Questions tagged [balun]

Devices for connecting balanced and unbalanced feed lines/antennas. Also covers questions about ununs, unbalanced-to-unbalanced connection.

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3
votes
1answer
476 views

Balun identification from picture

I thought maybe this was a 4:1 balun, but a number of 4:1 single core balun diagrams that I found online had different connections. N1HFX's balun page and the bottom of G4WPW's page show a connection ...
1
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2answers
139 views

what is choking reactance in TLT?

I was studying about the Guanella 1:1 balun and came across the term "choking reactance". What does this mean? Why does its value need to be large?
2
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1answer
538 views

Will adding a balun to a full-wave dipole help?

I have made a dipole for 40 m, no swr to speak of on 7040 kHz, but I've been told that it should also work on 20 m as it is 20 meters long (2× 9,92 m) but there I get SWR in the 7-9 range. Will this ...
5
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2answers
499 views

Why aren't there baluns that do BOTH balanced/unbalanced transformation and common mode current attenuation?

I have read myself blue, about baluns. Especially 1:1 ones. Some claim they're only there to balance the unbalanced signal, and that's what's in the name also, but I find several that claims that the ...
8
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2answers
2k views

Why isn't twisted pair used for feedlines?

My son was asking about some Ethernet cable (Cat 5 unshielded twisted pair), and since he recently passed his Technician exam and we both have "radio stuff" on our minds, I tried to make the analogy ...
1
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1answer
299 views

how does slotted coax Balun eliminate common current?

how does slotted coax Balun eliminate common current? why the length of the slot should be quarter wavelength?
3
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1answer
579 views

What do we mean by “RF in the shack”?

What does "RF in the shack" mean? How does it interfere with devices around coax?
4
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2answers
2k views

How to measure a balun for effectiveness?

It seems there are almost as many "balun" designs as there are web pages about "baluns". There's lots of accusations pointed in all directions ("design Z isn't a balun OR a choke", "design Y is ...
20
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3answers
29k views

Why are some 1:1 current baluns twice as complicated as others?

I would like to add a balun/choke to my dipole for the reasons outlined in Using a balun with a resonant dipole. In the spirit of continued kit and/or DIY building for my ham shack, I set out to ...
2
votes
1answer
1k views

Balun and impedance matching suggestions for dipole antenna

I'm a newbie who is attempting to build a half-wave dipole antenna that will be located in the rudder of a sailplane. 123.3 MHz is the most important frequency to me, although it's reasonable to ...
4
votes
3answers
2k views

Recommended 9:1 unun core type(s)

I would like to construct a 9:1 unun that connects my QRP transceiver to a random-wire antenna. The transceiver's antenna connection is an unbalanced BNC jack and the random-wire antenna is, well, a ...
3
votes
2answers
9k views

How is a 1:1 current balun different from a choke?

I have a 10m dipole and am going to feed it with 50 ohm unbalanced feed line (coax). My understanding is the feed point of this style antenna is about 50-75 ohms and since it is a balanced antenna I'...
6
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2answers
2k views

Understanding coax radiation and “current on the shield”

I'm having trouble understanding what seems to be the fundamental principle behind baluns (and probably other related topics). Perhaps some of my confusion comes from an audio background, where one ...
2
votes
1answer
961 views

Do I need a Balun for a single band QRP antenna?

I have a little MFJ QRP CW 20m rig that I plan to turn into a portable kit for SOTA peaks. I have everything figured out except for the antenna. I am wanting to make a dipole. However, I was wondering,...
2
votes
1answer
995 views

Is there a 4:1 current balun model for 4nec2?

I don't seem to be able to find the data to enter a 4:1 current balun in the 4nec2 software. Has anyone found or written one? I am building a 75 Ω fed OCFD and need to model the radiated patterns, ...
6
votes
2answers
4k views

How does a folded balun work?

A folded balun is made from two quarter-wavelength, parallel conductors. A picture is worth a thousand words: Here are some pictures of an actual construction from Gisela & Joe Noci on diydrones....
5
votes
1answer
1k views

Connect Printed Yagi-Uda Dipole Array with Balun to coaxial cable correctly

I am making the Printed Yagi-Uda Dipole Array with Balun (that is the full name). I used Antenna Magus to calculate dimensions. I am not sure how to properly connect it to coaxial cable. Here is what ...
6
votes
3answers
2k views

Impedance Matching Different Feedlines

(I promise there will be a question in this wall of text. I'm just giving context.) I've been wanting to try my hand at building my own antenna system for the last few weeks and in doing research, a ...
35
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7answers
34k views

Using a balun with a resonant dipole

I am preparing to construct a resonant, center-fed, horizontal dipole. I have seen people use baluns at the feedpoint of the antenna, and some people swear by them, but I have never gotten a ...
13
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1answer
5k views

What is the purpose of a balun and a unun in a feed line?

I have never understood how a balun or a unun works and under which situation I need to use either of them in an antenna feed line.

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