Ka-band RF MEMS phase shifters

As the need for low-loss phase shifters increases, so does the interest in radio frequency (RF) MEMS as a solution to provide them. In this paper, progress in building low loss Ka-band phase shifters using RF MEMS capacitive switches is demonstrated. Using a switched transmission line 4-bit resonant phase shifter, an average insertion loss of 2.25 dB was obtained with better than 15-dB return loss. A similar 3-bit phase shifter produced an average insertion loss of 1.7 dB with better than 13 dB return loss. Both devices had a phase error of Less than 13 degrees in the fundamental states. To our knowledge, these devices represent the lowest loss Ka-band phase shifters reported to date.