QUASI-OPTICAL TRANSMIT RECEIVE FRONT-ENDS

Quasi-optical (QO) active circuits have originally received interest f or power generation by large-scale power combining of solid-state devi ces at microwave and millimeter-wave frequencies. Here, we present an overview of QO components developed with functionality in mind, with a n emphasis on bidirectional amplifier arrays for transmit/receive (T/R ) front ends. We discuss possible advantages of the QO architecture fo r communications and radar. The following three QO bidirectional array s are presented: 1) a nine-element X-band patch antenna array with dif ferent polarizations in T/R modes; 2) a 24-element X-band slot lens ar ray with switches for the T/R paths; and 3) a 22-element Ka-band patch lens array using monolithic microwave integrated circuits (MMIC's).