A low‐loss compact six‐bit DMTL phase shifter for phased array antenna applications

Summary A phase shifter is one of the main components of radars and phased array systems. In this paper, a novel three‐state two‐bridge unit cell is presented for a compact low‐loss six‐bit distributed microelectromechanical systems (MEMS) transmission line (DMTL) phase shifter. The proposed unit cell includes a coplanar waveguide (CPW) transmission line, a MEMS bridge on the signal line, two metal‐air‐metal (MAM) capacitors on a glass substrate, and two additional electrodes under the MEMS bridge, near the signal line. Using these electrodes, it is possible to generate two different phase states employing the MEMS bridge, and the third state is produced by a metal‐air‐metal (MAM) bridge. Hence, the designed structure can generate three different phase shifts per unit cell (i.e., 5.625°, 11.25°, and 22.5° phase shifts). The novelty of this design is that the number of unit cells is considerably reduced from 64 in a conventional six‐bit phase shifter to only 17 in our design. Therefore, the total length of the six‐bit phase shifter and average loss are considerably reduced. The designed structure is calculated and simulated at 32 GHz using MATLAB and ANSOFT HFSS, respectively. According to the calculation and simulation results, the lateral size of the phase shifter is only 8.5 mm, the root mean square (RMS) phase error is 1.38°, and the average loss is 1.1 dB. The feasibility of the proposed design is investigated using the proposed fabrication process. The designed phase shifter can be easily scaled to other frequencies for radar and satellite applications with more bits. In this paper, a novel three‐state two‐bridge unit cell is presented for a compact low‐loss 6‐bit distributed microelectromechanical system transmission line (DMTL) phase shifter. The novelty of this design is that the number of unit cells is considerably reduced from 64 in a conventional 6‐bit phase shifter to only 17 in our design. Therefore, the total length of the 6‐bit phase shifter and average loss are considerably reduced. The root mean square (RMS) phase error, average loss, and total length are 1.4, 1.1 dB, and 8.5 mm, respectively.