Abstract: In this paper a new complementary quad band omnidirectional planar microstrip antenna array has been proposed. This antenna consists of cascaded connection of three rectangular shaped patches on the upper side, two rectangular shaped patches on the ground side and one “I” shaped resonator at the ground to produce the effective structure of antenna array which can radiate omnidirectionally with high efficiency, moderate gain, low reflection and useful radiation pattern. This cascaded quad band antenna array operates at Bluetooth (2.35-2.53) GHz, WIMAX (3.25-3.50) GHz, HIPERLAN (4.06-4.30) GHz and WLAN (5.37-5.86) GHz with S₁₁ <-10 dB and stable radiation pattern having gain 2.8dBi, 3.32dBi, 3.49dbi,and 6.4dBi respectively. The bandwidth of these bands for proposed antenna becomes 180 MHz, 250 MHz, 240 MHz and 490 MHz respectively.

Keywords: Antenna array, BLUETOOTH, WIMAX, HIPERLAN, WLAN