Transmission-Line Schematic for Harmonic-Controlled Bandpass Filters

This article presents a rigorous synthesis method of transmission-line filter whose second passband can be placed at any multiple the center frequency, in theory. Two coupled-line schematics for harmonic-controlled bandpass filters are derived from fundamental LC prototypes. Their design parameters provided closed-form expressions so dimensions acquired rigorously without relying on EM-simulation-based coupling tests. Three were designed and fabricated verification purposes, their measurement results exhibited excellent agreement with