Compact dual band microstrip patch antenna for Wi- Max communication systems

In this communication, a rectangular patch antenna is modified to achieve a compact multi-layered dual band antenna for application in lower and median bands of Wi-Max communication systems. The considered multilayered structure initially had two rectangular patches (with dimensions 28.5 mm × 31.5 mm) designed on two identical Glass epoxy FR-4 substrates and were separated through a thin foam layer. The lower patch was modified later by converting into slotted pentagonal patch. The lower patch was excited using insight feed network and upper patch was parasitically coupled to the lower patch. The proposed antenna operates in the lower band (2.3 GHz to 2.7 GHz) and median band (3.4 GHz to 3.69 GHz) of Wi-Max systems. The measured impedance bandwidth of proposed antenna in lower band with central resonant frequency 2.4 GHz is approx 11.0% while in median band with central resonant frequency 3.51 GHz, impedance bandwidth is close to 4.0% without much loss in its radiation performance. The variation in gain is well within 1dBi in the entire desired bands. The radiation patterns of antenna within two achieved bands are almost identical in shape.