Application of Dual TM Modesto Triple- and Quadruple-Mode Filters

The cylindrical cavity dual orthogonal transverse magnetic (TM) mode is introduced as a basic building block for the realization of microwave multiple-coupled-cavity bandpass filters. This concept is shown to offer significant advantages in the design of triple-mode filters and permits the design of the new quadruple-mode filter. Experimental verification is provided by the realization of a triple-mode, six-pole elliptic function bandpass filter with dual TM₁₁₀ and single TE₂₁₁ (transverse electric) modes and a quadruple-mode, eight-pole bandpass filter with dual TM₁₁₀ and dual TE₁₁₂ mode cavities. All units exhibit good agreement between theory and experiment.