Design optimization of linear arrays and time‐modulated antenna arrays using meta‐heuristics approach

Abstract

AbstractThis article presents an approach to design a non‐uniformly excited linear array antenna (LAA) and an alternate solution to LAAs in the form of time‐modulated linear arrays (TMLA) for optimum far‐field radiation pattern synthesis. The performance analysis of both the antenna arrays is studied, and the advantages and limitations of the proposed design approaches are presented with numerical outcomes. The far‐field radiation pattern is optimized to reduce the interference by simultaneously lowering the sidelobe levels and increasing the directivities of LAAs and TMLAs. A recently proposed meta‐heuristics computation technique called whale optimization algorithm (WOA) is employed to get the optimal results. The current excitation amplitude and the inter‐element spacing of the 16‐element LAA are optimized with WOA to attain the desired results. However, due to the large dynamic range ratios (DRRs) of excitation weights, array feed network complexities are increased, which restricts the design of typical LAAs. TMLAs can be regarded as an alternative solution where the problem of large DRRs as well as the design complexities of LAAs are eliminated. The concept of ‘time’ is vital in time‐modulation as it plays the role of an added degree of freedom realized by periodically turning ON and OFF the radio‐frequency switches with an electronic control circuit to achieve an enhanced array radiation pattern. WOA is utilized to determine the optimal switch‐ON time periods for each array element and the optimal inter‐element spacing of a 16‐element TMLA. A set of numerical results validates the advantages of TMLAs over LAAs, and the limitations of TMLAs with respect to LAAs are also indicated. The performance of both the arrays is then compared with other published literature results to establish the superiority of the proposed approach.