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Author Topic: Loop or Longwire?  (Read 818 times)

Offline ultravista

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Loop or Longwire?
« on: April 03, 2020, 0123 UTC »
Will a loop out perform a long wire of similar length?

I have two spools of black 14 gauge wire and enough backyard & tall trees to string up at least 500-700 feet.

A 600 foot loop or longwire?

Offline redhat

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Re: Loop or Longwire?
« Reply #1 on: April 03, 2020, 0147 UTC »
*Cue Chris Smolinski...

A loop AFAIK will have lower noise than a long wire, although lower overall sensitivity.

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Offline ThElectriCat

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Re: Loop or Longwire?
« Reply #2 on: April 03, 2020, 0236 UTC »
Are you specifically interested in low frequency? high frequency? or just general coverage?
I rarely venture above 10 MHz and spend most of my time below 5, and I prefer the wire any day, but I used to use a loop for HF ham radio a lot, and they're pretty nice.
In another life, I could have been a telephone engineer.

Offline Pigmeat

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Re: Loop or Longwire?
« Reply #3 on: April 03, 2020, 1230 UTC »
It depends on your use for it, listening or transmitting. In about a week the static levels here on longwires makes them worthless and it's time to switch to beverages on the ground, BOG's for dx listening. If you can get it to match at 15 ft. you're into Wayne Green of "'73 Mag's" Lazy Loop territory. It's a single loop of wire that works from the upper part of the commercial AM radio band  to the top of 20 meters. These are all one man antenna's as I never wanted drag someone into my trouble making.

Offline ChrisSmolinski

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Re: Loop or Longwire?
« Reply #4 on: April 03, 2020, 1546 UTC »
Your loop would be about the same size as my sky loop (presently 670 ft or so, give or take some repairs done over the years). It works well over all of HF, and is excellent on the upper and of MW where it is about a wavelength. Signal levels then drop as you go lower in frequency, and it's pretty deaf on LW, I assume because the impedance is very low. Dedicated antennas for a particular band always work best, but it's a great antenna overall, and my primary antenna for 43m listening.

I feed my sky loop with a 4:1 balun, and can load it up nicely on 160, 80, and 40 meters with a tuner.  Or if you are going receive only, get one of my Cyclops or Jellyfish transformers (shameless plug time):
https://www.blackcatsystems.com/rf-products/cyclops_rf_ham_shortwave_radio_matching_transformer.html
https://www.blackcatsystems.com/rf-products/potted_matching-transformer-unun-balun-beverage-longwire-k9ay-flag-ewe-dipole-antenna-shortwave-ham-radio.html


If you have the space for a several hundred foot terminated longwire / beverage antenna or two as well, you might find it is useful as it will have some directionality. They will also work better at lower frequencies (LW and MW) than a loop antenna with the same amount of wire. I don't find my terminated longwire/beverage antennas to be particularly noisy. If you leave it un-terminated it will have directionality in both directions along the length of the wire. And hey, the Cyclops and Jellyfish transformers work great for these antennas as well!  :)

Chris Smolinski
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netSDR / AFE822x / AirSpy HF+ / KiwiSDR / 900 ft horizontal loop / 500 ft northeast beverage / 58 ft T2FD / 120 ft T2FD/ 300 ft south beverage / 43m / 20m / 10m  dipoles / Crossed Parallel Loop / Discone in a tree

Offline ultravista

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Re: Loop or Longwire?
« Reply #5 on: April 04, 2020, 1328 UTC »
The antenna is for receive only and I tune from below broadcast AM to about 20,000 KHZ - there doesn't seem to be anything above 20 K. The long wire I use is also deaf on LW, although when the conditions are good, 160 meters is pretty hot.

If I do a skyloop, what is the best way to connect coax, something similar to a dipole?

What is the theory of a terminated long wire? How does it eliminate directivity and reduce noise? How do you terminate it?

As far as a beverage, I do have pretty big backyard with a lot of trees and space. I could easily trench and bury wire. Would the beverage be a loop, specific length of wire, or as long as I can go? How do you connect the coax and do you need anything else, an amp, or?

Offline ultravista

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Re: Loop or Longwire?
« Reply #6 on: April 04, 2020, 1342 UTC »
f you can get it to match at 15 ft. you're into Wayne Green of "'73 Mag's" Lazy Loop territory. It's a single loop of wire that works from the upper part of the commercial AM radio band  to the top of 20 meters.

Have a link, I searched but didn't find 'Wayne Green Lazy Loop' results.

Offline ChrisSmolinski

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Re: Loop or Longwire?
« Reply #7 on: April 04, 2020, 1645 UTC »
If I do a skyloop, what is the best way to connect coax, something similar to a dipole?

As I mentioned in my post above, feed with a transformer, around 4:1 impedance ratio.

Quote
What is the theory of a terminated long wire? How does it eliminate directivity and reduce noise? How do you terminate it?

As far as a beverage, I do have pretty big backyard with a lot of trees and space. I could easily trench and bury wire. Would the beverage be a loop, specific length of wire, or as long as I can go? How do you connect the coax and do you need anything else, an amp, or?

Terminate with a resistor equal to the impedance of the antenna, from the far end of the antenna to ground. Or just guess and go with 300 or 400 ohms. And as I also mentioned above, use a transformer  :)
Chris Smolinski
Westminster, MD
eQSLs appreciated! csmolinski@blackcatsystems.com
netSDR / AFE822x / AirSpy HF+ / KiwiSDR / 900 ft horizontal loop / 500 ft northeast beverage / 58 ft T2FD / 120 ft T2FD/ 300 ft south beverage / 43m / 20m / 10m  dipoles / Crossed Parallel Loop / Discone in a tree

Offline Charlie_Dont_Surf

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Re: Loop or Longwire?
« Reply #8 on: April 06, 2020, 0024 UTC »
there doesn't seem to be anything above 20 K.

Yes, for now. In about 4 or 5 years from now, it should be pretty good though. There will be periods between now and then when that area may show flashes of brilliance but you've got plenty of time to prepare for that.
"Every minute Charlie squats in the bush, his signal gets stronger..."

Offline Pigmeat

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Re: Loop or Longwire?
« Reply #9 on: April 07, 2020, 0100 UTC »
I remember my first couple of go rounds with Wayne's loop. It would be cooking as whole loop, I used KIPM as source signal as it was always up and going all night when Max was transmitting. I was using a Sangean 909 as the test receiver, and quality mixer/ amp patch cord for the 6 ft of coax for the antenna hook-up. (it was some grade of mini-coax, RG 173 or something like that).

That loop was the deal on most static ridden nights, so I started playing with it. If I unhooked one or the other side, the signal took a nose-dive into the static, about as good as the whip on the thing. Hook one side up,it was a longwire on the ground. Hook up both, it sounded like someone screwing around at a local AM TX between it's sidebands with a powerful signal. (Max liked SSB so it was fairly easy to make a comparison to his signal)

That's been nearly 20 years ago,it seems like a lifetime. Have fun with whatever it is you're doing.

Offline hdofu

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Re: Loop or Longwirer
« Reply #10 on: May 25, 2020, 0523 UTC »
Wire in my experience has always been the better experience with coverage