Time modulated switching and reactive loading techniques applied to a circular array antenna using genetic algorithm optimisation

Adaptive arrays have the capability to direct or steer the main beam in real time in a desired direction, or towards signal of interest (SOI), whilst suppressing interference or multipath signals. Reactive loading and time modulated switching techniques are applied to steer the beam of a uniform circular six element antenna array having a source element at its centre. Genetic algorithm (GA) optimization is used to calculate optimal values for the reactances loading the parasitic elements, from which the gain can be optimized in a desired direction. For temporal switching, the GA is also used to determine the optimal on and off times for the parasitic elements. This gives the difference in the induced currents, optimies the gain and steers the beam in a desired direction. These methods are demonstrated for a vertically polarised array configuration operating at 2.45GHz. Simulation results show that near optimal solutions for gain, sidelobe level reduction, with VSWR 3 over a 100MHz bandwidth, and beam steering is achievable by the GA optimisation.