Coupled Line Bandpass Filter for Sub-6 GHz Applications

With the increasing demand for sub-6 GHz applications, especially in 5G and WLAN (Wireless Local Area Network) systems, highly efficient frequency selectivity and robust interference rejection become extremely important. However, designing compact bandpass filters that effectively address these requirements still remains one of the biggest challenges. This paper attempts to deal with this problem by presenting a novel 5.5 GHz Coupled Line Bandpass Filter that has been designed for WLAN systems using microstrip technology. It is optimised for selectivity in compact form factor, to offer a 10% fractional bandwidth that covers the 5 GHz WLAN band. Using the LineCalc from ADS (Advanced Design System) for initial design and the Ansys HFSS (High-Frequency Structure Simulator) for simulation, to achieve an attenuation of at least −30 dB at 4.4 GHz and 6.6 GHz, hence reducing the adjacent channel interference by a huge amount. A very low insertion loss and compact structure, the filter will surely be very effective in sub-6 GHz applications.