A pseudo-correlation type radiometer based on astrophysical instrumentation is proposed for biomedical applications. The working frequency band is centred at 3.5 GHz. The prototype performance and functionality are assessed. The theoretical analysis of the receiver topology is described, as well as the subsystems employed in its configuration, such as a customized on-body antenna and microwave circuitry based on off-the-shelf devices. Experimental characterization of the individual subsystems and preliminary measurements of the radiometer prototype are presented. Furthermore, customized phantoms, based on polyvinyl alcohol cryogel, are employed for the characterization of the on-body antenna, as well as the radiometer.