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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2k views

Voltage vs. Current Balun for Dipole

I'm a new radio amateur setting up a half-wave 10-meter inverted vee antenna fed by 50 ohm coax. I understand that the inverted vee lowers the normal 72 ohm dipole closer to 50 ohms, so I only need to ...
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1answer
188 views

Power Amplifier Balun Question

Second (and last hopefully) question on the classic Solid State Design for the Radio Amateurs (SSDRA) book by Hayward et al. Again it's a power amplifier circuit (Chapter 4, pg. 66), and again it's ...
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1answer
1k views

Connecting a coaxial cable as feed to a halfwave dipole

I have as assignment to make a half wave dipole antenna, that radiates at 433 MHz. I am trying to figure out how to use a coaxial cable as transmission line. I know that the coaxial cable is ...
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4answers
6k views

How do you construct a 1:1 balun?

I have been researching how to construct a 1:1 current balun. I have a few questions and am looking for feedback on what I plan to do. First, I want to use the balun from 10m to 160m at 100w. I plan ...
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2answers
169 views

Is a balun really necessary for a small loop antenna?

I am in the process of designing a small receiving loop antenna for the lower HF bands. By small I mean a circumference of less than $0.2\lambda$. Thus, a uniform current distribution can rightly be ...
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1answer
582 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 ...
2
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1answer
561 views

300 ohm to 50 Balun at antenna feedpoint, or near receiver?

If I build a folded dipole, it will have an impedance close to 300 ohms. I have to match this impedance to the 50 ohms of my transceiver. I know many people match that impedance with varying lengths ...
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1answer
1k views

Feedline and balun for 80m horizontal delta loop

I am new to HF. I'd like to put up an 80m delta loop. Due to aesthetic considerations I need to use coax to the shack. If tuned for 3.55MHz, I anticipate having a good SWR on 80m, 40m, and 20m. The ...
2
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1answer
131 views

What effect does a balun have on s-parameter, beam patterns?

I have a dual-dipole antenna with a subreflector slightly above it and a ground plane below it, and attached to the ground plane is a balun. While simulating in CST microwave studios, I didn't include ...
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1answer
94 views

What is the delay through a 1:4 Guanella balun?

I need to estimate the signal delay through the 1:4 Guanella balun shown here: Is the delay simply the delay through the winding on CORE1 or CORE2? For example, assume each winding comprises 0.1-m ...
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1answer
73 views

Rotatable Dipole & RF Choke

I have a Diamond HFV-5 (rotatable dipole) in the attic fed by ~30ft of coax. The antenna system comes with a Balun at the feedpoint. Would it be worthwhile to add an inline RF Choke (Unun) in addition ...
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2answers
154 views

Serial matching stub combined with RF choke

If I use RG6 coaxial cable in odd multiples of 1/4 wavelength as a serial matching stub, can I also use it, without modifying the length, as a coiled RF choke balun at the antenna feed point?
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1answer
2k 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 ...
2
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1answer
1k 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, ...
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2answers
211 views

Why some hams test their baluns with an SWR meter?

There are videos on YouTube that show how to make a 1:1 current balun. When the balun is done some people connect a 100W 50 Ohms resistor to the balun and measure SWR say in 7.000-7.200 MHz range. If ...
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2answers
157 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?
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2answers
92 views

2 meter coax cable balun dimensions for use with a ground plane?

I have a commercially manufactured ground plane antenna for 2 meters. It will be fed with about 150 feet of RG 8/U . I've seen pictures of a coil of the feed line going to a 2 meter ground plane; this ...
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3answers
160 views

Can I build a guanella balun using single strand wire instead of coax?

I am trying to homebrew a cobweb antenna and need some help understanding the guanella balun used as described here: http://www.karinya.net/g3txq/cobweb/ This author used RG316 coax around the ...
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3answers
2k views

How to calculate impedance in antenna design's practice?

I would like to make a match half wave length (λ) dipole antenna (or probably a short dipole antenna). So I would like to make it by measure using LCR meter. What I am still confuse is about what is ...
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2answers
225 views

Using a common-mode choke on symmetrical antenna system

I am curious as to what happens to a symmetrical dipole center-fed with balanced feeder-line. Let's assume the dipole is arranged as a sloper - that means it's not parallel to ground (horizontal). ...
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1answer
59 views

Can I use two voltage baluns to make a common mode choke?

I have two 1:4 voltage baluns. If I connect them together so that I have 1:4-4:1, is that the equivalent of putting a 1:1 common mode choke on my feed line?
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1answer
359 views

Folded balun, impedance matching

I am planning on building a half-wave dipole that is fed by a coaxial cable. I found a way to do this on antenna-theory (http://www.antenna-theory.com/definitions/foldedbalun.php). The article talks ...
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1answer
334 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?
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0answers
32 views

UHF cubical quad VNA analysis interpretation (part2)

This is the follow up to: UHF cubical quad VNA analysis interpretation This is a S21 and S31 analysis of an oversized 385 Mhz 50 Ohm to 90 Ohm balun between 100 Mhz and 600 Mhz I tested phase ...
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0answers
61 views

advice needed for balanced line terminals

I am designing a portable antenna with a radiating element and a balun that are not close to each other. The impedance has been designed to be close to 50 ohms. ...
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3answers
72 views

Weatherproofing coax connection to balun

How should a coax-to-housing connection like this be weatherproofed? It doesn't seem like taping is going to do much good here
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3answers
471 views

RF ground and balanced antennas

Suppose that a ham radio setup uses several antennas with a 50 ohm coaxial switch to operate some natively unbalanced antennas and some balanced ones through baluns at the feedpoint. An RF ground for ...
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2answers
1k views

Simple Longwire/Dipole Antenna design

In a couple of days I am going to a mountain cabin and I were thinking about making myself a semi broadband antenna for LF/HF (300KHz - 20MHz or so) for receiving only. I was thinking about creating ...
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1answer
93 views

Pondering variations on the vertical bazooka antenna

I've seen these antennas built out of coax that are called a bazooka vertical. It's a kind of 1/4 wave vertical, or perhaps a 1/2 wave dipole. Constructing such an antenna is to roll back the outer ...

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