Modeling and design of interdigital structure

A computer-aided-design-compatible model is described for an interdigital structure in microstrip configuration. The interdigital structure is modeled by using the admittance matrix of the coupled microstrip lines and modified to include the discontinuities and the distributed elements. The model takes into account all the distributed effects of the structure and models them as circuit elements. The equivalent circuit elements of the interdigital structure are computed in closed-form expressions. The results are compared with other models and also with the experimental results. Even though the model does not consider the phase shift along the terminal strip, it is shown to be valid well into the gigahertz range.<
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