Abstract: Monolithic microwave integrated circuit (MMIC) technology is advantageously used to fabricate microwave circuitry for an antenna-converter system to enable an antenna and its associated converter circuits to be integrated together into a unitary package. Small reliable radio frequency (RF) circuits, polarization switch matrix circuits, intermediate frequency (IF) circuits and power and control circuits for the converter are manufactured and integrated onto a plurality of small area microwave circuit disks using MIC/MMIC technology. The plurality of converter circuit disks are sandwiched together and directly mounted flat against the back of the antenna to form a unitary package. The disks for the converter circuits are further sized such that the circuit disks fit within an envelope volume defined by the size and shape of the antenna.