Coupling-compensated 180#x00B0; phase shift coupled-Line filters terminated in arbitrary impedances

摘要

Coupled-line filters (CLFs) with a 180° phase shift are analyzed and coupling compensated design equations are derived. They can be applied for arbitrary termination impedances and arbitrary coupling coefficients. To verify the design equations reasonable, a microstrip CLF with a coupling coefficient of −7 dB is fabricated on a substrate ( εr= 3.5 , H = 30mil , tan δ = 0.04) and tested for 100 Ω and 70 Ω termination impedances. The measured results show good agreement with the simulated ones.