Design of microwave filters using a binary coded genetic algorithm

We present a procedure for designing multilayered microwave filters that incorporates combinations of different dielectrics using a binary coded genetic algorithm (GA). The GA simultaneously chooses, optimally, the material in each layer as well as its thickness. The result is a multilayer composite that provides a maximum absorption of both TE and TM waves for a prescribed range of frequencies and incident angles. This technique automatically places an upper bound on the total thickness of the composite as well as on the number of layers that form the composite. The GA-based combinatorial optimization technique presented offers several advantages over the existing approaches: (i) the GA provides a mechanism for global search; (ii) it succeeds in designing filters consisting of only a few layers and, therefore, almost always leads to a physically-realizable structure; (iii) it typically presents multiple options for the design rather than a single choice as offered by most other techniques; and, (iv) it is considerably simpler to implement than the gradient-based search procedures.