When selecting a radio wave detectors, look for key features such as wide frequency range, sensitivity, and ease of use. A good detector should cover a broad spectrum of frequencies to ensure comprehensive detection. High sensitivity allows for the detection of weak signals, which is crucial for identifying hidden devices. User-friendly interfaces, with clear displays and straightforward controls, make operation easier. Additional features like sound or vibration alerts, memory storage, and rechargeable batteries can further enhance the usability and effectiveness of the device.