Conference Papers
Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/28506
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Item Tuned dual beam low voltage RF MEMS capacitive switches for X-band applications(2012) Shajahan, E.S.; Bhat, S.M.This paper presents a low voltage, low loss tuned RF MEMS (Radio Frequency Micro Electro Mechanical Systems) capacitive shunt switches for use in X-band. The tunable switch is designed using two shunt beams with meander springs. The switch achieved low actuation voltage along with small up state capacitance. Simulation using CoventorWare shows the actuation voltage as 7.5 Volts and up state capacitance of 47fF. HFSS simulation reveals the insertion loss in the range of (0.1-0.2) dB and up state return loss better than -25 dB in the X-band (8-12 GHz). The switch offers down state isolation of 60 dB at 12 GHz and is better than 40 dB in the frequency range 8-25 GHz. © 2012 IEEE.Item Inductive Tuned High Isolation RF MEMS Capacitive Shunt Switches(Institute of Electrical and Electronics Engineers Inc., 2014) Shajahan, E.S.; Bhat, M.S.; Bheesayagari, B.C.This work attempts inductive tuning of Radio Frequency Micro Electro Mechanical (RF MEM) capacitive switches for independent operation in X and Ku bands. The usual isolation characteristics of MEMS switches show wide bandwidth and moderate isolation of around 30 dB. Inductive tuning increases switch beam inductance by a few tens of pico henries. This enhances the Q factor and has the effect of improving the isolation and reducing the bandwidth of the switches. Inductive tuning is achieved by creating notches in the coplanar waveguide (CPW) ground plane in close proximity to the membrane. Membrane inductance enhancement can also be achieved by employing folded suspension beams. Since the current is concentrated on the edges of the signal and ground plane, the part of the beam over the CPW gap will have a dominating effect over the beam inductance. Beam inductance can be extracted from the simulated isolation characteristics of the switch by curve fitting. This paper presents tuning of two different rectangular coil suspension beam geometries to improve the isolation characteristics in the respective bands of frequencies. © 2014 IEEE.Item Design of a triple band-notched circular monopole antenna for UWB applications(IEEE Computer Society, 2014) Bheesayagari, B.C.; Shajahan, E.S.; Bhat, M.S.A novel triple-band notched circular ultrawideband (UWB) antenna with a band rejection characteristics at WiMAX, WLAN and C-band is presented. A design involving two concentric G-shaped circular slots etched on the circular patch structure and a U-shaped slot on the CPW transmission line is used to reject and control the notched frequency bands. The proposed antenna has good UWB characteristics from 3-12 GHz with VSWR < 2, except frequency bands of 3.3-3.6 GHz, 3.7-4.2 GHz, and 5.1-5.9 GHz. The designed structure exhibits good radiation characteristics over the desired band and is a good candidate for UWB applications. © 2014 IEEE.Item Fabrication and characterisation of RF MEMS capacitive switches tuned for X and Ku bands(Inderscience Publishers, 2018) Shajahan, E.S.; Bhat, M.S.Microelectromechanical systems (MEMS) capacitive switches discussed in this paper employ electrostatic actuation to perform switching. Capacitive switches employ inductive tuning for excellent switching characteristics in X and Ku bands. Employing inductive tuning is found to increase the switch beam inductance by a few tens of pico-henry. This enhances the Q factor and enables tuning of isolation over a narrow band of frequencies. Beam inductance can be extracted from the simulated isolation characteristics of the switch by curve fitting. This paper presents design, fabrication and characterisation of inductive tuned MEMS capacitive switches tuned for X and Ku bands. The devices are fabricated on high resistive (10 KΩ) silicon substrate by a five mask process. The characterisation of the fabricated devices are conducted using Cascade probe station and high frequency Power network analyser. Characterisation results show an actuation voltage of 18.5 volts. The insertion - loss and isolation are better than 0.5 dB and -40 dB respectively in the 8-18 GHz band. © © 2018 Inderscience Enterprises Ltd.Item High Isolation Single Pole Four Throw RF MEMS Switches for X band(Institute of Electrical and Electronics Engineers Inc., 2018) Shajahan, E.S.; Bhat, M.S.This work presents low loss RF-MEMS Single Pole Four Throw (SP4T) switch for X band. The present work is inspired from the fact that electrostatically actuated RF MEMS switches have superior RF performance over the state-of-the-art solid-state switches. Since an optimized design for Single Pole Multi Throw (SPMT) switch is difficult to realize, this work proposes a new design to achieve low loss and high isolation. The idea is to realize a combination of SPST (Single-Pole-Single-Throw) series and shunt switching in each arm of the SP4T model. The actuation voltage, isolation and insertion losses are optimized. The electro-mechanical modeling of the proposed device is done in CoventorWare and electro-magnetic modeling in HFSS. The simulation of the proposed design shows an actuation voltage of 12 V for capacitive shunt configuration and 13.75 V for the lateral series switch. The insertion loss and isolation are better than 1 dB and -50 dB respectively in the X band. The excellent RF characteristics make the switches suitable as MEMS varactors for high frequency applications and in tunable MEMS filters and phaseshifters. © 2018 IEEE.