I went to the link you previously gave, and I disagree with one thing
totally, and I've been doing this stuff for over 40 years. A qarter
wave length is not not a good length to use. Think about it, a quarter
wave at the given frequency is oposite of what it is. In other words, a
shorted length appears open and an open appears shorted. If you put a
dummy load at the end of an open quarter wave stub, it won't appear as
50 ohms, it will appear shorted. I'd stay away from a quarter wave
length unless you're doing it for fazing and such as that. The only
systems I ever saw a quarter or 3/4 wave lengh used was on sual mirror
mounts I use to sell to truckers. These were actually 72 ohm cables and
were in parallel feeds. Ideally, the whips should be a half wave apart,
but seldom where. This gave a figure eight pattern front and behind the
truck.
73
Butch
WA0VJR
Node 3148
Wallace, ks.
On Fri, 18 Nov 2011, Steve wrote:
> BlankMike, I agree with what you said in principle. If you have a perfect
> match, feedline length is completely irrelevant except that you want to keep
> the feedline shorter to avoid signal loss. Of course, at 160 meters, this
> is not really much of a consideration.
>
> But, sometimes, trimming a bit from the feedline can help the tuner because
> of the VSWR measurements. I was always taught that if you can't measure the
> SWR at the antenna feedpoint, there could be differences as you measure
> along a feedline unless you measure at true half-wave equivalents.
>
> Here is a good discussion of SWR and how it is really unimportant in antenna
> radiation, as long as it is reasonable it hardly contributes to signal loss.
> Most signal loss is due to inefficient antennas.
>
> http://www.antennex.com/preview/vswr.htm
>
>
> Steve
> Lansing, MI
>
>
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