[TowerTalk] Portable Phased Arrays!

[Jim Lux]

At 07:08 PM 6/27/2006, Dino Darling wrote:
>New thread; lets hear about the portable phased arrays Jim!


Still in the tinkering stage.

Design criteria:
 From wheels stop to fully deployed and on the air in <20 minutes.  This is 
a pretty challenging constraint, in itself.. No fiddling with hose clamps, 
for instance.  It gives you about 3-4 minutes to put up each element, and 
another 5 minutes to hook it up and run the calibration.

Basic concept:
Simple vertical antennas (trapped or not.. I'm still doing experiments on 
that, there's some interesting vertical angle tradeoffs between a trapped 
vertical and a plain non-resonant vertical with a suitable matching 
network), arranged in an arbitrary array.
{you might be in a roadside parking lot.. you just have to take what you 
can get}
Array calibration (determining mutual Zs and relative positions of 
elements) in-situ
{relays to connect cal signals to each element in turn, listening on the 
other elements, etc.}
Computer controlled phasing networks to do the phasing.

Primarily the phasing approach is for transmit.  On receive, I think you 
can do better with suitable E-field probes, separate receivers, and lots of 
DSP.

It's not going to be a 4 element SteppIR at 100 ft, but it should be 
interesting.  And, once it works for this, it's generically extendable to 
all sorts of other applications.


Jim, W6RMK