Faraday bags a con?

The effect I have just described.

Almost certainly bits of them are *not* metal and they will have a huge loop of cabling coming into them and that will act as a nice transit route for centimetric signals.

And these days stuff that people go into is *made* to be (reasonably) transparent to wifi and mobile phone signals.

Deprive people of their shiny thing and they go very grumpy.

I would hope that lifts are designed to let mobile signals in; it would be very useful for anyone stuck in one to supplement the (presumably) fixed emergency line to somewhere that you hope is manned?

nib

An RF signal in general will not penetrate an aperture much less than its wavelength unless there is a wire going through it.

Wavelengh at 2.4GHGz is 5" roughly. Probably any gap less than half an inch makes sod all difference

Which is why light gets through your microwave door, but your hand doesn't cook when you open it.

The inside of your phone will have perforated wire mesh in it to shield Not solid metal.

BUT as I have pointed out, signals can travel along the surface of incoming wires. It is even possible theoretically to have an aerial on the lift top that couples to an aerial inside the lift cage, connected by coax.

Like the old car aerials did

I can definitely say for sure that three layers of foil backed plasterboard even with two doorways punched in them knocks my Wifi signal back around 40dB.

If I want 4G I have to stand by a window with my phone. The windows have apertures of around 4x6" in the lead lights.

By all means use a biscuit tin if you feel paranoid. Just be aware that you don't need to

A handbag lined with copper mesh will do fine :-)

You have to work bloody hard to get that.

The basic design of a lift predates mobile phones by over a century ...

My SEAT is the same. If the fob is in vicinity *and* you touch the door handle it unlocks.

Well yes, but quite a lot will have been made since about 1990?

nib

There can be a pico-cell or a Wifi, on the ceiling of the elevator. The car is flooded with signal. In a high crime area, an elevator might even have surveillance video.

Modern elevators are a lot more sophisticated than the old freight elevators you traveled in as a young lad at a student job.

Similarly, in a mall, there can be RF transceivers on the ceiling providing services. Broadcast signals from outside the mall, it does not matter that they can't get into the building, as the building has "copies" of the function inside the building.

Paul

But how many of those are still running?

I do wonder what the floors of a lift are made out of, especially those high speed lifts which add a bit of g force to the weight of the passengers at the start of the ride. I'm pretty sure that one inch ply would do nicely. And the lift's ceiling could well be wood.

And it might well be possible to drill a hole for an antenna in the older ones

If the cables themselves didn't provide a conduit for RF. When you think about it, the cable loom feeding a lift cage is as long as the whole shaft. And ends inside the cage at the control panel

Also my ancient 2012 VW Passat.

Indeed. I've been amazed to see people making and receiving mobile phone calls when in a lift, when it looks like we are inside a metal box with 6 metal sides joining well at the edges. One would think that the radio signals couldn't get it, but obviously they do. So one does need a very careful watch on the size of the gaps to make a Faraday cage out of a biscuit tin.

so there were no buttons on the lift at all? No controls?

A sheet metail celng with no ventilation holes?

One would think that the

Plenty of holes even if just to avoid passenger suffocation. Plenty of wires coming in, and these days probably positive measures to ensure moibiuole sihgnal penetrate

So one does need

Completely false conclusion from a completely false assumption.

Look up RF mesh shielding. It's more holes than metal

And that is before you consider it may have been a design feature.

ISTR that long road tunnels have "leaky feeders" to allow RF (and thus broadcast radio) to work.

They do today.

Older tunnels still make a mess.

Thankfully, my BMW does not do that. I'm glad, one less thing to go wrong!

Some metallized plastic food packaging, works just as well. The thing is, to test it - put the key, in a package, and try it near the car.

In article snipped-for-privacy@4ax.com, Dan Green snipped-for-privacy@hotmail.se scribeth thus

Try keeping it in the microwave oven;?...