An 18‑zones door‑frame metal detector (18‑zone DFMD) is a high‑end precision multi‑zone screening device widely deployed within a security guard system. Compared with 12‑zone models, this equipment divides the full‑height archway into eighteen independent, overlapping vertical‑horizontal detection zones. When concealed metal weapons or forbidden metal articles are detected, corresponding LED zone indicators on both left and right sides illuminate to show ultra‑fine‑grained approximate height and left‑right position of metal objects on human bodies. Security staff can then use a handheld metal detector to quickly pinpoint threats without broad full‑body scanning. Sintronic 18‑zones door‑frame metal detectors have been delivered for overseas security projects including the Colombia shipment reference project.

Core Working Principle of 18‑Zones Door‑Frame Metal Detector

Sintronic 18‑zones door‑frame metal detector adopts digital pulsed‑induction electromagnetic technology. Multiple groups of independent transmitter‑receiver coil pairs are embedded on both sides of the arch frame to form eighteen separate overlapping detection sections covering from head down to feet, supporting left‑right differentiated detection. The complete detection workflow is shown below.

1. Power‑on self‑check & multi‑zone magnetic‑field generation

After power‑on initialization and self‑diagnosis, each of the eighteen coil groups generates its own stable pulsed low‑frequency electromagnetic field, covering different vertical‑horizontal height sections across the passage. Operators can set independent sensitivity parameters for every single zone according to on‑site high‑security requirements.

2. Magnetic‑field disturbance triggered by metal objects

When a pedestrian walks through the archway carrying concealed metal items, eddy currents will be induced inside the metal. It generates reverse secondary magnetic field and disturbs the local electromagnetic field of one or several detection zones. Only receiver coils of disturbed zones capture abnormal signal data.

3. DSP signal processing & zone‑targeted alarm trigger

Built‑in DSP digital signal processor analyzes signal amplitude from each of the eighteen zones separately. Once the signal exceeds preset sensitivity threshold, the detector activates combined audio‑visual alarm: buzzer beeps, meanwhile the LED indicator lights corresponding to disturbed vertical‑horizontal zones illuminate on both sides of the arch.

Key feature for 18‑zone model: It provides much finer vertical plus left‑right positioning than 12‑zone units. Security guards know more precisely which body segment (left / right / middle) the metal threat locates on, greatly narrowing inspection scope and accelerating pedestrian throughput at busy high‑security checkpoints.

4. Reset and prepare for next pedestrian screening

After security personnel finish secondary inspection and handling for alarmed persons, the detector automatically resets all zone status and stands by for the next passing‑through pedestrian.