Powerlines and Skyloop Antenna

[radioetc]

I am considering the installation of a "skyloop" type of antenna due to its reputation for reducing noise.

In my backyard, I have low voltage and distribution voltage power lines. My question is how close can an antenna be to those lines? And I am asking this question not only through the lens of a safe distance but also from a performance perspective too.

The concern is I would have to run portions of a skyloop parallel to both the low voltage drop to my house and also the distribution and low voltage lines along the back property line. So the question is how close could a parallel installation be where it is both safe and reasonable for performance?

For example, should a sky loop be 10 feet away, 20 feet away, or no distance because it work so don't do it kinda thing?

Here's the noise profile on my property. While I have weird intermittent noises coming from lines in the neighborhood about 250 feet from my house up the street (suspect aerial cable trunk amplifier), the lines in my backyard near where the antenna would parallel are not bad at all. If I take a portabe shortwave radio with a whip antenna and walk right under them I get some variant of white noise. But then it immeadately goes away once I walk away a few feet or so. All things considered, a pretty good noise environment for a subdivision.

FYI, I've been experimenting with the MLA-30 magnetic loop antenna and I really like this thing and this has inspired me to wonder about a backyard skyloop.

Thoughts, comments, suggestions?

 

[ka3jjz]

I would think the greater the distance the better. Your experiment with the portable strongly suggests this. However before you go whole hog on this, what radio are you going to put this on? Not knowing where you are (county/state is fine), it's hard to judge, but I would hesitate putting a skyloop up for, say, a SDRPlay, but for a Drake R8 series, no worries. Overloading can and may well be a concern if you are near an area with lots of MW and FM stations nearby and you're using a SDR. Solid front end filtering is yet to really happen but it is getting better. But it's not on the level of a Drake or JRC receiver - yet...Mike

 

[ka3jjz]

It would also help to know what kind of skyloop you plan to erect. A delta loop is popular,but there are others - if you are lucky enough to have the space...Mike

 

[radioetc]

The main radio would be Tecsun PL-880. I know this is not high end but what I can afford. As far as exactly skyloop type, not sure. Any suggestions would be great.

While keeping the antenna as far away from power lines is understood, the question is exactly how far? Because the answer to this question governs whether I should attempt this at all, and if so, exactly how large the loop can be, etc. I have the space to erect a large loop but in order to do that, one side would have to run parallel to power lines and another side paralell to low volatage distribution lines. Otherwise, if I have to keep the antenna X distance from this, then it is going to be rather small loop.

 

[ka3jjz]

One of the most common kinds of skyloop is the Delta. You can google that. It's rather large, and is created in the rough shape of a triangle (the Greek letter delta) which is where it gets its name.

I'd hesitate to put such an antenna on a portable - any portable short of maybe an Eton E1. While skyloops aren't high in gain just the sheer amount of wire needed for a skyloop means there will be a lot more RF coming to that front end. Portables generally aren't designed to handle this. A passive preselector such as the one below might be a good investment in this case;

MFJ-956 Preselector

It's impossible to be quantified about how far the antenna should be from the power lines simply because each situation is different. You've already learned that the noise vanishes a few feet away from one set of lines; does that hold true about these low voltage distribution lines too?
If so then you know how far away you must be from them.

There are other low noise antenna options besides a loop - the Vibroplex (boy is this going to take some time to get used to saying) PAR End Fed is one solution, and it is very popular. You can replace the wire lead with another length. There's the EWE and even a loop on the ground (but this takes a good bit of experimentation to make work). There are definite advantages to having different kinds of antennas - a signal that isn't doing so well on one antenna might be coming in better on another.

Mike

 

[ka3jjz]

Here are a few links on the subject of quiet HF antennas. Included in here is something on the T2FD, and one or two other sources.

Delta Loop for HF

Par EF-SWL, LNR Precision EF-SWL End Fed Dipole SWL Antenna. Par EF-SWL.

