Low-dispersion metamaterial-based phase shifters with reduced size and number of MEMS switches

This paper reports a low-dispersion metamaterial-based 3-bit phase shifter which occupies an area of approximately 5 mm2 and uses only six microelectromechanical systems (MEMS) switches. The phase shifter is based on a coplanar slow-wave structure with defected ground and comprises three unit cells of 180°, 90° and 45° phase shifts, respectively. Each unit cell uses two single-pole-single-throw MEMS capacitive switches in series and parallel configurations, respectively, to switch between right-handed (low-pass) and left-handed (high-pass) states for the specified phase shift. Three-dimensional finite-element electromagnetic simulation was used to help optimize the compact layout. The worst-case performance across the band of 24-28 GHz was simulated to have less than 9° root-mean-square phase error, less than 1.7 dB insertion loss, and greater than 13 dB return loss.