Frequency Selective Surface-Based Switched-Beamforming Antenna

Abstract

A novel switched-beamforming antenna designed using active frequency selective surfaces (AFSS) is presented. The antenna consists of two parts: a source with an omnidirectional radiation pattern and a novel active triangular frequency selective surface (ATFSS) surrounding the source. Each unit cell in the ATFSS structure contains two diamond shaped patches connected with each other by a high-frequency pin-diode. The ATFSS elements are designed using CST microwave studio. The pin-diodes are applied to achieve beam switching. By switching the applied biasing voltage, the ON and OFF states of the ATFSS exhibit reflection and transmission characteristics in the operating WLAN band. By arranging the AFSS unit cells in a triangular structure with three panels and choosing different combinations of the diode states, the beam switching at various azimuthal directions is achieved. To validate this concept, the proposed antenna is fabricated and measured. A good agreement between simulations and measurements in terms of beam directions, reflection coefficient, and gain has been achieved @5.8 GHz.

Keywords

• Active frequency selective surface
• directional radiation pattern
• frequency selective surface
• omnidirectional radiation pattern
• switched-beamforming antenna
• pin diode