*Thank You Bob,*
* An Antenna is a System. My Antenna System is
126 feet of #12 wire at 36 feet high. ( flat top ) With Window Line ( 450
ohm ) running down to the eve of the house. We bring the feed line away as
perpendicular as possible. The Ladder/Window Line ties directly to an Ugly
Balun/Choke Balun which consists of 27 feet of RG-8 Coax wrapped around a 3
inch piece of PVC Pipe. Sixteen feet of the Coax wrapped around the pipe
and the rest as short as we could make it into the Shack. With a good
Tuner, we operate at Full Legal Limit when we Want Too. Only 15 Meters has
any problems and we just learned not to Tax the Tuner by running QRO on 15
Meters. The Lobes and Nulls you speak of on 20 Meters. I find to be Gain in
the favor of the Lobes. This has been my Antenna for over 25 years. Every
year we put one up at Field Day with our Club. And Every year the station
we provide is the Favored Station by the Field Day OP's. By comparison we
beat the pants off of the various OCF and Inverted L stuff the others dream
up. Not bragging here fellows just stating the facts. *
* 73 from Wade/KJ4WS*
On Tue, Oct 20, 2015 at 9:17 AM, Rob Atkinson <ranchorobbo@gmail.com> wrote:
> >Perfect example. Another would be a full wave dipole. :)
>
> A full wave center fed dipole will be voltage fed and have a Z of
> around 5K ohms and put a vswr on the line of around 10:1. The line
> loss is negligible because it is a balanced line with an air
> dielectric. I will go up against a horizontal 1/2 wave balun and coax
> fed dipole on 40 m. with my balanced line fed horizontal 1 wave center
> fed dipole on 40 any day of the week and I will come out ahead across
> 40 m. Both same height.
>
> >
> >But more generally, I'm talking about putting up a single dipole, whether
> center-fed or off-center fed, feeding it with open wire or window line, and
> loading it on all bands.
> >
>
> Brown, you are off in your own world of open wire line hating and you
> are free to be irrational about it to your heart's content but you
> occasionally pop up in some on-line forum somewhere and I see your
> dis-information. Perhaps you attempted the folly of feeding an
> unbalanced (i.e. off center fed) dipole with balanced line as you
> included it in your description above. Surely you understand the
> concept of unbalanced load fed with unbalanced line and balanced loads
> fed with balanced line. You don't feed an unbalanced load directly
> with balanced line.
>
> A high dipole 1/2 wave on the lowest frequency of interest and fed in
> the center with decent open wire line with a characteristic impedance
> of at least 600 ohms and matched with a correctly designed and
> constructed truly balanced link coupled matching network, will run
> rings around any coax fed dipole, especially on 80 meters where the
> band is 500 kc wide. You won't need a ridiculous ferrite core balun
> at the feedpoint, sitting there adding to your losses with heat
> reactance; you won't need a dozen dipoles to cover HF, and such a
> system will deliver more power to the load on average on any HF
> frequency than some hammy coax fed dipole will. If any ham wants to
> be obsessed with feeding a balanced load with an unbalanced line he is
> free to do so and live in denial (I work everyone I hear blah blah)
> but professionally designed and constructed shortwave broadcasting
> plants always use balanced antennas and feed them with balanced line.
> If they didn't work they wouldn't do it.
>
> To be objective, there is one problem with a low band dipole used on
> the high bands, and that is the pattern you wind up with. An 80 m.
> half wave dipole on 10 meters has many lobes going off in all
> directions and even though the system in terms of power transfer is
> efficient, the pattern is not reliable if the operator wants a good
> idea of where is signal is going. For that reason, I employ a second
> dipole, 1/2 w. on 20 meters to cover the high bands.
>
> 73
>
> Rob
> K5UJ
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--
*Living one day at a time with Jesus as my Savior. But, still having Fun.*
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