The short answer is that RF Engineers are research and development (R&D) electrical engineers who specialize in designing, developing, testing, and deploying innovative new wireless networks and radio frequency (RF) payloads, subsystems, wireless networks, and component technologies for use in aircraft systems,
Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around 20 kHz to around 300 GHz.
RF engineers primarily work with electronic products that transmit radio waves, such as cell phones and Bluetooth devices.
Many electronics engineers choose to specialize in this area of engineering due to the excellent job security and competitive salaries that the career path typically offers.