An LTCC-based 8-channel 4 to 12 GHz hybrid channel-dropping multiplexer for a CubeSat radiometer mission

We present an ultra-compact channelized radiometer back-end implemented in an LTCC process, featuring an 8-channel, wide bandwidth multiplexer. The multiplexer has 8-channels covering 4.3 GHz to 11.1 GHz (104% overall fractional bandwidth) with 2.1% to 8.4% fractional bandwidth channels, designed using a hybrid channel-dropping approach. The multilayer module integrates the stripline multiplexer with microstrip diode detectors, SMT amplifiers and other components in a 30.5 mm by 61.0 mm footprint. Design, simulation, and fabrication of the multiplexer and its application to small and low-power radiometers is discussed, along with results of the flight module scheduled for launch in a 2017 CubeSat mission.