Ku-band double-sided suspended substrate microstrip coupled-line bandpass filter

A Ku-band double-sided suspended substrate microstrip (DSSSM) coupled-line bandpass filter with less than 2 dB insertion loss is presented. The design utilises five sections and is specified to be centred at 15 GHz with a moderate 10% bandwidth which is fabricated on an alumina substrate (/spl epsi//sub r/ 9.9, h=0.381 mm and airgap=0.381 mm). The versatile configuration of the DSSSM provides a significant size reduction with easily realisable bandwidths due to a wider range of couplings obtainable from the overlapping (nonoverlapping) sections as compared to conventional suspended substrate microstrip.