CUED Publications database

Highly anisotropic LC material with low dielectric loss for the application of tunable notch filters

Cai, L and Chu, D (2019) Highly anisotropic LC material with low dielectric loss for the application of tunable notch filters. Journal of Electromagnetic Waves and Applications, 33. pp. 1070-1081. ISSN 0920-5071

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Abstract

© 2019, © 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. We present here a compact liquid crystal (LC) based tunable notch filter with a narrow 3 dB bandwidth and a high quality factor. The structure of the proposed filter consists of two embedded resonators in serial, with an impedance adaptor and linear taper at each port. The notch filter combines tunable dielectric material LC with inverted microstrip technology, and was designed, fabricated and characterized to deliver a continuously tuned rejection frequency range from 3.545 GHz to 3.731 GHz, together with a narrow 3 dB bandwidth of ∼ 0.8 GHz and a high quality factor of ∼ 4.6. Such a notch filter is both compact (41 mm × 13 mm) and light weight (18.08 grams, including SMA connectors). It is suitable for working in the S band to suppress WiMAX signals that may cause interference in UWB communication systems. The narrow stopband and high quality factor of the device can be further improved at the expense of a certain extent of tuning efficiency, by using a thicker LC layer, and this is verified in experiment. The measured results of the proposed devices confirm the feasibility of using the current LC technology to manufacture tunable notch filters with a narrow bandwidth and a high quality factor.

Item Type: Article
Subjects: UNSPECIFIED
Divisions: Div B > Photonics
Depositing User: Cron Job
Date Deposited: 18 Feb 2019 20:08
Last Modified: 25 Feb 2021 08:16
DOI: 10.1080/09205071.2019.1591308