A CPW-fed fractal monopole antenna with a reduced ground plane in frequency range of 500 MHz-5.5 GHz

In this article, the authors propose a super wide band CPW-fed fractal monopole antenna suitable for phased array antennas with a shaped beam radiation pattern, operating in the frequency ranges below and above 1 GHz at the same time. The antenna has an octagonal radiator with fractals of the same shape added to its edges and sides. Also, the symmetrical elliptical ground planes have reduced the antenna size and, consequently, the mutual coupling in the antenna array. Despite the super-wide frequency range, the antenna's radiation pattern is relatively steady in the E-plane, and the negligible ripple on the radiation pattern makes it suitable for shaped beam radiation patterns in phased array design. The single-element antenna with an overall size of 0.24λ × 0.38λ at 500 MHz is printed on an FR-4 substrate. The outcomes of the simulation and measurement are well agreed in the frequency band of [500 MHz to 5.5 GHz] with an impedance bandwidth (|S11|< −10dB) of 166.67% and VSWR< 2. Also, the fidelity factor of the antenna is studied to investigate the SWB performance.