An edge-coupled bandpass filter with sharp skirt characteristics using tapped-line method

In this paper, an edge-coupled bandpass filter is presented using tapped-line method. In order to determine the tapped-line feeding position, J-inverter of the input resonator can be represented by its equivalent circuit using an input admittance. This filter provides compact design using a simplified mathematical design method for tapped-line geometry and sharp skirt characteristic by transmission-zero. This filter shows the insertion loss of 3 dB and return loss of 21.06 dB at the center frequency of 5.8 GHz.