A planar band rejection filter composed of slit-loaded side-coupled filter for 3rd-order PIM measurement

A planar band rejection filter is proposed for the 3rd-order passive intermodulation measurement in this paper. It is a side-coupled microstrip filter loading a slit at the strip-line edge. The characteristics of two section filter are examined using IE3-D simulator to confirm the validity of the edge-slotted stripline filter. The simulated input characteristics agreed well with the measurement result of prototyped filter. The concept of edge-slitted strip line filter is also applied to a 3-section side-coupled filter, and its simulated characteristics are demonstrated. As a result, good band elimination performance greater than 50 dB with the low insertion loss is obtained for 2 GHz passive intermodulation measurement.