Loop project

[KU0DM]

Hey gang, am working on a loop antenna this time. Another project where I have no experience, so lets get ta learnin!

What I want to do, is remove my 320' dipole at the farm, and in its place make a nice big loop.
I have a vertical down there for DX, and am looking for something that will work great for stateside for contests and just ragchew every now and then.

Some info:
I can feed it with 450 ohm ladder line
The feed point will be roughly 50-60'
The lowest point one of the legs might get would be 30'
My primary focus is 40 and above
I have a Dentron MT-2000A to tune it with
----

So what do you guys think? What suggestions might you have for me in terms of length, or anything really.

I am all ears :geek

[ki4itv]

Another birthday and there you go getting all loopy on us... :mrgreen:
Happy Birthday OM.

We use 2 full 160M loops every year during field day (about 520, or so, feet of wire each) and I always enjoy using those antennas. We usually pull these up a little higher than most people could get them, stadium lighting can be very handy.
If you have no interest in 160 or 80, make one for 40m and you might get a more reasonable radiation pattern on the higher frequency bands. A little antenna modelling on this might give you insight as to what you could expect, we modelled our loops at a club meeting using various heights, on various bands and it was interesting to see the changes in radiation patterns, on 40, 20, 15, and 10.

A full wave on 80m is slightly shorter than your dipole, you could probably just attach the ends together on it and see what happens. You might like it, and it is almost already completed. If your feeding it with balanced line, the dfference in length may not be a significant problem.
Sounds like a happy accident waiting to happen.

Good luck and I;m interested in some of the answers to this as well.
Trey-

edit:whoops

[N9FE]

560 feet. Feed it in the corner. Your going have to tweek it to get it resonant wherever you want it on each band. Someday if you can have a relay in the opposite corner from the feed point. Then you'll really have a bomber... P.S. If you can find a copy of William Orr's antenna book. Get it ...

[WØTKX]

Sounds like the loop I have here. Dentron Supertuner with 450 Ohm balanced line. I added about 100 feet of wire to it about a week ago from about 350' feet to about 450'. It works great, and it's fantastic for SWL. Even AM Broadcast Band DX.

Definitely make it shorter than this if you want 40 and up.

With the shorter length version, I played with lowering the west (feed point) side of the loop, as a sloping loop. It helped to kill the QRN a little, and I was louder on the left coast.

Called it the Sloppy Loop.

[KU0DM]

All good points and ideas, keep em' coming!

[WØTKX]

Are you using trees? I use the "Hyperdog" tennis ball slingshot with fishing line to get the wires up there. I still want a PVC cannon though.

http://sparrowlegs.com/nest/wp-content/20060421-hyperdog.jpg

http://www.wd6cmu.antennalaunchers.com/CRW_2590_RT16_800.jpg

[W9PDS]

KU0DM,

I put up my first loop a few weeks ago. It's a 40 meter full wave at about 40' high fed with ladder line.

The bottom line is it's working amazingly well on all bands > 40, not so great at 40 & pretty crappy lower than that (but I really don't care about 75 & 80).

If you have the room, build out a full wave 80 meter loop, and you'll have a great performer on 40 & up. If you model it out, you'll see as the frequency increases, you start getting nice lobes forming off all sides of the loop in an omnidirectional patter. The higher the frequency gets, the more lobes form & they can give you some nice gain.

Here is a thread I've been writing in to discuss this antenna:
http://www.eham.net/forums/TowerTalk/15519

& here http://w9pds.org/loop.jpg is a pic of the feedpoint. I'm on a pretty small city lot but the loop just fits inside my property. It's damn near invisible & you would never notice it from the street unless I pointed it out to you. It is impossible to get a picture of the whole thing, it just doesn't show up on camera.

You won't regret putting one up. I'd like to hear your experiences if you do.

W9PDS

[WØTKX]

http://w9pds.org/loop.jpg is a pic of the feedpoint.

Same ladder line, same color of shingles... What are you doing on my roof? :shock:

And you're sure right about the lobes, with the multiple wavelength loops... purpose built, there is serious gain in those flower petals. I'm concerned that adding the extra wire to my loop changed the lobes on 10 meters to something resembling a Chia-Pet's hair do. :roll:

[W9PDS]

I'm concerned that adding the extra wire to my loop changed the lobes on 10 meters to something resembling a Chia-Pet's hair do.


Hehe, Exactly. I wish the higher bands were open, I'd love to see how this thing is working.

What is really intriguing to me is I'm getting great SWR untuned on 6 meters. Like 1:5 or better across the whole band. It will be very interesting to see what this thing does on 6 when it picks up again.

[W9PDS]

KCØTLW:

I know you recently mentioned in another thread about how quiet your loop is. I'm curious what your overall impression of it is?

What size did you build your's?, How high? What do you think of the performance?

