A compact elliptic-function BPF using triple-mode cavities for terrestrial digital television transmitters

A compact six-pole elliptic-function BPF for terrestrial digital television transmitters is developed using two triple-mode cavities. The BPF needs a very sharp cut-off response to reject neighboring channels. Therefore, it needs to achieve exact coupling parameters without parasitic couplings. A new coupling method is presented to achieve these couplings independently of each other through one wall between two triple-mode cavities. A compact BPF test model which uses this method has resulted in good performance for digital television transmitters.