Balun's are they useless?

Hi fellow members,

Are balums useless? For a start starter most people don't know what they are are or how they relate to antennas that includes myself.


Most of the time they're simply used to prevent radio frequency interference and electromagnetic interference. 

Of course the simpler choice then is to use a ferrite choke. A couple of snap ons just before the antenna and another near the transmitter.

What's your view?

73

Mr Scientist

Hello Peeta,

The balun far from being useless is a pretty essential part of any antenna system where a unbalanced feed line is being used with a balanced antenna such as a dipole. This will prevent a radiating feed line and prevent distorting the antenna's radiation pattern as well as the interference that you've already referred to.
I always use one in this situation.

73 Gary.

I am waiting for our Victor on this one lol.

Ah you beat me to it Alan.

It's never because I'm 'opinionated', but rather sharing any knowledge available to help people in any way.  


Gary has already put it well and I agree that they are an essential part of an antenna system.

You can run a dipole without one and I did happily for some time but as I discovered they run a heck of a lot better with one. I'd also do my best to impedance match were I could or should but sometimes you can get away with the 'little' things. (Such as my penchants for running 75 ohm coax.  )


The nice thing about a radio interest is that there is always something to learn and those of a radio persuasion are more than happy to help out where they can. It can clearly be seen by such discussions here at Charlie Tango and the wealth of information published elsewhere.


+1 from me regards BAL-UN's, UN-UN's and other antenna impedance matching methods.  

(Just remember you can easily build them yourself than pay often 'over the top prices'.)


All the best,
Victor

Victor wrote:

Gary has already put it well and I agree that they are an essential part of an antenna system.

You can run a dipole without one and I did happily for some time but as I discovered they run a heck of a lot better with one. I'd also do my best to impedance match were I could or should but sometimes you can get away with the 'little' things. (Such as my penchants for running 75 ohm coax.  )

Hello fellow members,

Whats is it balancing? A Balun is in essences is a crude transformer (solenoid) from what I can tell, altering impedance (resistance) of a AC current. preventing the RF which is AC coming back down the coax from entering ones transmitter. 

My position is if that all its doing would not a few ferrite beads or rings be better. If its to match any voltage, current or impedance going from the inner core of the coax to the outer braid than that a different story. but from what I observe they are simply use to stifle RF feed back along the outer braid. 

Also I gather some radio hobbyist mix and mach coax and cable, that would present different impedance, so would a Balun be useful there?

over to chaps.

73 Mr Scientist

Hi Peeta,

I congratulate on your willingness to learn about such things and the questions that arise from the learning process.

There are indeed as the old proverb states, "many ways to skin a cat", and a number of solutions may present themselves to the enthusiast. Which solutions are better is a matter of speculation and usually an enthusiast will explore options that they either understand or are able to procure with sufficient knowledge.

For myself it's so that I can build my own equipment and accessories, for others it may be to attain sufficient knowledge to make an informed decision on a purchased item. Some just simply enjoy the learning process.


There are yet others that dedicate their lives to appreciating and fully understanding such subject material becoming an eminently qualified member in their field. Many of them publish their findings on the internet and can be a useful source of information for those wishing to learn more.

If it helps any here is one such example :-

https://www.antenna-theory.com/definitions/balun.php

There are many more examples besides.


I'm sure that it's true for most of us here and other radio enthusiasts that we wish to simply understand enough to make informed decisions to assist our activities. Such enthusiasts usually stand out by not being hindered by what is theoretically possible but by what we can practically achieve. Examples include fitting antennas for 160m onto a small plot, zig-zagging dipoles to fit in an attic space, winding 'ugly baluns' or chokes from coaxial cable etc. etc.

For many 'necessity' truly is the mother of invention and we will do whatever we can to achieve results for our chosen interest even if the solutions are not perfect but simply better than what we have.

The 'best' of them will happily share their findings with others simply to assist them - even if they can't truly explain them to the Nth degree.


I wish you the best in your learning path, you may have to travel a few and they won't always be in one place or a particular heading.


All the best,
Victor


P.S. - Yeah I know, I've pretty much just said in an eloquent fashion, "Have you tried Googling it?"

As one of my old tutors always said, "Research is the key", and someone else more famous said it better with "If I have seen further, it is by standing on the shoulders of giants.”

Mr Scientist wrote:

Whats is it balancing? A Balun is in essences is a crude transformer (solenoid) from what I can tell, altering impedance (resistance) of a AC current. preventing the RF which is AC coming back down the coax from entering ones transmitter. 

My position is if that all its doing would not a few ferrite beads or rings be better. If its to match any voltage, current or impedance going from the inner core of the coax to the outer braid than that a different story. but from what I observe they are simply use to stifle RF feed back along the outer braid. 

Also I gather some radio hobbyist mix and mach coax and cable, that would present different impedance, so would a Balun be useful there?

over to chaps.

73 Mr Scientist

It's not balancing anything although it does keep the normal flow of current in the feedline balanced.
It's primary role is to choke the Common mode current on the feedline, another role is impedance transformation.

Mr Scientist wrote:

Whats is it balancing?

It's not supposed to be balancing anything, it acts a an interface. BALUN refers to the feeder and the antenna, BALanced antenna (dipole) to UNbalanced feeder (coax).

UNUN...UNbalanced antenna (endfed) to UNbalanced feeder (coax). 

Some transform impedance, some don't, all prevent or reduce RF common mode current flowing down the outside of the braid of the unbalanced feeder.