80m Loop

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After trying my hand at an inverted L and not really seeing the performance I desired, plus it had a really long coax run I decided after much reading to look into a loop.

I used "MeasureLot" to plot out the rough distance I had.  GPS is a wonderful thing.  Before this I would have had to trek about and figure out the perimeter and see if it was big enough or perhaps use a laser distance device from tree to tree.

The benefits of this loop antenna and why I selected it is my radio and shack so to speak are right near the main highest tree.  Getting feed line to the tree was a cinch.  Here is the top view layout:


Another major benefit is this thing is almost completely invisible from both streets.

I selected a 2.5:1 balun from Balun Designs.  I ran about 100 feet of LMR 400 from the shack to the feet point.  The feed is up close to 60 feet.

The only issue with this loop is that the two trees to the left (west) are downhill some.  So while they are fairly tall trees the slope is down.  This view shows kind of how it looks from the side:


So the "wide" end of my loop is lower than the feed end.  I've heard it is best to have them the other way but not sure how I can manage that.  I might be able to raise the ropes at the west trees up by using some poles that I strap to the tree but for now this will have to do.

At all points the wire is 30 feet or more above the ground.  The wire is 12ga FlexWeave.  The west corners are Dacron 1/4 inch line shot over the tree to a pulley.   Dacron rope through the pulley to an insulator for the wire.   So at both points the wire is well separated from the pulley.  The system makes it fairly easy to adjust tension and lower for maintenance.

I used a RigExpert to trim the antenna.  I have a dip on 80m at 3.625.   40m dips at 7.100.  20m is the odd ball and dips at like 13.999.  I would have expected more like 14.200.

I have a Palstar AT Auto tuner that tunes this antenna just fine just about everywhere I might want to go.

But as Ken, NM9P said, the proof is in the contacts.  Since it was a work week I did some prelim work using WSPR which I could run remotely from work.

Granted the bands have not been great but 40m at 35w produced hearing stations down to Brazil and well up into Canada as well as all across the US.  Earlier in the morning I managed Japan listeners as well.

I moved up to 20 meters at about noon.  I selected 40w and let it run.  I receive listeners in England, Belgium, Kazakhstan, Costa Rica and New Zealand as well as Canada and a good part of the states.

I moved over to 30 meters where I have almost no experience.  This also produced listeners, some with strong reports in Alaska as well as north tip of Brazil.

The antenna seems to hear well.  I am hopeful this will be "my antenna".  I've struggled, being an HOA with different ideas.  While I'd love a beam it will be a while.  I don't have any misconceptions this loop is optimal, but it sure seems to work ok.

Combine that with operation on just about any band (I can even tune it on 6 meters but who knows how it will work there) it seems to be the answer I've been looking for.  It also is virtually invisible.

I read many articles about people trying different antennas and settling eventually on loops.  Some after putting up the loop took down everything else.  I am hopeful I will get good results.  Every station I've work that has had a loop has had a pretty good signal.

Mark - WS7M
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Mark - WS7M

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Posted 9 months ago

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KF4HR

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I'm getting really good performance from a RadioWorks SuperLoop 80.  At most frequencies the Flex internal tuner handles it.  On rare occasions when it doesn't I used my Palstar HF-Auto tuner.
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Mark - WS7M

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I should have done a loop a long time ago!  Glad your's is working well!
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Paul

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Hi Mark. If you're thinking of increasing the lower edge of your loop with poles on the trees, it might be worth testing the effect before you go to the trouble. As you already have pulleys / halyards you could easily lower the high end to see if there is any noticible effect . If it's improved by being level (albeit lower), or there's no difference, then leave it lowered and use as it is. If it's degraded *then* look at raising with poles.

Clearly if it is degraded by lowering the higher end, you wont know if that's due to decreased height or the new geometry. But if it's better, its a win for very little effort.

I have a 560ft topband loop which I put up using a combination of EZ NEC simulation and iterative tweaks. It's only 30ft high and still performs very well on all bands.

