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Receive Antennas (below 30MHz) - For all topics related to receive antennas used on HF, MW, LW, etc. For transmit antennas use the Amateur Radio Antennas forum.

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Old 11-17-2017, 10:10 PM
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Default 100' Endfed Wire Question

I'm just wondering-due to space limitations, my 100' end-fed wire has to make an abrupt turn at the 45' mark. By abrupt, I mean it makes an immediate bend there around a 2" wood dowel. My question is this-does that hard bend that makes this wire a "horizontal "L" cause a change in the receive characteristics of this wire? Should I take steps to "round out" that turn to make it more continuous? Or do you think it makes no difference? It works very well as it is but I wonder if it's all it could be.
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Old 11-18-2017, 5:01 AM
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Ridge don't you have the loop on a rotator? The end-fed wire is pretty redundant and you could probably just take it down... as the loop should out-perform it.

The hard turn will make it inefficient but for Rx it's not as important. You really just have a 100ft random wire antenna...

I'm presuming you're using an antenna switch on the R75? The switch is taking away an S-unit from your signal so removing the random wire means removing the switch... and giving a slight gain.
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Old 11-18-2017, 6:13 AM
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Actually there are some advantages to having more than one kind of antenna. It's difficult to predict how a given signal will be heard at your location - it might be inaudible or weak on one, but perfectly readable on another.

Like the other poster said, you have a 100 foot wire; the bend probably makes for some weird patterns on some frequencies though. But having 2 antennas makes your setup more flexible.

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Old 11-18-2017, 6:57 AM
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I didn't see that he was using two receivers. That's preferred rather than using a switch. If the random wire works well then why bother fixing what's not broke?
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Old 11-18-2017, 8:57 AM
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If the 100ft wire was in free space, or 150ft up in the clear and horizontal, you could easily predict its pattern based on frequency and fractions of a wavelength, etc. Put a bend in it and it gets complicated. Put it a few feet above a building with all that metal around and the chance of estimating its performance is out the window unless you can precisely enter all the building parts into a good antenna analysts program like EZNEC.

I suspect its good for picking up stuff in the 2 to 10MHz range out to 500mi in the cloud burner mode (NVIS). Since its on a roof a few stories up that would improve its low angle pick up a little but the close proximity to lots of metal in the building will always have a serious effect on its performance.

With all that said I think it would outperform a loop in many ways except for the loops ability to null out specific noise sources. I would experiment with a 9:1 balun or other balun ratios and an additional 1:1 choke balun to reduce noise pickup from the building traveling up the coax. You can only play in the space available and it may be close to the best you can do at this point.
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Old 11-18-2017, 10:30 AM
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Quote:
Originally Posted by devicelab View Post
Ridge don't you have the loop on a rotator? The end-fed wire is pretty redundant and you could probably just take it down... as the loop should out-perform it.

The hard turn will make it inefficient but for Rx it's not as important. You really just have a 100ft random wire antenna...

I'm presuming you're using an antenna switch on the R75? The switch is taking away an S-unit from your signal so removing the random wire means removing the switch... and giving a slight gain.
Yeah I do have the Wellbrook, and it does a better job than the wire in MW, but the wire out-performs the loop below 7megs. But like Mike says below, the loop is capable of cleaner signals above 9megs by way of nulling. For example, at night I like 9455/9395kHz WRMI out of Florida and their signals are messy with the wire, but way cleaner on the loop pointing east.
I need to update my signature below as I am now running the wire (via an AlphaDelta 2-way switch) to the R75 in the living room-and the SX-88 (through 30' LMR240 patch) in the bedroom. I see no discernible loss of S-units on that SX-88 meter.


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Originally Posted by ka3jjz View Post
Actually there are some advantages to having more than one kind of antenna. It's difficult to predict how a given signal will be heard at your location - it might be inaudible or weak on one, but perfectly readable on another.

Like the other poster said, you have a 100 foot wire; the bend probably makes for some weird patterns on some frequencies though. But having 2 antennas makes your setup more flexible.

Mike
You're so right Mike. Like I said to devicelab, each antenna "out-performs" the other at different points throughout the bands, so what I do have is diversity. I'm in hog heaven antenna-wise here.
Far as the bend, that's what I'm wondering-is that bend sharp enough to cause an "electrical interruption" in the receive pattern of the wire, similar to say the "squiggly" in a scanner antenna does at higher frequencies.