I'm probably still in the honeymoon stage with mine, but the more I use it, the more I like it. I've yet to see it beat my inverted V, Alpha-Delta DX-EE dipole in any tests I've run (I have both antennas hooked up via an AB switch). My main criteria for testing is using the internet beacon receiving stations & the automatic PSK reception report system. I constantly get 50% more stations responding to beacons on the loop than I get on my dipole.

I have some issues with the lower bands (my loop being cut to 40m), but the more I play with 30 & 20 meters, the more I'm starting to love this antenna...

[N9FE]

Not being an a-hole here. But when someone say's an antenna is quieter than another.. That means its not recieving as well.. The better, or "efficient" an antenna, The louder it will be...

[WØTKX]

Oh I still like it... there are odd noise sources from the seriously urban environment I'm in, downtown is 6 miles ENE of me :shock: and it's LOUD!

Experimenting with dropping the SE corner to get some stronger coverage to the SE... Roughly square shaped, oriented with sides parallel to the outline of Colorado. ;)

About 110' per side. Feed point is in the middle of the west side, up about 45 feet, the opposite (eastern) side is up about the same. The feed line is maybe 60 foot long.

The NE corner droops to about 25 feet, and I'm playing with drooping the SE corner to see if I can change the pattern by sloping it as well... Apparently, I'm really loud in Michigan, and I work NY and Maine pretty easily. So it may work.

The NW corner droops about 10 feet, and the SE corner does not, but could. Looking at adding more wire, to try to lower the angle a bit more. It's getting vaguely tent shaped. It's a compromise, but I feel lucky to be able to put up that much wire.

I'd love to have one hanging up higher on pulleys, in the clear so you could tilt the heck out of it. When camping and playing with radios I've messed with tilting antennas and moving the legs around. It works.

Running 500 watts on 75 meters I have worked Hawaii and the east coast at the same time a couple of times. No VK's yet, but last year I did with the smaller 320' loop, and it was lower, about 30 foot average. So it's working. :D

Switching to the Gap Titan is interesting when the band is swirling and twirling. I use the Gap on 40 and up a lot more. But I switch back and forth for the weak ones, and that helps a lot sometimes.

What I really want to do is a reversible Moxon wire beam. That would be... sick. :twisted:

[WØTKX]

Not being an a-hole here. But when someone say's an antenna is quieter than another.. That means its not receiving as well.. The better, or "efficient" an antenna, The louder it will be...

The loop seems quieter with nasty city noises than the big dipole I had up, an obtuse angle inverted V up abut 45 feet at the feed point. But heck yea, it's louder with signals than the dipole was. I hear thunderstorms in 360 degrees! :shock:

So that's a bit more specific about what I mean by quieter. When I hear impulse noise and buzzy stuff... the loop seems quieter, but since I took down the dipole and use it for camping, I can't do a side by side... and the comparison with the Gap is not fair, because it's a vertical dipole. I did make the antenna change in one day.

I will slink away with my small city lot urban subjectivity... :oops:

[W9PDS]

I feel lucky to be able to put up that much wire.


If your city lot is anything like mine, I'd say you really are lucky. I'm jealous with loop envy. I really do wish I could build a bigger one.

I'm at about 160 feet total length. It encompasses about 1/2 my lot, but I do not have the supports for anything more. I think something like a Gap vertical would pretty much be about all I'd be able to put together to complement the loop. I do not have the space for a big radial farm. I probably do not have much hope on doing much with 80 meters, but that is OK with me right now.

Are you using open feedline &/or a tuner?

I'm using 450 ohm ladder line into a 4:1 Balun, and then about 20' of coax to an ATU (LDG AT-897).

No more than 50 watts (PSK) and I can work most of the EU stations I hear on 30 & 20, so I'm pretty happy, and it's just damn cool to be able to transmit into a big old short circuit :)

[W9PDS]

Are you using open feedline &/or a tuner?



Duh....

I just read one of your earlier posts about the tuner & feedline.

I have a 20 and 10 meter Full wave loop and the work very well, Very broad banded and much quieter than a beam or dipole.

[n0eq]

...What is really intriguing to me is I'm getting great SWR
untuned on 6 meters. Like 1:5 or better across the whole band...



For some reason, it seems like nearly any piece of metal
I stick in the air looks great on 6m on the analyzer.
2m GPs, 75m dipoles, multi band trap verticals
(that aren't designed for 6m), every mobile antenna
I've ever installed, just about everything.


Craig 'Lumpy' Lemke

www.n0eq.com (http://www.n0eq.com)

[KG4CGC]

...What is really intriguing to me is I'm getting great SWR
untuned on 6 meters. Like 1:5 or better across the whole band...



For some reason, it seems like nearly any piece of metal
I stick in the air looks great on 6m on the analyzer.
2m GPs, 75m dipoles, multi band trap verticals
(that aren't designed for 6m), every mobile antenna
I've ever installed, just about everything.

Yep. My FT100 did the same thing.
That's why they call it, "The Magic Band."

[ki4itv]

It's magic, you know. Never believe it's not so.
:doh: