Biasing vector network analyzers using variable frequency and amplitude signals

Nobles, Jason E.; Zagorodnii, V. V.; Hutchison, Andrew; Celiński, Z.

doi:10.1063/1.4959109

Cited by 3 publications

(1 citation statement)

References 9 publications

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“…It is designed to sustain the characteristic impedance over a wide bandwidth in the transition from CPW to microstrip. The top and bottom‐layer ground planes have cut‐outs (in the shape of an exponential curve) which are designed to smooth out the electric field distribution of the electromagnetic wave propagating along the planar structures . Such design transitions are necessary to optimize the power transfer of the signals through the filter structure.…”

Section: Device Fabrication and Characterizationmentioning

confidence: 99%

Liquid crystal based tunable spurline filters with notch frequencies at 50 and 85 GHz

Economou

Lovejoy

Harward

et al. 2018

Micro & Optical Tech Letters

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Electrically tunable double‐spurline notch filters with a nematic liquid crystal (LC) material as a dielectric medium were modeled, manufactured, and characterized. The spurlines, which were embedded into an inverted microstrip, consisted of quarter‐wavelength resonant elements. A Finite Difference Time Domain solver was used to model the filters. Photolithography and thin film deposition were employed to create the filters, followed by standard LC cell assembly. The filters, with central notch frequencies at 50 and 85 GHz, were characterized on‐wafer with a vector network analyzer. The stopband frequencies were tunable by 3% when a 14 volt peak‐to‐peak AC bias was applied across the 38 μm thick LC layer (electric field of 0.19 V/μm). The minimum stopband insertion loss of both filters achieved lower than −50 dB, while the stopband return loss varied from −4 to −12 dB. The −3 dB passband widths of the stopband filters were 12.2 and 28.3 GHz for the 50 and 85 GHz filters, respectively, giving a Q‐factor of 3–4.

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Section: Device Fabrication and Characterizationmentioning

confidence: 99%

Liquid crystal based tunable spurline filters with notch frequencies at 50 and 85 GHz

Economou

Lovejoy

Harward

et al. 2018

Micro & Optical Tech Letters

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Microwave interferometer for phase and response time measurements

Nobles

Hankiewicz

Baques

et al. 2020

Review of Scientific Instruments

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We report the development of a microwave interferometer using a quadrature intermediate frequency (IQ) mixer designed to measure the relative phase change and response time of microwave devices tested in the Ka and upper K bands (22–40 GHz). The interferometer is currently used to test liquid crystal based devices. The system allows for the application of an AC bias beyond the amplitude/frequency limitations imposed on vector network analyzer bias ports. Our IQ mixer based design uses bias signals ranging from 0 to 100 V peak-to-peak in a frequency range from DC to 100 kHz. This range of bias signals is necessary to properly test the response of microwave devices designed with liquid crystal materials. The setup enables us to measure changes in the output phase of the device as a function of both the voltage and frequency of the applied bias signal. The setup also measures the phase difference as a function of microwave frequency and response times for the device under test. Our system can be integrated into a stand-alone test setup without the need for a vector network analyzer.

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