Synthesis of filters with transmission zeros at real frequencies bymeans of trisections including source/load to resonator coupling

Filter synthesis based on trisections is extended to the case where coupling is between the source/load (input/output ports) and the resonators. Using this coupling, two transmission zeros can be placed at different real frequencies (jw axis of the complex plane) and independently controlled. For odd order filters: a new network transformation between the ladder network and the equivalent trisection is proposed. To validate the above transformation, a fifth degree two-trisection filter has been synthesised