On Wed, 01 Aug 2007 11:06:38 -0400, Michael Coslo
wrote:

However, returning to the original link, and the design behind it, it
is called beam forming as practiced through controlled delays.

I'm curious about the technology to sense the incoming angle.

Hi Mike,

I've spent all day aboard the USS Bunker Hill and had a tour of their
phased array RADAR systems. They use roughly 4000 separate elements
with computer controlled delays to steer the beam anywhere they want
(within a quadrant as there are four panels). The 'tronics consume 3
decks of rack equipment.

If the
math reveals that a signal is peaked with one particular setting of a
combination of delays, and if that combination reveals an apparent
source coming in from a particular angle; then we can say that yes,
Virginia, there is a take off angle. We can reasonably expect that
calling back through the same combination of delays through to those
various antennas will result in a more optimum link.

I certainly expect that to be the case. But that little experiment I
ran a year or so ago made me not want to accept it without any reservation.

Just as well when you have only onsey-twosey variables to control. The
OP had 6 which raises the resolution (the Bunker Hill, 16000+).

That, or through this design, you can adjust to obtain that optimum
(which will more than likely reveal another take off angle). You will
then be able to ponder why they come in best at one angle while you go
out best at another. Yes, a distinct possibility that becomes more
distinct through this control, and the resolution of take off angles.

If the ionosphere was a static thing, I would expect the matter of
propagation would be pretty straightforward. Of course it isn't, and a
good thing, else some bands would be useless for certain purposes. But
if there is turbulence, I wouldn't be surprised to have the conditions
change over the course of time, perhaps on the time scales of a typical QSO.

No argument there. With phase control you could follow the changes to
some degree (if the incoming signal sweeps out over the horizon, no
phase control is going to capture that).

Now, as to the matter of this "some sort of blob that leaps off the
antenna." Modeling propagation will reveal if you define a circuit
(the point of origination and the intended audience's location), and
you chip in the general antenna radiation lobe characteristic; then at
significant distances a matter of one degree can be resolved. For
sharply lobed antennas (and this 6 bay is quickly approaching that),
the roll-off response and a one degree shift can plunge the listener
into deafness. Of course, the vagaries of propagation can easily
upset the apple cart - but again, this sharply reveals how "some sort
of blob" has become distinctly important compared to the gross
distribution of possibilities.

This setup might just be the ticket for exploring such.

Jerry, KD6JDJ, has offered a stable means to build a small physical
model and test these things. Consult the thread "Request EZNEC
computation."

73's
Richard Clark, KB7QHC