T2FD, The Forgotten Antenna -- antenna special on hard-core-dx.com

EWE Antenna review :: DXing.info

The Loop on Ground Antenna - the "LoG"

A prototype receiving antenna for HF

kk5jy.net

160-20m LOG loop-on-ground

Like jjz, this I love my loops but this time decided to try on that is totally on the ground. RX ONLY. I don't have room for beverages, and have been down the so-called "snake" on ground antenna before, with unpredictable results. This loop is predictable. Basically it is a 15-foot square...

forums.radioreference.com

Wire - Interesting short half wave antenna

Mike

 

[WA8ZTZ]

From a safety viewpoint, NEVER run an antenna wire under or over any powerline.
Other than that, you won't really know how an antenna will perform at a certain location
with a certain radio until you try it.
IMHO, an elaborate antenna system is overkill for a portable.
The nice thing about a portable is that it is portable... you can move it away from the noise.

 

[ka3jjz]

I quite agree. Most portables simply don't have a front end that can handle long elaborate antennas. The PAR is known to work well with that radio. You can substitute a longer length of wire and if you have the space point it away from the power lines. Without knowing where you are, it's hard to say for sure, but this (and the short half wave) are likely to be your best bets, with the EWE a close second since it doesn't have to be very long. Mike

 

[radioetc]

Here are a few links on the subject of quiet HF antennas. Included in here is something on the T2FD, and one or two other sources.

Delta Loop for HF

Par EF-SWL, LNR Precision EF-SWL End Fed Dipole SWL Antenna. Par EF-SWL.

T2FD, The Forgotten Antenna -- antenna special on hard-core-dx.com

EWE Antenna review :: DXing.info

The Loop on Ground Antenna - the "LoG"

A prototype receiving antenna for HF

kk5jy.net

160-20m LOG loop-on-ground

Like jjz, this I love my loops but this time decided to try on that is totally on the ground. RX ONLY. I don't have room for beverages, and have been down the so-called "snake" on ground antenna before, with unpredictable results. This loop is predictable. Basically it is a 15-foot square...

forums.radioreference.com

Wire - Interesting short half wave antenna

Mike

Thanks! I'll take a look!

 

[radioetc]

I quite agree. Most portables simply don't have a front end that can handle long elaborate antennas. The PAR is known to work well with that radio. You can substitute a longer length of wire and if you have the space point it away from the power lines. Without knowing where you are, it's hard to say for sure, but this (and the short half wave) are likely to be your best bets, with the EWE a close second since it doesn't have to be very long. Mike

For whatever it is worth, I have the cheapo MLA-30 amplified magnetic loop antenna. I run it with the 3 position sensitivity switch on the Tecsun in the lowest "local" mode. Strong stations rarely exceed 70 dbμ. On a handful of occasions with the best conditions 85 dbμ. On a random long wire or with the whip, the strongest is usually in the 60 dbμ or somewhat north of that.

 

[radioetc]

From a safety viewpoint, NEVER run an antenna wire under or over any powerline.
Other than that, you won't really know how an antenna will perform at a certain location
with a certain radio until you try it.
IMHO, an elaborate antenna system is overkill for a portable.
The nice thing about a portable is that it is portable... you can move it away from the noise.

So let's say noise wasn't a problem if I run a loop segment parallel to the power lines, not going over or under those lines. Let's say the power lines are about 30 feet off the ground. Let's say my loop segment is 10 feet off the ground. And then let's say this segment is 10 feet away from the power lines (if my antenna was the same height as those lines). I 10 feet away enough from a safety point of view?

 

[WA8ZTZ]

Working on an antenna 10' from a powerline
is just too close for comfort.
Stay far away from powerlines from both a safety and
a noise standpoint.

 

[scancomms]

I agree the PAR antenna is great and might be your best option. The antenna wire goes directly to ground on the primary winding and the secondary winding couples to the radio. Attach one end of the secondary winding to the coax center and the other end of the secondary to the coax shield and the ground post. This is why it is good on a portable radio. Signals are reduced, reducing signal over load but the noise is reduced more than the signal. I made one and then bought one and I can't tell the difference. Very easy to make.

 

[fourgres]

Good Advice, Stay away from power lines. In storms many times High Voltage lines fall on Low power lines. (Ex Utility Worker)

 

[casper150]

Not to hijack the thread but what about running coax 90 degrees under the house utility line. will this have any effect for swl ony.