FM radio in a metal trailer?

[deceiver]

I've been wanting to put a built in FM radio in the camper. I don't have one to try right now so I'll ask. The radio is a class D amplifier with built in antenna. That's not important. The question is, if it gets decent reception out of doors will I be able to tune in stations inside the camper without an external antenna? It's an all aluminum cargo conversion. I'm thinking that the camper might act like a faraday cage and shield it form a signal.
I'm really interested in people who have tried this with a radio and can say yes it will work, or it just won't work and rethink it and get something with an outside antenna. I'd rather not go that route if I can avoid it though. So if it will work that's what I'd like to know.

Thanks.

[noseoil]

I don't know the answer to your question. A metal skinned box will most likely cut signal quality for FM reception, but doors, windows & other penetrations in the box will allow the signal to get in, just not as well as if the antenna is outside the box. Why not use a small transistorized FM hand-held radio to see what effect moving into or out of the trailer has? It may be negligible, or the location of the radio inside the trailer might be the issue you have to deal with for good reception.

Here's what we did to get around the problem completely. This isn't a great antenna, but it works. It's a bit more "directional" than a plain old whip type, but it's better than nothing. FM can be a bit tricky when compared to AM reception.

[deceiver]

I don't know the answer to your question. A metal skinned box will most likely cut signal quality for FM reception, but doors, windows & other penetrations in the box will allow the signal to get in, just not as well as if the antenna is outside the box. Why not use a small transistorized FM hand-held radio to see what effect moving into or out of the trailer has? It may be negligible, or the location of the radio inside the trailer might be the issue you have to deal with for good reception.

Here's what we did to get around the problem completely. This isn't a great antenna, but it works. It's a bit more "directional" than a plain old whip type, but it's better than nothing. FM can be a bit tricky when compared to AM reception.

Thanks. I'd try the radio inside thing but I don't have one, have no use to buy one and these days I don't know anyone who even listens to the radio any longer so they don't have one. I've seen those antennas like you've got on cars. I'm trying to avoid drilling another hole in the camper if I didn't really have to, and just for a radio antenna, but I might have to if I want to do this. The unit I'm looking at has a built in antenna but no connection for an exterior one. Class D amps are really nice as they sound pretty good and have sd card slots, inputs for other things and bluetooth and are very, very inexpensive. I may have to put something in like it but an automotive unit just to get the antenna connection. But a cheap car radio, in my experience, is asking for trouble. Thanks for your help

[Squigie]

I would be looking at something else if that unit has no provision for an external antenna. One would probably be needed.
As for the antenna - You don't, necessarily, have to drill a hole in the roof. You could go through the floor and have the aerial on a pole or stick that you stand up when you want it. With such, you could go for an omni-directional antenna instead of one of the low profile fins or angled whips that tend to be semi-directional.

[Shadow Catcher]

We have a Jensen 44US01R Rubber Mast AM/FM Top or Side Mount Antenna And I used a marine XM radio antenna.

[dogcatcher]

Years ago I installed a radio that I bought at KMart, one of the cheapest they had. It was an aluminum skinned 18 footer, I added an antenna, but did not install it. It just was hooked up by cable and laid on the shelf in the cabinet behind the radio. It worked good in areas where we mostly camped. The exception was in the Big Bend National Park, but back then even my truck did not get the best radio stations.

[MickinOz]

Years ago I installed a radio that I bought at KMart, one of the cheapest they had. It was an aluminum skinned 18 footer, I added an antenna, but did not install it. It just was hooked up by cable and laid on the shelf in the cabinet behind the radio. It worked good in areas where we mostly camped. The exception was in the Big Bend National Park, but back then even my truck did not get the best radio stations.

Good work mate. I'm doing something similar. The antenna for my TV is plugged into the TV, and hangs from the ceiling inside the cupboard, so no penetrations.
Works pretty good.

[flboy]

An aluminum skinned trailer is a good Faraday cage. You may get some signal with windows and vents, but to get the best reception, especially in fringes, you will need an external antenna.

Sent from my SM-N970U using Tapatalk

[aggie79]

in my former teardrop, I installed an AM/FM radio. Initially, I tried an internal antenna, but couldn't get any signals because of the aluminum skin and because of the distance from campgrounds to radio broadcast stations. So I installed a retractable exterior antenna. It worked quite well.

[Tom&Shelly]

This isn't quite the same thing, but we have a metal garage



and I happened to walk in there today while streaming a radio station on my telephone. Remembering this thread, I pulled the door behind me; still worked fine! So I called my wife (on the phone); that worked great. I then tried a portable FM radio, and it worked great.

I'm an electrical engineer, and I thought it would act as a Faraday cage. Shelly was a middle school teacher, and she thought I was silly, until I explained what a Faraday cage is. (She may have thought it was the cage I used to take my cat, whom I'd named Faraday, to the vet some twenty years ago.)

So my current theory is that the garage also doesn't know what a Faraday cage is

Tom

[flboy]

If you could measure absolute signal strength, you'd likely see some attenuation. It may not be a perfect faraday cage, but surely not ideal as standing outside of it. I can't tell the difference between full bars and 2 bars by a conversation or streaming audio either. A bar or two is all the difference in a fringe area and an antenna outside vs inside will work better.

[Sparksalot]

The radiant barrier roof deck on my current and prior homes has made a fine Faraday cage. So much that I’ve had to install a Weboost just to get cell signal from the tower a mile away.

[Squigie]

Yea, it can be situational and very dependent upon construction of the 'cage'.
The answer seems to be, 'test and see'.

My first motorhome was an aluminum-skinned 'wood sandwich' with minimal steel framing. It was a radio signal nightmare. When inside, you were in a dead zone. Wifi, radio, cell signal, all affected.
My second motorhome was partially fiberglass-skinned, partially aluminum-skinned, partially steel-lined (large sheets for wall reinforcement), and the main structure was a rectangular tube steel skeleton. I swear, that thing was a signal amplifier. Crappy reception with whatever device? Go stand by or inside the motorhome. Problem solved.
Beyond those, everything else has been fiberglass and/or pop-up tent trailers. So, no issues there.

I miss that motorhome. It died a premature death, caused by hidden damage from the previous owner.

(She may have thought it was the cage I used to take my cat, whom I'd named Faraday, to the vet some twenty years ago.)

So my current theory is that the garage also doesn't know what a Faraday cage is

Tom