Frequency reconfigurable hourglass shaped microstrip antenna

A compact hourglass shaped microstrip antenna having frequency reconfiguring ability from 2.362 GHz to 2.525 GHz range is proposed. A varactor diode is used in the gap between the two segments of ground plane in order to achieve frequency agility. By varying the capacitance of the varactor diode, six operating frequencies 2.395 GHz, 2.435 GHz, 2.445 GHz, 2.455 GHz, 2.47 GHz and 2.495 GHz are achieved with impedance bandwidth of 2.92%, 2.42%, 2.46%, 2.40%, 2.45%, 2.45% and 2.44% respectively. The antenna exhibits stable omnidirectional radiation patterns with realized gain varying from 2.55 dB-1.05 dB for all the bands. These features make the antenna suitable for different wireless application standards like Wi-Fi (2.412 GHz-2.483 GHz), Bluetooth (2.402 GHz-2.48 GHz), WiMax (2.3 GHz-2.4 GHz) etc. The proposed antenna has compact dimensions of 0.44λ×0.25λ×0.013λ at 2.4 GHz frequency which is suitable for many handheld devices.