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Author Topic: 160 Full Wave Loop  (Read 1027 times)
N4JOH
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Posts: 193




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« on: January 11, 2006, 02:27:40 PM »

Is a 160 meter full wave loop in the Horzionatal postion directional at all? Thank You 73 n4joh/John
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W4JVY
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Posts: 10




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« Reply #1 on: January 11, 2006, 07:30:51 PM »

I used an inverted "L" for years.....Until
I put up a 160 loop. the loop is 25 foot off
the ground. After using the loop for a while I took down the "L". Have worked some DX with the loop. A great
ant.
Don.
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NA4IT
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« Reply #2 on: January 11, 2006, 08:40:31 PM »

I could very well be wrong here, but I thought a loop fed on the side of a leg was non-directional, and one fed on the corner was directional to the opposing corner.

Correction appreciated if I am wrong.

Scott NA4IT
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W2PA
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« Reply #3 on: January 11, 2006, 08:51:11 PM »

A 160m one wavelength horizontal loop will be nearly omnidirectional on 160, and will have more complicated lobes on higher frequency bands.  It will radiate mostly straight up on 160 and then the radiation pattern will move to lower angles as you use it on higher frequencies, making it good for DX on 80m, 40m and higher.

For a really thorough treatment of horizontal loop behavior (and many other antennas), check out Cebik's web site (W4RNL): http://www.cebik.com/radio.html
Look for the link on horizontal loops.

73,
Chris, W2PA
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W8JI
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« Reply #4 on: January 12, 2006, 03:42:28 AM »

John,

The primary advantage of a horizontal loop is feedpoint impedance. It gives a low impedance at any harmonic of the design frequency, while a dipole gives a very high impedance on even harmonics and a low impedance only on odd harmonics.

If you have a 1.8 MHz loop, it will have a low impedance near any multiple of 1.8MHz.

If you have a 1.8 MHz dipole, it will have a low impedance only at 3,5,7, etc times 1.8MHz and a very high impedance at 2,4,6 etc times 1.8MHz.

While the pattern is different than a dipole at 3.5MHz and higher for a 1.8 MHz loop, the gain and pattern are essentially the same at 1.8MHz for both a dipole and a low horizontal loop. So the only difference comes in at 3.5MHz or higher, and that difference is the loop pattern breaks into many minor lobes.

This doesn't necessarily result in useful gain, since on high multiples of frequency evey peak is narrow and there is null right next to it. So statistically someone is as likely to fall into a hole as onto a gain peak.

While we all get enthused about a particular favorite antenna, in fact every apparent advantage comes with a disadvantage. If there was one antenna that had a clear universal advantage, almost everyone would use that antenna on every band.

On 160 meters, virtually eveyone finds an inverted L or tall vertical works better for almost anything, except QSO's within 100-200 miles or occasional unusual propagation.  The vertical or L does require a good ground system, but even a low loop or dipole benefits as much as several dB from a good counterpoise when close to ground.

If I could only have one antenna and wanted to work in general QSO use on multiple bands, I'd either use a loop or a ladder line fed dipole with proper feed systems. If I wanted a 160 meter specific antenna, I'd use a vertical or Inverted L with a good ground.

73 Tom
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K9FV
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Posts: 480




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« Reply #5 on: January 12, 2006, 10:11:10 AM »

Agree with everything W8JI says - except the 100 o 200 miles.  Extend that out to 300 to 400 miles and I agree.  The biggest lobe on a 160  square loop, (makes a difference how many sides it has) mounted about 40/50ft up, will take off somewhere around 50/60 degrees, maybe up to 70 degrees.  This should give you contacts out to a few hundred miles, but NOT thousands of miles....

Just check, and if you have a 400 mile radius from your QTH, you'll be able to do a LOT of ragchewing on 160meters.

73 de Ken H>
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