Design principles of analytical methods for calculation of dual-band strip directional couplers with full structure symmetry
Keywords:directional coupler, two-pole network, dual-frequency mode, reactive element, full symmetry, stub
Conditions ensuring the dual-frequency operation of directional couplers with two symmetry planes were defined, and an approach to the development of methods for calculating the electric parameters of coupler elements was considered. This approach is based on using input impedances of partial two-pole networks of the co-phase (symmetrical) and opposite-phase (asymmetrical) excitation. Examples of using such approach to the classical circuit of double-stub directional coupler and to its modification with two additional reactive elements were also presented.
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