Four-pole versus five-pole filter comparison

Test results obtained on the prototype five-pole cavity filter as constructed to meet the requirements of the John Hancock Building (Chicago, Illinois) combiner project are presented. A comparison is made of the performance of that prototype filter with the results obtained using the standard four-pole filter. The five-pole filter was designed to use approximately 16-in square aluminum cavities with copper inner conductors and, thus, differs from the standard four-pole filters (which are approximately 24-in on a side) in both size and number of cavities. The size difference will affect some of the parameters that are being compared, as a 16-in four-pole filter is not available. Among the parameters that are compared are match, insertion loss, and group delay