Right on the receive capabilities of the antenna.
Valocity factor is kind of magical.
As I imagine it, electrons in free space travel at the light.
Resistance slows them down, which allows for the phasing of antennas.
So say inside a piece of coax, the factor is 66 per cent.  That looks like
2/3 of the speed of light.
Ron could say much more, but you will not hear any improvement in your
receiver.


-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of Richard B. McDonald
Sent: Sunday, December 13, 2015 8:59 AM
To: [log in to unmask]
Subject: Report on 10M Loop Project, and Request for Feedback

Hi!

 

I want to report on my 10M full wave loop (FWL) project, and ask for
feedback on it.  My aim was a resonant antenna at 28.4 MHz for RX only on my
TS-2000.  I viewed this project as practice for the antenna I *really* want
to make - an 80M FWL for both RX and TX (inspired by Ron).

 

To make my loop, 14 gauge insolated stranded copper wire sits inside 1" PVC
~12' atop my wooden shack.  It is in the shape of an octagon.  I measured
the length of the wire at 1005 / 28.4 = 35.39', which I rounded to 35.5'.
There is a 25' run of 75 ohm coax (the kind for TV, which I was told is fine
for RX antenna purposes like this) properly soldered to the ends of the
wire.

 

So, my friend from our ham club measured this antenna with his analyzer.  It
turned out to be resonant at 25.5 MHz : (  Now, only because I am obsessed
with my project and by way of learning, I should like feedback on the
following:

 

1)      I am told that one thing affecting resonance is the "velocity
factor" of the wire.  Apparently, the insulation of both a) the wire itself
and b) the PVC affects the velocity factor.  I have no idea what "velocity
factor" is, nor how it affects the calculated length of a wire for a FWL as
per the above.

2)      To bring the resonant frequency up to 28.4 MHz, I *think* I need to
decrease the size of what I have built.  Is that right?  "Decrease" as in
shorten rather than "increase" as in lengthen?

3)      To decrease the size of my loop, I plan to cut 6" (0.5') off each of
the eight sides of the octagons for a total of 4' (including obviously the
wire therein).  Check my math (reasoning) on this.  28.4 / 25.5 = 1.11;
meaning I am too big by 11%.  0.11 * 35.5 = 3.9; say 4'.

 

Incidentally, even though my loop is a little off, it seems to RX better
than my 43' vertical does on 10M.  Some have said that for RX only this
resonance differential is insignificant.  In other words, they say that even
if I tune my loop precisely to 28.4 MHz, on 10M it would be imperceptible as
to 25.5 MHz for RX.  What do you think about this?

 

73,

Richard KK6MRH