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Author Topic: Multiwave length large loops 2 wave lengths say for 160. Anyone try 1,2 or 3 wav  (Read 937 times)
KZ4USA
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Posts: 293




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« on: November 06, 2017, 04:38:05 PM »

Just wonder if anyone has tried one if they have the room.
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KE8ICK
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Posts: 30




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« Reply #1 on: November 06, 2017, 07:38:02 PM »

A full wave at 160m is almost a quarter mile. In a square configuration that comes to 130' on each side, which would require roughly 2 acres. Even a dipole for 160 is almost a football field long. With my 1/2 acre lot, I can only dream of working 160.
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ZL1BBW
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Posts: 1220




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« Reply #2 on: November 06, 2017, 08:47:01 PM »

I am working on getting a 1 wl loop on 160 up, it will be fed with about 70mtrs of open line back to the shack.
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ex MN Radio Officer, Portishead Radio GKA, BT Radio Amateur Morse Tester.  Licensed as G3YCP ZL1DAB, now taken over my father (sk) call as ZL1BBW.
KZ4USA
Member

Posts: 293




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« Reply #3 on: November 06, 2017, 09:36:54 PM »

A full wave at 160m is almost a quarter mile. In a square configuration that comes to 130' on each side, which would require roughly 2 acres. Even a dipole for 160 is almost a football field long. With my 1/2 acre lot, I can only dream of working 160.


Yes 554ft for 160 is full wave but you could double that too. Im going to put up a 554ft and play with that then maybe
double that and see what happens. Im here on 6 acres so I have the room. 4:1 balun is one way to feed it. The ladder line
could be used too but I worry about RF using ladder line.
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KZ4USA
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Posts: 293




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« Reply #4 on: November 07, 2017, 05:15:01 AM »

Wonder if it effects the antenna if I ran some of it through the trees with insulated wire. If I ran a 2 wL  I would need the extra
room and would need to run it through tree limbs..  With just the 554ft I can run that out in the open.

Just wondered about running  insulator wire through tree limbs.
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KU3X
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Posts: 411




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« Reply #5 on: November 07, 2017, 06:14:05 AM »

If you have enough room for a 160 meter loop that is 4 wavelengths or more, why not build a rhombic instead?
Barry
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KZ4USA
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Posts: 293




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« Reply #6 on: November 07, 2017, 06:43:10 AM »

If you have enough room for a 160 meter loop that is 4 wavelengths or more, why not build a rhombic instead?
Barry

Only problem they will be directive.. I though about a V beam running NE to SW from Fla into Europe and out to the
VK land. There is one V beam design that fires both ways. 6 acres is rectangle shape running east and west.
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KZ4USA
Member

Posts: 293




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« Reply #7 on: November 07, 2017, 08:51:44 AM »

The trouble that I always have with large loops is pulling the wire tight and getting sag out of the wire and that puts
lots of tension in the feed point like on a 4:1 balun. Now if the wire is run up through tree limbs then I don't have that problem since there is plenty of support and I can get almost a round circle shape too.
So I might be better with the better shape and 554ft of wire and supported through the trees then rectangle shape and thrying to pull that tight hanging in the clear?HuhHuhHuh

Which would be best?Huh?
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WB6BYU
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Posts: 17053




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« Reply #8 on: November 07, 2017, 11:51:11 AM »

Quote from: KZ4USA

... I can get almost a round circle shape too...



Don't get confused between small loops, where a circle has a slight advantage in radiation resistance
vs. a square loop, and large loops (a wavelength or more), where a circular loop may not be optimum
for a particular size / band / desired radiation pattern.

I just modeled a circular (well, 12-sided) loop, and any improvement over a rectangular loop isn't worth
the bother of creating the model.  That doesn't mean that you shouldn't make it multi-sided when you
have the supports to do so, but rather than any potential differences would have to be evaluated over
a range of specific elevation angles, distances, and frequencies to see which is better.  My general sense
is that a circular loop has less distinct lobes and nulls than a square loop:  which is better over a particular
path will depend on how the major lobes of the square loops are aimed, as those are stronger than the
lobes of a circular loop, but the nulls are deeper as well.

There are issues with making a loop too big, however.  This 160m circular loop used on 10m has
30 major lobes, each with a beamwidth of perhaps 5 degrees, of which 7 appear to have significant gain
over a dipole.  On 20m it has 16 major lobes, but the strongest is only 1 to 2 dB stronger than a dipole.
By comparison, a square loop has 12 lobes, and the peaks are 1 dB stronger.

What I found on Field Day with a square 80m loop fed in a corner was that the main beamwidth was
rather narrow on 15m, so I could only focus on a portion of the East Coast from here in Oregon.   It did
well in that direction, but a beam of some sort would have given me better gain over a wider area.  On
10m the pattern broke up into a lot of individual lobes that I really couldn't steer in a particular direction.


The real advantage of a large loop (2 wavelengths or more) is that it reduces high angle radiation and gives
you more radiation at low angles, assuming the loop is high enough to support that.  Most practical
loops are too low to see much improvement on 80m, though there may be some, especially if you can mount
your loop up 60' - 80'.  On 40m and 20m there isn't a lot to be gained by increasing the loop size past
80m:  at that point height gives more improvement than a larger loop.  With a 2-wavelength loop for 160m
your low angle radiation will still be limited by height above ground, and you'll have an overhead null that
will make it more difficult to work local stations using NVIS.  It may be worth trying if you want to reduce
interference from local stations coming in at a high angle, however.


If you do want to try a large loop, I wouldn't worry about running it  through the trees, especially if you are
using insulated wire.  If you are using a kW then you may want to provide intentional insulators where the
wire makes a bend, so you don't wear the insulation down at that point as could happen if it is just bending
around a branch or a tree trunk.
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N7ZDR
Member

Posts: 110




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« Reply #9 on: November 07, 2017, 12:02:48 PM »

I have ran my insulated wires through the trees for years-- It dont hurt anything! You will come across all the naysayers that always come up with all the reasons not to. Don't pay any attention to them as they most likely have not tried it. I use the cheap 14ga wire from the big box store sold in 500' lengths.
Does is break--- Sometimes sure-- just get out there and splice it back together with yellow wire nuts--- good enough till spring!

I have tried all different lengths of loops over the years and have ALWAYS came back to the single full wave. Unless you have tall supports of say 150' plus I have come to the conclusion the extra length is not worth the trouble. I fact, I would say from my experience, a length more than a full wave degrades performance on 160 meters.

Again I am referring to heights above ground at at about 25-60 feet

Cheers
Larry

BYU-- you beat me to the post!! ha ha
« Last Edit: November 07, 2017, 12:05:30 PM by N7ZDR » Logged
KU3X
Member

Posts: 411




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« Reply #10 on: November 07, 2017, 02:22:46 PM »


If you do not terminate a rhombic, it does fire in two directions. Terminated, it is then one direction.
Barry
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WE6C
Member

Posts: 18




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« Reply #11 on: November 09, 2017, 09:44:34 AM »

I have ran my insulated wires through the trees for years-- It dont hurt anything! You will come across all the naysayers that always come up with all the reasons not to. Don't pay any attention to them as they most likely have not tried it. I use the cheap 14ga wire from the big box store sold in 500' lengths.
Does is break--- Sometimes sure-- just get out there and splice it back together with yellow wire nuts--- good enough till spring!

I have tried all different lengths of loops over the years and have ALWAYS came back to the single full wave. Unless you have tall supports of say 150' plus I have come to the conclusion the extra length is not worth the trouble. I fact, I would say from my experience, a length more than a full wave degrades performance on 160 meters.

Again I am referring to heights above ground at at about 25-60 feet

Cheers
Larry

BYU-- you beat me to the post!! ha ha

Larry, I've also run that same insulated wire through trees for years with no problems, and a KW. I also don't worry about some sag. No station on the other end will know but it does give some room to move with the wind etc.

To the op, I've used ladder line/open wire line for years with no RF problems.

