Miniaturized Half-Mode Fan-Shaped SIW Filter With Extensible Order and Wide Stopband

Abstract

In this letter, a miniaturized half-mode fan-shaped substrate integrated waveguide (HMFSSIW) resonator is proposed to form different order of filters without increasing the size. The resonator is based on a semicircular substrate integrated waveguide (SIW) cavity with metallized vias distributed along the circumference. A metallized via located on the circle center and a semicircular ring slot etched along the circumference to realize half-mode resonances. By introducing one or two radial slots with different lengths, the four half-mode resonant frequencies can be controlled independently, which enables to form second- or third-order filter with controllable bandwidth and wide stopband. Finally, a second-order Chebyshev filter is well designed and a third-order filter centered at 1 GHz with a fractional bandwidth of 15% and a transmission zero (TZ) on the right side is designed, fabricated, and measured. The measured results show good agreement with the simulated ones.