Control Points Rearrangement of Spline-based CPW-fed Spearhead Monopole Antenna Using Particle Swarm Optimizer

This paper performs the control points rearrangement of a spline-based spearhead monopole antenna fed by a coplanar waveguide (CPW) to improve its bandwidth characteristic using particle swarm optimizer (PSO). The proposed antenna configuration is formed by involving two spline curves, one each on the radiator or antenna patch and the groundplane. On the radiator, a closed spline curve is configured by 14 control points. While on the groundplane, the outer side facing the radiator has a spline contour consists of 13 control points. For both the radiator and groundplane, a shape that has one symmetrical axis applies. PSO is involved in determining the distribution of control points both on the radiator and groundplane. The antenna configuration that uses a straight CPW feedline is then changed by applying a tapered CPW feedline to suppress the notch response occurred, thereby yielding a single wide bandwidth response to accommodate ultra-wideband (UWB) applications. Next, the antenna configuration is realized and verified through measurements, which produces the prototype that works from the frequency of 2.33 GHz to 20 GHz, or the geometrical bandwidth of 258.8%.