11 meter dipole problems

[Turbo T]

I decided to try my hand at building a dipole for 11 meter use.

I used two pieces of 16 gauge insulated copper wire, 9 feet long each.

I used a nylon insulator to separate the two wires from touching. I also used nylon insulators on each end of the wires, so I could secure the wires up without them touching anything.

I then soldered on a SO239 connector and used an 18 ft piece of good RG8X coax to connect dipole to radio.

I then hooked up my SWR meter inline between the dipole and the radio. (I don't have an antenna analyzer). My SWR's are over 3.

I'm not real sure where to start to fix this, but below are some pics so you can see how I mounted it. The red wire is the center feed and the green is the ground. The insulator for the red was stuck on the end of a metal pole using a zip tie and the green's insulator was secured to the back porch wooden support using a piece of 18 gauge wire that was not affiliated with the ground wire.

Please advise how I can fix this.

Thanks in advance.

 

[Robb]

1) Don't attach the dipole ends to a metal pole.
2) Use rope instead of wire at the ends of the dipole to support it.
3) Get it about 18 ft high off of the ground surface.

Then re-check it . . .

 

[522]

idk if its the camera angle or what ... BUT.. the angles of your ends seem to be very different.

me personally, id do one of three things:

totally horizontal. OR totally vertical. OR an inverted "V" ( basically 45 degrees slopping at either end)


do any of the following, and tell us the results

 

[HomerBB]

If it is still 9' long on each side it is too long, too.

I agree that the dipole needs to be tighter, flattened out horizontally, or the middle higher than the ends.

 

[Turbo T]

Thanks I will try putting it up higher using rope. You say 9 ft long in either end is too long? How many ft should it be?

 

[IMD262]

Thanks I will try putting it up higher using rope. You say 9 ft long in either end is too long? How many ft should it be?

KWARC Dipole Calculator

 

[jazzsinger]

When you say "good" rg8x, what exactly do you mean by good, rg8x isn't a military spec cable, therefore quality will vary wildly depending on the source/manufacturer.

if you know the cables velocity factor it would be much better to feed the dipole with a measured multiple of a halfwave, that way you can be fairly sure the cable length isn't giving bad readings,

would be a good idea to fit an rf choke, line isolator or a 1:1 balun at the feedpoint too.

have you tried feedingit with a different length/type of cable? if the swr changes you know your close to sorting it out.

the other glaringly obvious cause could be poor pl plug connections, i'd be double checking those poste haste.

 

[jazzsinger]

after i signed in and posted and the pics became visible, i notice that the solder connection on the green wire to the so239 socket looks a tad iffy, i might be wrong, but if its a dry joint it could cause all sorts of issues.

 

[mackmobile43]

You should take into consideration the length of your wires when tying the ends off, when you tie like that you shorten its over all length..

A choke or balun there in the middle will go a long way in isolating the 2 halves and stopping any CMC'S present.

All other advice here should be considered also.

 

[W5LZ]

You've got a good start, but there are a few things that will certainly help.
Getting the thing higher will help. How high? As high as you can get it. A few hundred feet would be nice, but sort of impractical, so, at least high enough you don't 'clothes-line' your self on it. Got any trees within reasonable distance? How about the eaves of the house? Keeping the ends of that antenna away from things is also nice. A few feet away from metal things especially.
How long should the thing be? That calculator gives you a pretty good estimate. But the exact length varies a bit according to height above ground, the frequency of use, and what the thing may be close to. There's no 'set in stone', always correct exact length that will be just right for every installation. You will have to 'tune' that antenna (adjust it's length) for it's surroundings and how it's mounted.
How about the 'droop', or the 'sag' of the thing? It isn't that big a deal, really. The 'droop' as you have it now will work. Along with adjusting the antenna's length, that 'droop' or 'sag' is another way of lowering the input impedance (SWR) or a dipole. The more 'droop' there is, the lower the SWR. There are limits to that, so don't get too carried away with it. Once the angle between the two legs of that dipole get to somewhere around 100 degrees (about 40 degrees 'sag' on each side) things start getting 'odd'. It isn't worth the trouble, it isn't 'helping' things.
That 18 feet of feed line just isn't important at all. The feed line should be long enough to reach the antenna from the radio. Using multiples of 18 feet usually means it isn't going to be long enough, or you'll have lots more than is needed. Feed line length can be used for several things, but unless you have a very specific need for one of those 'things', it's just a waste of time and effort. You don't have such a need, so don't worry about it.
- 'Doc

