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Temperature Characterization of Liquid Crystal Dielectric Image Line Phase Shifter for Millimeter-Wave Applications

Tesmer, Henning ; Razzouk, Rani ; Polat, Ersin ; Wang, Dongwei ; Jakoby, Rolf ; Maune, Holger (2021):
Temperature Characterization of Liquid Crystal Dielectric Image Line Phase Shifter for Millimeter-Wave Applications. (Publisher's Version)
In: Crystals, 11 (1), MDPI, e-ISSN 2073-4352,
DOI: 10.26083/tuprints-00019309,
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Item Type: Article
Origin: Secondary publication via sponsored Golden Open Access
Status: Publisher's Version
Title: Temperature Characterization of Liquid Crystal Dielectric Image Line Phase Shifter for Millimeter-Wave Applications
Language: English
Abstract:

In this paper we investigate the temperature dependent behavior of a liquid crystal (LC) loaded tunable dielectric image guide (DIG) phase shifter at millimeter-wave frequencies from 80 GHz to 110 GHz for future high data rate communications. The adhesive, necessary for precise fabrication, is analyzed before temperature dependent behavior of the component is shown, using the nematic LC-mixture GT7-29001. The temperature characterization is conducted by changing the temperature of the LC DIG’s ground plane between −10°C and 80°C. The orientation of the LC molecules, and therefore the effective macroscopic relative permittivity of the DIG, is changed by inserting the temperature setup in a fixture with rotatable magnets. Temperature independent matching can be observed, while the insertion loss gradually increases with temperature for both highest and lowest permittivity of the LC. At 80°C the insertion loss is up to 1.3dB higher and at −10°C it is 0.6dB lower than the insertion loss present at 20°C. In addition, the achievable differential phase is reduced with increasing temperature. The impact of molecule alignment to this reduction is shown for the phase shifter and an estimated 85% of the anisotropy is still usable with an LC DIG phase shifter when increasing the temperature from 20°C to 80°C. Higher reduction of differential phase is present at higher frequencies as the electrical length of the phase shifter increases. A maximum difference in differential phase of 72° is present at 110 GHz, when increasing the temperature from 20°C to 80°C. Nevertheless, a well predictable, quasi-linear behavior can be observed at the covered temperature range, highlighting the potential of LC-based dielectric components at millimeter wave frequencies.

Journal or Publication Title: Crystals
Journal volume: 11
Number: 1
Publisher: MDPI
Collation: 14 Seiten
Classification DDC: 600 Technik, Medizin, angewandte Wissenschaften > 600 Technik
Divisions: 18 Department of Electrical Engineering and Information Technology > Institute for Microwave Engineering and Photonics
Date Deposited: 19 Aug 2021 13:31
Last Modified: 19 Aug 2021 13:31
DOI: 10.26083/tuprints-00019309
Corresponding Links:
URN: urn:nbn:de:tuda-tuprints-193094
URI: https://tuprints.ulb.tu-darmstadt.de/id/eprint/19309
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