car antenna with serpent

Actually, I don't believe that is the purpose. I think I've read that on automotive antennas, the winding is simply a means to reduce wind induced oscillation and noise.

Terry

Ah Scruton Strakes, interesting if that's the reason ...

Well, either one is a good reason and I'm glad to hear that there is a reason.

It's triply important to me to reduce wind noise becausethe car is a convertible, and I'd hear any noise it made, but I should mention that this is my 8th convertible over 50 years and all the other ones had standard antennas, usually in the front** but sometimes in the rear, and I never heard any noise from them. I used to drive on the highway at

75 or even 80, but noise was the reason I dropped my max to 65. Noise seemed to increase sharply over 65mph. So I do notice this, but it wasn't noise from the antenna. It was wind in general, and it applied/s whether the top was up or down. (although later cars have had a top liner, and maybe they would be tolerable above 65mph.) The previous car, also a Solara, a 2000, had a standard electrically retractable antenna, also in the right rear fender, and no noise that I've noticed.

So maybe Toyota says it will be more quiet but it's just a gimmick. If so, that would just be my second choice, "to impress people".

I still have the previous car until I get the new one repaired if necessary and inspected, so if I can, I will take out both the old and new ones and go 80 for a while and see if I can hear a difference. The old one needs a lot of work but it's still as quiet as it ever was, as the new one is.

**One or more GM cars didn't have the round antenna that deliquents used to break off. It's cross-section was shaped like a football. At the very least, it prevented the antenna's use for zip guns. Another was just a wire, not telescoping, not retracting. No one ever broke my antenna however, and the fad seems to have gone away. The custom of slashing tops and tires of cars whose owner one doesn't know and even when not trying to steal eanything seems to have also disappeared.

You can use Ls and Cs to make "loaded" vertical antennas, i.e. ones that are resonant but much shorter than 1/4 wavelength, but in those the L goes on the bottom and the C on the top. Putting extra L on top doesn't make immediate sense electrically, so I expect it's for acoustics or pedestrian protection or something less obvious like that.

Cheers

Phil Hobbs

My fuzzy recollection is there's a bit of a tradeoff.

Without the helical spoiler, the antenna tends to generate a fairly uniform "wake vortex" - an alternating flow of air behind the antenna, which switches directions repeatedly. It'll tend to be "in sync" from the top of the antenna to the bottom. If the frequency at which the vortex is alternating happens to match the resonant frequency of the antenna, the antenna can vibrate - a bit like a reed in an oboe. So, at certain speeds, the antenna can buzz or hum.

The spoiler breaks up the airflow, making it more turbulent... and due to the helical winding it makes the turbulence different at each point up the antenna. As a result, you can get more "broadband" wind noise, overall, but the turbulence won't excite a physical resonance in the antenna anywhere near as well as a "regular" vortex would, and so the antenna doesn't sound off at specific driving speeds.

necessary

new

Today, those youngsters seem to have given-up on keying cars and graffiti and even being outdoors at all any more. Who knows? I guess that drugs and being in front of computer screens have finally become THAT absolutely addictive.

That must be it. At least some good has come from it.