Cosecant-squared pattern synthesis method for broadband-shaped reflector antennas

A new technique based on the invasive weed optimisation (IWO) algorithm and geometrical optics (GO) method for synthesising broadband cosecant-squared pattern reflector antennas is presented. The main feature that distinguishes this technique from others is the wide bandwidth. Moreover, compared with the previous methods, the proposed method allows to obtain extremely smaller ripples in the shaped region and lower sidelobe level (SLL). To achieve the desired performance over the entire 18-40 GHz operational bandwidth, the reflector surface is synthesised using a complex and accurate frequency-dependent fitness function including optimum weighting values. The simulation results via FEKO software package further prove the validity and versatility of this technique for solving reflector synthesis problems. In addition, experimental investigations are conducted to understand the complete reflector antenna system behaviours. Measurements show a good agreement with the simulation results. At last, the efficiency of the proposed frequency-dependent IWO (FDIWO) method both in bandwidth and optimality of the results are compared with original IWO method, common GO method and electromagnetic radiation (TICRA) software package. Comparison results show that the FDIWO method outperforms the other techniques.