WHEEL STATIC ONLY ON SOME PATCHES OF PAVEMENT? WHY?
With the financial mess, I have started to listen to AM radio in the
car on the way to and from work for the past few weeks and I've
noticed some random static at certain locations. At first I
attributed this to some power line noise. Bit it didn't really sound
like 60 Hz buzz hash, it was more random popcorn like but I know power
lines can blow around in the wind and have strange discharges so I
didn't think too much of it for a while. But after a few days I
noticed that the static is there only when the car is moving. OK, so
its wheel static. Static electricity from the wheels or brakes or
something. OK that's not unusual either. But it is the combination
that has me curious. This static only occurs when the car is moving
and it only occurs at certain repeatable locations on my drive.
Everyday when I turn the corner from X to Y, I get the static as the
car is moving, but not when stopped at the same corner. And I never
get the static when turning the corner from A to B. If it was power
line, stopping the car wouldn't stop the static. If it is wheel
static, why does it not happen all the time and happen only at certain
locations. It seems as if these certain locations have something
special about the pavement or the water content of the soil or
something. None of that seems likely to me though, I see nothing
changing in the pavement as I drive from an area of static to an area
of non-static. It is not related to stepping on the brake or gas or
shifting gears or going over bumps or any other aspect of the car that
I can tell other than it's speed down the road.
As an experiment, I attached a drag wire under the car. The wire
drags on the ground to discharge any static build up the car. This
made no difference. Another clue, we've had no rain here in a
while. The static all stops during wet weather. Also I am in the
Philadelphia area and the AM station is in the New York area so it is
on the weak side.
I've been a ham for over 30 years and I have a lot of experience with
EMI, but this one has me scratching my head. The wheel static
changes repeatably in different locations for no apparent reason.
It's got to be something to do with the pavement. Anybody have any
experience with this?

Mark