Continuously variable W-band phase shifters based on MEMS-actuated conductive fingers

Abstract

This paper presents four continuously variable W-band phase shifters in terms of design, fabrication, and radiofrequency (RF) characterization. They are based on low-loss ridge waveguide resonators tuned by electrostatically actuated highly conductive rigid fingers with measured variable deflection between 0.38 and 8.258 (at a control voltage of 0-27.5 V). A transmission-type phase shifter based on a tunable highly coupled resonator has been manufactured and measured. It shows a maximum figure of merit (FOM) of 19.58/dB and a transmission phase variation of 708 at 98.4 GHz. The FOM and the transmission phase shift are increased to 558/dB and 1348, respectively, by the effective coupling of two tunable resonances at the same device with a single tuning element. The FOM can be further improved for a tunable reflective-type phase shifter, consisting of a transmission-type phase shifter in series with a passive resonator and a waveguide short. Such a reflective-type phase shifter has been built and tested. It shows a maximum FOM of 1018/dB at 107.4 GHz. Here, the maximum phase shift varied between 08 and 3778 for fingers deflections between 0.38 and 8.258.

Waveguide‐integrated MEMS‐based phase shifter for phased array antenna

“…So far, MEMS phase shifters have been designed mainly for transmission lines [19][20][21]. To our best knowledge, there has only been one attempt by another research group www.ietdl.org to study waveguide-based MEMS phase shifters [22]. A single ridge transmission type phase shifter with integrated MEMS actuators in [22] has achieved a phase shift of 70°a nd an insertion loss of 3.6 dB at 98.4 GHz, and a triple ridge transmission type phase shifter has achieved a phase shift of 134°and an insertion loss of 2.4 dB at 92.8 GHz.…”

“…The assembly solution needs to provide a stable chip fixture for mechanical reliability and reproducibility of the measurement without leaving any air-gap between the chip and the waveguide wall, which contributes to loss and often introduces spurious resonances. A few methods have been reported to integrate MEMS chips into rectangular waveguides including assembling the MEMS devices directly into the waveguide without any interposer layer [26,27] and with copper foil pads as interposer layer [22], using screws to connect the hard-wired MEMS devices and the waveguide [28], and using conductive epoxy to attach the MEMS membrane to the waveguide wall [29]. Furthermore, conductive adhesive polymer sheets are reported to be used to electrically connect and mechanically fix MEMS tuneable W-band high-impedance surfaces [30] and a V-band MEMS reconfigurable surface [31] to rectangular waveguides.…”