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

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 (RC), it has become a popular facility to perform OTA tests nowadays. In the RC-based OTA tests, loading the RC with radio frequency (RF) absorbers is a standardized procedure to control the frequency selectivity of the RC 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 RC. 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.