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Author Topic: Yet another impossible antena location question.  (Read 3758 times)
W9KDX
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Posts: 771




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« on: August 23, 2011, 09:17:29 AM »

I am sorry to keep bugging you guys but you are my only source for hard questions and the help is greatly appreciated.

I know that any location questions are very subjective and hard to answer without a "try it and see what happens" testing, so I am hoping for a broad general answer.

I have two options for installation of my off center fed Hy Power Dipole.  The first would be about 16 feet above ground but only 10 feet from an aluminum sided 2 story house.  This option would have the coax run down for about 5 feet and then 90 degrees and 12 feet into the house.  The second option would be be about 25 feet from the house but about 6 feet loser to the ground.  This would have the coax feeding at 90 degrees and running about 27 feet.

Generally, am I better off getting away from the house but losing height or not.

Thanks,

Sam
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Sam
W9KDX
WB2WIK
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Posts: 20636




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« Reply #1 on: August 23, 2011, 09:40:52 AM »

I go for the higher above ground option.

Even 16' above ground is very low for an HF antenna and this invites both reduced performance and also increased likelihood of radio frequency interference to and from electronic systems and appliances in the house.  Best way to "get away" from those problems is "more height," and the more, the better.

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WA4FNG
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Posts: 162




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« Reply #2 on: August 23, 2011, 10:40:57 AM »

I agree with Sam. Higher is better. I think either way it's a compromise with a 2-story house. You may not get much signal in the direction of the house. Have you thought about wrapping the eaves of the house? That's a lot higher and may be less of a compromise.
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N5EP
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Posts: 6




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« Reply #3 on: August 23, 2011, 12:09:19 PM »

I assume that your real estate is horizontally challenged and that you don't have supports to suspend a dipole at a more effective height.  If that's the case, you might try erecting a mast at one end of the house that would extend up above the roof.  You can even secure the mast to the house to help support it.  You could then use that as a center support and install your dipole as an inverted Vee.  That could get the center up to 35 to 50 feet, depending on the mast, and you will be a lot better off.  I don't think you mentioned what band your dipole is designed for, but at the low heights you are planning you could have primarily near-vertical radiation, which may or may not be what you want, depending on your goals.  The inverted Vee configuration could be a way around that, allowing for more horizontal radiation (i.e., more distant contacts and DX).

Good luck.

Steve, N5EP
 
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W9KDX
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Posts: 771




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« Reply #4 on: August 23, 2011, 03:01:37 PM »

I can only use what nature provided so I am limited to trees and the back yard which is lower than the surrounding area.  Going on top of the house is pretty much out.  I am primarily on 20 meters and occasionally 40 and I was hoping to get some contacts outside of the US.  I am in Minnesota.

Thanks guys,

Sam
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Sam
W9KDX
K9IUQ
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Posts: 2056




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« Reply #5 on: August 23, 2011, 05:55:41 PM »

I can only use what nature provided so I am limited to trees and the back yard which is lower than the surrounding area.  Going on top of the house is pretty much out.  I am primarily on 20 meters and occasionally 40 and I was hoping to get some contacts outside of the US.  I am in Minnesota.

Thanks guys,

Sam

16 ft is not high enough for a horizontal dipole antenna and 6 ft lower is even worse.
Forget the dipole and get a vertical of some sort. I believe even a hamstick or other mobile vertical would be better than what you propose..

Stan K9IUQ
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W9KDX
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Posts: 771




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« Reply #6 on: August 23, 2011, 06:11:05 PM »

Well, the vertical is out for more than a few reasons, first the minimum height exceeds code limits and second, anything ground mounted will have too many neighborhood children all over it.

One thing, I currently have a horizontally mounted Pare EndFedz SWL at about the same location.  I have no trouble hearing hams on 20 and 40 all the time from coast to coast.  Is this any indication of how a dipole tuned specifically for 20/40 will do for transmitting?  I'm hoping that the old "can't work em if you can't hear em" works both ways.

Maybe I'll just work really hard to learn code (sigh).  At least I can listen.


Thanks,

Sam

Added:  I have been looking at this article: http://www.qsl.net/aa3rl/ant2.html

Could someone please take a look at the radiation plots and help me understand what they represent as far as the strength of the signal.  I can see what the extreme elevation does for the patter radiated out at lower angles from the horizon, but what is lost in the strength of the signal as the antenna goes closer to the ground?  Looking at 70 feet at 45 degrees, the signal of the white plot is at 0db while at 14 feet, the same plot is at -3db.  Just what does this mean for a 100 watt transmitter or, what does it mean for someone trying to get out over 8000 miles? 

Maybe I'm wrong here, and I'll soon be finding out when I get my dipole up as High as I can, but it strikes me that no one ever could possibly get a dipole up high enough unless you lived on where you could build your own set of 100 ft towers.  I just know that people have been talking all over the world with dipoles at much lower heights and with much lower wattage than the usual 100 that seems to be the start today.
« Last Edit: August 23, 2011, 06:52:18 PM by CHAS0039 » Logged

Sam
W9KDX
KG4WXP
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Posts: 165




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« Reply #7 on: August 23, 2011, 06:44:05 PM »

Well, the vertical is out for more than a few reasons, first the minimum height exceeds code limits and second, anything ground mounted will have too many neighborhood children all over it.

One thing, I currently have a horizontally mounted Pare EndFedz SWL at about the same location.  I have no trouble hearing hams on 20 and 40 all the time from coast to coast.  Is this any indication of how a dipole tuned specifically for 20/40 will do for transmitting?  I'm hoping that the old "can't work em if you can't hear em" works both ways.

Maybe I'll just work really hard to learn code (sigh).  At least I can listen.


