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Article

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

Institute of Microwave Engineering and Photonics, Technische Universität Darmstadt, 64283 Darmstadt, Germany
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Crystals 2021, 11(1), 63; https://doi.org/10.3390/cryst11010063
Received: 15 December 2020 / Revised: 11 January 2021 / Accepted: 12 January 2021 / Published: 14 January 2021
(This article belongs to the Special Issue Nematic Liquid Crystals)
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 10C 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 10C 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. View Full-Text
Keywords: millimeter wave; microwave liquid crystal; temperature coefficient; characterization; dielectric image line; phase shifter millimeter wave; microwave liquid crystal; temperature coefficient; characterization; dielectric image line; phase shifter
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MDPI and ACS Style

Tesmer, H.; Razzouk, R.; Polat, E.; Wang, D.; Jakoby, R.; Maune, H. Temperature Characterization of Liquid Crystal Dielectric Image Line Phase Shifter for Millimeter-Wave Applications. Crystals 2021, 11, 63. https://doi.org/10.3390/cryst11010063

AMA Style

Tesmer H, Razzouk R, Polat E, Wang D, Jakoby R, Maune H. Temperature Characterization of Liquid Crystal Dielectric Image Line Phase Shifter for Millimeter-Wave Applications. Crystals. 2021; 11(1):63. https://doi.org/10.3390/cryst11010063

Chicago/Turabian Style

Tesmer, Henning, Rani Razzouk, Ersin Polat, Dongwei Wang, Rolf Jakoby, and Holger Maune. 2021. "Temperature Characterization of Liquid Crystal Dielectric Image Line Phase Shifter for Millimeter-Wave Applications" Crystals 11, no. 1: 63. https://doi.org/10.3390/cryst11010063

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