Property Analysis and Experimental Study of the Broadband Transmission- Line Transformer in Multimode Feed Network

ABSTRACT

Transmission-line transformers are circuits useful for microwave impedance matching applications due to their broad operating bandwidth. Multimode feed network is composed of two substructures, which are constituted by the transmission-line transformer. Beginning with the broadband transmission-line transformer with 4:1 impedance transformation, supposing the currents on the two lines are not equal but opposite and with the application of two line transmission- line theory, the current-voltage relationships of the asymmetrical (current) bifilar even transmission-line are obtained. An equivalent model with mutual coupling between the subject transmission-lines has been proposed, and its characteristics for impedance transformation have been analyzed. Also, a useful and effective analytic method for bifilar transmission- line transformer has been proposed. The calculated values are in good agreement with the metrical values. So in real application it can better improve the performance of the component and can be used more efficiently.

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