Figure 1

Conformal mapping of the coupler cross-section. (a) Original z-plane. All of the points \(a_{j}\), \(b_{j}\), and \(c_{j}\) are real and located on the real axis. (b) Transformed w-plane. The points \(a'_{j}\), \(b'_{j}\) and \(c'_{j}\) are the transforms of \(a_{j}\), \(b_{j}\), and \(c_{j}\), respectively. In the notch-port configuration, conductor 1 is the feedline, conductor 2 is grounded and conductor 3 is the resonator, and both the feedline and resonator can extend from both ends of the coupler. In the butt-port configuration, conductors 1 and 3 are terminated on one end of the coupler. On the other end conductor 2 is terminated, and conductors 1 and 3 are connected to each other.