effect of ohmic contact of microstrip pcb

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what happens if i use a metal carrier that have about 2-3 ohm surface resistance (not ~zero) to fabricate a microstrip board on it.

it seems that one of bad effect will appear on signal loss...

can anyone describe it...
 

What do you understand as "surface resistance"? Sheet resistance of the metal layer? How do you "fabricate" the microstrip? Can you show a cross section?

If you have a clearly defined geometry and material specification, you can simulate the setup with an EM tool.
 

consider a multimeter that we put the probes slightly on the surface of metal carrier without any pressure.
if the carrier has a good finishing, or it is a pure and good metal, the resistance measured by multimeter is a number for example under 1 ohm.
but otherwise, it may shown a number also about a few decades of ohms that is not constant and depend on the position of probes, the measured resistance will change rapidly.
if this carrier used to montage a board, the ground of ms line may degrade in quality and will affect in insertion loss.

i can simulate a ground with bad conductivity and see the results|! but i want to know in real world, any experience, any idea that may happen for other ones.

any idea,,, plz
thanks..
 

when you use full-wave simulation for any structure (your case is a simple one), the result of your simulation should be like the result of fabricated one. this is achievable when you define all elements(such as transmission line, inductor, capacitance, I/O connectors and etc) correctly in your structure.
for a transmission line (TL) in the low frequency( e.g. up to several GHz), this is usual that for TL is considered a real conductivity. in fact, it shows the amount of ohm of the TL.
so, if you define a correct conductivity for your metal carrier (or TL), the result of your simulation and experiment must be the same.

I hope these words be helpful.
 

A thin dielectric layer, e.g metal oxide, between metal and dielectricum won't affect the microstrip properties. A problem can be with semiconducting layers like copper or silver sulphide. So you'll need to ask for the exact material properties. The ohmeter test is probably not significant.
 

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