Development of A Tapered CPW-fed Spline-based Planar Monopole Antenna with Ultra-Wideband Characteristics

This paper proposes the development of a spline-based planar monopole antenna with an ultra-wideband (UWB) characteristics. The proposed antenna consists of a patch section and a groundplane section which are developed by utilizing a quadratic spline formed from a sequence of control points (CPs). The feedline section utilizes a tapered-type of coplanar waveguide (CPW). In order to attain an UWB characteristic, the patch and groundplane sections are configured using 14 and 13 CPs, respectively. The simulation result shows that the proposed antenna has UWB characteristics with the working bandwidth from the frequency of 1.76 GHz to more than 20 GHz, with the geometrical bandwidth of $307 \%$. Meanwhile, verification through measurement demonstrates that the realized antenna has the working bandwidth within the frequency range from 2.33 GHz to more than 20 GHz or its geometrical bandwidth of $259 \%$. The measured results of radiation pattern and gain at the frequencies of $4 \mathrm{GHz}, 6 \mathrm{GHz}, 9 \mathrm{GHz}$, and 18 GHz, which are carried out to confirm the simulated results, also show good agreement.