DIFFERENTIAL MICROWAVE FILTERS WITH QUARTER-WAVE RESONATORS.

摘要

The present disclosure is related to a microwave band-pass differential filter based on quarter-wave resonators and 180° phase-shifters. The differential filter is made of micro-strip, operating at frequencies that can oscillate between 100MHz and 300GHz. The filter generates a band-pass in differential mode because a virtual open circuit is generated along the symmetry line passing through the resonators, which excites the resonance frequency of the same. On the other hand, when the filter is fed in common mode, a virtual short circuit is generated in the symmetry line blocking the signals in common mode. This allows increasing the spurious free band in common mode up to a frequency 10 times higher than the central frequency in differential mode.