Patent ID: 9147922
Filing Date: 2015-09-29
Classification: H01P

Abstract:
1. An electrical filter for filtering an electrical signal, the filter having a transmission characteristic comprising a first band edge having a band edge transition frequency, the filter comprising: a circulator having a first circulator port for receiving the electrical signal to be filtered, the circulator being adapted to transfer the electrical signal to be filtered received at the first circulator port to a second circulator port and being further adapted to transfer the electrical signal to be filtered received at the second circulator port to a third circulator port; and, a reflection mode filter connected to the second circulator port; the reflection mode filter comprising: a filter network comprising a single resonator, the filter network having a network input connected to the second circulator port; and, a further resonator connected to the network input, the further resonator being arranged to provide an extracted pole providing a transmission zero closest to the band edge transition frequency; wherein the further resonator has a higher Q than the Q of the single resonator of the filter network.