[Antennas] Loop vs Dipole

Wed, 1 Oct 2003 18:13:30 -00

Ron,
 I have used loops many times in the past, and
have also found a few  times when the loop did not
out perform the dipoles.
 I have  noticed that when I try to feed them anyway other 
than in the center of the bottom, they just don't seem to
work for me. 
 When I was living in NM, I used to work into Europe
quite easily on 40 Mtrs. The bottom wire was less than 6 feet
off the ground. That was a real problem...not because it didn't work
but because I am 6'5". Hihi.

73, Tom K5IID

> [Original Message]
> From: Ron & Madhavi <[email protected]>
> To: <[email protected]>
> Date: 10/1/03 17:19:04
> Subject: [Antennas] Loop vs Dipole
>
> Here's a tough one....or is it?!
>
> I live in a townhouse in Kingston - the backyard is no more than 32' long
> and 10' wide, with a concrete parapet wall at the back.
>
> I have a 25' tall aluminum pole clamped to the wall and ran an inverted
vee
> on 20m (25' at the apex). Results were fair and with my 850S, I worked
into
> Asia and more consistently into Europe.
>
> Wanting to improve on it, I replaced the vee with a full wave loop and
> expected it to outperform the inverted vee. The loop has perfect resonance
> (a nice 1.1 SWR). The matching is done with a  1/4 75 ohm transformer.
> HOWEVER, even though I have tried to move the feed to a corner, 1/4 from a
> corner, center, apex etc., nothing seems to make it outperform the
inverted
> vee. I know that this does not confirm theory -- as the loop is larger,
has
> a lower take off angle (at least so they say!) and better SWR etc.
> Adddmitedly, the base of the delta is a FEW feet lower off the ground than
> the ends of the vee, but I expected the claimed superiority of a full wave
> loop to offset that.
>
> Used many 40/80m lops in the past, but never compared them to dipoles and
> vees at the same height! The results however were quite pleasing. First
time
> I am running comparisons on  loops and dipoles on  20m . Is the
superiority
> of the loop greatly exaggerated or am I missing something here?  I have
> written articles encouraging people to use lops instead of dipoles and now
> wonder if I lead them astray!!!!
>
> Again...perfect resonance (checked witha  RF1 at the feed point, end of a
> half wave section of coax and after matching with the 1/4 transformer
too! I
> can't see I have made any mistakes here! If its the height......how come
the
> inverted vee works MUCH better?
>
> Any thoughts. comments, advise?
>
> 73,
> Ron, 6Y5/4S7RO
>
>
>
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