Hello,
The Antenna Book says is not as good as ladder line regarding losses. The
impression I had when I read it, is that it was better than coax anyway, and
not for the doubled power rating. There is even a suggestion of using four
coaxials to get a balanced line with the same impedance of one of the single,
unbalanced, coaxials.
I have used this type of line several times and not with unsatisfactory
results, feeding 80m delta loops on resonant and higher frequencies, long
dipoles, verticals. QRO. Maybe I've been lucky with the lenghts of antennas and
these TX lines.
David
HK1KXA
EC5KXA
> Date: Thu, 5 Nov 2009 19:18:09 -0800
> From: richard@karlquist.com
> To: r_bakalov@yahoo.com
> CC: topband@contesting.com
> Subject: Re: Topband: Open wire line vs. Paralleled coaxials.
>
> Rudy Bakalov wrote:
>
> > the impedance of a single cable of the same type. However, the power
> > rating will be about the same as for a single cable, since the current-
> > carrying ability of the center conductors has not changed. However, in
>
> No. The power handling capability is doubled. The insertion loss
> is unchanged.
>
> > The losses on a coax are because of dielectric losses. But here you are
>
> Dielectric losses in coax are neglgible on 160 meters. Nearly all
> loss is conductor loss.
>
> > not using the shield as RF conductor, so the PE of foam dielectric is
> > working in a different manner. The return goes on the other center
> > conductor and not the shield. Loss figures are between those of coax and
> > those of "real" open wire lines; they are closer to the open wire and not
>
> Again, the dB/100 ft loss of two coax lines in a balanced configuration
> is exactly the same as one coax line in an unbalanced configuration,
> assuming the shields are tied together, and assuming a matched load.
> If unmatched, losses in general tend to go up.
>
> >
> > Rudy N2WQ
>
> Rick N6RK
>
> _______________________________________________
> 160 meters is a serious band, it should be treated with respect. - TF4M
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160 meters is a serious band, it should be treated with respect. - TF4M
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