All that I've ever measured lie in the range 0.95 to 0.99.
Did you notice that I said *COMMON-MODE* velocity factor? Signals
flowing on the outside of the braid are Common-Mode signals - signals on
the inside are Differential-Mode; they can have totally different
On 02/01/2012 02:41, firstname.lastname@example.org wrote:
> What coax cable has a velocity factor of> 95?
> To: email@example.com
> Subject: Re: [TowerTalk] Pattern Distortion caused by faulty balun?
> From: Steve Hunt<firstname.lastname@example.org>
> Date: Sun, 01 Jan 2012 21:57:54 +0000
> It would be the length from the feedpoint to the ground; you also need
> to factor in the Common-Mode velocity factor of the line - probably in
> the range 0.95 to 0.99.
> If I model that feedline length connected to a half-wave 20m dipole,
> assume a velocity factor of about 0.97 and a ground connection
> resistance of 10 Ohms, I get 40% of the leg current flowing back down
> the shield as CM current.
> If you are trying to estimate whether or not the conducted CM impedance
> is high or low at the feedpoint, remember you need to do it for all
> bands on a multiband antenna!
> Steve G3TXQ
> On 01/01/2012 21:30, Tony wrote:
>> The total length of feed line to the rig is about 85 feet. It's
>> grounded at 70 feet where it then goes into the shack using a 15 foot
>> jumper. Which do you take into account as being a multiple of
>> half-wave? The total length of the coax or the length between the
>> antenna and ground? Tony
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