Current flow in an MRI receive coil

[toreil]

I am a physics student with very limited experience in electronics and I have been tasked with making an receive coil for use in an MRI machine. The design of an RF coil amounts to constructing to what essentially amounts to an LC resonator with a set resonance frequency. The design of my coil is somewhat similar to this http://web.stanford.edu/~jbarral/Coil_RcTx.jpg

Though I have a two capacitors in series between A and B rather than the single capacitor in this illustration. My question is, current cannot flow through a capacitor but if I connect a network analyser across E and F a signal passes through the circuit, how does that work? I am certain the answer is simple but I cannot find the answer. Thank you in advance.

 

[zoki85]

I know practically nothing about designing MRI machines, but why do you think current cannot flow through a capacitor?
If you connect AC source to terminals E-F, current should flow through all capacitors in the schematic.

 

[berkeman]

I am a physics student with very limited experience in electronics and I have been tasked with making an receive coil for use in an MRI machine. The design of an RF coil amounts to constructing to what essentially amounts to an LC resonator with a set resonance frequency. The design of my coil is somewhat similar to this http://web.stanford.edu/~jbarral/Coil_RcTx.jpg

Though I have a two capacitors in series between A and B rather than the single capacitor in this illustration. My question is, current cannot flow through a capacitor but if I connect a network analyser across E and F a signal passes through the circuit, how does that work? I am certain the answer is simple but I cannot find the answer. Thank you in advance.

DC current does not flow through an ideal capacitor. AC current most certainly does. :-)

 

[zoki85]

Hmm, maybe he meant current can't flow through the capacitor placed between points C-E while nothing is connected between E and F?

 

[toreil]

Ah thanks, I guess I should've seen that from the expression for the impedance of the capacitor, I had just assumed that because there was a physical barrier separating both legs that no current would flow but there must be some induction between the plates. Is there anything from stopping the current not going through BA but through DC to F?

 

[zoki85]

Is there anything from stopping the current not going through BA but through DC to F?

I beg your pardon?