RF in the Cabin: What Actually Transmits Inside a Modern EV

A modern electric vehicle is one of the densest concentrations of radio transmitters most people spend time in. Whether that matters to you is a personal judgement, and one we are not going to make for you. What we can do is set out what is transmitting, at what frequencies, and what shielding does and does not do about it.

What is transmitting inside an EV

Unlike a purely mechanical car, an electric vehicle runs a large number of radio systems continuously, most of them without any user action:

• Cellular modem — connected services, telemetry and over-the-air software updates. Transmits on cellular bands, typically 600 MHz to 6 GHz, and transmits harder in weak-signal areas.
• Wi-Fi — cabin hotspot and home-network updates, on 2.4 GHz and 5 GHz.
• Bluetooth — every paired phone, headset and sensor, on 2.4 GHz.
• GNSS receivers — GPS and equivalents. These receive rather than transmit, but the navigation system that uses them usually also reports position over cellular.
• Keyless entry — the fob and the vehicle exchange signals on low-frequency and UHF bands. This is also the system relay attacks target.
• Tyre pressure monitoring — each wheel transmits periodically, typically on 315 or 433 MHz.
• Driver assistance radar — automotive radar operates around 77 GHz, aimed outward from the vehicle.
• Traction and charging electronics — high-current switching produces low-frequency electric and magnetic fields, which behave quite differently from the radio systems above.

Why a cabin is a particular case

A vehicle body is largely conductive, with large glass apertures. That means it behaves as a partial, leaky enclosure: it reflects some RF internally rather than letting it disperse, while the windows let plenty in and out. Combined with the number of onboard transmitters and the fact that occupants sit close to them for extended periods, the RF environment in a cabin is genuinely different from a room in a house.

Different is not the same as harmful. We take no position on health outcomes and we make no health claims. What follows is simply what shielding can and cannot do in this environment.

What shielding can do in a vehicle

A conductive fabric attenuates RF energy reaching whatever it covers. In a car, that means:

• A lap wrap or blanket reduces the energy reaching the area beneath it, while it is in place.
• A sealed Stuff Guard takes a phone off the network entirely — no cellular, no Wi-Fi, no Bluetooth, no GPS. For most people, a phone is the nearest and hardest-working transmitter in the car, so this is the single most effective thing you can do.
• A Key Guard isolates the fob, which also removes the relay-theft risk while the vehicle is parked.

What shielding cannot do in a vehicle

This is the part most articles on this subject leave out.

• You cannot shield the cabin. The transmitters are inside it with you. Draping fabric over yourself does nothing about a source on the same side of the fabric.
• Conductive textiles do not shield low-frequency magnetic fields. The fields from traction current and charging electronics are exactly the type that pass straight through conductive fabric. Blocking them requires ferromagnetic shielding, which we do not supply, and which is not practical in a vehicle.
• A garment is not a sealed enclosure. Openings, gaps and fit all matter.

What we would actually suggest

If your concern is your phone rather than the vehicle, a sealed Stuff Guard is the direct answer, and it costs a fraction of any garment.

If it is the fob, a Key Guard addresses the relay-theft risk, which is a documented and increasing problem for keyless vehicles — and unlike anything else in this article, that is a risk with a clear, measurable outcome.

And if you want to know what the levels in your own vehicle actually are, measure them. An EMF meter costs less than most shielding garments and will tell you more about your specific car than any article, including this one. Take readings at the driver's seat with the vehicle off, then on, then with your phone in the cabin, then with your phone in a sealed bag. The comparison is usually instructive.

A note on sources

Research on RF exposure in electric vehicles is limited and ongoing. Where you see confident claims in either direction — that EVs are dangerous, or that the question is settled — check what is actually being cited. We would rather give you the frequency list and the meter than an opinion.

We make no health claims about EMF exposure in vehicles or anywhere else.