Calculating Distributed Capacitance of a Bifilar Coil?by HMS776 Tags: bifilar, capacitance, coil, distributed 

#1
Mar2511, 01:31 PM

P: 63

Hello everyone,
I have been tirelessly searching the net trying to find out how to calculate the distributed capacitance of a multilayer bifilar coil. Just wondering if anyone here can point me in the right direction? 



#2
Mar2511, 03:05 PM

P: 4,664

For HiQ high frequency coils, you want Litz wire. The turntoturn capacitance is the same as single conductor wire, but the eddy current (skin depth) losses are less. Litz wire is multiconductor wire with insulated strands. What do you mean by bifilar coil? See
http://www.die.ing.unibo.it/pers/grandi/papers/ia99.pdf Bob S 



#3
Mar2511, 04:54 PM

Mentor
P: 39,683

http://en.wikipedia.org/wiki/Bifilar_winding I'm not sure of a good way to calculate the capacitance, though.... 



#4
Mar2511, 10:35 PM

P: 4,664

Calculating Distributed Capacitance of a Bifilar Coil?C = πε_{0}/[cosh^{1}(D/2R)] where D is the centertocenter spacing of the two round conductors, each of radius R. (See Smythe Static and Dynamic Electricity Third Edition, Section 4.14). It is also possible to get to this number by calculating the transmission line impedance of a twisted pair or a twinline transmission line, and knowing that a) The signal velocity in an airfilled transmission line is c = 1/sqrt(LC), and b) The transmission line characteristic impedance is Z = sqrt(L/C) where L and C are the inductance and capacitance per unit length. Also look up Lecher Line capacitance in http://en.wikipedia.org/wiki/Lecher_lines Bob S 



#5
Mar2511, 11:20 PM

P: 63

Thanks Bob S, I greatly appreciate it. although I am really hoping to find the equation one would use for a multi layer coil.



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