Do cars with plastic bodies, like the Saturn, give bad radio reception?

For AM radios in cars, the ground plane effect is almost nill. There is some capacitance coupling from the frame to the gound, but that plays very little in the AM band. The FM antennas are often built in the windshelds and the metal of the car does not com into play there either to ammount to anything.

To be much of a ground plane at the AM band you would need a plate of around 100 feet, 200 feet would be better. Just look at how tall the AM transmitter antennas are. Those antennas have about 120 wires as long as the antenna is tall burried in the ground.

This is the big difference in spectra that I looked at:

Shorter wavelengths penetrate better.

I have T1-11 siding, not alumininum As to foil clad insulation, I don't think so. I've been in the walls a little bit when I put a floodlight in the outside bedroom wall. House built in '79, not cheap but not the most expensive either. Plus there is a 6-foot wide window facing DC from the bedroom, where many of the radios have been, with aluminum window frames but the frames are not very big.

Only one car had the antenna in the windshield. A long time ago, I can't remember which.

So what can I do to get reception inside as good as what I get in the car? Especially FM. In the past year, reception for WAMU, 88.5 and C-Span, 90.1, seems to have gone downhill.

I beg to differ. Nobody seems to have mentioned the bane of all MF (medium frequency) reception, RF noise. A metal ground plane (car body) does a tolerable job of isolating the AM antenna from the noise generating ignition, black boxes, and gizmos. With a plastic body, the antenna will pickup more noise from the engine.

The typical car antenna is sometimes located as far away from the noisy engine as possible and connected to the AM receiver with RG-62/u

You can have a really sensitive AM receiver, and still not be able to hear much. The threshold of sensitivity is atmospheric and man-made noise.

Car AM radios tend to have the minimum sensitivity and RF front end gain needed to function in a strong signal environment. They're not made for digging signals out of the noise. That's NOT because AM car radios are made to be inexpensive. It's because the receiver is sitting next to a very noisy car engine. Were it designed to be as sensitive as an LF or HF receiver, all you would hear is engine noise. Try it. Build yourself a BCB (broadcast band) RF amplifier and attach it to your car radio antenna input. In most cases, you'll hear your engine, pump motors, and atmospherics quite well, but the distant AM stations will still be buried under the noise.

I don't have any suggestions to improve your mobile AM reception. Well, maybe the obvious suggestion to do what you can to eliminate, move, shield, or isolate sources of RF noise. If weak AM signals magically appear when you turn off the engine, the source of the noise is obvious. The problem is that you might do a wonderful job of noise reduction on your car, such as buy a diesel, but that does nothing if you're stuck in traffic and surrounded by other noisy vehicles. Notice that the ultimate noise generator, the all electric car, usually does not come with an AM radio. For example, Tesla will sell you an optional overpriced infotainment package that includes AM:

Vendors used to sell rubber grounding straps, that discharge any static buildup on the car body. That should get rid of some noise. However, I believe carbon doped car tires have largely eliminated the need for those straps.

So, to answer your question, yes a plastic body gives lousy AM reception if your engine belches lots of RF noise and your receiver is reasonably sensitive. If your receiver is stone deaf, it doesn't matter.

Good luck.

How about TuneIn or iHeart internet? Price is right for either.

For in the house put up an outside antenna and feed it with coax cable.

Clare is living in the '20's -- the 1920's. I've built some of the historical designs. If you want to talk about interference an oscillating regenerative receiver is its own little radio station.

It's a little different today:

This is a simpler version that doesn't require building a frame:

And for the best outcome, build in a swamp.

Well, I use Alexa in the bedroom, and I guess I could use that. it's a pain, Echo has only 10 levels of, one is too low and the next one up is too high. But what bothers me more is that I've been buying radios with push button tuning so I can go from one station to another and on to a third in a split second.

And I have no shortage of radio in the room with the computer, and can put that audio on the transmitter and send it to other rooms.

And C-span is really boring anyhow 80% of the time (not Saturday night and on a few special occasions, plus I think 5PM every day, but maybe it's 6 or 9 PM. I can hardly complain since I never listened.

I do like WAMU but if I don't like C-span that much, why does it bother me that I can't get it? I guess I just don't like moving backwards.

So, yours is a good suggestion. Thanks.

I have radios in every room and just don't have the enthusiasm anymore to run antennas to each of them. Wish I'd done it when I first moved in. (Not sure C-apan radio even existed the first couple years I lived here.)

Thansk and thanks Ralph.

I don't know how well or even if they will work , but I have seen some advertisements for antennas that are large ( well, a foot or two square or diameter) that you set your radio that has the built in antenna next to.

Look for AM indoor antenna or AM signal booster.

The theory is they act as a passive amplifier or repeater. The large loop picks up the signal and that is coupled to the radio similar to a transformer.

My 1986 Chevy C10 has a windshield antenna. Then again, it has many parts from a 1976 also (including the VIN and title). It's hard to say which year had that windshield; maybe both.

Thank you!! I think I'll try that first antenna with the frame. I can put it out of place in my attic, if I can make a run downstairs easily enough.

If I were to make the other antenna, do you think I could use my home's breaker box grounding rod for the antenna, or might there be electrical interference from the circuits and appliances in my home?

I have a '75 Dart on the road with a factory AM-only radio. Unfortunately, the fuse in the fusebox is good, but the radio does nothing when turned on. It appears that all of the wires are in place, including to the one dash speaker, but the only think I can see it do when I turn it on is slightly dim the dome light when switched on - absolutely no audio.

I bet if it were working, being designed solely for AM transmission, it would pick up stations quite well. It's solid state... I might have to tear into it at some point. The preset station buttons still seem to work as intended.

It should work. There are several DX sites but I don't know how useful they are. DX Magazine was good but it was produced by one man who died in 2017. Arnie Coro had a 'DXers Unlimited' show on Radio Habana but I think that's been off the air for several years too.

The sad truth is many of the knowledgeable radio people are aging out. Even the international broadcasters that kept the airwaves interesting

I've spent some time in Arizona south of Gila Bend. In the evenings I enjoyed the AM oldies station in Oklahoma City. Mornings I could get news and music from California. Curiosity about the whys and wherefores got me into ham radio.

I never got into HAM radio, maybe one day. I used to sit at night and tune through distant AM stations that I could pull in from eastern Ohio. One of my favorites to listen to is still 650 WSM in Nashville. Kind of an odd hobby for a pre-teen/teenager growing up in the internet era (I'm 26 now for reference), but I've always enjoyed it.

Done. Locally, KSCO's antennas are located in Corcoran Lagoon (Santa Cruz, California):