A True Inline Coaxial-Cavity Filter With Two Symmetric Zeros

This work deals with the design of true inline filters with two symmetric transmission zeros. A new filters category named “path filters” is introduced (including the considered filters), its general features are discussed and analyzed and a general method for the synthesis of the low-pass prototype network is proposed. To validate the proposed design approach, a coaxial-cavity filter with a true inline topology exhibiting two symmetrical transmission zeros has been designed and fabricated. The realized prototype shows a response in good agreement with the theory.