Title: Design of Compact Wideband Circularly Polarized Conical Helix
Abstract: A novel compact wideband circularly-polarized (CP) helix antenna is presented in this paper.Unlike conventional helical geometry, our design adopts a tapered metal strip which is rolled into a conical shape and is simply fed by attaching to a 50Ω coaxial cable.All the configuration parameters are optimized by using modified multiobjective evolutionary algorithm based on decomposition (MOEA/D) for broad operation bandwidth.The proposed helix antenna provides a -10 dB impedance bandwidth of more than 81% from 2.1GHz to above 5GHz, a 3-dB axialratio bandwidth of 58% (2.4GHz~4.36GHz),and a 8dBi axial gain bandwidth of 72.5% (2.18GHz~4.66GHz),which leads to an effective CP operation bandwidth of 58%.The overall size of the design is 40mm×40mm× 40mm, i.e., 0.45λ×0.45λ×0.45λat the centre frequency of 3.38GHz.The compact size and wideband CP performance of this antenna make it promising for high speed wireless communication systems today.