Sensors & Transducers (Jan 2022)
Defected Ground Structures tuned by MEMS switches- Review
Abstract
This paper presents a review of the applications of Radio Frequency Micro electro mechanical (RFMEMS) switches for the tuning of Defected Ground Structures (DGS). In wideband communication systems, tunable systems are preferred over multichannel systems as they offer compactness. Microelectromechanical system (MEMS) based switches are replacing semiconductor based switches in tuning of RF devices such as filters, phase shifters, antennas etc. Defected Ground structures are employed as filters or as slow wave structures for achieving compactness for other filter designs. This review includes MEMS based tuning of Defected Ground Structure based filters over planar transmission lines such as CPW and microstrip transmission lines. Compared to microstrip based designs, CPW based DGS filters have ease of implementation with other coplanar elements, since it does not require via holes. MEMS DC contact switches are employed for inductive tuning by varying the effective area of DGS, while shunt switches are employed for the capacitive gap tuning. A large number of distributed MEMS switches over CPW line forms a Distributed MEMS Transmission Line (DMTL). DMTL based structures are also employed for tuning of DGS structures.
