Wide-Band High Directivity in MIC Proximity Couplers by Planar Means

A simple semi-empirical design method has been developed for serpentining -improved wiggling- and slotting of proximity couplers. Phase equalization of even-and odd mode resulted in 40 dB isolation from 2-8 GHz for 25 mil alumina couplers between -6 and -25 dB. Coupling values were within 1 dB with experimental ones.