EPOXI

8th January 2009 DEEP Impact / EPOXI is down linking a very strong signal from its 8434.1203MHz transmitter as can be seen below;

Epoxix 080109

The TWTA draws 54 Watts during transmission, with an RF output averaging 42.6 dBm (18.2 W). The LGA is composed of two coupled hemispherical microstrip patches radiating in opposite directions, +Y and –Y, providing a near-omnidirectional antenna pattern. Each of the two elements includes a receive patch and a transmit patch. The receive patches and the transmit patches are each connected via 3-dB couplers. The LGA system has a receive gain and transmit gain of approximately 3 dBi in the +Y and the –Y directions. The HGA is a 1-m-diameter parabolic dish antenna providing 35.6 dBic gain and 2.36° beamwidth at 8.435 GHz for the downlink, and at least 34.25 dB and a 2.76° beamwidth at 7.179 GHz for the uplink.

This is the block diagram of the telecommunications subsystem onboard EPOXI;

Epoxi telecoms

An excellent technical document on EPOXI telecommunications can be found here