A Switchable Metamaterial Absorber for Fine-Tuning of the Coherence Bandwidth in a Reverberation Chamber

Abstract

Since wireless communication technology has been widely applied in our daily lives, wireless devices exhibit explosive growth. A reliable, efficient, and repeatable over-the-air (OTA) testing method is vital for the research and development of wireless devices. Due to the particular advantages of the reverberation chamber ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RC</i> ), it has become a popular facility to perform OTA tests nowadays. In the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RC</i> -based OTA tests, loading the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RC</i> with radio frequency (RF) absorbers is a standardized procedure to control the frequency selectivity of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RC</i> channel according to the cellular telecommunications industry association (CTIA). However, this procedure involves iterative manual calibrations and, therefore, is tedious and time-consuming. Moreover, it may be difficult to tune the coherence bandwidth (CBW) to a desired value accurately given fixed RF absorbers. In this work, a locally switchable metamaterial absorber (MA) is proposed for fine-tuning of the CBW of the channel in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RC</i> . It is experimentally verified that the CBW can be easily controlled by switching on and off of the absorbing/reflection units of the MA. The proposed MA can provide fine-tuning of the CBW in an efficient and convenient manner.