Design of an Ultrawideband Monopole Antenna for Portable Radio Transceiver

This letter describes the design of a compact monopole antenna for use in a portable transceiver to access almost all modern wireless services from 850 MHz to 6 GHz. Initially, a microstrip-fed planar monopole of quarter-elliptical shape accompanied by a ground plane of 60 x 90 mm(2) on FR-4 substrate is designed. To generate an ultrawide impedance bandwidth, this radiating element is accompanied by a parasitic microstrip stub and a ground plane cut. To reduce its projection area, the planar monopole is folded to occupy a volume of 13 x 60 x 5.6 mm(3). This antenna is then fabricated and experimentally tested. Both simulation and experimental results show its operational band from 0.85 to 6 GHz, with reference to the 6-dB return loss (VSWR 3:1). Its radiation patterns are omnidirectional in the lower band and become directional at higher frequencies, with the gain varying between 1 and 7 dBi.