Can ferromagnetic detection find a mobile phone hidden inside a person?

Yes. Ferromagnetic detection responds to the ferrous content every mobile phone contains — principally the speaker and vibration motor magnets — regardless of whether the phone is switched on, switched off or has the battery removed. Because it senses magnetic mass rather than surface metal, it detects devices carried, taped to the body or concealed internally, which is where a walk-through metal detector and a physical pat-down are both unreliable. RedteQ supplies and supports the Metrasens Ultra in the UK.

How do you stop recording devices in confidential meetings?

Screening people as they enter the room is the practical control. A ferromagnetic detection system such as the Metrasens Ultra can be set up outside a boardroom or conference room and screens each attendee in seconds, indicating where on the body a device is located. Attendees divest their personal items as they would for any search, and the system finds what remains on or inside the person. It detects phones, voice recorders and similar devices because of their magnetic components. It screens people rather than sweeping rooms, so it complements a technical surveillance counter-measures survey rather than replacing one.

What if the concealed item is not metal at all?

Ferromagnetic detection responds to ferrous content, so an item with no magnetic signature — a ceramic blade, a wrap of powder, banknotes — does not register. For those, passive terahertz body scanning is the complementary technology: Thruvision images what a person is carrying beneath their clothing, metallic or not, at up to seven metres, without contact and without emitting anything. RedteQ supplies both and will advise which, or whether both, fits the risk.

Does a phone need to be switched on to be detected?

No. Ferromagnetic detection is passive and responds to the magnetic material inside the device, so a phone that is powered down, in flight mode or has had its battery removed is detected just the same. It emits nothing itself, which is why it is safe around pacemakers, pregnant visitors and medical implants.

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Metrasens Ultra · ferromagnetic detection

Concealed Item Detection — Metrasens Ultra

Metrasens Ultra is a rapidly deployable search system that finds weapons, phones and recording devices on people — including items taped to the body or concealed internally, which is where a metal detector and a pat-down can't reach. Set up in minutes, anywhere you need it.

Get Metrasens pricing Brochure (PDF)

Unmatched Precision

Finds what needs finding, from weapons to small recording devices, with five distinct zone indicators locating risk items head-to-toe.

Deploy Anywhere

Freestanding or wall-mounted, indoors or outdoors, fixed or portable, with adjustable sensitivity. Set up and screening in minutes.

Integrates With Your Systems

Powered by Xact ID with a secure WebAPI/REST interface for third-party security management integration, and software-updatable as requirements evolve.

Corporate & boardroom

Keeping Recording Devices Out of The Room

Board meetings, results announcements, merger discussions, legal negotiations, R&D reviews: rooms where a single recording can cost more than the entire security budget. Asking attendees to leave phones outside only works if you can confirm they actually did.

Metrasens Ultra sits outside the conference room door and screens each person as they walk in — in seconds, with no archway to build and nothing to install. Attendees divest their belongings as they would anywhere else; the system's job is finding what is still on or inside the person. Five zone indicators show where, so the conversation is "anything in your left jacket pocket?" rather than a pat-down.

Finds phones and voice recorders by their magnetic components, whether switched on, powered down or with the battery out
Detects concealment methods a pat-down misses: taped to the body, inside clothing or internally
Portable: deployed in minutes for a single sensitive meeting, then packed away
Rapidly deployable: carried in, stood up and screening within minutes — no power infrastructure, no archway, no building work

An honest boundary: this screens people, it doesn't sweep rooms. It sits alongside a technical surveillance counter-measures survey of the room itself, not instead of one — and we'll tell you that before you buy, not after.

Metrasens Ultra ferromagnetic detection system positioned to screen people entering a room — Positioned at the door: everyone entering is screened, nobody is delayed.

Custodial & secure facilities

Mobile Phones In Prisons

Illicit phones drive continued offending from inside: drug supply, witness intimidation, escape planning. They are small, they are routinely concealed internally, and they defeat conventional screening.

On Or Inside The Body

Ferromagnetic detection senses magnetic mass rather than surface metal, so it finds handsets taped to the body, sewn into clothing or concealed internally — the methods that make a walk-through archway and a rub-down search unreliable.

Off Doesn't Mean Invisible

The system is passive and responds to the magnets inside the device. A phone that is switched off, in flight mode or stripped of its battery still shows, and so do SIM-sized components with ferrous content.

Where It Earns Its Place

Visits halls, reception and admissions, staff entrances, workshop and wing transitions — anywhere you need a search capability that can be moved to where the pressure is, or placed where fixed equipment can't be installed.

Metrasens Ultra head unit showing a green clear indication as a person is screened — Green: clear. The operator sees the result at a glance, without looking at a screen.

Metrasens Ultra indicating an alarm in red with zone indicators showing the height of the detected item — Red: something magnetic is on or inside the person, and the lit zones show roughly where — so the search starts in the right place.

It emits nothing, which makes it appropriate for pregnant visitors, pacemakers and medical implants, and repeatable often enough to screen the same people daily without cumulative concern.

Considering Martyn's Law compliance? Ferromagnetic detection works alongside walk-through metal detectors rather than instead of them — the archway screens the main entry, the Ultra goes where an archway can't be built or where you need a search capability you can move. Read our Martyn's Law guide.

The other half of the picture

Ferrous Inside, Non-Metallic Outside

Ferromagnetic detection is the right answer for anything with ferrous content — phones, voice recorders, blades, handcuff keys — wherever it is hidden, including inside the body. What it cannot see is the item with no magnetic signature at all: a ceramic blade taped to a thigh, a wrap of powder, a bundle of notes under a jacket.

That is the gap Thruvision fills. Passive terahertz imaging shows what a person is carrying under their clothing — metallic or not — from up to seven metres away, with nobody touched and nothing emitted. People keep walking; the operator sees the concealed item rather than the person.

Run together, the two leave very little room. Thruvision finds what is concealed on the body whatever it is made of; the Ultra finds what is ferrous wherever it is hidden, including internally. Neither requires anyone to be searched by hand to get an answer.

Thruvision body scanners →

Thruvision operator screen showing an item concealed under a person's clothing as they walk past — Thruvision sees through clothing, not through skin — so it finds the non-metallic items the Ultra is not looking for.

Where Does It Fit In Your Search Regime?

Tell us what you need to find and where. We'll tell you honestly whether the Ultra, an archway, or both is the right answer.

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