Jiri Sanda wrote:
[snip]
> Another example is your car radio antenna. It is a round-ish shape on
> the top to reduce the static buildup that would otherwise make the radio
> unlistenable. If the top of the antenna was spikey, wind generated static at
> 60 MPH would be horrendous.
>
> Cheers, Steve K7LXC
>
> Not so sure about this one, since the ball on the car antennas is mainly for
> safety reasons. If you remove the ball - I did it once - the difference in
> noise while driving is negligible. Also you have a lot of various rubber car
> antennas with no ball functioning perfectly.
[snip]
Just happened to be putting a new antenna on the car when this was
posted, and happened to have a fine stainless steel wire brush lying
around. I thought it might be interesting to try the new antenna with
the brush (slightly larger than a toothbrush) installed in the manner of
a static dissipater and report the results to the group.
For testing, the radio was first set to AM between stations so that the
only thing coming from the speaker was noise. The brush was taped on so
that the antenna ball was jammed tightly into the bristles which were
facing toward the rear. The car was then driven down a rural highway at
65 mph. I couldn't go any faster with the brush taped on because of the
occasional wild gyrations, which I was afraid would damage my new
antenna.
I was unable to detect any difference in the noise level between several
runs with the brush and without the brush. Just to be sure, I tried it
a few more times with and without brush while listening to strong and
weak AM and FM stations as well. There was still no apparent difference
except for one anomalous run without the brush. In that case, listening
to a weak AM station, noise would increase then drop sharply off, only
to rise again and repeat the cycle. I was unable to duplicate the
results on succeeding runs.
I have to conclude the car antenna balls have no effect on static--at
least here in hot and humid Florida. It would be interesting if someone
could try the same experiment in a cold and dry location. Just be
prepared for some strange looks if you too have an audience.
73
Malcolm KR4HP
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