Good point. I think you're correct for most applications, although I've
never been convinced that effects like diffraction are fully symmetrical
(I happen to believe in one-way skip for really low angle signals over
irregular terrain) . And I agree that for HF you'd have to be out
quite a distance, but if you use a transmitter on the drone I don't see
that being a problem. In fact, the further away from the test antenna
the more viable GPS positioning becomes.
I've also thought that the transmitted signal could be low level
broadband noise, so if the drone was transmitting it the receiver on the
ground could be a broadband SDR that pretty much characterized
everything at once.
73,
Dave AB7E
On 1/5/2016 1:00 PM, David Robbins wrote:
easier to put a small transmitter board with short antenna on the drone and
just match the gps track with received signals sampled on the ground.
the biggest problem is deciding how far out from the antenna makes a valid far
field pattern in real conditions... it may not be too bad for vhf, but
for most hf stuff you would need a pretty big pattern to get valid results.
Jan 5, 2016 01:47:31 PM, xdavid@cis-broadband.com wrote:
I've suggested before that it should be possible to attach something
like a Softrock to a drone along with a small 3-axis sampling antenna.
The output could either be stored in memory or fed real time back to the
ground via some sort of link. The drone could be programmed via GPS (or
simply positioned via a tether) to run concentric circles around any
existing antenna in place at it's normal location to plot the radiation
pattern. The result would take into account not only the antenna itself
but also the impact of its surroundings (terrain, buildings, other
antennas).
I don't think it would take too much engineering or cost to put
something like this together, but I suspect that not many people would
be willing to pay to cover the hassle of doing so. Maybe cell tower
owners ...
I still think it's an interesting idea, though.
73,
Dave AB7E
On 1/5/2016 8:05 AM, Chris wrote:
## whats needed is a ham version of consumer reports.
Jim VE7RF
Steve and Ward's Tribander comparison book is the closest thing we have. Too
bad it's so much work to set up a fair antenna test range; I would love to see
dozens of antennas compared. Of course, it could put some people out of
business....
Chris
KF7P
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