A system‐level performance evaluation of a reconfigurable filtenna in the presence of in‐ and out‐of‐band blockers

Abstract

Direct RF sampling has been suggested as a solution for receivers that are flexible in frequency and across standards, while utilising only a single radio frequency front-end. However there are concerns about their robustness in the presence of out-of-band and in-band blockers. Tunable filtennas offer a solution to this, incorporating filtering into the antenna space while providing rejection of unwanted signals. This paper presents a filtenna containing reconfigurable frequency selective surfaces to provide tunable filtering between 1.44 and 1.95 GHz. The filtenna is characterised as an antenna and a filter, showing minimum 18 dB rejection across the principle beamwidths. It is then implemented in a direct RF sampling receiver and is shown to provide sufficient rejection of blockers to cause no degradation in the received error vector magnitude (EVM) and block error rate (BLER) of LTE signals when subject to 5G NR-compliant blocking signals. The in-band blocker performance is also characterised, showing at most 3 dB degradation in EVM and BLER.