A high-rejection substrate integrated waveguide filter for Q-LINKPAN applications

In this paper, a compact high-rejection substrate integrated waveguide (SIW) bandpass filter with a pair of finite transmission zeros (TZs) is presented for the Q-LINKPAN application. This filter consists of six cascaded cavities and a cross-coupling structure on the basis of a single-layer SIW. A folded topology of cavities make the cross-coupling path could be achieved easily between two non-neighboring cavities, which dramatically enhance the frequency selectivity. The designed filter has been fabricated using standard PCB process. The measured results exhibit an insertion loss of 2 dB at the center frequency of 42GHz, a return loss of more than 23dB over the passband (40.5GHz-43.5GHz), a 40dB rejection bandwidth of 6.5GHz (~15.5%) and an excellent frequency selectivity, which are in good agreement with simulated results. This filter has advantages of planar structure, low-cost, small size, easy be integrated with planar circuits, etc. It could be a good candidate for millimeter applications.