An electronic device has wireless communications circuitry that includes transmitters and receivers. Antenna structures may be coupled to the transmitters and receivers to support radio-frequency signal transmission and radio-frequency signal reception operations. Switching circuitry such may be used to support multiple communications bands of interest. One or more low band receivers may be associated with the first switch and one or more high band receivers may be associated with the second switch. The switches can be configured in real time to switch a desired communications band into use. A diplexer may be used to simultaneously pass low bands to the first receiver and high bands to the second receiver. In this way, a data stream in the low band may be simultaneously received with a data stream in the high band.