[Antennas] 248ft dipole

[Ronald KA4INM Youvan]

n3drk wrote:

> I dont know exactly what one would call this antenna but i have a 248ft
> dipole which is about 20ft of the ground at the feedpoint and the ends are
> 60 ft high. In addition to this, the angle of the ends is 90 degrees apart.
> So you name what  i have here. It is fed with 300 ohm tv twinlead. I tune it
> with a roller inductor tuner and use it on 160-10 meters.
 

   I would call it bent dipole tuned just above 160 meters with a too low center.
It has an entirely different radiation pattern of multiple nulls on every
band, useful if you don't want to contact someone in a particular area. *
	
   I think:  pulling it up to get the center up to 60 feet would improve
the efficiency, (adding transmission line won't hurt) the important high
current area at the feed point needs to be high.  Changing to 450 Ohm
`window line' would improve the physical endurance of the feed line
at the expense of weight, and would improve the efficiency slightly.
(a special plastic feed point clamp will improve the life of the connection
point, sold by ARS and others about $13)

> I have heard that the feedline should and/or should not radiate.


   Here it doesn't matter, when the feed point radiates you get
some vertical energy, at the expense of your horizontal power,
your multi lobed (because it is not symmetrical from the bend)
could use a bit of null fill.

> How do i know the antenna is efficient? 

> And the april issue of Qst talked about horizontal loop antennas which got 

> me to thinking that maybe this is the way to go instead of this present 

> antenna system.

   Add what ever antenna as long as it is not in the near field of this one,
then compare receive signals, I mean copy QSO's from Chicago, New England,
the West etc. on every band you wish to operate, don't worry about any band
you have no interest in working.

	1. You may want to use each for some contacts, some bands, some times
of the year.
	2. You may want to stick with the bent dipole, so re-use the loop
materials and try something else, perhaps a half buried loop.
	3. You may want to switch to the loop and disassemble the bent dipole
so use it's materials to build a different alternate antenna.

   This bent dipole should favor the lowest bands and have a multiple leafed
pattern with a different number of maximuma and minima on each band and not
be symmetrical, a lower radiation strength away from the center of the "V".
   The direction of the Apex of the "V" should be favored on most bands.
(it is also a "V" antenna, but the angle is kind of loose)
It should not be so directional that it does not easily cover your entire
state on the lower bands.

   Your antenna will not be as efficient in any direction as a dipole
uniformly erected, tuned to one frequency angled to one direction,
fed with a balun and RG-11 coax. (not near other objects)
Does this matter to you?
(it's hard to beat a dipole on each band aimed at your target)
(beams/quads/directional verticals do, but cost much more that wire)

   A ground mounted (with lots of radials) multi band 1/4 vertical
should beat your bent dipole at DX, because of the angle of radiation.
I understand (now) that 1,000 miles is not DX, the other continents are DX.

   If you don't care whom you talk with (or hear) your antenna can
be anything, you get what you get, it's up to you to know if you like
what you get.  A gud idea would be to go over the the shack of old timers in
your local HAM club a few times and listen to `their antenna', and learn.
(If you don't belong to a local HAM club, join the most balanced club)

*  If this antenna works for you and you have no reason to favor one area,
such as the retired folks here in Florida frequently wish to favor where
they came from, I would only bring up the feed point.
(unless you improve it mechanically)

       73 (= Best Regards) de: Ron ka4inm@tampabay.rr.com
    100% LINUX, 100% of the time.   SENT Time and Date are UTC
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