--- In firstname.lastname@example.org
, g.preston@... wrote:
> At 05:19 AM 2/19/2013, you wrote:
> >Thanks John and John. I'm wondering whether I even need litz wire.
> >Is one of the reasons for it to increase bandwidth?
> >Also, I think the Q on the antenna I just made is too high. It has a
> >very sharp peak that's too narrow to pass the full station passband.
> I would think a narrow BW means a high Q which means low
> losses. Would an increased BW indicate higher losses? Are higher
> losses preferred?
> 73 de k5gp
If a loop antenna is tuned with a capacitor it forms a tuned circuit. The Q of this circuit is the inductive reactance divided by the resistance. This tells you how large a voltage will form from a constant level of stimulus as the oscillations build up. A higher signal level of course is better at the input of the receiver. But it makes the circuit slower to respond to changes in the level of stimulus. This is manifested as a narrower bandwidth with a higher Q.
Think of a pendulum swinging. One with a heavier weight is like a circuit with a higher Q. It takes longer to get it swinging and once you stop pushing it, it takes longer to slow down. So it responds more slowly to changes and has a narrower bandwidth.
The tradeoff is between the signal level and the bandwidth. If you add more resistance to increase the bandwidth, you lower the signal level.