Re: [Discuss-gnuradio] software controlled antenna

[Lamar Owen]

On Tuesday 20 December 2005 16:30, Eric Blossom wrote:
> On Tue, Dec 20, 2005 at 03:30:56PM -0500, Marcus Leech wrote:
> > Paul Shuch was working on a phased-array panel antenna for
> >  SETI work.  I don't know how many elements, but it was
> >  steered using varactors.  For some environments, this would
> >  be really nice--no need to build mechanicals to swing a dish
> >  around.

> For narrow-band arrays (bandwidth < 1% of center freq), we think we
> can steer the array with DSP in the FPGA and/or host.  This would
> allow us to build 4 antenna arrays with a single USRP.

Having been chief engineer for a directional AM broadcast station, phased 
arrays are right up my alley, even though this particular array was a 
transmit array (four inline 1/4-wave towers, spaced 1/4 wave apart, throwing 
the equivalent to a 20-element yagi pattern; front to back was 6KW:180mW).  
I've done 3D modeling of transmit phased arrays, and tuned them (the classic 
'rocking the phasor' routine (yes, the phasing equipment is really called a 
phasor).

See http://www.pari.edu/telescopes/RadioTelescopes/ETA and 
http://www.ece.vt.edu/swe/eta/ for details on a big phased array project 
being built at PARI.  The short form: imagine repointing a dish after the 
observation has been taken.  12 terabytes per day required storage.  Big time 
phased array; uses multiple Xilinx XC2VP30 boards (ML310) for the beam 
forming calculations.
-- 
Lamar Owen
Director of Information Technology
Pisgah Astronomical Research Institute
1 PARI Drive
Rosman, NC  28772
(828)862-5554
www.pari.edu