Accurate design of microstrip directional couplers with capacitive compensation

An accurate design is presented for microstrip directional couplers with high directivity using capacitive compensation. The method utilizes symmetry analysis and equivalency principals to develop closed-form solutions of the compensating capacitance and a new odd mode characteristics impedance necessary to realize an ideal microstrip directional coupler. The design approach is valid for any degree of coupling, thereby overcoming limitations of previous approaches to this design concept.<
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