Dual-Band Filtering Balun Using Dual-Mode Resonators.
Electronics and Communication Engineering
EC303, Seminar Room
Date & Time
02 Jun 2023 11.00AM
Prof U K Sahoo
In this letter, a compact dual-band bandpass filter (BPF) and its balun filter are proposed. Initially, a two-port dual-band bandpass filter is designed, and then it is extended to design a three- port balun filter. The design includes one pair of square open loop resonators loaded with an open-circuited stub to obtain dual-band filtering properties and enhance matching. The properties of the balun filter and the dual-band bandpass filter are investigated. The simulation results of the proposed bandpass filter (BPF) show effective filtering at 2.4 GHz and 4.48 GHz as the center frequencies with good insertion loss (IL) of 1.02 dB and 1.23 dB in both the passbands, which can be suitable for WLAN applications. Further, the same design is extended to form a three-port balun bandpass filter (BPF), with port 1 as the input port and port 2 and 3 as the output ports. Port 1 is a common feed between both the resonators, and port 2 and port 3 are asymmetrically rotated. This orientation helps to achieve good isolation and excellent amplitude and phase imbalance, which is hardly observed in any other literature. The insertion loss (IL) at the desired frequencies 2.4 GHz and 4.32 GHz is 3 dB and 3.64 dB which also shows effective power division between the output ports. There is an exact 180o phase difference between both the output ports and an amplitude imbalance of about 1.03 dB and 0.61 dB in both passbands, respectively. Also, the balun filter can be suitable for WLAN applications. In the future, this method might be useful to design a multi-band filter with balun characteristics.