60 GHz Capacitively Probe-Fed Patch Arrays with Suspended Elements

A major drawback of current millimeter-wave technologies used for integration of phased arrays on a chip is low efficiency (5-10%) and consequently low realized gain. In this work, we present integrated antenna arrays on silicon that exhibit radiation efficiency of > 80% at 60 GHz. This is achieved by suspending the radiating elements of a phased array in air using micro-electro-mechanical systems (MEMS) processes, effectively replacing a lossy silicon substrate (under each element) with air. In the latest design we used capacitive feeding with pin and patch height of 40 and 60 mu m, respectively. Finite element simulation results verify the performance of the array. A finite array with 5x5 elements achieved -10-dB bandwidth of 1.7 GHz. Array is well matched at 60 GHz with S11<-19 dB. Maximum realized gain (at broadside) is 20 dBi with sidelobe level of -13.3 dB. The efficiency is calculated to be 89%. Integration of antenna on a chip, provides enormous advantage in miniaturization of the systems and is essential for next-generation active electronically scanned arrays.