Re: Permeability Tuning
If the loss resistance is independent of frequency - ie mostly the DC resistance of the coil, then:
Q = (1/R)[√(L/C)]
We also have:
Q = fres / BW (bandwidth)
and fres = 1/[2π√(LC)].
Putting these together, we have:
BW = R/(2πL)
Thus for constant bandwidth, you should vary C because bandwidth is independent of C!
In practice, as Al Skywave says, DC resistance is not the whole story, there is some parallel loss resistance as well as frequency-dependent series resistance. But this analysis is revealing, nonetheless!
|