Ridge Gap Waveguide Based Liquid Crystal Phase Shifter

• Published in: IEEE access Vol. 8; pp. 77833 - 77842
• Main Authors: Nickel, Matthias, Jimenez-Saez, Alejandro, Agrawal, Prannoy, Gadallah, Ahmed, Malignaggi, Andrea, Schuster, Christian, Reese, Roland, Tesmer, Henning, Polat, Ersin, Wang, Dongwei, Schumacher, Peter, Jakoby, Rolf, Kissinger, Dietmar, Maune, Holger
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: bed of nails; Connectors; Decoupling; Direct current; Electrodes; Electromagnetic waveguides; Figure of merit; Functional materials; gap waveguide; Insertion loss; Liquid crystals; Liquid crystals (LC’s); Nails; Phase shifters; phased array; Topology; tunable phase shifter; Tuning; Waveguide discontinuities; Waveguides
• ISSN: 2169-3536; 2169-3536
• DOI: 10.1109/ACCESS.2020.2989547

In this paper, the gap waveguide technology is examined for packaging liquid crystal (LC) in tunable microwave devices. For this purpose, a line based passive phase shifter is designed and implemented in a ridge gap waveguide (RGW) topology and filled with LC serving as functional material. The inherent direct current (DC) decoupling property of gap waveguides is used to utilize the waveguide surroundings as biasing electrodes for tuning the LC. The bed of nails structure of the RGW exhibits an E-field suppression of 76 dB in simulation, forming a completely shielded device. The phase shifter shows a maximum figure of merit (FoM) of 70 °/dB from 20 GHz to 30 GHz with a differential phase shift of 387° at 25 GHz. The insertion loss ranges from 3.5 dB to 5.5 dB depending on the applied biasing voltage of 0 V to 60 V.