A filtered electromagnetic coupler includes a main transmission line extending between an input port and an output port, and a coupled line section extending between a coupled port and an isolation port. The coupler is configured to couple signal power from the main transmission line to provide coupled signals at the coupled port, and a filter subsystem is connected to the coupled port to filter the coupled signals. The filter subsystem includes filters configured to pass or reject coupled signals by frequency, and the filter subsystem provides the filtered output signal to a measurement node.