A Simple Four-Beam Reconfigurable Antenna Based on Monopole

A simple pattern reconfigurable antenna based on monopole is presented in this paper. The antenna consists of four folded monopoles and a windmill-shape ground plane. The central patch is fed by a coaxial probe to decide which monopole is excited. Four reconfigurable modes can be achieved by changing the states of four PIN diodes mounted on the feeding lines. And the maximum radiation directions of the proposed antenna are deflected from <inline-formula> <tex-math notation="LaTeX">$\varphi =30^{\circ }$ </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">$\varphi =120^{\circ }$ </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">$\varphi =210^{\circ }$ </tex-math></inline-formula>, and <inline-formula> <tex-math notation="LaTeX">$\varphi =300^{\circ }$ </tex-math></inline-formula> at azimuth plane in four operating modes. The proposed antenna is simulated, fabricated, and measured. The experimental results indicate that the antenna can achieve a measured 10-dB bandwidth of 25.7% (3.32–4.3 GHz), a 10-dB front-to-back ratio of 17.7% (3.6–4.3 GHz), and a stable average gain of 3.3 dBi within the operating band. These characteristics make the designed antenna fit for <inline-formula> <tex-math notation="LaTeX">$C$ </tex-math></inline-formula>-band satellite communication system.