Investigations on Ultrawideband Pentagon Shape Microstrip Slot Antenna for Wireless Communications

An ultrawideband (UWB) pentagon shape planar microstrip slot antenna is presented that can find applications in wireless communications. Combination of the pentagon shape slot, feed line and pentagon stub are used to obtain 124% (2.65-11.30 GHz) impedance bandwidth which exceeds the UWB requirement of 110% (3.10-10.60 GHz). A ground plane of 50 mm × 80 mm size is used which is similar to wireless cards for several portable wireless communication devices. The proposed antenna covers only the top 20 mm or 25% of the ground plane length, which leaves enough space for the RF circuitry. Three variations of the antenna design using the straight and rotated feed lines on two different substrates are considered. Effect of the conducting reflecting sheet on back of the antenna is investigated, which can provide directional radiation patterns but with reduced matching criteria. Finally, experimental verification of the fabricated antenna for its impedance bandwidth is carried out, which shows agreement with the simulated data.