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user1234
Romania
6 Posts 
Posted  Mar 01 2019 : 23:59:02

What is the utility of the real part of the mutual term in FastHenry? Should it be considered for something, does it have any physical meaning? 

Enrico
424 Posts 
Posted  Mar 04 2019 : 13:42:41

It has physical meaning, and you may need to consider it, depending of what you are trying to simulate.
I see you deleted another post that asked about the capability of FastHenry2 to account for proximity and skin effect. The answer to the first question is strictly related to the answer to this one. FastHenry2 is quite able to simulate proximity and skin effects, as it solves the Maxwell's equations, with all its consequences. The only limit of FastHenry2 is the magnetoquasistatic approximation, i.e. we assume no radiated field or, if you want, that the dimensions of the structures under analysis are much smaller than the minimum wavelength of interest.
Now, let's have some intuitive understanding of the mutual resistance term. Assume you have two parallel circular wires nearby, with some current flowing in the wire (in the AC regime). When the frequency increases, the current tends to flow towards the boundary of the wire, and this is the socalled skin effect. Due to this fact, the self inductance decreases a bit (as there is slightly less area enclosed by the current) and the selfresistance increases, as there is less conductor area for the current to flow. However, also the current in the second coil will influence the current distribution in the first coil, and this is the socalled proximity effect. But, if the current flowing in the second coil causes a change of the effective conductive section of the first coil, then the resistance shown by the first coil will change as well. This effect can be modeled with a mutual resistance term. Now usually this term is quite small and can be neglected. However there are situations where you may not want to discard this term. In this case, remember that if you want to simulate the structure in a Spicelike simulator, you will need to use some currentcontrolled voltage generator.
Best Regards, Enrico




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