Authors: MEHDI TAHERKHANI, ARASH AHMADI
Abstract: In this study, a broadband stripline multisection coupled-line coupler is designed and fabricated. The coupler has 50 dB coupling in the frequency range of 30 to 1000 MHz. The coupler is designed by cascading several unit section couplers consisting of two unequal length coupled line sections connected by different length uncoupled transmission lines. The unequal length coupled line sections with different coupling coefficients introduce a degree of freedom for bandwidth improvement and can help to reduce the overall dimensions of the multisection coupler. A lumped-element compensating circuit is used in series with the coupling port of the coupler to flatten the overall coupling response of the coupler over multioctave frequency bands. The fabricated coupler is compact in size and handles up to 200 W of RF power. The flatness of the coupler depends on the frequency response of the multisection coupler and the compensating circuit. The designed coupler has maximum 1 dB ripple in the coupling response over multioctave bandwidth.
Keywords: Coupler, stripline, multisection,
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