Post subject: RF Shielding Posted: Sat Mar 17,
2007 12:14 am
Joined: Tue Feb 27, 2007 6:16
Hello. Can anyone direct me to a manufacturer of
RF shields that will supply free samples?
Lastly, can anyone
direct me to where I can find some literature on RF shielding? Im particularly
interested in learning whats the best practice, i.e can I shield my
reference oscillator and PLL together or will one intefer with the other....
how I can avoid the need to provide shielding? Thankyou
Post subject: Posted: Fri Mar 23, 2007 6:59 pm
Joined: Mon Jun 27, 2005 2:02 pm
You can find many manufacturers by running
a Google Search.
Here is an example to one:
You can't avoid shielding if you design Oscillators and other
frequency sources. Usually the reference oscillator and the PLL should
be placed as close as possible to each other. If you have forward and
reverse links on the same PCB then you should shield each of them to
avoid coupling between the two which can produce feedback and lead to
The purpose of shielding is to prevent radiation
from propogating and to prevent coupling between adjacent frequencies.
Post subject: Posted: Mon Mar 26, 2007
Joined: Fri Feb 17, 2006 12:07 pm
Location: London UK
The Engineering Director of a
well-known company for which I once worked (as a very young green-horn)
often maintained that "the cheapest development equipment is a hacksaw",
by which he meant "cut the lid off someone else's box and learn from
what you see inside". Whilst I would not dream of advocating plagiarism,
or still less, copyright infringement, you could learn more about screening
by looking into existing products that use PLL-VCO circuits than by
reading up the theory.
Screening theory is notoriously difficult
from which to formulate strict rules. Even simple analytical situations
of say a cylinder of metal enclosing an oscillator requires several
types of Bessel Functions to derive the leakage field outside the can.
Oisch, my brain hurts already, thinking of the pages full of math.