U-shaped microwave resonators implemented by RF MEMS switches can be considered the result of a novel design approach for obtaining small-footprint tunable resonators, owing to the bent shape of the resonator and the microsystem solution for changing the frequency of resonance. In this paper, we discuss the design approach for potential configurations of U-shaped structures combined with ohmic RF MEMS switches. Owing to their prospective application in RADAR and satellite systems, the devices were assessed for K-Band operation, specifically for 15 GHz, 20 GHz, and 26 GHz. The ON-OFF states determined by an electrostatic actuation of metal beams composing the RF MEMS ohmic switches allow for selecting different path lengths corresponding to different frequencies. In this contribution, initial configurations were designed and manufactured as a proof-of-concept. The advantages and critical aspects of the designs are discussed in detail.

—This paper deals with a general analytic approach for the design of RF microelectromechanical system (MEMS) switches. The chosen configuration for these microwave devices is composed of twocoplanar transmission line sections separated by a metal membrane providing a shunt connected variable impedance. Using a bias voltage it is possible to actuate the switch. The adopted methodology for the development of the circuital model is based on the image impedance parameter representation of a two-port network. Synthesis equations are presented, and design considerations are discussed. The proposed approach is validated by means of electromagnetic simulations.

In this paper, a permalloy layer has been employed in the fabrication of a coupled line electromagnetic bandgap (EMBG) device to tune both amplitude and phase. A magnetically biased microwave coplanar configuration manufactured with evaporated permalloy has been measured, and a circuit modelling has been studied to evaluate the measured effects in terms of variable attenuation and phase shift. Starting from a permalloy made by the mixture 80% nickel and 20% iron content, we fabricated an electromagnetic bandgap (EMBG) structure based on a periodic arrangement of single sections of a transmission line with variable impedance, also including a central region with coupled lines. The bandpass characteristics of the EMBG device can be tuned by changing permalloy's permeability through the application of a DC magnetic field H 0 (parallel to the plane of the structure). In particular, using a magnetic field up to 3000 Oe, it was possible to change the phase by ca. 45° and the amplitude by ca. 7 dB in the X band.

Composite Right / Left Handed (CRLH) Based Devices for Microwave Applications | InTechOpen, Published on: 2010-03-01. Authors: Stefan Simon, Romolo Marcelli, Giancarlo Bartolucci, et