Have fun!
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Milen KG2C

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How long is the loop?
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Mark WS7M

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287.5 feet.  Trimmed for a nice SWR on 80m 3.625.
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Milen KG2C

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Thanks! I currently use a 130' loop for 40m and above but I will try to have a 220-230' loop at the new QTH. It's a bit too short for 80 but I have two excellent tuners (HF Auto and AT2K) and some window line to experiment with.
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Mark - WS7M

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Oops mistype:  277.5 feet.  This is the length that tuned where I wanted using RigExpert.
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W5XZ - dan

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if you're looking for a mult-band antenna that works really well, everywhere...good luck...

if  you're serious about 80m dx, it's another story....just my experience..

73, w5xz
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W5XZ - dan

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then, make a model in EZNEC...not that hard...then you'll get an idea what to expect.

JM2C....

are antennas, in general, 'off topic' in this forum? i dunno..

no matter what your rig is, the antenna is the REAL secret to success, IMHO...

73, w5xz
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Mark - WS7M

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Agreed.  I have never tried EZNEC but will give it a shot and yes antennas make the difference.  I have heard QRP stations booming in with 10w or less when a guy in the same rough area running 1.5 kw was down in the noise.  The QRPer reported a HUGE optimized antenna for that frequency.

As far as "off topic", I personally consider the Flex Forum my ham radio forum home.  Until I am booted from this forum I will post just about anything as long as it is related to my use of my Flex Radio.  If someone doesn't like it they can choose not to read it.

mark
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Richard McClelland, AA5S

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Did you consider putting a balun on the outside wall of your shack and running ladder line to the feed point?  I gather that you're running the LMR400 to the balun located at the feedpoint? 
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Mark - WS7M

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Yes. See below.   The ladder line from the outside is still an option.  The way the coax comes out I could put a balun at a point near the edge of a deck and go ladder the rest of the way up to the feet point.

But I'm a try and see guy.  I don't have ladder, I don't have the right balun for that and I did have the 2.5:1 and it seemed to be a workable solution.  So I'm going to give this a try probably for the winter and see how it goes.  

So far the reports are pretty good.  Next spring I can work on some optimizations.
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k3Tim

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"Antennas are on topic."  Tim

-- and while we're talking of antennas a "BoG" (beverage on ground) maybe of interest. There is a commercial version that uses RG-6 as the antenna and can switch directions 180 degrees plus the feed point can be from anywhere along the length of the antenna - not just the ends. 

For transmit a 1m to 2m diameter loop made to look like a Dream Catcher.  
This system would seem to be a very neighbor friendly and have decent performance. 

Tim
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Richard McClelland, AA5S

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I tried to get a full 80 meter loop up but I only managed 250'.  The loop works well except for 3.7mhz and below, which is a bit of a disappointment because I don't use phone.   I noticed that trimming the feed line made a big difference in how it tunes.  I only trimmed one arbitrary length off the feed line and I managed to get the tuner to match on everything above 3.700.  I used a 4:1 Balun Designs balun and it has worked well.  I fed the antenna with 450 ohm open wire feeder which will handle a lot more power than I'll put into it.  I think this is the best antenna that I've had up but the bar is pretty low when considering the various low dipoles I've previously had up.
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Richard McClelland, AA5S

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OK, you'll have to wait for your atta boy. 

Saying that an antenna can't be working at all sounds a bit absolutist from a psychological perspective.  I've heard several times of people having QSOs when transmitting into light bulb dummy loads.  Anything you put up in the sky has to be better than a light bulb. 

I'd still like to put up an antenna farm outside of town and bridge my wifi network over UHF to the remote site but I think that'll have to wait.  Maybe I can get you interested in doing that and we can watch :-)
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Mark - WS7M

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Well it is funny you bring that up Richard...

Ever since the release of SmartSDR 2.x and actually before that I have dreamed of relocating my station to a really good remote site.

It would be a long project but I have considered trying to find someone that lives up in the foothills behind us that would be willing to lease out a small part of their land for a remote site.

I my mind I imagine building a nice, security cinder block building on site with power and backup generator to provide cooling and ventilation.

I envision installing perhaps a 50 foot tower and putting a nice beam on it.  If the space was big enough then add an 80 or perhaps 160 meter loop.

