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Open AccessArticle

Design of a Tunable Absorber Based on Active Frequency-Selective Surface for UHF Applications

1
College of Information Engineering, Communication University of China, Beijing 100854, China
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Science and Technology on Electromagnetic Scattering Laboratory, Beijing 100854, China
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Author to whom correspondence should be addressed.
Materials 2019, 12(23), 3989; https://doi.org/10.3390/ma12233989
Received: 11 October 2019 / Revised: 21 November 2019 / Accepted: 26 November 2019 / Published: 2 December 2019
An ultrathin tunable absorber for the ultrahigh frequency (UHF) band is presented in this paper. The absorber is a single-layer structure based on the topology of a Salisbury screen, in which the conventional resistive layer is replaced by an active frequency-selective surface (AFSS) loaded with resistors and varactors. The reflectivity response of the absorber can be controlled by adjusting the reverse bias voltage for the varactors, which is verified by both simulated and measured results. The experimental results show that the reflectivity response of the absorber can be modulated below −10 dB over a frequency band ranging from 415 to 822 MHz. The total thickness of the absorber, 10 mm, is equivalent to only λ/72 of the lower limit frequency. The absorbing mechanism for the designed absorber is illustrated by simulating the volume loss density distributions. A detailed analysis is also carried out on the basis of these parameters, such as the AFSS shape, resistor, thickness of the foam, thickness and permittivity of the dielectric substrate, and incident angles, which contribute to the reflectivity of the AFSS absorber. View Full-Text
Keywords: tunable absorber; active frequency-selective surface; ultrahigh frequency; varactors tunable absorber; active frequency-selective surface; ultrahigh frequency; varactors
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MDPI and ACS Style

Qi, K.; Li, L.; Su, J.; Liu, Y.; Chen, J. Design of a Tunable Absorber Based on Active Frequency-Selective Surface for UHF Applications. Materials 2019, 12, 3989.

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