On Wed, 01 Feb 2012 21:53:16 -0800
Jim Lux <[email protected]> wrote:
> You don't need the ADC: you just need a limiter/comparator.
Yes, but this degrades sensitivity quite a lot.
> You don't need insane sampling rates. Think in terms of subharmonic
> sampling.
This requires that you have an ADC that has the anlog bandwidth of
the signal. And ADCs with a analog BW in the GHz range are damn expensive
and hard to get.
Also a problem is to get the sampling frequency right if you want to
sample more than one band. Downmixing solves both of these problems
at the cost of higher complexity and a bit more noise.
> >> Is there a publically-available antenna design that's easy to
> >> fabricate, has a stable phase center, covers 1100--1600 MHz, and has a
> >> good pattern over this band with low cross-polarization? Even a large
> >> choke-ring design would be okay if it's fully specified.
>
> I think there are some crossed dipole designs around. What about quad
> helix?
Crossed dipole are narrow band and not easy to build as dual band designs
at least at those frequencies. Quad helix needs quite a precision to get
the right frequency and dual band designs (stacked helixes) get even more
difficult.
Attila Kinali
--
The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
-- Tirin, The Dispossessed, U. Le Guin
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