Do I need a Balun?

[W8ARR]

I want to make a wire antenna cut for 30 meters. I'm confused about the need for a balun. Can i just attach the wire to the end of my coax? Could anyone who has made a few wire antennas enlighten me. I'm using a LDG AT-897 auto tuner with my rig.
Thanks & 73
Art W8ARR

 

[VE3RCI]

It would be better to run your dipole with a balun rather than just connecting your wires to the end of your cable.

Baluns are fairly easy to make and as a matter of fact here is the one I am currently working on building.

BUILD AN AIR WOUND 1:1 CHOKE BALUN FOR HF - THE UGLY BALUN!

 

[Beetle]

You want to make a "wire antenna cut for 30 meters."?

Dipole or some other kind?

If it's a dipole, you MIGHT need a balun, but in half a century of hamming I've never had to...and I've built and used a few dozen different dipoles in that time.

That "ugly balun" is really only an RF choke; it doesn't do any converting of balanced to unbalanced, and it doesn't transform impedances. You can build or buy a 1:1 current balun, but I wouldn't do that until the antenna is up and on the air.

If you do use the "ugly "balun"", consider that it's not a one-size-fits-all item. It will work best on and near one frequency, meaning that what you make might itself have to be tuned for best operation on 30M.

 

[wavrider]

1:! current balun at the feed point of the dipole.

BALUN takes the coax, ( un-balanced transmission line) and connects to a balanced antenna (dipole).

Do you need one?

Only if you want equal current distribution on each leg of your dipole.

Only if you want to keep any rf off of your transmission line (CMC).

Why wold someone build an balanced antenna and not use a current balun at the feed point?

It would seem that any one who takes the time to build an antenna and install it would want it to work as efficient as it can be made to work.

http://static.dxengineering.com/pdf/Choosing the Correct Balun.pdf

Good read, then you can decide if you need one or not.

 

[W8ARR]

Lots to think about

i use an rf choke on my 2 meter j-pole. I think I will try a balun on my antenna. The essence of amateur radio is experimentation. I wanted to get some opinions.
Thank you all who answered
thanks & 73
Art

 

[W5LZ]

Do you absolutely need to use a balun with a dipole/doublet type antenna? No, you don't. Quite a few people don't and seem to be doing just fine.
Baluns do two things, make for a 'smooth' transition between a balanced antenna and an unbalanced feed line, and can transform impedance. A balun's primary job is making that transition from a balanced to unbalanced state, the impedance transformation is a secondary ability. So -why- you use one can make a big difference in what 'kind' of balun to use. Another secondary characteristic of a balun is that it can provide some 'isolation', sort of keeping that RF where it's supposed to be and not where it shouldn't be. That's a lot like a transformer in an audio line and just like an audio transformer, that 'separation/isolation' depends on using the right transformer in the proper way. Which brings up another characteristic of a balun, and that is that they are frequency specific, or maybe 'band' specific is a better way of saying it.
Confused yet? To simplify it a lot, using a balun isn't strictly necessary. They have abilities that can certainly 'help' things, but they also have liabilities that are bothersome. They are not a 'miracle' cure by any means. So what should you do? Why not make your antenna, try it without a balun, then try it with a balun? Then you can decide for your self. You will see small differences in performance, not huge ones.
- 'Doc

 

[VE3RCI]

Do you absolutely need to use a balun with a dipole/doublet type antenna? No, you don't. Quite a few people don't and seem to be doing just fine.
Baluns do two things, make for a 'smooth' transition between a balanced antenna and an unbalanced feed line, and can transform impedance. A balun's primary job is making that transition from a balanced to unbalanced state, the impedance transformation is a secondary ability. So -why- you use one can make a big difference in what 'kind' of balun to use. Another secondary characteristic of a balun is that it can provide some 'isolation', sort of keeping that RF where it's supposed to be and not where it shouldn't be. That's a lot like a transformer in an audio line and just like an audio transformer, that 'separation/isolation' depends on using the right transformer in the proper way. Which brings up another characteristic of a balun, and that is that they are frequency specific, or maybe 'band' specific is a better way of saying it.
Confused yet? To simplify it a lot, using a balun isn't strictly necessary. They have abilities that can certainly 'help' things, but they also have liabilities that are bothersome. They are not a 'miracle' cure by any means. So what should you do? Why not make your antenna, try it without a balun, then try it with a balun? Then you can decide for your self. You will see small differences in performance, not huge ones.
- 'Doc

Well said Doc But for some reason I have never had any luck with a no balun dipole so I gave up which was about 10 years ago lol . I guess I was not doing something right. How ever I have decided to try again but with a balun.

 

[VE3RCI]

You want to make a "wire antenna cut for 30 meters."?

Dipole or some other kind?

If it's a dipole, you MIGHT need a balun, but in half a century of hamming I've never had to...and I've built and used a few dozen different dipoles in that time.

That "ugly balun" is really only an RF choke; it doesn't do any converting of balanced to unbalanced, and it doesn't transform impedances. You can build or buy a 1:1 current balun, but I wouldn't do that until the antenna is up and on the air.

If you do use the "ugly "balun"", consider that it's not a one-size-fits-all item. It will work best on and near one frequency, meaning that what you make might itself have to be tuned for best operation on 30M.

So I am assuming that the ugly balun is just a contradiction to how a balun is actually made?? Don't mind me I am still a newb at constructing wire antennas so I am just curious is this guys design truly not a balun at all? This fella also states that this will operate between 1.8 Mhz and 30 Mhz.

 

[Beetle]

So I am assuming that the ugly balun is just a contradiction to how a balun is actually made?? Don't mind me I am still a newb at constructing wire antennas so I am just curious is this guys design truly not a balun at all? This fella also states that this will operate between 1.8 Mhz and 30 Mhz.

Correct. It is a CHOKE. It affects RF on the outside of the coax shield (commonly called "common mode current") but does nothing to the RF between the center conductor and the inside of the shield.

As for the bandwidth, I'm pretty sure that SOMEWHERE between 1.8 and 30 MHz, it will be a reasonably effective CHOKE.

 

[Captain Kilowatt]

It will work between 1.8 and 30 MHz it's just that on some frequencies it will work GREAT, on some it will work GOOD, and on some it will work PISS POOR. I guess that is what is meant by saying it works on all frequencies between 1.8 and 30 MHz.

 

[HomerBB]

It will work between 1.8 and 30 MHz it's just that on some frequencies it will work GREAT, on some it will work GOOD, and on some it will work PISS POOR. I guess that is what is meant by saying it works on all frequencies between 1.8 and 30 MHz.

:laugh:

 

[VE3RCI]

It will work between 1.8 and 30 MHz it's just that on some frequencies it will work GREAT, on some it will work GOOD, and on some it will work PISS POOR. I guess that is what is meant by saying it works on all frequencies between 1.8 and 30 MHz.

I am going to be trying this out on the 15, 20, 40 and 80 meter bands. Honestly I think this will make things look more neat than just simply slapping a couple pieces of wire on the end of my feedline from the shack

Either way I am not going to get discouraged as I have already just about completed one of these. If it works then hey a pat on the back for myself for successfully completing a dipole that actually works If not ah well life goes on as it cost me literally only $1.00 to build :w00t: Yea only $1.00 as I already had what I needed to construct this project.

We will see how it goes and I will report back in my own thread.