Study of Microwave and Millimeter-Wave Quasi-Optical Planar Mixers.

摘要

Quasi-optical mixers promise to simplify microwave and millimeter-wave receiving and remote sensing systems, especially where imaging of the field of view is desired. Two types of quasi-optical mixers were studied both experimentally and theoretically. One mixer used a slot-ring antenna, while the other used a bowtie antenna and an antiparallel diode pair to allow subharmonic local oscillator pumping. Both mixers are suitable for monolithic integration at millimeter wavelengths. The slot-ring antenna is formed by cutting an annular slot in a metallic sheet coated on one side with a dielectric layer. If a simple radial electric field distribution in the slot is assumed at the resonant frequency of the first-order mode, a Hankel-transform domain analysis permits prediction of the radiation patterns and radiation resistance of the antenna. These predictions were confirmed by measurement. An X-band balanced mixer model showed a measured conversion loss of 6.5 dB + or - 3.1 dB when fed by a local oscillator source behind the antenna.