This document describes techniques and systems that enable a smartphone-based radar system facilitating ease and accuracy of user interactions with a user interface. The techniques and systems can be implemented in an electronic device, such as a smartphone, and use a radar field to accurately determine three-dimensional (3D) gestures that can be used in combination with other inputs, such as touch or voice inputs, to interact with the user interface. These techniques allow the user to make 3D gestures from a distance—and enable seamless integration of touch and voice commands with 3D gestures to improve functionality and user enjoyment.