Setup for PAR EF-SWL antenna

Status
Not open for further replies.

MisterLongwire

Amateur radio operator/QC tech for radio mfr.
Premium Subscriber
Joined
Jan 1, 2014
Messages
430
Location
San Marcos,Escondido, CA.
Finally have the chance to register onto this website as others I have visited and signed on to had the members being too pompous, etc. I find Radio Reference more informative in my daily activities in the shortwave world. To start, let me tell you about my receivers. They include an Icom IC R75, Alinco DX R8, Hallicrafter SX110, and an S108 amongst a few others. I don't have an "antenna farm" yet, as I am working on it. I live in a rural part of north San Diego where interference is 0. I have a Pixel loop about 25 feet in the air on a rotor which extends high above the apex of my roof. Now the problem I am having is on the receiving end- the loop. Don't get me wrong...the loop works great for any static crashes and QRM/QRN. A friend down the road who has a ham license owns a Steppir beam about 90 feet on a tower. When he is on and doing DX he gives reports of people I hear and sometimes I don't hear with signal reports of 5-7 and so on. I point my loop in the direction he has his beam pointed at and sometimes I don't hear anything. I know that the loop picks up signals in a different way than a horizontal beam, but I am really surprised being the distance from my residence to his that this happens. I found in the garage a PAR EF SWL wire antenna that someone had given for a gift a while back just never hung it up. Now my question is this- instead of stringing the wire up horizontally could I wrap it around a 1 1/2 inch diameter PVC pole with the wire spaced apart about 4 inches on the wrapping? I have a pole about 15-20 feet long that I could put up vertically next to the eve on a second story section. Of course the connection box would be at the base and the supplied insulator would be near the top. A while back I had an AOR LA390 which I think was a waste of my hard earned money, but oh well....we all learn.Thanks for reading my post and feel free to inform me of your opinion.
Bill
 

ka3jjz

Wiki Admin Emeritus
Joined
Jul 22, 2002
Messages
22,345
Location
Bowie, Md.
To be honest I'm not certain that would work. All you're doing there is creating a big oversized coil - and how that load would be handled by the transformer at the end of the antenna is a huge question mark. I probably wouldn't try it, if it were me...

I'd mount that antenna nice and high somewhere, away from your house, and use that as a second antenna. There are plenty of switching arrangements that you can build or buy (building something like this is rather fun, actually). It could be as simple as a series of jacks, on one side, one for the loop, the other for the PAR - the other side, jacks for each of your receivers. It would be very flexible since you could have them connected in any number of ways. I cobbled this kind of setup together once and it worked very well

Many well known DXers use different antennas for their different receive characteristics - what you might not hear on one antenna, you might on another because they're a different type. You have discovered this yourself, although on a rather extreme level (there's really no way to compare a beam at 90 foot with a Pixel loop at 25 - you're comparing apples to grapes and coming up with grapefruits, hi :D )

I guarantee you won't damage your receivers in the slightest if your experiment doesn't fly - just your wallet

HTH..;.Mike
 

SpectreOZ

Member
Joined
Mar 31, 2013
Messages
185
Location
Mildura, Australia
I found in the garage a PAR EF SWL wire antenna that someone had given for a gift a while back just never hung it up. Now my question is this- instead of stringing the wire up horizontally could I wrap it around a 1 1/2 inch diameter PVC pole with the wire spaced apart about 4 inches on the wrapping?

Your description reminds me somewhat of a helically wound 11m mobile antenna (just on a larger scale), if you have the parts on hand I'd give it a go, you may experience an increase in atmospheric noise however compared to both your magnetic loop and a traditional (horizontal) wire antenna, personally I'd try the antenna in a longwire configuration first so as to establish a performance baseline...

Good luck with your antenna farm :D

Edit: an example of an end fed vertical (strung not helical) Vs. an OCFD

End Fed Half Wave Vertical Antenna - YouTube
 
Last edited:

vagrant

ker-muhj-uhn
Premium Subscriber
Joined
Nov 19, 2005
Messages
1,060
Location
California
Hello Bill,

Everyone's conditions are generally different because of their particular location and propagation at the time. That being said, why not try both configurations or a combination of the two? It's a wire, so have fun with it. The best thing you did is take it out of the garage, now string it up and give it a try. Once you've had some fun, report back with your results.
 

