Instrument: Antenna

The antenna subsystem performs beam steering, transmission, and high power amplification on transmit and low noise amplification on receive. The antenna is a dual-polarization corporate-fed planar phased-array with 2 x 12 T/R modules and phase shifters for electronic beam steering from radar pulse-to-pulse. The peak transmit power for each T/R module is 100 W and the combined power of the 24 T/R modules is approximately 2.0 kW. Typical efficiency for Lband solid state amplifiers (SSPAs) is 40%.

On the transmit end, there will be a polarization switch to direct the transmit signal to either the H or V-polarization feed of the antenna element. On the receive end, each T/R module will have two receiver front-ends (pre-select filter, high power limiter, and low-noise amplifier) to accommodate radar echoes from both the H and V-polarizations. The high degree of phase fidelity required for interferometric applications has lead to the inclusion of an active calibration scheme to track the phase variation of the array over temperature and time.

Additionally, the antenna supports an elevation “monopulse” mode whereby the signals from the top and bottom half of the antenna can be recorded separately.