Nonresonating Modes Do It Better!: Exploiting Additional Modes in Conjunction With Operating Modes to Design Better Quality Filters

Resonances and reactive effects due to higher-order modes represent a rather popular concern among microwave engineers dealing with the design and modeling of passive components. The terms spurious and parasitic are indeed the words of choice when referring to those effects, and, although such a historic bad reputation is well deserved for most applications, in the last decade or so, there has been a particular discipline where these parasitic effects have suddenly earned new respect and dignity: the discipline of microwave filters.