Size reduction of printed quadrifilar helical antenna using simulated annealing

We have presented a method to reduce the size of a printed quadrifilar helical antenna (PQHA) by the modification of the antenna pitch angle on each segment of the wires. A global optimisation method (simulated annealing) has been used in order to obtain the optimum pitch angles according to the desired radiation pattern. A size reduction of 14% has been obtained in comparison to the conventional PQHA while maintaining the same features (half power beamwidth, axial ratio, impedance).