Thanks,

Sam

What about a magnetic loop? Or a tripod on the rooftop with a small pole to mount one end of the dipole?
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VE3FMC
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Posts: 1001


WWW

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« Reply #8 on: August 23, 2011, 06:53:17 PM »

Well, the vertical is out for more than a few reasons, first the minimum height exceeds code limits and second, anything ground mounted will have too many neighborhood children all over it.

One thing, I currently have a horizontally mounted Pare EndFedz SWL at about the same location.  I have no trouble hearing hams on 20 and 40 all the time from coast to coast.  Is this any indication of how a dipole tuned specifically for 20/40 will do for transmitting?  I'm hoping that the old "can't work em if you can't hear em" works both ways.

Maybe I'll just work really hard to learn code (sigh).  At least I can listen.


Thanks,

Sam

Hi Sam

Have you tried transmitting to see who and where can copy you? You never know until you try.

My first adventure into HF was when I was limited to 160/80 meters. 160 was out of the question, not enough real estate. So I strung up a full wave 80 meter around the perimeter of my property.

Highest point was at 28 feet. Lowest around 8 feet. Insulated wire had to be run through 4 trees.

Now, I was not the strongest signal on the band by any means. But I managed to get my WAS 75 Meter Phone Endorsement using that antenna. I also worked some DX to Europe and VK land with it, and only 100 watts.

So never give up when it comes to HF antennas. Hey 16 feet is not ideal but you can still make contacts. I have a friend in Indiana and his G5RV is actually mounted on the top of his 7 foot wood fence. He makes contacts all over the U.S./Canada with that antenna, and he works DX too on CW and digital modes.

You have 10 feet on him  Grin
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W9KDX
Member

Posts: 771




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« Reply #9 on: August 23, 2011, 06:56:54 PM »

Well, the vertical is out for more than a few reasons, first the minimum height exceeds code limits and second, anything ground mounted will have too many neighborhood children all over it.

One thing, I currently have a horizontally mounted Pare EndFedz SWL at about the same location.  I have no trouble hearing hams on 20 and 40 all the time from coast to coast.  Is this any indication of how a dipole tuned specifically for 20/40 will do for transmitting?  I'm hoping that the old "can't work em if you can't hear em" works both ways.

Maybe I'll just work really hard to learn code (sigh).  At least I can listen.


Thanks,

Sam

What about a magnetic loop? Or a tripod on the rooftop with a small pole to mount one end of the dipole?

I may have to try that if I am dead in the back yard.  As I look at it, I might be able to get up to 20 feet in the back yard if I really stretch it.  I'll have to see how high I can jack the ladder.  

I looked a bit at loops earlier and didn't see anything that I could use.  Do you have a link of two that will head me in the right direction?  Is this the right idea? http://www.standpipe.com/w2bri/build.htm

Thanks
« Last Edit: August 23, 2011, 07:19:58 PM by CHAS0039 » Logged

Sam
W9KDX
W9KDX
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Posts: 771




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« Reply #10 on: August 23, 2011, 07:02:38 PM »

VE3FMC,

I haven't been able to try anything yet.  I just passed my tech and general a week and a half ago and the FCC has yet to get me in the database.  I figure I'll get as high as I can go in the back yard, I may get to 20 feet, but because of the slope in my lot, I can only get really above ground level in the front yard and that is a no-go.  As you said, lots of things work and I am very patient, heck I have been listening for 50 years so any contact anywhere is a pure bonus.  A lot of getting this thing up is to keep it from the neighbors.  If I go on the roof, it will stand out like a sore thumb.  Anything in the back yard is hidden enough so they won't bother to see it.

« Last Edit: August 23, 2011, 07:07:09 PM by CHAS0039 » Logged

Sam
W9KDX
KB9CRY
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Posts: 4283


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« Reply #11 on: August 23, 2011, 07:16:43 PM »

I am sorry to keep bugging you guys but you are my only source for hard questions and the help is greatly appreciated.

I know that any location questions are very subjective and hard to answer without a "try it and see what happens" testing, so I am hoping for a broad general answer.

I have two options for installation of my off center fed Hy Power Dipole.  The first would be about 16 feet above ground but only 10 feet from an aluminum sided 2 story house.  This option would have the coax run down for about 5 feet and then 90 degrees and 12 feet into the house.  The second option would be be about 25 feet from the house but about 6 feet loser to the ground.  This would have the coax feeding at 90 degrees and running about 27 feet.

Generally, am I better off getting away from the house but losing height or not.

Thanks,

Sam



Sri but both options are so low that you can only assume to talk to very close in folks.  You might do an occasional DX but will be lucky to go beyond a few hundred miles.

You need more height.
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W6CD
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Posts: 213


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« Reply #12 on: August 23, 2011, 07:20:33 PM »

How about a flagpole verticle?
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W9KDX
Member

Posts: 771




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« Reply #13 on: August 23, 2011, 07:21:58 PM »

Sorry but both options are so low that you can only assume to talk to very close in folks.  You might do an occasional DX but will be lucky to go beyond a few hundred miles.

You need more height.

Does my ability to receive at this height have no relation to what I will be able to transmit?
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Sam
W9KDX
W9KDX
Member

Posts: 771




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« Reply #14 on: August 23, 2011, 07:25:52 PM »

How about a flagpole verticle?

Thanks.  I thought of that but the code height limitations are too short for any vertical I have seen that works 20/40 meters.  Plus, I would be down in the bottom of the back yard with tons of kids running around on the radials and prone to RF burns if they touch the "flagpole" at the wrong time.  I could sort of get around this with a vertical mounted on the deck, but I have no way to make the ground radials work 15 feet above the ground.

By the way, I really appreciate all the advice I am getting here.  One way or the other, I'll find something that will work.
« Last Edit: August 23, 2011, 07:27:38 PM by CHAS0039 » Logged

Sam
W9KDX
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