"jawod" wrote in message ...
Dave wrote:
well, 'adaptive beamforming' is two words...

'beamforming' means forming a directional 'beam' using an antenna. be it
a simple parasitic array like yagi's or a complex array of driven
elements like a flat panel radar. most often when you talk about
beamforming it is more like the radar arrays or other large array that
combines signals from many small antennas to form a very directional
beam.

'adaptive' means forming the beam in a way that makes it work better in
the environment, or adapt to it's surroundings. this is often used to
form beams to maximize a received signal while notching out interference.
so you use an algorithm to measure s/n ratio or some other parameter and
adjust power and phasing of the individual elements to get the best
signal you can. its harder to adapt a transmitting antenna since you need
some kind of feedback from the far end to let you know if the beam is
getting better or worse as you adjust it.


"john" wrote in message
...

I came across a reference about adaptive beamforming in the ARRL
Handbook. The reference was from QEX which I don't yet subscribe to.

Anyone care to explain/discuss this neat concept?

John
AB8WH



Dave,

Thanks for responding.

Given the need for "stealth" antennas, Is there /are there design(s) that
create small footprint antennas that function as larger traditional ones?

Can a longwire be divided into small segments that are independently
controlled such that the sum of the parts behave differently than the
whole?...and can this effect be altered via software?

Has anyone been working on this approach?

John
AB8WH


no, you can't make antennas smaller this way... you can make small parts
behave differently, but you can't get more gain or efficiency than a
simillarly sized 'normal' antenna. i don't know of any hams actively
working in this area, mostly because on hf the antennas get huge quickly.
and on vhf/uhf and up there are much simpler ways to get gain for single
point to point use that most hams are interested in. the real applications
for things like this are radar and multi-point fixed or mobile systems that
have to deal with multipath reflection and interference.