Improving helical antennas using a deep-cut ellipsoidal algorithm

In this paper, uniform helical antennas are used as starting point to generate optimized non-uniform ones. The improvements in the input impedance and gain are obtained varying the shape of the helix using a second order polynomial function. The optimal polynomial parameters are found using the deep-cut version of the ellipsoidal optimization algorithm. The use of the well known formulae and diagrams for the design of uniform helical antennas as a initial point of the deterministic method can reduce the search domain and provides a fast convergence rate. Results are presented for WiFi application using a center frequency of 2.45 GHz. It shows that the input impedance and the antenna length can be considerably improved using a simple and efficient parametrization.