What is a balun circuit?

A balun (balanced-to-unbalanced) is a transformer used to connect. balanced transmission line circuits to unbalanced ones. Two conductors having equal and opposite potential constitute a “balanced” line. Microstrip and coaxial cables use conductors of different dimensions – these.

What does balun stand for?

balanced to unbalanced
A balun /ˈbælʌn/ (from “balanced to unbalanced”, originally, but now dated from “balancing unit”) is an electrical device that converts between a balanced signal and an unbalanced signal.

Why is a balun used?

This transformer is known as a balun, and they are in operation in anything from telephone lines to transmitters. Baluns are used both to sort out the flow of AC signals and make the necessary impedance transformation between coaxial cable, which has a low impedance, and balanced loads, which have higher impedances.

What is the difference between a balun and a transformer?

Baluns convert between balanced and unbalanced lines, and RF transformers perform impedance matching, voltage or current step-up or step-down, and DC-isolation between two circuits.

What does a 1 to 1 balun do?

Key uses for the 1:1 current-balun: a) is to marginalize the “inverted-L current” in the transmission-line feeding a dipole-antenna. This will prevent a radiating Feedline and prevent distorting the antenna’s radiation pattern. There will be some flux in the core but it’ll be minor due to the small current causing it.

Do I need a balun for receiving?

Yes, you do need a balun. A simple quarter-wave dipole is balanced, coax cable is not.

What does a 4 to 1 balun do?

A balun with a ratio of 4:1 or more will transform the already low impedances appearing on some bands to even lower values. This will greatly reduce system efficiency and reduce tuner power ratings. The 1:1 ratio balun will just pass the low impedance through.

What is a 4 to 1 balun?

A 4:1 balun has four times the balanced impedance as unbalanced impedance. Balanced and Unbalanced. Balanced lines and loads, by definition, have equal voltages from each terminal to ground. Each balanced terminal or conductor must also carry precisely equal and exactly out-of-phase currents.

Why use a balun on a dipole?

A dipole is what is termed a balanced antenna. In an ideal world a balun should be used with coaxial feeder (which is unbalanced) to make the transition between balanced and unbalanced systems. The use of a balun will prevent the coax radiating any power or picking up any noise.

Is a choke a balun?

The 1:1 choke “balun” is not actually a balun. It’s function is to help eliminate rf currents from flowing on the outside of coaxial cable using the principle of choke action. Another “name” for it is the air choke.

Do I need a balun for a dipole?

How do you test a 4 to 1 balun?

A straightforward way to test a 4:1 balun is as follows:

  1. Disconnect the output side of the balun from your antenna or ladder line.
  2. Locate a NON INDUCTIVE (Carbon composition, for example) 200 ohm resistor and connect it directly across the output terminals of the balun.