Modelling of ultra‐wide stop‐band frequency‐selective surface to enhance the gain of a UWB antenna

Here, an ultra‐wide stop‐band single‐layer frequency‐selective surface (FSS) with high‐incidence angle independence has been proposed to enhance the gain of an ultra‐wideband (UWB) monopole antenna. The unit cell (0.2 λ  × 0.2 λ ) of the proposed FSS consists of four asymmetric rectangular patches with circular slots embedded in it. This concept of four slotted patches is conceived to achieve ultra‐wide stop‐band characteristic over 4.7–14.9 GHz. An equivalent lumped circuit model for the FSS is proposed to provide insight into the working nature of the FSS. A UWB monopole antenna is also designed and integrated with the proposed FSS. Ultra‐wide stop‐band single‐layer FSS converts the omnidirectional pattern of the monopole antenna into a unidirectional one and thereby registers a significant increase in its gain by 4.5 dBi. The design concept has been discussed and experimentally verified using simulated and measured results.