A novel ninth-order suspended stripline low pass filter with three transmission zeros is presented. The technique use a pseudo-elliptic synthesis with grounding improvements. Suspended stripline low-pass filters are most widely used for applications that require high suppression of spurious and harmonic signals, and grounding could affect stopband rejection. The designed low pass pseudo-elliptic filter has a cutoff frequency of 2.5 GHz and an insertion loss less than 0.5 dB, and a stopband from 3.6 GHz to 6 GHz with a rejection better than 60 dB is achieved.