MisterLongwire

Amateur radio operator/QC tech for radio mfr.
Premium Subscriber
Joined
Jan 1, 2014
Messages
430
Location
San Marcos,Escondido, CA.
Well I tried the spiral wrap. Propagation was pretty weird today. Little peephole let Europe in for a few. As for aero HF which is what I mostly listen to it was"ok"...nothing spectacular. For the meantime I'll just listen on the loop and enjoy what I have. Since my antennas are in the back of my house which is in a HOA, I got to be stealthy, yet INGENIOUS. Thank you again to all those that educated me in this great hobby!
Stay safe
Bill/North San Diego
 

ka3jjz

Wiki Admin Emeritus
Joined
Jul 22, 2002
Messages
22,345
Location
Bowie, Md.
We're in the midst of a solar wind stream right now, and a couple of sunspots look particularly big. Solar conditions are picking up...

Anyway keep in mind that the 45 foot wire that comes with the PAR can be removed. You could, for example, string a wire around the perimeter of the soffets around the house, then connect that to the transformer and feed that into the house. If anyone asks about the coax, tell 'em it's for cable TV. No one will ever know the difference :.>> and the antenna will be all but invisible

GL with the experiments...Mike
 

MisterLongwire

Amateur radio operator/QC tech for radio mfr.
Premium Subscriber
Joined
Jan 1, 2014
Messages
430
Location
San Marcos,Escondido, CA.
Ingenious idea Mike!

That sounds very interesting....an idea I might employ. A question- would 3/4 coverage around the house suffice? And, if I do it that way, would placing the wire under the soffets so close to the body of the roof invite RF and other intereference to my receiver(s)? I read that one should ALWAYS get it up as high as possible from the roof? How about if I just run it corner to corner on top of roof?
 

ka3jjz

Wiki Admin Emeritus
Joined
Jul 22, 2002
Messages
22,345
Location
Bowie, Md.
The best option is to get the antenna as far away from the house as possible, so yes, there is a chance that you will get some interference from noise sources in the house. But the transformer should help somewhat with that.

If you have to get creative because of the HOA, you end up with some compromises. Sometimes it's just unavoidable. But what I suggested is only 1 possibility. Your method may also work. As I mentioned before if it doesn't, you won't have damaged your receivers in the slightest. Experiment, and see what happens Mike
 

nanZor

Active Member
Joined
May 28, 2009
Messages
2,807
.. A friend down the road who has a ham license owns a Steppir beam about 90 feet on a tower. When he is on and doing DX he gives reports of people I hear and sometimes I don't hear with signal reports of 5-7 and so on. I point my loop in the direction he has his beam pointed at and sometimes I don't hear anything. I know that the loop picks up signals in a different way than a horizontal beam, but I am really surprised being the distance from my residence to his that this happens.
A few things - a small loop has poor low-angle reception, although this is compensated for somewhat with an extremely low noise floor so that even weak stations are nearly armchair copy! Still, there are times that your neighbors beam with it's very good low-angle reception will definitely hear things you won't.

The small loop has most of it's directivity perpendicular to the plane of the loop, usually being a sharp null instead of a wider signal peak. BUT, for most of the skywave signals that rise well above the horizon, directivity is poor - and if you listen carefully should be somewhat oblong. The higher the skywave signals come in, the less directivity / nulls can be obtained.

One way to improve your loop for low-angle SKYWAVE reception, is to lower it! One only needs to place it at least one diameter above ground, although from a practical standpoint most try not to get it so low that it places it nearer sources of household noise.

The best way to describe it is that when placed somewhat close to the ground, the reception pattern is like someone squashing a balloon down onto the surface of a table a little bit. By having it 25 feet in the air, the balloon is now perfectly round and is a cloud-warmer. Yes, the perpendicular directivity is still there, (useful for nulling local noise, or other low-angle noise signals) but from a SKYWAVE standpoint, low-angle reception (at the bottom of the balloon so to speak) suffers.

One always has to be on the lookout to make sure the loop antenna and it's associated feedline is well connected and balanced. If you have poor connections, it is entirely possible that a 25-foot high loop can become nothing more than a common-mode vertical with a lollipop on the end. You can test for bad balance by not being able to obtain two equal null-depths on a noise signal as you rotate the loop 180 degrees.

If you seem to notice a cardiode type pattern, or perhaps only a null on one side when you rotate it, then it is likely your loop is unbalanced. Basically, the outside shield of the coax has become part of the antenna. Keep those connections tight!

Small loops can also be just swamped by nearby metallic objects OR in the case of an antenna farm where the loop is shared on an antenna-switch with other numerous antennas, the vast amounts of nearby coax common-mode current can distort the loops pattern too.

Swamping the loop with current from the shields / grounds of other antennas is why I always ran mine *directly* without any shared switching among multiple antennas.

I'd try reducing the loop height, and just know that you won't get much directivity the higher the skywave signals come in, although the perpendicular noise-nulling directivity will always be there.
 
Last edited by a moderator:
Status
Not open for further replies.
Top