On 29/09/2018 16:00, brian wrote:
writes

The azimuthal RCS of an aircraft results in what's sometimes known as a
'fuzzball' which can have high peaks and deep nulls. I suspect the
stated RCS is some average of this.

If you're targeting large transport aircraft having two or four large
turbofans, then perhaps your best best is to choose those aircraft that
are approaching along a vector that results in roughly equal angles
between your station, the aircraft itself, and the distant station. and
bounce your signal from the fans, which in themselves will have high
RCS. Masking the fans from radar is a critical requirement for stealth
or low RCS aircraft.You'll probably be able to recover the Doppler from
the fan rotation, if you wanted to.

It's a long time since I last referred to Skolnik - my interests at the
time centred around travelling and creeping waves, and backscatter
rather than forward scatter, so I wrote the above in those terms. This
is of course a completely different kettle of fish! I had no idea such
forward-scatter enhancements could be useful, although aircraft
reflections have been used for many decades by Radio Amateurs. ISTR some
Amateurs living within ground range of airport/field long-range radar
using the pulses to time a receiver display to show the echo from
aircraft many miles away.

Airscout identifies the type of aircraft, the bigger ones like Airbuses
and 777s are particularly good. I can guarantee to work a station at
380km in the North of Scotland from a location in SW Scotland on 70cm
pretty well guaranteed when these are about.

Is there a station or two located at some distance to one side from the
line between you and the distant station you mention that could check to
see what signals could be recovered? You might have more coverage than
you think!

This guy here has developed some models based on projected areas

http://www.nitehawk.com/w3sz/vk7mo_2000.pdf

That's a very interesting paper, which I'm enjoying reading.

I'm looking to see how the 4NEC2 wire grid models compare.

Keep us posted on this interesting topic!



--
Spike

"Nearly all men can stand adversity,
but if you want to test a man's character,
give him an internet group to manage"