Planar pattern reconfigurable antenna with eight switchable beams for WiMax and WLAN applications
A planar pattern reconfigurable antenna designed for IEEE 802.11 b/g standard 2.4 GHz WiMax and WLAN applications is presented. The design is realised using a uniform arrangement of eight switch-controlled tapered strips symmetrically placed around a central circular disc on the top layer of an FR4 board. The antenna has a compact circular structure with overall diameter of 0.64λ 0 in the free space for 2.4 GHz. To control the radiation pattern of the antenna, each of the tapered strips is connected to the ground via a PIN diode. Depending on the switching status of the eight PIN diodes, the tapered strips work in grounded or open-ended mode and thus the antenna offers eight switchable patterns. To validate the design, the antenna is prototyped and its performance is verified in a far-field anechoic chamber. The simulated and measured results prove the antenna's reconfigurability of the main beam in eight directions with 45° steps in the azimuth plane and a vertical tilting angle of 36°. Over the operating band 2.35–2.61 GHz, the antenna has a stable gain of around 4.5 dBi, and front-to-back ratio of more than 18 dB. Compared with recent designs, this antenna is more compact, has larger beam deflection off the boresight and more beam steering states.