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Author Topic: FULL SIZE 75M LOOP..  (Read 28148 times)
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ve6pg
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Posts: 1108



« Reply #50 on: June 22, 2005, 10:17:01 PM »

OK..THIS HAS BEEN A GOOD DEBATE...HOW ABT THIS THEN...HOW WELL DO YOU THINK THIS LOOP MIGHT PERFORM ON THE OTHER BANDS...WIRE IS TO BE 270FT,OPEN WIRE FED...SO,WHAT DO YOU THINK IT WILL DO,AT 30FT,FOR 40/20/15/10...?..TIM..SK..
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...Yes, my name is Tim Smith...sk..
wn5t
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« Reply #51 on: July 15, 2005, 10:32:05 PM »

Greetings.  I've been reading for quite some time and finally found something with which I have experience!

I have an 80m 1 lambda (well, actually a little more than 1 lambda) loop at about 30' fed with 450 ohm ladder line and a "tuner."  Why 30'?  Cuz that's where the wire snagged on limbs.  I'm lucky enough to have trees at four corners.  I started with a horizontal dipole in an "L" configuration.  When I completed the loop a friend asked if I'd bought an amp.  Yes, he was within 300 miles.  However, I routinely use this loop (corner fed, BTW...I know, that's supposed to be wrong) from 160m through 10m.

On 160m, it's a tough match and is so so out to 200 or 300 miles.  On 80m, I routinely hear AM sigs from 2-land and talk on SSB from Arkansas into Michigan.  I have even heard Cali and Europe.  I know...a 1/4 lambda vert would be better for DX, but hey...it's what I've got.

Now, for modeling.  I've modeled the loop with EZNEC several times.  On 160m and 80m it's a big bubble.  On 40m it's a jelly bean.  On 20m I have four lobes with about 9 dbi gain.  I can work the Carribean barefoot and they think I'm running an amp.  The pattern continues through 10m with increasing gain and an increasing number of lobes and nulls.  With decent propagation I have worked as far as Hong Kong and Australia to the West and the Urals in the east.  That said, for 20m and up, my 80m dipole that is configured as a V-beam ( both legs slope down from the feed point...the interior angle is rather acute...<45deg).  The "V-beam" seems to be equal to a nearby friend's A3S @ 60'...it just doesn't rotate. Sad

So, from Arkansas, I can do surrounding states on 160m, continental on 80m, some DX on 40m, lots of DX on 20m & up if the DX is in a lobe.  Is it perfect? No.  I'd prefer a rotatable, directional, gain antenna on 20m & up.  For 40m and down I'd prefer the loop at >60'...or >90'...   As for tuning...the 80m loop seems to match easily from 80m up...  160m can be a challenge.  

For more reading try http://www.cebik.com and check out "Tips and Technicals."  He's got a ton of stuff on many types of antennae, including modeling tips and tables.  

Well, that's my $0.02 (what ever happend to the "cent" sign on kbds?).  Now I won't feel so bad asking for help when I get to resurrecting my hamfest special DX-100.
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