Then like you stated we'd put in a high speed radio link to that station.  We'd be able to control antenna, amp, beam, radio.   I would propose we have an onsite computer with the ability to be remote controlled.   

This would be a multi year project I think as I could not afford to do it right away.  We'd have to find a suitable land owner.  Ideally another ham that could chip in and get use of the station in return for the land.  

If it could be high enough up on the mountain doing a line-of-sight radio link from our houses would be simple.

Anyway it is a dream.  It would let me stay in my HOA but have a much better site and antenna.  RFI would be non-existent except perhaps for the remote site owner but we'd try to minimize that.

I only have a 1K FA amp but if we did something like this we should put in one of the 2K FA amps.

Anyway it would probably never happened but I have considered trying to forum a consortium of interested members willing to pursue such a thing.

For me personally it would be idea.  I'd probably relocate most stuff there and down here I'd probably buy a used 6300 or something similar just to have a local station on the air for when the remote was used by someone else.

The RemoteHamRadio guys are doing this with BIG stations but they are using all Elecraft gear.  No panadapters.  I would miss mine too much.

I do amateur astronomy and for years I had thousands invested in tripods, scopes, cameras and I would pick the weekend of new-moon and drive to far away locations only to be disappointed by bad weather.

Now you can join a group called itelescope.net.  For not much money you can join and use MASSIVE scopes all over the world.  You suffer none of the maintenance or other issues.  You just login, schedule your shoot, and wait for results.  All of it costs a little but not bad.

Granted ham radio is a lot more interactive but a few dedicated hams that wanted to make a great remote station and share it might be workable.
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Richard McClelland, AA5S

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I'll look at itelescope.net, that sounds interesting.  I think a lottery win and retirement are the enabling factors for me to undertake such a project; though, it has crossed my mind as well.  A 160' tower with stacked beams might work well, too.

I posted about the remote link last September (remote operations: question about networking) and WX7Y provided a wealth of good information.  He recommends Ubiquity equipment and discussed this in detail on the post. 

Let me know when you're going to get started.  :-)
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Ken K7YR

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Hi Mark,

I have used inverted vertical loops in the past as resonant antennas both on 160 and 80 meters, they worked great.  The base of both of my antennas were at about 100 feet and the feed point was on the bottom point.  I never operated them as multi band antennas.  Your experimentation interested me and I did a little research, please view the impressive study below that answered a lot of my questions.  I think folks who claim great gain are blowing smoke, but whatever floats your boat, go for it.

http://dk5ec.de/deltaloop-eng.htm

I had thoughts of great losses in the coax, however looking at the reported antenna impedance at certain resonate frequencies on each band as noted in the attachment and that losses for LMR-400 seem low, seems to work.  I do note that the bandwidth on 80 & 40 meters are quite narrow.  I might suggest balanced feed-lines be used along with a balanced tuner witch would allow full band operation  on 80 and 40 meters.

"If you don't learn something every day, you fall behind." I did learn something, Thanks.  Good job

Ken K7YR
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Mark - WS7M

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Hi Ken,

That is a great document I had not run across before.  Thank you so much for linking it here.

In my case "experimentation" is by necessity. I have an HOA to contend with.  I have a big lot but I can't string loop wires wherever I want.  So my experimentation was to find something that basically worked.   

As I said above I harbor no beliefs that this is an optimal antenna in any way shape or form.  I have no doubt that this antenna pitted against a frequency and location optimized antenna will fall well short.

But, in general, considering that much in life is a compromise, this antenna seems to offer reasonable performance in my areas of interest and it was easy to put up.

Since it was up I've made CW contacts to New Zealand, Japan, England, and some place near the northern tip of Brazil.  All of these on 300W PEP or less.

My phone signal reports across the states are close to or above S9 in both directions.

WSPR shows people hear the station even at 35W as far away as Europe.  Canada reports good SNR.

So what I can say is it works.  Is it a good as a Stepper IR on a 100 foot tower?  Probably not.  But can that Stepper do 80 meters?  I don't think so.  Does my antenna on 80m match or perform like a 100 foot elevated ladder fed loop?  Probably not.  But I think the difference might be a couple S units.

Anyway I am hopeful it gets me through until I can do something even better.
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Rick - W5FCX

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Mark,

Thanks for sharing your antenna design and experience. Congrats on the successful design. Great to hear it's working so well.

You've got me thinking about something similar now. My land is about 80' by 80' with another 30' out over my boat house on a lake that could extend the longest sides of the triangle up to '110' over the lake with a mast on the boathouse, so it sounds like I could fit 277.5 feet easily enough.

But this would result in a triangle with two long sides with a narrow angle less than 60 degrees from the boathouse mast. Are there any known issues with cancellation or other problems with one of the angles being so narrow?

Rick
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Mark - WS7M

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Rick, I am no expert but look at my picture above, the second one with the green dashed lines.  This is more like what mine looks like.  And if you take the point that is just to the right of the white roofed house that point is shown lower than the point to the left.  That is how it is in reality as well.

So my triangle is narrow with one far point lower than the other.  The feed point is easily 25 feet higher than the two corners.  And it seems to work.

One thing I read which is probably even more important than shape is that the loop will perform best over open space.  IE if you have to put it over your boat house the higher you can get it over that the better.
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Brad A. Steffler

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My horizontal loop is 265 feet long, at between 35-45 feet, and also triangular. I took the apex and split it between two trees about 15 feet apart and now have a very odd trapezoidal loop antenna., But it works. Feed with 600 Ohm open wire line. Feed line comes into the garage and then into shack through garage wall. I use an MFJ 976 balanced line 1.5 KW tuner. I run about 700-900 watts out with an Ameritron AL-82 (which will be relegated to retirement when my Power Genius XL arrives) It works well 80-10 meters although the tuning is a bit peaky/touchy on the lower end of 10 meters. When a horizontal loop is operated above its fundament frequency, it radiates at a progressively lower take-off angle as the frequency rises. The pattern also  bcomes very complex as the frequency rises, however. It has worked very welll for me and my 6500. I just got a 6700 in the trade up program and I haven't tried it with the loop but I see no reason to expect any degradation in performance - I am busy building my Steppir DB 18E after recently installing a tilt-over telescoping tower and a NN4ZZ Tilt Plate, so I haven't been on the air much lately.

The new tower and beam will interfere with the loop as it stands right now. I will move it and convert it to about 540 feet for a full wave 160 meter loop and a lower angle radiator on 80 meters. Height will be a little better at about 70 - 45 feet. I love my loop, if you can't tell.   YMMV.

Brad
KE4XJ
(Edited)
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Mark WS7M

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Brad,

Thanks for the input.  I am a convert.  My loop is a crazy lopsided triangle that is getting me 59+ reports across the country on 75 watts!

It also seems to hear better.  I mean the signals simply look bigger. I don't have concrete data to support this but on my EF wire I was typically seeing S7 to S8 stations and once in a while I big signal.  Now I see LOTS of S9 and 10 over stations.

It is an easy antenna to build and hang and for those of us battling the HOA wars my loop is almost invisible and I'm sure it can't been seen by the double Octogenarians that live in this neighborhood.  I'm quite surprised some of them are still allowed to drive!  Kinda scarey.   

In this neighborhood we seem to have an abundance of 90+ year old people and one or two households of younger families.  The neighbor down the hill has two teen daughters who are now driving.  Dad got both fancy little BMWs so it is a scary place to live.  Between the 90 year olds and the crazy teen girls in their BMWs in the winter it will be quite the circus and no neither BMW is X drive model so I fully expect to see both girls in the ditch the way they drive!

I wish I had more time to op with the antenna.  My few contacts have been great.  Nice reports on very little power.   

So we will see how it turns out... but yes I love my little strange looking loop so far!
(Edited)
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Ken - NM9P, Elmer

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I ran a full-wave loop on 80 for a season or two a few years ago. It was only 10-18 ft high in a horizontal square. I only used it on 80. It was a cloud burner, but was solid 10-20 over 9 out for several hundred miles. As a loop, it was very quiet on receive. I wish the trees and tower here were compatible with a loop configuration. I tried one here, but one big big wind storm blew one of the wires over my chimney mounted 6 meter squalor and around my chimney and almost yanked some of it down. Poor placement of the trees!