CPW-fed star shaped UWB antenna with and without band-notch characteristics

Abstract

A CPW-fed star shaped slot like monopole antenna with and without ITU-8 band notch characteristics for ultra wideband communication are proposed. They comprise a stage 1 Koch fractal star shaped radiating patch, modified feedline and slot loaded CPW ground plane. The band notch characteristic is achieved by loading the radiating patch with half wavelength long meander line slot. An impedance bandwidth of 3.1-17.6 GHz with band rejection for 8-9 GHz band (ITU-8 band) (S11 ≤ -10 dB) is achieved. The band notch characteristic is modeled by an equivalent RLC resonant circuit. The equivalent circuit is validated with simulated input impedance and VSWR results. The proposed antenna provides an average gain of 4.4 dB over the entire band of operation for without band notched antenna. The radiation patterns are also observed to be omni-directional and bidirectional at lower frequencies with some distortions at higher frequencies. Non-band reject antenna configuration provides a fidelity factor of 90% along with a constant group delay over the entire operating band. The effect of various critical parameters on antenna performance is also analysed.