A new class of wideband multisection 180/spl deg/ hybrid rings using vertically installed planar couplers

A new class of wideband multisection 180deg hybrid rings using the vertically installed planar (VIP) coupler is proposed. On the basis of the reconfigured ideal single-section 180deg hybrid ring (i.e., the 180deg hybrid ring with an ideal phase inverter), the multisection 180deg hybrid rings can be realized by properly cascading of single-section 180deg hybrid rings. Compared with the conventional hybrid ring, the two-section hybrid rings exhibit wide bandwidth, size reduction, and easily achievable high power-division ratios. Design equations based on the equal-ripple functions are derived. Design curves for the equal and unequal power-division ratio are also described. In addition, a cascade of single-section cascadable hybrid rings with a unit element at each I/O port can be used for bandwidth enhancement. Good agreement is obtained between the experimental and simulated results