Design of wideband stepped-notch arrays using multi-section impedance transformer design rules

An efficient method of designing wideband stepped-notch arrays is presented that does not involve using time-consuming numerical optimization of the slot widths and lengths. Provided that a well matched and wideband feed has been designed, it is shown that it is straightforward to design the stepped-notch section of the antenna elements using design rules for multi-section impedance transformers (e.g. Chebyshev or binomial). Simulation results are presented for infinite arrays consisting of single-polarized stepped-notch elements with a Chebyshev design. Comparisons are made with arrays consisting of Vivaldi elements of equal length. Apart from illustrating the efficiency of the proposed method, Chebyshev stepped-notch elements are shown to be useable at lower frequencies than Vivaldi elements of equal length, especially for short elements.