In article , craigm
wrote:

Telamon wrote:

In article .com,
"N9NEO" wrote:

Does higher bands mean like 160m is higher than 75m or 3.885MHz
is higher than 1.945MHz?

Would your Idea be practical Telamon considering the reverse
voltage capacitance of a varactor is limited to a small swing in
PF? Maybe lots of diodes in parallel?

Ack Ack, 12:59, back to work.

Well a couple of things come into play.

Local noise goes up, along with atmospheric, and loops tend to have
greater local noise rejection over a voltage type. This is
especially true for a shielded loop. There is no loop advantage in
atmospheric noise save for lightening storm noise so it might make
a better summer antenna.

The lower in frequency you go the signals tend to be directionally
phase stable and so with a loop receive pattern you can null
signals.

The higher in frequency you go the less advantage there is in a
loop over a dipole but it will work just fine.

I think paralleling diodes to get more capacitance than what one
diode can provide will work. Can't think of a reason why it would
not work.



There are available diodes that can provide swings of more than 300
pF.

What is important, if you want tuning range, is the ratio of maximum
capacitance to minimum capacitance. Paralleling many identical diodes
will not change the ratio. Selecting the appropriate diode is better.

The capacitance range may not be as great with the ganged diodes
depending on the diode specifications but it certainly is easier to use
one diode that has the need range.

One diode is 40 to 400 pF or four in parallel of 10 to 100 pF each
should work out to the same range. I just made up the numbers as an
example. In reality you could be correct because diodes in my example
may not exist. We were speaking in generality and not specifically.

--
Telamon
Ventura, California