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Dipole Questions

Bob,

I just talked to 722 in Trinidad W.Indies on my dipole !<img src=http://www.wwdx.org/smilies/posticon23.gif ALT=":23">


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Yepper. I had one I made but I saw this one Thursday night, bought it and got it yesterday. I am very pleased with it.I'm listening to skip with it now on 475


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Hey Ron, Glad you got your static situation under control......We've had some rain pass through this weekend....The soil is good and wet. It seems to have helped a little on my end.....I have a 8ft grounding rod right behind the wall where my rig is.....I grounded radio, switch box and Lowpass TVI filters......When I use a pushup, I run a seperate grounding rod right at base of mast...How can I ground my dipole being up on the peak of roof? Just curious, it never hurts to have to many grounds.........73's Ron


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Hey Bob, How much higher did ya go with it.<img src=http://www.wwdx.org/smilies/posticon56.gif ALT=":56"> ......Just curious.....<img src=http://www.wwdx.org/smilies/posticon58.gif ALT=":p58"> .........73's




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Hey Bob, good deal......I should get mine, somewhat elevated and off the surface mount on shingles.....I wonder if that will help out my deal...........73's Bob<img src=http://www.wwdx.org/smilies/posticon62.gif ALT=":62">


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</p>Edited by: <A HREF=http://p067.ezboard.com/bworldwidecbradioclub.showUserPublicProfile?gid=phil501>phil501</A> 
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at: 3/20/05 4:55 pm
 
Phil,

I was doing some reading and came up with 2 posibilities.

One is a counterpoise. If your coax connects at the antenna with a connector and not bare wires, put a "T" at the connection. Connect your antenna coax to one and the counterpoise to the other. At the other end of your counterpoise tie the inner wire and outer shield together. I believe the counterpoise is around the same length as one side of your dipole.

The second is something I heard from CDX-3030 Jonbah. He has ladder line connected at the antenna. It goes down part way and is then connected to coax. Where they connect he took a ground wire and connected it to the braid wire of the coax and the other end to ground.

Hope this helps !


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I'm going to experiment further. I'm going to take 2 dipoles and cross them horizontally. Then co-phase them for circular polarization to make an omnidirectional, horizontal dipole.I was told for it to work correctly it needs to be phased-out of phase.

Below is a diagram of the harness-

cp_harness.jpg


The instructions for the harness can be found at-



cophasing



Has anyone used a dipole vertically ? I heard this makes a good omni.


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</p>Edited by: <A HREF=http://p067.ezboard.com/bworldwidecbradioclub.showUserPublicProfile?gid=sonwatcher>Sonwatcher</A> at: 3/20/05 8:47 pm
 
<blockquote>Quote:<hr>Has anyone used a dipole vertically ? I heard this makes a good omni. <hr></blockquote>



I have....works just fine. Oriented this way, the antenna has vertical polarization, which is usually how most locals have their antennas set up.


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"Shield-grounding (for static and

> lightning protection) at the feedpoint will achieve 99% of the

> noise-limiting benefit that a grounded Balun does. The missing 1% is an

> equal loss of signal and noise through the Balun."



"A 1/2 wave horizontal dipole is a "complete"

antenna and has no benefit from radials, but it must be elevated

sufficiently to avoid ground losses. The coax-shield of feedline to a dipole

should still be grounded per above para."



"The horizontal dipole system has a minimum gain of 0 dBi at 51 degrees elevation, while the counterpoise system has a minimum gain of 0 dBi at about 42 degrees of elevation. Alternatively, antenna gain comparisons at all elevation angles show that the counterpoise gain is greater than the dipole system by 2.53 ( 0.05 dB. This demonstrates that the counterpoise is a more effective ground system; the counterpoise reflects more energy into the half-space so less is wasted in the intrinsic ground resistance and more is radiated."



Conclusions



The placement of a counterpoise below a horizontal antenna can improve the antenna efficiency by a reasonable amount. The effect under a horizontal antenna is similar to the effect of elevated ground-planes for vertical antennas (Ref 2). You can measure this effect by observing an increase in field strength or by observing the lowering of your feedpoint resistance when adding the counterpoise (Ref 3). "



These are some examples gleaned from the internet in refrence to helping with dipole problems. They are not suggested mandatory but helps for certain situations that don't fall in the "perfect world" I am not an antenna tech nor do I play one on tv <img src=http://www.ezboard.com/intl/aenglish/images/emoticons/tongue.gif ALT=":b"> I was just trying to help Phil out with a question and shared my findings.



Thanks Mole ! CDX-4540 was asking me about the vertical dipole as he is without a base antenna at this point.<img src=http://www.wwdx.org/smilies/posticon40.gif ALT=":40">


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</p>Edited by: <A HREF=http://p067.ezboard.com/bworldwidecbradioclub.showUserPublicProfile?gid=sonwatcher>Sonwatcher</A> at: 3/21/05 4:25 pm
 
<img src=http://www.wwdx.org/smilies/posticon58.gif ALT=":p58"> Ron, Very informative stuff you found there.....I'll look into it on correcting my static on RX.....As for the comment "You can never have eneogh grounds", that was me........I've always grounded all my equiptment as well as antenna's with seperate grounding rods one at the bottom of mast where they're erected and a seperate one in a different location for my equiptment.....I've just never grounded a Dipole bofore, Thanks again Ron, Bob and the rest of ya's...........73's<img src=http://www.wwdx.org/smilies/yelclap.gif ALT=":yelclap">


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</p>Edited by: <A HREF=http://p067.ezboard.com/bworldwidecbradioclub.showUserPublicProfile?gid=phil501>phil501</A> 
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at: 3/21/05 5:10 pm
 
My fishing season is still over a month away and I've been bored out of my mind so I made a Dipole to experiment with. I wanted something with horizontal polarity as I have a vertical antenna.



I do have a few questions, if you'd all be so kind.



The noise level is consistantly 2-5 S-units higher on the dipole compared to my vertical. Is there anything I can do or buy to reduce the noise? Perhaps an RF choke made with wraps of coax? Or would that just help the transmit?



I'm not sure how high it should be mounted for the best DX.



I can tell you that it's about 3' above a shed so that would put it about 7'-9' above the ground.



In testing it with my mobile, I am getting a S 5-6 from the Dipole to my truck at a distance of 1.5 miles. And that's in the direction of one of the radials (east to west)....I know that wouldn't not be the best side to check for it's radiation pattern. I really can't get too far away (about 1/2 mile) to check one of its best sides north to south) as I'd be in the Atlantic Ocean, but that's the direction I'd like it to best transmit and receive.



One local fellow about 1 mile away in the opposite (re, wrong) direction I checked with my truck says there's no real difference in its signal or modulation compared to my vertical.



Other people I talk to from 5 to 15 miles away notice a huge drop in the signal and the audio compared to my vertical.



All tests were done with the same radio for transmiting.

Perhaps I should buy new Coax as I used some old Radio Shack RG-8 I had laying around?



I have talked DX a few operators who were using dipoles with my vertical and was really impressed by their signal and sound, but I know the conditions have a LOT to do with that.



So I know it's possible (conditons permitting) to transmit and receive good signals with a dipole.I'm just looking for the best way to set it up for DX and to reduce the noise level.



Thanks in advance to all.



73's,

Bob701


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