Bob  WE6C
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WE6C
Member

Posts: 18




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« Reply #12 on: November 09, 2017, 09:49:59 AM »

A full wave at 160m is almost a quarter mile. In a square configuration that comes to 130' on each side, which would require roughly 2 acres. Even a dipole for 160 is almost a football field long. With my 1/2 acre lot, I can only dream of working 160.


You can do it with a half acre. I have only 6/10 acre and do fairly well on 160. On line there's loading coil calculators so you can install some loading coils in each leg of a dipole and get on 160.

This is the one I like...
http://www.k7mem.com/Electronic_Notebook/antennas/shortant.html

Give it a try.  Bob  WE6C
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KZ4USA
Member

Posts: 293




Ignore
« Reply #13 on: November 10, 2017, 07:04:59 PM »

I have ran my insulated wires through the trees for years-- It dont hurt anything! You will come across all the naysayers that always come up with all the reasons not to. Don't pay any attention to them as they most likely have not tried it. I use the cheap 14ga wire from the big box store sold in 500' lengths.
Does is break--- Sometimes sure-- just get out there and splice it back together with yellow wire nuts--- good enough till spring!

I have tried all different lengths of loops over the years and have ALWAYS came back to the single full wave. Unless you have tall supports of say 150' plus I have come to the conclusion the extra length is not worth the trouble. I fact, I would say from my experience, a length more than a full wave degrades performance on 160 meters.

Again I am referring to heights above ground at at about 25-60 feet

Cheers
Larry

BYU-- you beat me to the post!! ha ha

Are you working any DX with the large loop Far east  JA into EU land or India area from where you are???
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N4MQ
Member

Posts: 139




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« Reply #14 on: November 11, 2017, 06:00:37 AM »

Previously I relied on a E-W and N-S windom for my hf antennas and wanted to try something else.  My first 1 wave 160 m loop was a tight triangle due to the available supports and it was sad.

With planning and the use of my quad copter I hung pulley supports and ended up with a square-ish shaped 860 foot loop with supports at 40 to 100 foot elevation.  Fed with ladder line (600 ohm) and hung with pulleys for wire movement and a spring loaded pull down rope support at the feed point.

 I have the ladder line going to the  1 to 1 balun on the exterior concrete basement wall feeding, rg 213 into my shack's MFJ  killowatt autotuner. Previously I had used a 4 to 1 balun but the autotuner could not match spots in the hf bands and it appeared that the resulting impedance was too low for the tuner.

This loop works fantastically as the locals see a 10 db gain reported from NC to PA 0n 160 m and into Italy I5ZSS and Belgium ON7USB on 20 m SSB one afternoon, wow beat the windoms.  Receiving is a bit quieter noise wise than the windom but my 12' mag loop is still quieter.  Never the less, Iam stuck on loops for sure now.  The wire is the fine stranded wireman 14# copper heavy HPVC insulated style rated at about 100# strength.

For protection I have built a relay control system that grounds all antennas and the loop.  The dual relay system will also switch the loop to another relay control box that is controlled by the strain on the spring and it's mercury switch.  When the antenna rope strain exceeds the tilt switch setting, an adjustable isolated ac power supply of up to 50 volts is fed to the 4.3 ohm loop to heat the wires for ice protection.  Charts and my thermo-camera agree with about 10 degree rise which should be able to melt any ice formation that may occure,

I had to use a strain switch mechanism as the thought of running the heating system long term would use terrific amounts of power ( 10+ amps ) and the chance that an ice storm pops up when Iam not home leaves me exposed.  A temperature switch would be no better, loading on the antenna should be a solid signal that ice formation has begun.

Being way over a single wavelength 160 meter loop, shows me that they can really get out locally and still work DX.  Id recommend them and if I had more trees located elsewhere, Id go bigger at least for the experience.

My relay controls are partially shown on my link,enjoy.. Woody  

https://sites.google.com/view/n4mq-site/home
« Last Edit: November 11, 2017, 06:12:23 AM by N4MQ » Logged
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