A Sharp Roll-Off Wi-Fi 6E Microstrip Bandpass Filter with Asymmetric Frequency Response

This paper reports the design of a highperformance Wi-Fi 6E bandpass filter (BPF), featuring high selectivity, high stopband attenuation, and compact size. Two transmission zeros (TZs) in the low-frequency stopband are created due to the cross coupling, and thus forming an asymmetric frequency response and providing a narrow guard band between Wi-Fi 6 and Wi-Fi 6E communications. To verify, a BPF with fifth-order asymmetric bandpass response was designed and fabricated using microstrip technology. The simulation and measurement results of the developed BPF are in good agreement. The designed BPF has a sharp roll-off rate (ROR) of 321.1 dB/GHz, low insertion loss of 1.06 dB, and high stopband attenuation of > 45 dB from dc to 5 GHz, and it can meet the stringent requirements of the modern Wi-Fi 6E communication systems.