An Integrated Antenna-Mixer and MESFET Local Oscillator Circuit

A planar integrated receiver front end consisting of a coupled slot antenna, a Schottky diode balanced mixer and a MESFET local oscillator is described. The Schottky diodes are placed inside the half-wave coupled slot to form a planar antenna-mixer. This antenna mixer is fed by a MESFET local oscillator fabricated on the back side of the substrate. The even mode/odd mode characteristic of the coupled slotlines is utilized to achieve intrinsic RF/LO and RF/IF isolation. Due to its compactness and planar nature, MMIC technology is compatible with the circuit fabrication. The circuit forms a self-contained unit and has potential applications in receiver arrays and low cost receiver modules.