Ed, here's a question for you.
I installed a little HDTV/AM/FM/DVD player in our Scamp 5er. I ran a cable outside for an HDTV antenna mast (and am still looking for the ultimate & storable HD antenna to put on the top of tha mast, but that's another story), but have also found the nifty mylar-coated reflectix makes our AM/FM radio reception inside the trailer very weak. We can pull in stations when we're in-town, but head out to the toolies and we get nothing unless we take a portable radio outside.
The TV/Radio/DVD unit has AM and FM antenna jacks. Is there a simple antenna design that can be permanently mounted outside the shell but won't create a mess of drag or make my trailer look like a ham radio shack that might have expensive and stealable stuff inside?
Well Peter the short answer is probably "no".
Antenna' are not rocket science and unfortunately each band you need reception of presents different requirements and "opportunities" to reception balanced with being practical to carry and deploy.
TV frequency's even have differing needs between UHF and VHF and most TV antenna are dual banders with elements for each.
FM broadcast are yet another and AM even another.
There are all kinds of "Miracle" solutions out there but the simple truth is the more metal you can put and the higher in the air,the better your reception will be.
In town the signals are also dispersed all around you so more non-directional antenna will work better and not require aiming but then out of town you need the extra gain and narrow beam of directional antenna to reach out for the signal and reject noise.
So like I said there is no one solution really.
I have the best luck consistently with high quality name brand metal antenna and high quality name brand big powered antenna.
You really can get more with better electronics with certain antenna although many of them all look the same.
I install the Terk units a lot in homes in and out of the city and with some fiddling they can work well for us too. They are not small but are thin and light
The length is a requirement for VHF signals which have been really minimized in the DTV transition but I think it would be a mistake to buy a short UHF only model as VHF will be getting more use again before too long.
I just clamp one to a swimming pool cleaning pole that goes from 5' to 15' and are lightweight or a telescoping painters pole and get the height which really helps in the woods.
Then they fold up for easy transport and are not too bad to carry,depending on how bad you really want to get reception?
They are also decent for FM.
The Winegard Sensor are also nice and they make an RV model too. These are more directional but then have more gain too.
For AM only a cheap radio by itself(for a variety of reasons) or a long wire will really help but if you are using a pole for the TV antenna you might just send up some wire with it too as one side of a long L shaped antenna for AM.
One interesting thing about AM reception is that once you leave a city behind you often will also leave a lot of AM noise ad interference behind which can be a pleasent surprise.
Yo are also right about one thing,the Scamp Reflectix insulation really helps to shield the inside of the trailer from RF getting in,whether you want it to or not!
All of this is one reason Ham Radio can keep some of us busy just tinkering with receiving a signal at all. We think this is fun!?!