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Originally Posted by prcguy View Post
If the 100ft wire was in free space, or 150ft up in the clear and horizontal, you could easily predict its pattern based on frequency and fractions of a wavelength, etc. Put a bend in it and it gets complicated. Put it a few feet above a building with all that metal around and the chance of estimating its performance is out the window unless you can precisely enter all the building parts into a good antenna analysts program like EZNEC.

I suspect its good for picking up stuff in the 2 to 10MHz range out to 500mi in the cloud burner mode (NVIS). Since its on a roof a few stories up that would improve its low angle pick up a little but the close proximity to lots of metal in the building will always have a serious effect on its performance.

With all that said I think it would outperform a loop in many ways except for the loops ability to null out specific noise sources. I would experiment with a 9:1 balun or other balun ratios and an additional 1:1 choke balun to reduce noise pickup from the building traveling up the coax. You can only play in the space available and it may be close to the best you can do at this point.
prcguy
I actually put a 1:1 air-wound on the loop on a "what have I got to lose" theory and to this day I am not sure just how much it helps common-mode..but I did detect after initial deployment, some diminished "hiss" that I was getting without it.
I do have the 9:1 transformer from the PAR EF-SWL system on the 100' wire already. But that "sharp bend"; that is what I was curious about.
I guess some experimenting is in order and I will have to find a way to "round out" that sharp bend to see if it makes a difference.

BTW I was thrilled that I actually got a NDB last night on BOTH antennas out of Hawaii on 353kHz! Like 2600 miles on that one.
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Old 11-18-2017, 10:42 AM
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Ridge what PRCguy was saying is that [ideally] you need a straight piece of wire. Ideally it needs to be at least (1) wavelength high (at your listening frequency) -- which of course is not attainable for most regular SWLs...

See the below link -- the wire is running N-S in that image so the signal would come in from E-W. With any bends in the wire you are not getting that pattern. Remember thouugh that you're trying to use it wideband and things get interesting at diff frequencies -- as you have surely figured out. So yes if you can make the wire straight then do it... bit if it's not possible then it's probably not worth the trouble.

https://www.google.com/search?tbm=is...eiINCW5PJ6t-M:
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Old 11-18-2017, 10:52 AM
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I had a "Lazy L" on my end fed 120' line and it worked fantastic. Low SWR across most of the bands (160m was the worst but that was expected). The configuration gave me very nice N/S & E/W coverage. I had it about 20' off the ground and it was well grounded at the balun box.

I was say to give it a try and see how it works for you personally.
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Old 11-18-2017, 11:28 AM
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Quote:
Originally Posted by devicelab View Post
Ridge what PRCguy was saying is that [ideally] you need a straight piece of wire. Ideally it needs to be at least (1) wavelength high (at your listening frequency) -- which of course is not attainable for most regular SWLs...

See the below link -- the wire is running N-S in that image so the signal would come in from E-W. With any bends in the wire you are not getting that pattern. Remember thouugh that you're trying to use it wideband and things get interesting at diff frequencies -- as you have surely figured out. So yes if you can make the wire straight then do it... bit if it's not possible then it's probably not worth the trouble.

https://www.google.com/search?tbm=is...eiINCW5PJ6t-M:
I appreciate that. I wish I could run it in a straight line, but not only do I have that constraint, but I also need to run it at the perimeter of the roof, to keep in mind clearance up there for workmen and such as this is a 10-unit building. My intention is to not make waves with the powers that be.

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Originally Posted by RBMTS View Post
I had a "Lazy L" on my end fed 120' line and it worked fantastic. Low SWR across most of the bands (160m was the worst but that was expected). The configuration gave me very nice N/S & E/W coverage. I had it about 20' off the ground and it was well grounded at the balun box.

I was say to give it a try and see how it works for you personally.
I'm glad you added in here! So you had one as a transmit system-I need to know, how "sharp" was the bend in yours? I'm guessing since you coined it as a "lazy" L configuration, this means the bend was "lazy"?
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Old 11-18-2017, 5:03 PM
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When I mentioned a 1:1 choke balun I was referring to a very good ferrite loaded one like a MyAntennas CMC-130-3K, which is the best commercially unit I know of. Or for AM BCB through lower SW the MyAntennas CMC-0510-R. These can actually reduce your noise floor where an air wound choke made of coax will rarely do anything.

