Wideband Hybrid Coupler With Large Power Division Ratios/Arbitrary Output Phases and Low In-Band Amplitude/Phase Deviation

Abstract

In this article, a new type of wideband hybrid couplers with large power division ratios, arbitrary output phases, and low in-band amplitude and phase deviation are presented, which are enhanced from a fundamental single-band circuit that characterizes large power division ratios, arbitrary output phases, and adjustable phase deviations. By utilizing four transmission lines, two short-circuited parallel coupled lines and two short-circuited anti-parallel coupled lines, the performance of the enhanced hybrid couplers is significantly improved, including the bandwidth, out-of-band rejection, frequency selectivity, and amplitude/phase deviation. Using the even- and odd-mode analysis method, a detailed theoretical analysis is given under different conditions. Three prototypes with large power division ratios and different output phases are designed and fabricated. The measured results agree well with the simulated results, which not only prove that hybrid couplers possess constant and flat power divisions and output phases across a broad bandwidth but also verify the effectiveness of the proposed theoretical analysis approach.