Re: A Surprising Result--All-Sky Lens Produces Light Dome Around Yagi Antenna
- From: Helmut Wabnig <hwabnig@ .- --- -. dotat>
- Date: Mon, 14 Sep 2009 13:10:46 +0200
On Mon, 14 Sep 2009 02:51:34 -0700, "W. eWatson"
<wolftracks@xxxxxxxxxxx> wrote:
I have an all-sky video camera that I use to observe meteors. While
working with it, I had it on the ground rather than 10' off the ground.
15' away was a yagi TV antenna on a pole. I was testing the TV antenna
as one of several possible sites for reception of stations in
Sacramento. At dusk, possibly during the day, I noticed that the image
around the antenna produced a ghost or a dome (as in a domed building
like a state capitol) around it that extended to the ground when imaging
at night with a moon, near dusk, or sometimes in full sunlight during
the day. I could easily produce this effect during dark skies by turning
on an outdoor light on the back of the garage some 100' away from the
camera. A clear acrylic hemisphere protects the camera from weather.
Why a dome? I would have expected scattered light or the shape of the
pole and antenna. Nothing else in the yard seems to produces that
effect. I can see the garge clearly, trees, fences, etc. I do not recall
testing this with the acrylic hemisphere off. I did cover about 70% of
the antenna and pole with a quite opaque black felt cloth, but still got
the dome.
Clean the lens ang google for "fog filter".
w.
.
- References:
- Prev by Date: A Surprising Result--All-Sky Lens Produces Light Dome Around Yagi Antenna
- Next by Date: Wave Equation for a moving source??
- Previous by thread: A Surprising Result--All-Sky Lens Produces Light Dome Around Yagi Antenna
- Next by thread: Wave Equation for a moving source??
- Index(es):
Relevant Pages
|
