A single‑zone walk‑through metal detector (also known as single‑zone DFMD) is a cost‑effective primary screening device widely deployed within a security guard system. The entire archway forms one unified detection zone. It can detect whether a person carries concealed metal weapons or forbidden metal articles, but cannot indicate the exact body position of the metal object. When an alarm triggers, security staff need to use a handheld metal detector for secondary locating inspection. Sintronic single‑zone walk‑through metal detectors have been delivered for overseas security projects including the Colombia shipment reference project.

Core Working Principle of Single‑Zone Walk‑Through Metal Detector

Sintronic single‑zone walk‑through metal detector adopts pulse induction electromagnetic induction technology. Transmitter and receiver coils are embedded on both sides of the arch frame. The complete detection workflow is shown below：

1.Power‑on and generate uniform electromagnetic field

After power‑on initialization, the built‑in transmitter coils continuously generate stable pulsed low‑frequency electromagnetic field filling the whole passage space inside the archway. The device enters ready screening status. Operators can adjust overall system sensitivity according to on‑site security requirements.

2. Metal object disturbs magnetic field

When a person walks through the archway, if he or she carries metal items such as knives, blades or other forbidden metal goods, eddy currents will be induced inside those metal objects. These eddy currents generate reverse secondary magnetic field and interfere with the original electromagnetic field emitted by transmitter coils.

3. Signal analysis and whole‑zone alarm trigger

The receiver coils capture magnetic‑field disturbance signals and send data to the main control unit. The controller compares signal amplitude against preset sensitivity threshold. Once exceeding threshold value, the detector activates combined audio‑visual alarm: buzzer beeps and indicator lights turn on.

Important feature for single‑zone model: it only gives a global alarm for the whole archway. It does NOT show which height or body area the metal object is located on. Security guards must use handheld metal detector to scan the person and pinpoint exact threat position.

4. Reset for next passenger screening

After inspection and handling of the alarmed person, the detector automatically resets and stands by for the next pedestrian passing‑through.