Abstract:
For optimum performance, a ground antenna system must maximize the ratio of received signal to the receiving system noise power, defined as the ratio of antenna gain to system-noise temperature (G/T). The total system noise temperature is the linear combination of the receiver noise temperature (including the feed system losses) and the antenna noise contribution. Hence, for very low noise cryogenic receiver systems, antenna noise-temperature properties are very significant contributors to G/T.
It is well known that, for dual reflector systems
designed for maximum gain, the gain performance
of the antenna system is the same for both
Cassegrain and Gregorian configurations. For a
12-meter antenna designed to be part of the large
array based Deep Space Network, a Cassegrain
configuration designed for maximum G/T at X-band
was 0.7 dB higher than the equivalent Gregorian configuration. This study demonstrates
that, for maximum GIT, the dual shaped Cassegrain
design is always better than the Gregorian.
