
to the appropriate sector. An on-board computer would serve as an interface to an
inertial reference frame to allow a controller to compensate for satellite spin.
Two such antennas would cover 4 pi steradians; the gain of an individual unit antenna
would be approximately 16 dB; and the system would support circular polarization.
Because the antenna would be under software control, diverse and flexible operation
should be possible. 
	Phase I evaluated different, low-profile antennas for use in a switchable array;
designed and evaluated two different, pin-switch configurations; designed and built
a 5-unit directional coupler, and designed a microprocessor-driver for the prototype
pin switch. Hardware was produced but was not completely effective. The general conclusions
of this project are that it appears impossible to provide the necessary band-width
with a dielectric-loaded, patch-type antenna. The firm believes that two antenna
types, the cavity mounted helix and the flat, cavity-backed spiral, would meet (or
come close to) the specifications for a 16-unit antenna array and that either of
these two antennas might work in an 8-unit array if mated with a diverging dielectric
lens.

Potential Commercial Application:

Potential Commercial Application: The applications would be in switched microwave
antennas for aircraft, ships, and vehicles, especially for automobile-to-satellite
communications links.