Another thing to consider is at some point SW reception is governed by signal to noise ratio and more wire might increase the signal level but the noise goes up the same amount. The only way your going to improve a wire antenna is tune it for a specific frequency and locate it at a proper height and aim it at the transmitting station. Then it will probably degrade on something else you might want to receive. I also suspect putting a 90deg bend in 100ft of wire is not a big problem for a general purpose receive antenna where you want to pick up stuff from all directions.

I think taking steps to reduce local noise by installing a good common mode choke like the ones mentioned above would be the next step to improving reception. I didn't think I had a noise problem until I installed one and saw my noise floor go down on my receivers spectral display. Now I use them everywhere and enjoy a lower noise floor on everything.
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Old 11-18-2017, 9:21 PM
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Quote:
Originally Posted by prcguy View Post
When I mentioned a 1:1 choke balun I was referring to a very good ferrite loaded one like a MyAntennas CMC-130-3K, which is the best commercially unit I know of. Or for AM BCB through lower SW the MyAntennas CMC-0510-R. These can actually reduce your noise floor where an air wound choke made of coax will rarely do anything.

Another thing to consider is at some point SW reception is governed by signal to noise ratio and more wire might increase the signal level but the noise goes up the same amount. The only way your going to improve a wire antenna is tune it for a specific frequency and locate it at a proper height and aim it at the transmitting station. Then it will probably degrade on something else you might want to receive. I also suspect putting a 90deg bend in 100ft of wire is not a big problem for a general purpose receive antenna where you want to pick up stuff from all directions.

I think taking steps to reduce local noise by installing a good common mode choke like the ones mentioned above would be the next step to improving reception. I didn't think I had a noise problem until I installed one and saw my noise floor go down on my receivers spectral display. Now I use them everywhere and enjoy a lower noise floor on everything.
prcguy
Thanks prcguy! I appreciate you giving the name of those and I will search for them. I didn't know about them. Meantime I went up there today and put the wire turn point around a spare 8" PVC tube I had laying around to soften that bend. I don't see any difference-so far.
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Old 11-19-2017, 11:56 AM
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You mentioned the original turn point was a wood dowel. If the antenna wire is uninsulated bare wire then a wood dowel is not the best choice because it can absorb moisture and degrade the already weak received signal. So, the PVC tube is probably a better choice.

FWIW, if it were me, the wire antenna would remain as is for a more omnidirectional coverage and use the loop for null/peak purposes on specific signals.

btw... nice catch on 353 LLD, got QG on that freq here right across the river in Windsor ON so no chance of ever hearing Hawaii here although sometimes IN International Falls MN or LI Little Rock AR both on 353 will mix with the Canadian.
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Old 11-19-2017, 3:18 PM
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Quote:
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You mentioned the original turn point was a wood dowel. If the antenna wire is uninsulated bare wire then a wood dowel is not the best choice because it can absorb moisture and degrade the already weak received signal. So, the PVC tube is probably a better choice.

FWIW, if it were me, the wire antenna would remain as is for a more omnidirectional coverage and use the loop for null/peak purposes on specific signals.

btw... nice catch on 353 LLD, got QG on that freq here right across the river in Windsor ON so no chance of ever hearing Hawaii here although sometimes IN International Falls MN or LI Little Rock AR both on 353 will mix with the Canadian.
The wire is #12 bare solid-to me the perfect antenna wire. You are right about the wet wood thing although the antenna always worked very well and still does-I was just wondering if the sharp bend was a bad thing by possibly playing hell in certain spots, which I went ahead and addressed anyway.
I'm with you on leaving it in this configuration. I want that 100' and to run it straight I'd only have 45' which is OK but I bet I wouldn't even hear that LW DX with 45'. I recorded it and have it but it's so faint I didn't want to burden folks with straining to pick it out. But if anyone wants I'll upload it.
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Old 11-19-2017, 4:49 PM
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The wet wood thing may sound like being a bit overly obsessive but the guys that chase AM BCB DX with crystal sets claim that any wood used for coils or insulators or such will degrade the signal.
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Old 11-19-2017, 6:54 PM
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The wet wood thing may sound like being a bit overly obsessive but the guys that chase AM BCB DX with crystal sets claim that any wood used for coils or insulators or such will degrade the signal.
In our hobby when it comes to the delicate aspects of antennas, nothing is overly obsessive.
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Old 11-21-2017, 1:26 AM
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The wire is #12 bare solid-to me the perfect antenna wire.
I'm with you on leaving it in this configuration. I want that 100' and to run it straight I'd only have 45' which is OK but I bet I wouldn't even hear that LW DX with 45'.
Ridge, I don't understand why the wire antenna is your LW DX antenna. Your Wellbrook loop should be running circles around any wire antenna.

