On 3/5/2012 9:40 AM, Fuqua, Bill L wrote:
> They must be very well shielded!
They are operating at VERY widely separated frequencies, AND their
circuit board layouts must be carefully done to avoid both radiation and
reception. I would bet that most modern products use multi-layer boards
with ground layers to create microstrip and/or stripline techniques. By
doing so, every circuit trace becomes a transmission line, with return
current flowing on the ground layer below the trace. The primary reason
for doing this is to minimize crosstalk between circuitry within the
device, but it also serves to kill antenna action on those traces.
There's an excellent discussion of this in Henry Ott's classic text on EMC.
73, Jim Brown K9YC
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