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car antenna with serpent
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micky
Oct 11, 2017, 2:38:25 AM10/11/17
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The antenna that came on my 2005 Toyota is about 16" long and the top
ten inches have a wire coiled around in it, like the snake on a
caduceus. Does this wire do anything or is it just to impress people?
ten inches have a wire coiled around in it, like the snake on a
caduceus. Does this wire do anything or is it just to impress people?
Andy Burns
Oct 11, 2017, 3:46:30 AM10/11/17
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tschw...@gmail.com
Oct 11, 2017, 11:07:53 AM10/11/17
to
Terry
Andy Burns
Oct 11, 2017, 11:30:41 AM10/11/17
to
tschw...@gmail.com wrote:
> I think I've read that on automotive antennas, the winding is simply
> a means to reduce wind induced oscillation and noise.
Ah Scruton Strakes, interesting if that's the reason ...
> I think I've read that on automotive antennas, the winding is simply
> a means to reduce wind induced oscillation and noise.
micky
Oct 11, 2017, 12:35:58 PM10/11/17
to
In sci.electronics.repair, on Wed, 11 Oct 2017 08:07:50 -0700 (PDT),
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.
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.
Phil Hobbs
Oct 11, 2017, 1:33:45 PM10/11/17
to
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.
http://www.arrl.org/files/file/History/History%20of%20QST%20Volume%201%20-%20Technology/QS03-73-Sevick_opt.pdf
Cheers
Phil Hobbs
Dave Platt
Oct 11, 2017, 3:50:43 PM10/11/17
to
In article <39hstc55tv0do41lu...@4ax.com>,
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.
micky <NONONO...@bigfoot.com> wrote:
>>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
>
>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.
My fuzzy recollection is there's a bit of a tradeoff.
>>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
>
>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.
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.
bruce2...@gmail.com
Oct 12, 2017, 4:07:30 PM10/12/17
to
micky
Oct 12, 2017, 9:39:07 PM10/12/17
to
In sci.electronics.repair, on Thu, 12 Oct 2017 13:07:28 -0700 (PDT),
That must be it. At least some good has come from it.
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