This paper presents a bidirectional coupler which is designed by combining nonuniform wiggly lines and the reflected power canceller (RPC) method. The combination not only brings about a high directivity but also makes a wideband structure with a compact size. Although, in the RPC method, an idle port is used to produce a reflected signal in order to achieve a high directivity, there are not any idle ports in the proposed coupler. The coupler was built on an FR4 substrate. The measurement results show that this structure is suitable to monitor forward and reflected signals in high power applications. The fabricated coupler has the directivity of more than 22 dB and the coupling flatness of ±0.12 dB in the forward and backward signals in a wide frequency range of 140 MHz-190 MHz.
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