Design of a metasurface filtering antenna with tunable radiation nulls

Abstract

In this article, a low profile wideband metasurface filtering antenna with tunable radiation nulls is proposed. Metasurface structure is used to excite adjacent resonant modes to obtain broadband responses. A U-shaped slot is introduced into the microstrip line to generate a radiation null in the lower stopband. Complementary split-ring resonators (CSRRs) are etched on the metasurface unit to produce another radiation null in the upper stopband edge to improve the filtering effect. The radiation nulls position can be flexibly controlled by changing the size of U-shaped slot and CSRRs. For verification, the corresponding antenna is fabricated and tested. The antenna size is 0:556λ0 Â 0:556λ0 Â 0:044λ0 (30 Â 30 Â 2.4 mm 3 ). The measured results agree well with the simulated. The antenna operates from 4.9 to 6 GHz with a flat gain (5.5 dBi), a sharp passband skirt and stable radiation patterns.