How to Use an RF Detector to Find Bugs and Hidden Cameras

Surveilex Guides · Updated November 2026

An RF detector picks up the radio signals that wireless bugs, cameras and GPS trackers send out. Used the right way, it can lead you straight to a hidden device. Used the wrong way, it beeps at everything.

How an RF detector works

Wireless spy devices send what they record over radio frequencies: Wi-Fi, Bluetooth, cellular (2G/3G/4G) or analog transmitters. An RF detector listens across those frequencies (the K19+ covers up to 8GHz) and shows signal strength on a bar. The closer you get to a transmitter, the higher the bar.

Step 1: Remove your own signals

Your own phone, smartwatch, laptop and the room's Wi-Fi router are the biggest sources of false alarms. Switch off your phone and other devices, or put them in airplane mode, and note where the router is.

Step 2: Set the sensitivity low

Detectors start at full sensitivity, so they beep at everything. On the K19+, turn the knob down until the bar shows level 1 and the beeping stops. Starting low is the single most important step.

Step 3: Sweep slowly

Hold the antenna a few inches from surfaces and move about one foot per second. Work in a pattern: around the walls, then outlets, smoke detectors, lamps, clocks, vents, under furniture and inside drawers.

Step 4: Narrow it down

When the bar rises, turn the sensitivity down a little and keep moving. The signal should peak at one small spot. Repeat until you are within a few inches of the source.

Real signal or false alarm?

• Likely false alarm: one beep that doesn't repeat, a signal that's equally strong everywhere in the room, or one that's strongest at the Wi-Fi router, TV or a neighbor's wall.
• Worth investigating: a signal that comes back in the same spot, gets stronger as you get closer, and comes from an object that shouldn't transmit (a clock, smoke detector or charger).

What RF detectors can't find

• Wired or recording-only cameras don't transmit. Use the IR lens finder instead.
• Devices that are switched off or only transmit occasionally. Some GPS trackers report every few minutes, so scan for 5 to 10 minutes.
• Magnet-mounted trackers that are asleep. Use the magnetic probe for these.

That's why the K19+ combines RF, an IR lens finder and a magnetic probe in one device. See step-by-step button instructions.