Applications of the Pseudo-Correlation Microwave Radiometer

Three newly developed microwave and millimeter-wave radiometers which employ the pseudo-correlation architecture are discussed. This architecture-also described as the "continuous comparison" radiometer [1]-employs a hybrid power splitter to divide antenna and reference signals between two receiver chains which are later recombined by a second hybrid to again separate the antenna and reference signals. This scheme offers an alternative to the traditional Dicke switched radiometer design which otherwise places a reference switch between the antenna and receiver. We have applied the pseudo-correlation design to three unrelated radiometers to solve three (also unrelated) problems of (1) how to share telecommunication and radiometer functions in a single receiver without interrupting the communication channel with a Dicke switch; (2) how to maintain valid reference signals in the presence of strong radio interference; and (3) how to improve the noise figure of an internally calibrated millimeter-wave radiometer-by eliminating an electrically lossy Dicke switch.