Waveguide ASK Modulator Using Switchable FSS
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Waveguide ASK Modulator Using Switchable FSS Ghaffer Iqbal Kiani1
· Mohammed Abdullah Hussaini2
Received: 18 November 2019 / Accepted: 12 May 2020 / © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract A waveguide modulator using switchable frequency selective surface (FSS) for amplitude shift keying modulation (ASK) at super high frequency (SHF) has been presented. The FSS consists of rectangular loop aperture elements with two PIN diodes at 180◦ intervals on every unit cell across the aperture. A minimum transmission isolation of 30 dB has been achieved at resonance frequency when the diodes are switched between ON and OFF states. The PIN diode parameters are modeled using Keysight’s Advanced Design System (ADS) software to find the missing value of inductance and match the results presented in its datasheet. The proposed FSS modulator can operate either for transverse electric (TE) or transverse magnetic (TM) polarizations subject to the positioning of the incident wave due to its rectangular geometry. Positive direct current (DC) biasing is introduced from the front while negative DC biasing has been connected on the back-side of the unit cell FSS. Both the diodes are employed orthogonal to the principal axis of the FSS to reduce the impact of negative bias-line on overall frequency response. Both simulation and measured results have been presented. Keywords Waveguide · Amplitude shift keying · Frequency selective surface · Modulator · Switchable · PIN diode · Radio frequency
1 Introduction The need of efficient and high speed modulators for super high frequency (SHF) communication system is increasing day by day. Currently, not many such modulators Ghaffer Iqbal Kiani
[email protected] Mohammed Abdullah Hussaini [email protected] 1
Department of Electrical and Computer Engineering, King Abdulaziz University, Jeddah, Saudi Arabia
2
British Malaysian Institute, Universiti Kuala Lumpur, Kuala Lumpur, Malaysia
International Journal of Infrared and Millimeter Waves
are available commercially which makes high speed and wide bandwidth communication quite difficult. Therefore, there is a need of developing these modulators and related electronic components such as sources and detectors. Frequency selective surfaces (FSSs) act as a spatial filter for microwave, submillimeter wave, and millimeter wave frequencies [1]. Reconfigurable frequency response can be achieved by integrating MEMS, PIN and varactor diodes in FSS filters [2–10]. Passive and switchable FSSs are widely used to improve the transmission or reflection characteristics of an electromagnetic signal. A switchable FSS has been proposed in [11] to act as an amplitude shift keying (ASK) modulator for future highspeed communication applications. In [12], two PIN diodes are incorporated with FSS to alter the transmission between OFF and ON states. However, there are certain challenges while designing an FSS with active elements such as PIN diodes. At lower microwave frequencies an FSS with active elements can e
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