Thread: Velocity factor
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Old April 18th 07, 04:08 PM posted to rec.radio.amateur.antenna
Wimpie Wimpie is offline
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First recorded activity by RadioBanter: Aug 2006
Posts: 106
Default Velocity factor??

On 18 abr, 16:20, "John Doe" wrote:
I have made a indoor/outdoor STEALTH of sorts, a Multiband HF LOOP Antenna,
approximately 540ft long (from center connector back around to the other
side of the connector). I am using 13 gauge - copper - stranded plastic
cover - wire! Does anybody have a velocity factor chart?

At the present time - my MFJ Antenna Analyser has it resonating at approx
10.5Mhz, and I am trying to get it to resonate at 1.8Mhz (160M).

I need the info to try and figure out how much I need to reduce the overall
circumfrence.

73's

Howard W3CQH


Hello, John,

The effect of a 1mm thick PVC coating on 1.8mm diameter of copper on
phase velocity is less then 2 percent below that of light. So c is
about 0.98...0.99*c0. This is without correction for capacitive fringing
at the ends of the wire and without correction for influence of
ground.

As your wire is about 1 wavelength for 1.8 MHz, your loop should have
a low impedance and therefore you should find a point of resonance
around 160 m band (assuming you did connect the wire directly to the
MJF). Maybe you should use a balun between your MFJ and 1WL loop.
You will get resonance at near multiples also.

Best Regards,

Wim
PA3DJS.