"Daniel" wrote in message
m...
Hi again,

thanks for the quick answers. First of all, I have to apologize for
bad explaination. As you would guess, I am not a natural english
speaker, and so have difficulties to explain exactly what I am looking
for.

Hi there,

I am currently working on a project which leads to simulate EMC Field
coupling to printed circuits.

Without discussion of a frequency or band of frequencies, you are sure
to be either deeply disappointed or vastly rewarded in results.

What i want to simulate is a common EMC-Test. Put a PCB with the
circuitry in a shielded EMC-room (I dont know the english word) and
put a 10V/m E-Field around it in 3m distance from the sending antenna.
Frequency band is 80MHz to 1GHz


Not wanting to dampen your enthusiasm, but I think you'll find that the
modeling is quite limited in predicting what really happens in the above
scenario.

First, a real circuit board usually has far too many variables for a model,
and that's assuming you can even recognize all the variables. Second, the
exposure within an RF semi-anechoic enclosure is never quite so clean as you
posit. Support structures, such as tables (maybe not as RF invisible as you
assume) and cables, all add to the general fuzz. And the shielded chamber's
lining is SEMI anechoic, that is, not a perfect absorber. At 80 MHz, the
typical 24" pyramidal loaded-foam absorber will yield a return loss of less
than 10 dB, which is a significant reflection for your modeling effort.

Most board designers make some attempts at modeling EMC performance, but
they usually run into the concept of diminishing returns quite soon. The
pressure of costs and schedule usually limits the modeling effort anyway,
and the board gets designed more by rules of motherhood and sin than precise
modeling.

Finally, few electronic assemblies exist wholly unto themselves, life gets
very messy once you factor in the IO, command & control, and power
attachments. These externals are usually the path of more problems than
responses directly attributable to board components, especially in very
low-level RF fields like 10 V/M.

Ed