Dual-band bandpass filter designed by exploiting the second-order degenerated modes of the SIW-cavity

This paper presents a novel technique to design a dual-band bandpass filter by exploiting the second order degenerated modes of the SIW-cavity. The second order filter has been designed by using the proposed technique, at Ka-band of microwave frequencies; the ratio of two bands center frequencies - frequency ratio (FR) - is 1.073. Rogers RT/Duroid 5880 - with substrate height of 0.508mm - has been used as the substrate material for design purpose. The measured return loss of the filter in both bands is better than -15 dB, moreover, the isolation between two bands is also better than 40 dB.