Abstract: The mobile wireless communications device includes a printed circuit board (PCB), wireless transceiver circuitry carried by the PCB and operating on a plurality of frequency bands, at least one antenna, and a multi-bandpass transmission line coupling the wireless transceiver circuitry to the at least one antenna. The multi-bandpass transmission line includes an electrically conductive trace on a surface of the PCB defining a transmission line signal path, and an electrically conductive layer on an opposite surface of the PCB and defining a ground plane. The electrically conductive layer has at least one set of slot rings therein and defining a plurality of slot ring resonators being electromagnetically coupled to the transmission line signal path and operable at the plurality of frequency bands.