Outdoor loop antenna

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I work in a electrical central I m here 2 weeks and one week at home I want to do some dxing here but cannot install a diapole my room is on the 4 th floor was wondering if a loop antenna outside my window would do the job for weak shortwave signals
 

ka3jjz

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Quite possible; you can find many homebrew plans out on the web, or get a Pixel or Wellbrook. Both are well regarded (there's something of a friendly rivalry going on between the two via the numerous reviews on both). Both are expensive, but perform well.

If you go the homebrew route, you will need some sort of amp at or near the base, as signal levels from a small 1m or so loop would be very low.

One thing - what kind of radio would you be using the loop with? Mike
 

dsalomon

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I've used both Pixel and Wellbrook antennas. They're both great performers. I think Welbrook is shipping from the UK, so the shipping might be more expensive. Other than that, they're about equal performers and will both outperform many other receive only antennas, which, given their physical size, is quite a feat. They'll outperform most any lonwire or large wire unamplified loop. The really nice thing about those loops is that they are significantly lower noise than many other antennas. They'll cost around $500, but are well worth it. Given your location, you could literally hang it from the window or find a way to set it on a windowsill, if you have one.

There are much less expensive small loop designs available, which I've seen marketed mainly to the portable shortwave receiver market. They don't perform nearly as well as the larger Wellbrook/Pixel loops. I think that's why Mike asked what type of radio you're using. The portable shortwave receivers (Grundig, Sony, etc.) tend to be less sensitive than many mobile ham radios or other serious receivers. Putting a high gain loop like the PIxel on a portable shortwave might overload it, but it would be perfect for a receiver designed for more input. However, those less expensive loops are well matched for the portable receivers. Don't expect the kind of performance out of a portable shortware receiver that you'd get out of a serious HF receiver, regardless of the antenna. The difference will be in weak signal reception, which you're more likely to hear with the better receivers and miss with the low cost portables, regardless of the antenna. If you're trying to listen to the big shortwave broadcasters, then anything should work OK as they're typically very strong signals.

Also, like Mike said, you can homebrew. It's just wire, an amp and some way to make the wire hold it's shape. A quick Google will turn up a LOT of options.

Best regards - David
 

ridgescan

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I say YES. Yes on getting the antenna out of its RF cage. The stuff like metal building framing, house wiring, pick up the RFI-producing TVs computers etc. within and that could be all you hear in HF, especially with an active loop-so if you move the loop outside that trap you may open up more desired signals. I am only speaking to you from direct experience here. I am in a metal framed building, with that re-bar type screening within stucco walls and aluminum window frames and it's all bonded to ground. When I had to take down my Wellbrook loop from the roof for them to put a new roof on the building, I ran the loop here inside the apartment. Though it did receive stuff in here, it was not nearly as strong as when it's up there out in the open. Try it out and hopefully there will be better DX for you.
 

902

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Those loops do a very nice job. My friend in New Jersey built a 40 meter magnetic loop antenna because his apartment did not allow outside antennas. We had a successful QSO for about a 1,600 km path very early in the morning when the noise was low.

Loops are directional, so you will find it receives better in a given pair of directions. Also, the noise from various sources will be things you may fight against.

I saw the DX Engineering loop. I've bought DXE things before and have been satisfied with their products or modifications to an existing product. I was thinking of getting it and mounting it on a TV rotor just for receiving so I could tune out noise. If you get one, I would be very interested in knowing how well it works for you.

I also took a closer look at the Wellbrook antennas. I hadn't heard of them before, but they look very impressive, especially in their frequency coverage.

Best of luck!
 
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ridgescan

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Those loops do a very nice job. My friend in New Jersey built a 40 meter magnetic loop antenna because his apartment did not allow outside antennas. We had a successful QSO for about a 1,600 km path very early in the morning when the noise was low.

Loops are directional, so you will find it receives better in a given pair of directions. Also, the noise from various sources will be things you may fight against.

I saw the DX Engineering loop. I've bought DXE things before and have been satisfied with their products or modifications to an existing product. I was thinking of getting it and mounting it on a TV rotor just for receiving so I could tune out noise. If you get one, I would be very interested in knowing how well it works for you.

I also took a closer look at the Wellbrook antennas. I hadn't heard of them before, but they look very impressive, especially in their frequency coverage.

Best of luck!
902-I was told that the loop is directional "off the ends", my own experience probably due to the fact that mine is up 50' off the dirt, is it's sort of directional in SW and highly so in MW. But it sometimes fools me and is more directional in some instances "off the broadsides". I may have also complicated things by putting an ugly balun up near the loop. What's your take?
 

902

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902-I was told that the loop is directional "off the ends", my own experience probably due to the fact that mine is up 50' off the dirt, is it's sort of directional in SW and highly so in MW. But it sometimes fools me and is more directional in some instances "off the broadsides". I may have also complicated things by putting an ugly balun up near the loop. What's your take?
Well, I'm wondering if the directional characteristics are dependent on resonant frequency. I don't have a lot of experience with these, but it would stand to reason that some excursion from resonance would modify the pattern. I've seen this on vertical collinear antennas where the antenna has no electrical tilt at resonance, but can be "uptilted" or "downtilted" based on frequency.

Gonna look that up. That loop I was looking at was going to go about 35 feet up. The ones I see in the ads appear to be more or less ground mounted.
 
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