A band-stop filter comprises: a housing having a top wall, a bottom wall and at least one side wall, the housing defining an internal cavity; a signal input port and a signal output port that are respectively disposed on one of the at least one side wall; a resonating element that is disposed in the internal cavity and includes a top, a bottom, and a side; and a transmission line that is disposed in the internal cavity and coupled between the signal input port and the signal output port, the transmission line comprising a coupling section that is coupled to the resonating element, wherein the coupling section is configured to surround more than half of the side of the resonating element and not directly contact the housing and the resonating element.