Reduction of substrate-mode effects in power-combining arrays

We report a simple theory for the reduction of substrate modes in quasi-opt ical power-combining arrays. This qualitative theory predicts that detrimen tal substrate-mode effects can be greatly reduced through a judicious choic e of the array unit cell size. Experimental evidence from quasi-optical tri pler grids is presented to confirm the theory. Measured results show a dram atic improvement in the radiation pattern and effective radiated power of a rrays with both grounded and ungrounded substrates.