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摘要

In the above paper [1], a rat-race coupler having three equal arms of arbitrary electrical length has been analyzed. It has been shown that an infinite number of solutions exist for the coupler design, some of them having lower electrical lengths than a conventional 1.5lambda coupler. Theoretical predictions have been verified by implementing, in microstrip technology, a 19lambda/18 length coupler operating at 0.9 GHz.