# How to analyze resistor of an RF coil?

Discussion in 'Electronic Design' started by Jim, Nov 21, 2004.

1. ### JimGuest

I have an RF coil. Some material having strong absorption for 100MHz RF is placed
inside the coil. X", size and position of the absortive meterial is known.
How can I simulate the resistor of the RF coil at the specific frequency of 100MHz?
Thank you very much!

2. ### Don PearceGuest

Put a variable capacitor in series with the coil and resonate it with
the inductor at 100MHz. What remains is now only the equivalent
resistance to the lossy material. Measure this by placing the whole
thing in parallel with a 100MHz signal and seeing how much it is
reduced. Substitute fixed resistors to find the equivalent value.

d

Pearce Consulting
http://www.pearce.uk.com

3. ### Tim WescottGuest

Do you want to simulate this on something like SPICE, simulate the
conditions with a real coil in a real circuit, but without the
absorptive material, measure the resistance, analyze the loss in the
coil given the material characteristics, what?

If you are going to run at exactly 100MHz and none other you can
simulate this quite well by putting an appropriate resistance in
parallel or in series with the coil, either in the real world or in your
SPICE schematic. If you want it to be accurate for DC _and_ 100MHz then
only the parallel resistance will do.

But you really have to tell us more about what you're trying to do

4. ### JimGuest

Thank you both very much!
My object is to optimize the coil structure to get maximum resistor
change.

I hope I can use some simulation method like FEM, FDTD etc. to analyze
the relation of the resistor and coil structure.

Thanks again!