Broadside coupling mechanism between different patch resonators is deployed for designing power dividers to provide bandpassing effect. To demonstrate, two sector-shaped patches are combined and concentrically stacked on top of a circular microstrip resonator where pairs of concentric arc-shaped slots and radial notches are etched to perturb the current distribution so that an additional pole can be obtained to broaden the operational bandwidth. The use of circular patch enables the expansion of output ports without increasing the design complexity. Also, it was found that broadside coupling generates transmission zeros which can be used to sharpen the rolloff skirt for a better selectivity. In this paper, the corresponding design theory and methodology are elucidated, together with the detailed parametric analysis.
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