Improving the Second Harmonic Rejection of Side-Coupled Filters

摘要

The use of an in-line topology for a side-coupled microstrip filter results in a narrower footprint with minimal impact on filter performance. Incorporating notch filters for second harmonic rejection is practical and achieves 50 to 60 dB rejection with minimal degradation in the passband performance. For a filter mounted in waveguide or a closed channel, the side-coupled topology improves the rejection of higher frequencies up to the waveguide cutoff.