Which window films can block phone or GPS signals?
Films with metal in them. Dyed and ceramic films like LLumar’s don’t contain a metal layer; metallized films do, and metal is what gets in the way of radio waves.
LLumar’s performance data sheet shows the split inside a single brand. Each series carries LLumar’s own one-line description:
| LLumar series | Type, as the sheet lists it | LLumar’s description | Installed at Brookswood Tint? |
|---|---|---|---|
| ATC | Colour-stable dyed | “For good heat rejection, privacy and style” | Yes |
| ATR | Metallized | “For great heat rejection with a slightly reflective look” | No |
| CTX | Ceramic | Heat rejection “without blocking electronic signal transmission” | Not on the current menu |
| IRX | Infrared-rejecting ceramic | “Advanced nanoceramic IR-blocking technology” | Yes, as an upgrade |
| AIR | Clear | “Virtually invisible, ceramic protection” | Yes, as an upgrade |
LLumar’s IRX page lists “easy electronic connectivity” among the film’s features. The shop describes all three films it installs as metal-free.
Why does metal in the glass affect a signal?
Because a car’s body is largely metal, and its glass is where many radio signals get in and out. Put a metal layer across that glass and you’ve closed part of the gap.
Glassmakers deal with the same problem in their own coated products. AGC says its HeatControl windshield, which reflects infrared solar rays to keep the cabin cooler, can use “zoned decoating” to ensure radio wave transparency. That’s a glassmaker leaving holes in its own coating so signals can pass.
Where are the antennas on your car’s glass?
Often in the glass itself. AGC makes on-glass antennas “for AM, FM, DAB, DTV, RKE”, built with “conductive printing or thin wire embedded into the glass”, and lists the windshield, side windows and rear window as places they go. RKE is remote keyless entry.
That’s why carmakers sometimes warn about film. The Polestar 2 owner’s manual tells owners to keep film with a “metallised surface coating” off the rear window, because “the car’s radio antenna is located inside the window.” Non-metal film over the same glass doesn’t raise that concern.
Can a factory windshield block your signal?
Yes, with no tint involved. Some windshields have metal or an infrared-reflecting coating built into them at the factory.
Polestar’s Polestar 3 manual for Canada says that if a toll transponder is placed outside the marked areas, “the IR windshield will block the signal”. It shows three marked spots and adds: “Do not attach metal film or other metal objects to the windshield in front of the transponder.”
For trips into Washington State
BC drivers heading for Washington’s tolled roads can run into this. WSDOT says “some cars have metal in the windshield, which can interfere with the signal from a Good To Go! pass”, usually because of heated windshields or infrared blockers. Many such windshields have a designated area where passes work; without one, WSDOT says you’ll need a licence plate pass.
Tint plays no part in this. BC only allows film in a narrow band across the top of the windshield, so the glass causing the trouble is normally the windshield the car came with.
What if a used car’s old tint is causing poor reception?
Have the film identified and, if it’s metallized, replaced. A mirrored look from outside is one clue, since LLumar describes its own metallized line as “slightly reflective”.
Old film comes off rear glass with steam, so the antenna lines and defroster grid printed on the glass survive, as explained on rear window tint removal. BC’s 2025 Vehicle Inspection Manual also rejects “any tint that is reflective type” on the windshield, front side windows and back window (items 12e, 13d and 14c), which is another reason to swap a mirrored film. For more on that rule, see whether reflective or coloured tint is legal in BC.
Booking signal-friendly tint
Any of the three films the shop sells will do: ATC for shade and UV at the starting price, IRX for heat rejection, AIR for heat control with almost no change in look. The ceramic tint page compares IRX and AIR.
Prices for the rear glass in ATC run from $220 on coupes to $240 on sedans and pickups, and $260 when it’s a full-size SUV or wagon, ceramic extra per package. If there’s old film to strip first, say so, because removal is priced per window. Send the car’s details through the online tint quote or by text to 604 534 6433.
