An Efficient Implementation for the Analysis of Periodic Microstrip Lines Excited by Nonperiodic Sources

The current excited by a single delta-gap voltage aperiodic source on both completely shielded and open periodically loaded microstrip lines is here studied by means of the array scanning method (ASM). The ASM is applied to reduce the aperiodic problem to an integral superposition of infinite phased arrays of identical sources, each one expressed in term of a suitable Floquet-periodic problem. Efficient numerical implementations of the ASM are developed, for both the shielded and the open cases, based on a method of moments with entire-domain basis functions. Numerical results are presented for dispersion features and Bloch modes supported by the periodic microstrip line as well as for the current excited by the source. Different frequency ranges are investigated which correspond to pass-band and stop-band regimes of the fundamental perturbed quasi-TEM mode.