Dual-Band Hybrid Coupler With Arbitrary Power Division Ratios Over the Two Bands

For the first time, a patch hybrid coupler that can provide arbitrary power division ratios over two arbitrary frequency bands, is presented in this paper. Complementary split ring resonators (CSRRs) are loaded onto each quadrant of a patch hybrid coupler to enable dual-band operation. The unique property of CSRR was found to give different power division ratios over the two frequency bands, which is difficult to implement using conventional approaches. An equivalent circuit has been extracted and used to describe the operating principles, along with the presentation of parametric analysis. To demonstrate the flexibility in realizing arbitrary power division ratios in two different frequency bands, five dual-band patch hybrid couplers are designed, fabricated, and measured. Good agreement between the simulated and measured results consolidates the work proposed.