A new frequency selective absorber surface at the unlicensed 2.4‐GHz ISM band

Abstract

Wireless devices in the unlicensed ISM bands cause mutual interference in indoor environments. This interference does not only degrade system performance but also compromises security. An efficient approach to solve this problem is transforming a building wall to a frequency selective surface (FSS), which filters undesired signals, but allows signals of other devices such as mobile phones, radios and televisions. As a band‐stop filter, FSS acts as a reflector that causes additional multipath, delay spread and signal degradation. The aim of this study is proposing a design of FSS absorber (FSAS) at the unlicensed 2.45 GHz ISM band to eliminate the reflected signal while it still acts as a band‐stop filter. Absorber characteristic is achieved by placing a second FSS layer comprising lossy periodic FSS elements or placing lumped resistors on the conducting paths of periodic element geometries. HFSS software is used for simulation and design purposes. The minimum attenuation was obtained as 20 dB on the transmission (S21) coefficient, while it was obtained as 10 dB on the reflection (S11) coefficient, respectively. The simulation and measurement results obtained show that the desired frequency response is successfully achieved for both TE and TM polarizations. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2351–2358, 2016

Compact, dual polarized, mutliband frequency selective surface with wideband spurious rejection

“…For many years, FSSs have been attractive for their various applications in spatial microwave and optical filters. They have been used as polarizers, filters, subreflectors, band‐pass hybrid radomes for radar cross section reduction, pattern controlling, and EMC . Moreover, the used FSSs for waveguides coupling control, measurement purposes, superstrate, and metasubstrate in filters and antenna designs are their microwave applications .…”

Design of Ultrathin Absorptive/Transmissive Radome With Dual Passbands

“…Compared to the previous works in [9], one more passband is proposed. The resistors loaded DSL metal layer, instead of resistive surface, is used as resistive FSS, which is insensitive to polarization of incident wave [10]. Capacitors are loaded on the bandpass FSS to reduce the unit size, hence the grating lobes are shifted out of absorbing band to higher frequency.…”