N4KG comments follow
On Fri, 20 Jul 2001 "Kevin Hemsley" <kev@ida.net> writes:
>
> Brian/K3KO writes:
>
> > Low dipoles are also cloud burners. I suspect they will perform as
> > well as this loop plus you can feed them with coax. Burying 450
> line is a bad idea. Burying coax works and has no impact on loss.
> >
> > After fooling around with the loop for a while I suspect you will
> be back to the dipoles anyhow. I hope the structures are far enough
> > apart to permit this.
>
> I failed to mention that I plan to use the loop for more than 160M.
> One of its uses on 80 and 160 will be for in-state communications,
> so a high radiation angle is desirable. My experience with other
large
> horizontal loops at this height have been very good.
>
> ------------------------------------------------------
> Kevin Hemsley
> kev@ida.net
> KB7TYA
>
A full wave loop radiates broadside to the loop so on
the fundamental frequency a horizontal loop will radiate
straight up.
A TWO Wavelength loop (2nd harmonic) acts as two pairs
(at right angles) of half waves spaced 1/2 WL apart.
As a horizontal loop, it will have a NULL straight up.
At 35 ft, on 80M, the ground reflection is concentrated
at high angles and poor at low angles.
The radiated pattern is the product of the free space radiation pattern
and the ground reflection coefficients. Unfortunately, with a
LOW 2 WL Loop, the incident radiation does not coincide with
the ground reflection. Bottom line: it will make a poor high angle
radiator and a poor low angle radiator. A low 80M dipole would be
a better high angle radiator.
35 ft poles would make nice supports for higher angle (daytime)
high band antennas such as 2L Yagis or 2L Quads for 10 thru 20 meters.
Tom N4KG
________________________________________________________________
GET INTERNET ACCESS FROM JUNO!
Juno offers FREE or PREMIUM Internet access for less!
Join Juno today! For your FREE software, visit:
http://dl.www.juno.com/get/tagj.
List Sponsor: Are you thinking about installing a tower this summer? Call us
for information on our fabulous Trylon Titan self-supporting towers - up to
96-feet for less than $2000! at 888-833-3104 <A
HREF="http://www.ChampionRadio.com";>
www.ChampionRadio.com</A>
-----
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
|