Wideband microstrip bandpass filter using tapped wiggly-coupled lines

This paper proposes a novel tapped wiggly-coupling array composed of narrow stub and finger stubs to form a wideband bandpass filter. The bandwidth and center frequency are easily controlled by the alteration of the embedded narrow stubs, while the length of the inner array and stub with fingers responds for the lower and upper transmission zeros. By introducing finger stubs into the unsymmetrical tapped wiggly-coupling lines, a good wide passband response is achieved. The prototype filter is designed at 3.65 GHz with 33% fractional bandwidth. A good agreement is observed between simulation and experimental result.