An M-way coupler having a first port, M second ports, M transmission line sections, M isolation resistors and a phase shifting network is disclosed, where M is an integer number greater than 1. The M transmission line sections couple the first port to the M second ports, respectively. Each of the M isolation resistors has a first terminal and a second terminal. The first terminals of the M isolation resistors are coupled to the M second ports, respectively. The phase shifting network has M I/O terminals coupled to the second terminals of the M isolation resistors, respectively. The phase shifting network is arranged to provide a phase shift within a predetermined tolerance margin between arbitrary two I/O terminals of the M I/O terminals of the phase shifting network.