[Antennas] The "Perfect" Dipole

2003年3月04日 15:55:23 -0600

At 09:08 PM 3/4/2003 +0000, Durwydd MacTara wrote:
>In my quest for new antenna construction ideas I stumbled across Bob 
>Wilder's web site and a new project! A cheap, easily constructed, all band 
>HF antenna! It is a folded Frannklin constructed solely of 450 ohm ladder 
>line. He feeds this beast through a 4:1 balun. My question is "why not 9:1?"

A couple of comments...Why 4:1? Well that is what I had on hand and it 
worked great. I have
used 9:1 long ago and did not see that much improvement over 4:1. 4:1 is 
easier to find and/or
build, so why not go with the cheap if it works.
The 40 meter version works great on 75 meters and takes up a lot less room. 
When I say great, I mean
I was able to work WAS on 75 and in some cases QRP-QRP as far as Alaska 
from Alabama.
>My next question is this: He claims a lower radiation angle if the last 20 
>feet of each leg are "drooped" at 90 degrees. I am considering cutting 
>mine for 80 Meters, rather than his 40 Meter length (increased bandwidth), 
>does this 20 feet still have an effect

Have no mathematical proof, but only observation when being used that I 
could see better
signals with the ends dropped so I had some vertical polarization. As far 
as a 80 meter
version, again I have no mathematical proof but I would guess it would take 
30-40 ft ends
to be drooped to obtain the needed low angle
Right at the moment I have my 450 Ohm Franklin down and am trying a 
full-wave 80 meter
loop at 30 feet just to see how it works as an all band antenna.
> "Communications" is a People skill, the rest is technology.
> Durwydd MacTara
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Bob Wilder, AF2HD/AFA2HD
6032 Idlemoore Court
Theodore, AL 36582-4117
251-653-5274
http://home.earthlink.net/~bwild
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