NOVEL COMPACT MEMS-TUNABLE DIRECTIONAL COUPLER FOR DUAL BAND WIRELESS APPLICATIONS
A. OCERA, P. FARINELLI, F. CHERUBINI, P. MEZZANOTTE, R. SORRENTINO, B. MARGESIN, F. GIACOMOZZI

Abstract. This paper presents a novel MEMS-tunable directional coupler for dual band wireless applications. The structure is composed of four quarter-wavelength sections at a frequency located between the two operating frequencies and two pairs of open-ended stubs. The operating frequencies can be adjusted by simply increasing the electrical length of the open-ended stubs through the sequential actuation of cantilever ohmic contact MEMS switches. A three state MEMS prototype has been designed on a 525 µm high resistivity silicon substrate, employing the well-established eight-mask surface micro-machining process developed at Itc-irst in Trento, Italy. A dual-band tunability of 12% and 10% has been obtained in the S and the C band, respectively. The isolation and the return loss are better than 25 dB and 18 dB in the first and second band respectively, with a 0.5 dB average insertion loss.