Design of Skull-Cap Ended Monoconical Antenna for Ultra Wideband Systems

In this paper, design of a modified ultra wide band mono-conical antenna using skull cap is considered. First, a simple mono-conical antenna is designed using the opening angle (thetas) of 53deg due to previous works, but the height and radius of the cone is optimized separately. The final results showed a VSWR below 2 for 1.8 GHz to 9.7 GHz band and a VSWR below 2.2 for 1.6 to 13.6 GHz band. Adding a skull cap to the cone, the bandwidth is improved. Optimum designs showed bandwidths of 1.3 to 13 GHz and 1 to 18 GHz for VSWR less than 2 and 2.2 respectively which is relative bandwidth of 10 and 18. The omni-directional directivity is better than 5 dB for frequencies above 2 GHz but drops below 2 GHz due to the of fundamental gain limitation of small antennas