New type Di-pole?? Help opinions w/facts needed urgently.

[TD126]

Hello out there everybody. I was in the "Business" from 1972-1986-89? and had to quit due to job travel 50 weeks out of the year (exception od mobile). I have always been one who enjoyed experimenting with antenna set ups, building different antennas and things. I have made several "Wire" Antennas over the years. Most all for Horizontal use as a type of Beam. I have an idea for a dipole that would be very simple (For me) to make and IMHO work well...I NEED OPINIONS PLEASE!!!
I will use 2-102" Stainless Steel (SS) whips. One for the conductor or center piece and one for the grounding side. This should be the "perfect" length by theory and not have to get on the roof a dozen times adjusting for SWR...
I will make a mount out of a couple pcs. of angle Iron. (may use aluminum or SS if I can find it). Use the standard mounting studs. On ONE side or whip hook the center conductor of RG8U or RG213 (YES the big stuff). On the other, opposing whip, hook the braid too. Mount this onto a length (20 or 30 ft) of galvanized pipe and mount it 1 ft below ground centering it over a smaller diameter pipe. This will help ground the pipe and give freedom for moving the "Beam" from direction to direction. I used to make one like this from #12 AWG house wire. It worked great but had to spend a long time trimming and climbing the old trusty ladder. (THAT is a problem now for me as I get YOUNGER)...
Another idea for an all directional is with the same principle set up using 4 of the whips...2 up and down for vertical and 2 (as in above) for horizontal...
PLEASE COMMENT and let me know what you guys think? Would this work and be efficient? I need to be making things again, keeping myself busy and as occupied as I can now that I've ha to retire. I am severely limited in the amount I can do to a host of health issues that I won't bore folks with. Thank You all for any help you can give me.

 

[M0GVZ]

> This should be the "perfect" length by theory and not have to get on the roof a dozen times adjusting for SWR...

...for an antenna in free space. However it won't be in free space. The height of the antenna will affect the feedpoint impedance as will nearby objects so you're going to end up going up and down the ladder I'm afraid.

My advice if you're wanting an easy to build small rotatable antenna that gives excellent performance is to look at the Moxon. It is a simple to build 2 wire beam with a wide bandwidth that has very good gain over a dipole and there are plenty of online calculators to get the dimensions. If you tune it around 6ft high to be a couple of hundred kHz below where you want it to be then by the time you raise it up it'll be as near as damnit and given the >1MHz bandwidth it doesn't matter as much if you're not spot on compared to a dipole that has a far narrower bandwidth.

 

[W5LZ]

It isn't all that uncommon to make a dipole out of two 1/4 wave mobile antennas. There are some mechanical aspects of it that will be different than if it was made from wire, the center insulator/feed point for example. There are several of those center insulators sold commercially, shouldn't be too difficult to find one, or make one.
I have to agree with 'M0GVZ', two 102" whips may not end up being the 'exact' size needed, I suspect you will have to do some tuning to get the thing resonant where you want it. More of that up/down ladders stuff, oh well.
Have fun.
- 'Doc

One reason why people assemble an antenna like this is so that they can rotate/turn it. Depending on high you can place the thing it does get sort of 'directional'. Of course, that means you gotta have some means of turning it, a rotor. One of those old fashion "Arm Strong" rotors work too...

 

[Captain Kilowatt]

They even make a bracket made for exactly what you want to do. Just screw the whips into and you are good to go. BTW don't even think for a half second that the mounting scheme will even begin to ground that antenna unless you install a ground rod or two and some heavy bonding wire to it from the mast. The mast simply sitting over a smaller piece of pipe is nothing when it comes to grounds.

 

[M0GVZ]

They even make a bracket made for exactly what you want to do. Just screw the whips into and you are good to go. BTW don't even think for a half second that the mounting scheme will even begin to ground that antenna unless you install a ground rod or two and some heavy bonding wire to it from the mast. The mast simply sitting over a smaller piece of pipe is nothing when it comes to grounds.

WTF are you on about? Its a dipole, a balanced antenna. It doesn't need grounding.

You really should stop giving advice about a subject you know nothing about.

 

[Mudfoot]

 

[Robb]

You must be joking

 

[W5LZ]

Yeah C.K.! You ought'a learn what you're talking about first...
- 'Doc

(looking for a deep hole with a door...)

 

[vkrules]

WTF are you on about? Its a dipole, a balanced antenna. It doesn't need grounding.

You really should stop giving advice about a subject you know nothing about.

RF wise it might not be needed but last Thunder storm here there was 1000 lightning ground strikes reported By the BOM .I sure as hell ground my mast .Not a good idea to recommend not grounding!!, in fact ground the whole Bloody Aerial . Anyway back on track You will most likely have to adjust the dipole what ever you do. Test on a short mast first and get the swr in the ballpark then raise to full height( swr may change a bit with height so don't cut the elements to short)

 

[Captain Kilowatt]

WTF are you on about? Its a dipole, a balanced antenna. It doesn't need grounding.

You really should stop giving advice about a subject you know nothing about.

Take your own advise and maybe learn something along the way. The mast makes an attractive lightning target. If you cared to take the time to read it again you will see I said to install ground rods and run a heavy bonding wire to the MAST to ground it. I said nothing about grounding the dipole. What's the matter? The folks on qrz.com get tired of your arrogance so you thought you would try here?

 

[TD126]

Thanks for all the help Guys! I found some old notations from the late 70's, early 80's when I was really "into it" making antennas especially. One thing I tried was to use a length of the 300 ohm twin lead antenna wire like used to be for TV....I see where I tuned and tuned and finally got the correct length for 27.185 MHz..then sometime later I decided to "double" it use both sides soldering them together at one end to in effect, double the length...but the notes have become non legible and I can't remember what happened yesterday anymore much less 30 some odd years ago...anyone ever tried this? I used PVC pipe for the "Beam" to hold the wires horizontal as I did on all my wire antennas.
I am like a kid in a candy store when it comes to radio "Stuff"...I want it all...lol, only problemis I don't have the "Green Stamps" anymore to do all this stuff with...sigh!

BTW, when I spoke of GROUNDING I was talking of having the MAST in the ground making contact to the moisture. The inner "Guide" pipe is to help hold the mast in place! The place where I put my masts is always DAMP and rarely ever gets any direct sunlight. Even in the 2006 drought year it was still damp in this area. I ground other masts that are roof mounted in a different way (described earlier).