Quasi-elliptic 150 GHz highly selective LTCC filter

In this paper, and for the first time to the best of our knowledge, a very challenging 4-pole quasi-elliptic filter in the submillimetric wave range is studied and fabricated by the LTCC technology. The proposed 4-pole filter, centered at 150 GHz with 2 GHz band pass, is described and the coupling apertures used to provide the required positive and negative couplings are studied. The measured response is in very good agreement with the predicted behavior with a central frequency of 149.7 GHz (0.2% variation) and a 2.02 GHz band pass. The obtained manufactured filter is compact in size (3.32 mm × 2.36 mm × 0.6 mm), has a high performance with 5.5 dB insertion loss at the central frequency and a transmission attenuation over 20 dB for f0 ± 1.6 GHz.