On 6/9/20 7:39 AM, Rob Atkinson wrote:
I didn't see anything in the abstract that made me want to read it as
far as ham radio is concerned. A number of hams over the past years
have cited military work with cloud burners as a justification for
their usefulness in ham radio. I don't contest a horizontal antenna
that has its highest field intensity straight up, but I do contest the
argument for ridiculously low hanging antennas because that's what
other services do. There are several differences between ham and
other services that have to do with power limits, frequency
exclusivity, transmission modes, battle conditions, and radiation
efficiency.
what's interesting in the article isn't so much the NVIS stuff, but the
modeling approach. They're doing some ionospheric ray tracing using
ionosonde measurements. For what it's worth, the antennas they are
using are at 0.2 wavelength, which isn't one of those knee high wires.
At frequencies from 4-11 MHz it seems.
They're using Coleman's ray tracing approach
21] C. J. Coleman, “Point-to-point ionospheric ray tracing by a direct
variational method,” Radio Sci., vol. 46, no. 5, pp. 1–7, 2011.
Here's a report on it
https://apps.dtic.mil/dtic/tr/fulltext/u2/a271058.pdf
These days, there's a lot more real-time ionosonde data available - it's
sort of the next step beyond NCDXF beacons or various reverse beacon
networks.
Of particular interest is a paper I want to track down
[17] P. J. Coetzee, “A technique to determine the electromagnetic
properties of soil using moisture content,” South Afr. J. Sci., vol.
110, no. 5/6, pp. 1–4, 2014.
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