Intel® WiDi uses the same band and channel used by the laptop in WiFi, which is also depends on the router configuration. Intel® WiDi also works without a router, by default it should be connecting at 2.4 GHz.
My best recommendation in order to use Intel® WiDi at 2.4 GHz in a 5 GHz environment is basically not connecting the laptop to the local network (in 5 GHz). The article below may provide additional information.
Intel� Wi-Fi Products; The Access Point/Router is working in a not compatible mode