The first time is always the hardest, just too many things that vary. That's with everything, not just antennas, right?

 

[Turbo T]

When you say "good" rg8x, what exactly do you mean by good, rg8x isn't a military spec cable, therefore quality will vary wildly depending on the source/manufacturer.

Guess I should rephrase myself, "good" as in the coax itself is ok to use not shorting (that I know of) and recently worked on my base station. It's truck stop coax, probably Barjan.

after i signed in and posted and the pics became visible, i notice that the solder connection on the green wire to the so239 socket looks a tad iffy, i might be wrong, but if its a dry joint it could cause all sorts of issues.

You mean cold solder joints? Not so here. I actually used a pretty hot gun to do the work. the ground wire might be iffy, I wrapped it inside the screw hole on the connector then soldered it on.

A choke or balun there in the middle will go a long way in isolating the 2 halves and stopping any CMC'S present.

Is this a vital thing to have on a dipole?

That 18 feet of feed line just isn't important at all. The feed line should be long enough to reach the antenna from the radio. Using multiples of 18 feet usually means it isn't going to be long enough, or you'll have lots more than is needed. Feed line length can be used for several things, but unless you have a very specific need for one of those 'things', it's just a waste of time and effort. You don't have such a need, so don't worry about it.

Thanks i only used this feedline b/c it was all i had.

 

[Robb]

Guess I should rephrase myself, "good" as in the coax itself is ok to use not shorting (that I know of) and recently worked on my base station. It's truck stop coax, probably Barjan.

For the purpose of testing, go with it until it proves to be the problem. Just be sure that you took care of the visible mistakes already mentioned.

You mean cold solder joints? Not so here. I actually used a pretty hot gun to do the work. the ground wire might be iffy, I wrapped it inside the screw hole on the connector then soldered it on.

Probably OK then.

Is this a vital thing to have on a dipole?

Can't hurt it and will only help it if there is common mode current on the coax.

Thanks i only used this feedline b/c it was all i had.

Work with what you have. I saw some REAL problems in your pictures, as I mentioned in my first post here. Did you correct them yet?

 

[Grim Reaper]

you ll find that about a 1.5 inch space between the middle sections of the dipole and 72 ohm( rgu59) coax instead of 52 ohm RGU8 will help bring the swr down, alls left is fine tuning the lengths

 

[Turbo T]

Thought I'd give an update. So I took my dipole and got myself some twine and hung it up. Maybe 15 ft or so off the ground. I have one end of the twine tied around a down spout and the other end around a metal pole. The twine is probably a good 2 ft. long. I tied the twine to the end of each insulator.

Well, on channel 1 my SWR is 1.3:1 and on 40, it's almost to 3. Channel 20 it's roughly 2.2:1. Guess I need to make this guy a little bit longer...?

I was only able to strongly pick up channel 6 and 11 and 26 were faint. I don't know how hard skip has been rolling lately. But I have yet to be able to talk to anyone.

Oh and I had the dipole almost a perfect horizontal, but it did have a V shape to it. Just not a sharp V.

 

[W5LZ]

It sounds like it's too long, shorten it slightly and check again. The 'V' won't hurt anything. Higher would certainly help though. Since it's horizontally polarized, you aren't going to hear many strong signals locally unless the others are horizontally polarized too.
- 'Doc