Filter Pin Insertion Loss Under Nonideal Conditions

Several articles have been published^ over the past few years cautioning designers not to rely on insertion loss data for filters derived by the methods of MIL-STD-220A.2 Filters employed in actual applica­ tions may behave quite differently than in a 50-ohm system. In addition, insertion loss may change as a result of saturation of ferrite elements or devaluation of capacitive elements at high temperature. The ef­ fects of these nonideal conditions on the performance of a typical pi-section filter pin have been investi­ gated. The techniques presented here may be used to evaluate other types of filter pins or, possibly, gen­ eral types of filters. However, particular attention must be paid to distributed parameter impedance or electromagnetic resonance effects which may not be significant in the compact filter pin, but may play a vital role in other filters.