A PLANAR QUASI-OPTICAL MIXER USING A FOLDED-SLOT ANTENNA

A quasioptical mixer using only planar structures such as coplanar-wav eguide and slotline is presented. The mixer, which can be scaled for m illimeter-wave applications and placed on a substrate lens, uses ortho gonal modes in a folded-slot antenna to achieve intrinsic RF/LO isolat ion without RF filtering or subharmonic pumping. The folded-slot balan ced mixer was fabricated on RT/Duriod and obtained a minimum isotropic conversion loss of 1.2 dB at 11.6 GHz. Numerical integration of full two-dimensional antenna patterns yielded an antenna directivity of 7 d B, corresponding to a single side-band (SSB) mixer conversion loss of 8.2 dB. The mixer demonstrated -18 dB RF/IF isolation and -30 dB LO/IF isolation.