Design and optimisation of compact hybrid quadrifilar helical-spiral antenna in GPS applications using Genetic Algorithm

A novel circularly polarized antenna, called as “hybrid quadrifilar helical-spiral antenna” (HQHSA) is proposed in this paper. A prototype of the HQHSA, operated at 1.575 GHz and intended for applications in Global Navigation Satellite Systems (GNSS), is designed using Genetic Algorithms (GA). The antenna is placed on an infinite ground plane and optimized by using the GA. Performance of the GA optimsied antenna is compared with that of the typical quadrifilar helical antenna (QHA) and quadrifilar spiral antenna (QSA). The advantages of this new design are discussed. Performance of the optimised antenna design is validated and analysed by using commercial simulators in terms of impedance match, axial ratio and gain. It is shown that the proposed HQHSA antenna can achieve good performance as a circularly polarized antenna for GNSS applications. The design also shows the capabilities of GA as an efficient optimisation tool for selecting globally optimal parameters to be used in simulations with an electromagnetic antenna design code, seeking convergence to specific design specifications.