A hyperthermia apparatus includes a hyperthermia treatment subsystem, and a receiver subsystem combined to use jointly the parts common to both subsystems. The hyperthermia and receiver subsystems include, respectively, a power source and radiometer connected to a switch controlled by a central processing unit (CPU) to selectively connect either the power source and the radiometer to the common parts to complete the subsystems as follows. A power divider having output ports for feeding electromagnetic energy through a plurality of applicator circuits each circuit including a phase shifter connected to the power divider, a power regulating switch connected to the phase shifter, and an applicator connected to the power control switches. The power regulating switches are controlled also by the CPU. Thus, when the CPU connects the power source to the power divider the hyperthermia subsystem is complete for operation in the tissue heating mode; however, when the CPU connects the radiometer, the receiver subsystem is complete with the phase shifter and power divider operating as a phase focused power combiner. In a second embodiment a separate radiometer is connected to each antenna port. The received analog signals are digitized for time correlation using available algorithms in a high speed computer.