General Synthesis of $N$-Band Resonator Based on $N$-Order Dual Behavior Resonator

This letter deals with a general method and synthesis devoted to the achievement of N-band resonators. The general topology is based on the dual behavior resonator. Indeed, this kind of topology allows the independent control of different transmission zeros and resonances. Thus, the topology proposed in this study consists of a parallel association of N+1 different bandstop structures to get N bandpasses separated by a transmission zero. After introduction of the general synthesis, the principle will be validated by the achievement of a four-band resonator in microstrip technology