And IMHO, a 45ft bare, straight wire antenna should be a solid antenna... provided you are using it with a 9:1 un-un...

Still though, if the amplified loop isn't beating your wire antenna then you have other problems...

PS. Which Wellbrook loop model did you purchase?
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Old 11-21-2017, 8:21 AM
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Ridge, I don't understand why the wire antenna is your LW DX antenna. Your Wellbrook loop should be running circles around any wire antenna.

And IMHO, a 45ft bare, straight wire antenna should be a solid antenna... provided you are using it with a 9:1 un-un...

Still though, if the amplified loop isn't beating your wire antenna then you have other problems...

PS. Which Wellbrook loop model did you purchase?
The wire is not exclusively my LWDX antenna. I can get LW on both as I said. I also said that each antenna does better than the other in certain bands.
If there's a problem with the loop, it's that it's 50' up off the ground rather than say 10-15' off the ground so it likely isn't performing at its peak being so high up. This is because I cannot have it down low as it would be subject to theft or vandalism.
On the P.S. it's the ALA1530sNA.
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Old 11-21-2017, 4:47 PM
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Well if it's up that high it just becomes omni-directional and its directivity on LW/MW won't be as effective. It should still outperform your wire antenna however. It's possible you have a noise source that is being amplified by the loop and thus creating a bad SNR.

If you had a SDR then you could probably detect this...

Ever thought about getting one? They're affordable these days...

https://www.hamradio.com/detail.cfm?pid=H0-015446

More info: https://www.sdrplay.com/rsp2/

Video: https://www.youtube.com/watch?v=92Ijh_NAEfc
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Old 11-21-2017, 6:07 PM
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Quote:
Originally Posted by devicelab View Post
Well if it's up that high it just becomes omni-directional and its directivity on LW/MW won't be as effective. It should still outperform your wire antenna however. It's possible you have a noise source that is being amplified by the loop and thus creating a bad SNR.

If you had a SDR then you could probably detect this...

Ever thought about getting one? They're affordable these days...

https://www.hamradio.com/detail.cfm?pid=H0-015446

More info: https://www.sdrplay.com/rsp2/

Video: https://www.youtube.com/watch?v=92Ijh_NAEfc
devicelab-although the original subject of my thread here wasn't a S/N problem or loop performance, but was all about whether or not the sharp bend that I had in my wire antenna would create a pattern degradation or not, I can see where you're going with this. I do recognize the fact that you have a strong sense about an underlying problem I have here with S/N, especially on the loop. So, I will list all the villains my two antenna systems are up against at this QTH.
1. I live in a 10-unit building; all of which have computers, at least one of which has a plasma TV and that TV is right below me, and one of which has an ancient huge dish network from the 90s that gets him his Russian feeds.
2. There's a plumbing supply store right next door.
3. There's a glass shop next to him.
4. There's a neon sign shop next to him.
5. There's a school/ daycare/ church across the street.
6. There are power poles running along the south side and west side of my building; the south side ones are less than 20' from my living room windows as I am level with the lower utility lines and my antennas are level with the high power lines at the top that supply mega voltage downstream.
7. There is a 10-line TV cable bundle up on my roof that runs from one end of the roof to my end, right over my living room and kitchen and snakes down to the cable junction box just below my bedroom windows. The feedline for my 100' wire passes right underneath that bundle to reach the wire's feedpoint.
8. The feedlines for my Wellbrook and my D130j pass straight through holes that I drilled in the aluminum window frame of my bedroom to get outside; that frame is bonded to ground via the mesh and I-beam construct of this building.
With all of this, I am amazed that I get the mostly clean and reliable desired signals that I actually do get on all these antennas. Given all this, the mere fact that I could pull in a LW DX the other day over 2600 miles away, says a lot about steps I have thus far taken in making these antennas operate as good as they do.
Beyond all this, I am strongly leaning toward prcguy's balun suggestion...possibly for the wire AND the loop to attempt to squish RFI even more.
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Old 11-21-2017, 7:24 PM
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I did a video a while back when I first set up the wire, doing a comparison between the loop and the wire (which had that sharp bend around the wood dowel at the time) with shortwave station WWCR on 4840kHz. This video pretty much sums up one example of how much better the wire can do in certain bands.
https://youtu.be/yyl4RDf4XJc
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