"Eliptical Radiation that is not measured by Elnec"?
Sounds like "Smoke and Mirrors" to me Dave.
Ground Reflection coefficients are independent of
antenna type for horizontal polarization and are
solely dependent on HEIGHT above ground.
I know people who worked DXCC on 80M using
dipoles / inverted vees at 35 ft. That doesn't
mean they are EFFECTIVE DX antennas.
Tom N4KG
On Thu, 11 Apr 2002 21:14:03 -0400 "David L. Thompson"
<thompson@mindspring.com> writes:
> For a low horizontal loop you can wind it through trees (I use #12
> black
> plastic wire that comes in 500 feet rolls from Home Depot and less
> than
> $20). If not there is no reason why it can't be hung from towers
> but I
> feel that it needs to be several feet away and not connected
> directly.
>
> There has been a big discussion about low full wave loops (say 35 to
> 50
> feet). Dr. Dave W7FB (Ex W0MHS) has a PHD in Antenna ralated
> theory and
> claims a horizontal loop has what he calls elliptical radiation that
> is not
> measured by the modelling programs such as ELnec. This is why most
> find
> that it works better on the low bands than expected. Dave was in
> Atlanta
> long enough to help put up or design many horizontal loops. There
> was an
> article by a German ham in 73 in the late 1970's. He was living in
> Atlanta
> and going to Georgia Tech.
> The article is called the German Quad. He had good luck on 80 and
> 40 with a
> full wave 80 loop. I have a loop that started out as an 80 meter
> loop at
> my Island home on St. Simons Island, Georgia. The loop is actual 40
> feet
> longer than an 80 meter loop as I had to add to it to make the ends
> meet. I
> run it through a tuner. True it has great skywave on 80 and 40 but
> I have
> worked Europe on both bands running 100 watts during the ARRL DX
> SSB. I
> also have 6K QSOs on 20, 15, and 10 IOTA frequencies and have run
> big pile
> ups at times as NA-058. It does well on 17 and 12 also.
>
> I had up a 390 foot loop at my home QTH which I capacity loaded per
> the
> article in QST and later the ARRL Antenna Anthology. I forget the
> W7's call
> but in the April QST its mentioned in the 25 years ago in QST. He
> reasoned
> that since the quad was a magnetic antenna it was best to add
> capacity
> loading to electrically lengthen the antenna. Working from my roof
> I was
> able to tune the loop down to WSB (750) with what he called center
> in and
> back out capacity wires. Just with the center in wires (from the
> middle
> points between the feed point and the opposite side) I tuned the
> loop for
> 1845Khz. I found it mostly skywave on 160 ( I remember the ham in
> Kentucky
> that told me I was the loudest station in the CQ 160 SSB...just like
> a local
> and even louder than WB9Z). On DX (NA/SA/EU) I was beaten out
> easily by
> locals running L's and even inverted V's. But on 80 I coould easily
> run
> Europeans on SSB.
>
> Several have had good luck using a full wave loop at less than 10
> feet of a
> RX antenna. AB0X had an excellent article in the August 1989 CQ on
> using a
> version made from small coax as a shielded link loop. My version
> was laid
> on my roof and then run out in to near by trees.
> It worked very well although it was only 200 feet and part of the
> coax came
> down to the receiving antenna jack on the Yaesu.
>
> Dave K4JRB
>
>
> _______________________________________________
> Towertalk mailing list
> Towertalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
________________________________________________________________
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/web/.
|