Dual-Band Evanescent-Mode Substrate Integrated Waveguide Band-pass Filter for WLAN Applications

A new multi-layer substrate integrated waveguide (SIW) structure is developed to design dual-band evanescent-mode band-pass filters (BPFs). Two independent series LC circuits are implemented by incorporating metallic irises in the different layers of the structure. The combination of the metallic irises with capacitive-plates is embedded inside the SIW to independently excite two evanescent-mode resonance frequencies below the cut-off frequency of the structure. Two integrated series irises and capacitive-plates are incorporated in an antipodal configuration to minimize the coupling interference between them. A dual-band evanescent-mode band-pass filter is designed and characterized at 2.4GHz and 5.8GHz frequencies for Wireless Local Area Network (WLAN). The first resonance frequency of the filter is fixed at 2.4GHz (2400-2484MHz) and the second one is tuned at 5.2GHz (5150-5350MHz) to partially meet the standard IEEE 802.11 WLAN bandwidths and fully meet the WLAN frequencies. This approach demonstrates the miniaturized dual-band high quality- factor evanescent-mode band-pass filter. The structure is designed and simulated by taking into account of all fabrication aspects.