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Author Topic: Dipole mounting quandry  (Read 830 times)
KD7QLU
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Posts: 35




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« on: August 15, 2012, 12:35:07 PM »

I'm moving my current homebrew dipole from one side of my house to another.  For the ends, I will be using 16' poles with small pulleys as my attachment point for the tether cords.  The question is about mounting the center.  I know a local painter who will probably let me use his ladder to attach the center at the roof line of my second story.  This will of course cause some slope on the dipole, but will also keep the ends a little above 16' (approx 20'?) high since they won't extend all the way to the end poles.  The other option is to mount the center at 16' so the dipole is flat.  Is it better to mount the center as high as possible, or compromise on this height in order to keep the dipole flat?

73.. Mike, KD7QLU
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WB6BYU
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Posts: 13016




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« Reply #1 on: August 15, 2012, 12:41:03 PM »

Get as much of the antenna as high in the air as possible.

That assumes, of course, that the included angle between the wires isn't too small.
You can get by with the wires 90 degrees apart (each sloping down in opposite directions
at a 45 degree angle) but wider apart is better.  In your case, with only about 4' difference
between the center and the ends, it won't be a problem.
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KD2CJJ
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Posts: 368




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« Reply #2 on: August 15, 2012, 12:57:06 PM »

It is better to get the center higher as the signal radiates closer to the center of the V rather than the ends of the wire.  You need to be 90 - 110 degrees to be considered a V but you lose a little gain in that config - so a perfect T at 30 - 35 feet is the ideal... above 35 feet it could become directional then a V would be better.

I am 24 feet up with the same setup and the issue I have found is that my signals are far stronger in the direction opposite the side of the house (south)... I hear nothing north and east (hear very little - once in a while europe) and west I cant get further out then Minnesota... all on 20 Meter (forget 40 meter - I get about the same but with more noise).
 
I the lack of height coupled with it against my house is causing some issues with the pattern...  When the 20M is wide open I have hit Kuwait and Croacia... so I know I am radiating but it could be better.

Here is what I am doing...

I am putting up on the side of my house at the peak and just below, side antenna mounts, reinforced from behind.... Mount a 10 foot pole on that to get the antenna ABOVE my roof line plus using a 5 foot aluminum pipe bolted to the mast OUT perpendicular 5 feet from the house

That would get me roughly 30 - 34 feet, 10 feet above my house, 5 feet away from my house.... I suspect this will take a OK antenna and make it a great antenna (for 10 - 20M)... and greatly improve my 40M

My current setup I have contacts to Croacia, Czech Republic, England, but I can ALWAYS hear/make contacts to south america - that means my signal is good just not radiating in the other directions.

The net net - height and getting it away from objects would be your best bet... dont worry about getting the ends up as unless your at least 1/2 wave in the air its omni directional anyway - you need to be considerate most of what is possible reflecting/blocking the signal --- your house with the radiant barrier (which I have) is a great reflector...

The other option is to make it a slanter... you will get forward gain in the direction of the bottom of the antenna (not feed point)..

 
I'm moving my current homebrew dipole from one side of my house to another.  For the ends, I will be using 16' poles with small pulleys as my attachment point for the tether cords.  The question is about mounting the center.  I know a local painter who will probably let me use his ladder to attach the center at the roof line of my second story.  This will of course cause some slope on the dipole, but will also keep the ends a little above 16' (approx 20'?) high since they won't extend all the way to the end poles.  The other option is to mount the center at 16' so the dipole is flat.  Is it better to mount the center as high as possible, or compromise on this height in order to keep the dipole flat?

73.. Mike, KD7QLU
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73

Mike
KD2CJJ
KD7QLU
Member

Posts: 35




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« Reply #3 on: August 15, 2012, 06:20:25 PM »

Dale and Mike, thanks for the replies.

Mike, you touched on a concern I just thought of today and that is the directionality of the antenna.  My current setup is on the east side of the house so I think I'm am pretty directional to the east and west.  I've made contacts in Europe, Japan, Hawaii, etc.  I've made a few in Mexico.  I'll be moving this to the south side of the house which is the long side of my property.  Will I end up going silent east/west?  I have a very temporary/impromptu 16' vertical with 8 radials set up in the backyard right now for testing.  It's literally on three sections of pvc taped together with the wire taped to the pvc.  I'm actually hearing more dx stations and hearing them more clearly.  Now I'm second guessing my plan to stay with a dipole.  The problem with the vertical is the money and the wife.
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KD2CJJ
Member

Posts: 368




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« Reply #4 on: August 15, 2012, 08:37:06 PM »

Now that's funny because I was going to go with a vertical but decided against it due the lack of space for radials.

Im going to stick with my dipole and get that to work.

Unfortunately the dipole at low heights will raise the take off angle .. I suspect yours is so low it's poor for dx.   If you can get it to at or around 30 feet your good to go for 20 meter. 

Yes if you move the antenna to the south side lower than the roof line you may lose some or most east and west....Not totally but not as good as it is now And deaf north...  If you can get the first few feet of the v apex above the house Then it should open up the other directions minimizing absorbstion and reflection from the house.

You could get a 40 foot pushup mast and hang the dipole from there... or go with my future setup with a side wall mount and 10 foot mast to get it above the roof line.

Dale and Mike, thanks for the replies.

Mike, you touched on a concern I just thought of today and that is the directionality of the antenna.  My current setup is on the east side of the house so I think I'm am pretty directional to the east and west.  I've made contacts in Europe, Japan, Hawaii, etc.  I've made a few in Mexico.  I'll be moving this to the south side of the house which is the long side of my property.  Will I end up going silent east/west?  I have a very temporary/impromptu 16' vertical with 8 radials set up in the backyard right now for testing.  It's literally on three sections of pvc taped together with the wire taped to the pvc.  I'm actually hearing more dx stations and hearing them more clearly.  Now I'm second guessing my plan to stay with a dipole.  The problem with the vertical is the money and the wife.
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73

Mike
KD2CJJ
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