CB Dipole antenna

[Eldorado828]

100% on this!







Take note, you're feeding a balanced antenna with an unbalanced feedline such as coax and will cause the unequal current to flow back on the coax line…hence the term "common mode current".

A 1:1 choke balun is used to control this by adding enough choking impedance to a given frequency or broadbanded to cover a much wider range.

"Ugly" air wound chokes work and are simple to make. Better ones are small coax or teflon wire wrapped around a 2 x 1/4" mix 33 (or 43 if higher bands are used more) ferrite ring or in series with 2 rings and installed in a weather proof box. Typically 2 gang electrical boxes are used with RF connections for easy install.

Think of it this way by definition, Bal-un, balanced to unbalanced.

Thank you, that's a great explanation and definition. I've got a spool of 8x so the next thing is to build and "ugly" air wound choke before going any further.

 

[Eldorado828]

I did mine without because at the time, I didn't know that it needed one.

I'm doing the same because I didn't know any better either.

Currently running one as a backup antenna in the attic but I didn't build it. It does pretty good considering it's only in the attic above the garage not very high!


This one I'm working on is a home brew to see what I could build. It's the one below.

 

[FredTx63]

Eldorado,

I have one of the antennas in your top picture - bought it off e-bay a few years ago to stash away as a temporary/emergency antenna. Recently tried it out hung vertically about 25 ft. from a tree and it performed great on 11m & worked about 70 countries and made 300 contacts on 10m FT8 with it.

 

[metalguy66]

I like these:

Model 1115 - 1:1 Balun, 1.5-54 MHz, 3kW

balun baluns 1:1 dipole yagis

www.balundesigns.com

I build them, rather than buy them, but these guys have a good design. Why reinvent the wheel? They have a 5KW rated version too if you like mo-powa..