This is the accepted version of a paper published in IEEE Transactions on Terahertz Science and Technology. This paper has been peer-reviewed but does not include the final publisher proof-corrections or journal pagination.

This is the accepted version of a paper published in IEEE Transactions on Terahertz Science and Technology. This paper has been peer-reviewed but does not include the final publisher proof-corrections or journal pagination.

This paper presents a submillimeter-wave 500–550-GHz MEMS-reconfigurable phase shifter, which is based on loading a micromachined rectangular waveguide with 9 E-plane stubs. The phase shifter uses MEMS-reconfigurable surfaces to individually block/unblock the E-plane stubs from the micromachined waveguide. Each MEMS-reconfigurable surface is designed so that in the nonblocking state, it allows the electromagnetic wave to pass freely through it into the stub, while in the blocking state, it serves as the roof of the main waveguide and blocks the wave propagation into the stub. The phase-shifter design comprises three micromachined chips that are mounted in the H-plane cuts of the rectangular waveguide. Experimental results of the first device prototypes show that the microelectromechanical system (MEMS)-reconfigurable phase shifter has a linear phase shift of 20° in ten discrete steps (3.3 bits). The measured insertion loss is better than 3 dB, of which only 0.5–1.5 dB is attributed to the MEMS surfaces and switched stubs, and the measured return loss is better than 15 dB in the design frequency band of 500–550 GHz. It is also shown that the major part of the insertion loss is attributed to misalignment and assembly uncertainties of the micromachined chips and the waveguide flanges, shown by simulations and reproducibility measurements. The MEMS-reconfigurable phase shifter is also operated in an analog tuning mode for high phase resolution. Furthermore, a detailed study has been carried out identifying the reason for the discrepancy between the simulated (90°) and the measured (20°) phase shift. Comb-drive actuators with spring constant variations between 2.13 and 8.71 N/m are used in the phase shifter design. An actuation voltage of 21.94 V with a reproducibility better than σ=0.0503 V is measured for the actuator design with a spring constant of 2.13 N/m. Reliability measurement on this actuator was performed in an uncontrolled laboratory environment and showed no deterioration in the functioning of the actuator observed over one hundred million cycles.

QC 20170201

This paper reports on a submillimeter-wave 500-750 GHz MEMS waveguide switch based on a MEMSreconfigurable surface to block/unblock the wave propagation through the waveguide. In the non-blocking state the electromagnetic wave can pass freely through the MEMS-reconfigurable surface while in the blocking state the electric field lines of the TE10 mode are short circuited which blocks the wave propagation through a WM-380 (WR-1.5) waveguide. A detailed design parameter study is carried out to determine the best combination of the number of horizontal bars and vertical columns of the MEMS-reconfigurable surface for achieving a low insertion loss in the non-blocking state and a high isolation in the blocking state for the 500-750 GHz band. Two different switch concepts relying on either an ohmic-contact or a capacitive-contact between the contact cantilevers have been implemented. The measurements of the switch prototypes show a superior RF performance of the capacitive-contact switch. The measured isolation of the capacitive-contact switch designed with 8 µm contact overlap is 19 to 24 dB and the measured insertion loss in the non-blocking state is 2.5 to 3 dB from 500-750 GHz including a 400 µm long micromachined waveguide section. By measuring reference chips, it is shown that the MEMS-reconfigurable surface contributes only to 0.5 to 1 dB of the insertion loss while the rest is attributed to the limited sidewall metal thickness and to the surface roughness of the 400 µm long micromachined waveguide section. Finally, reliability measurements in an uncontrolled laboratory environment on a comb-drive actuator with an actuation voltage of 28 V showed no degradation in the functioning of the actuator over one hundred million cycles. The actuator was also kept in the actuated state for 10 days and showed no sign of failure or deterioration.

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