What does a coax balun do?
To avoid feed line radiation, baluns are typically used as a form of common mode choke attached at the antenna feed point to prevent the coaxial cable from acting as an antenna and radiating power.
What is a balun Why do we need that in dipole antenna?
BalUn means: Balanced to Unbalanced. This enables us to adapt an unbalanced fed system (coaxial cable) to a balanced antenna system (dipole antenna). The main reason for using a BalUn is to ensure that the coaxial cable does not become part of the antenna system and therefore radiates with it.
How do I choose a balun?
Select a balun closest to the antenna feedpoint impedance (you’ll have to get this from textbooks or modeling), and use it at the feedpoint or where the feedline from the antenna ends. Be sure the feedline between the balun and antenna feedpoint matches the antenna impedance as closely as possible.
Does a magnetic loop antenna need a balun?
Would a balun be needed on any antenna, including a small loop? Adding balun typically doesn’t hurt if it isn’t needed, especially if it’s just a few loops of coax (“air balun”). Common mode current isn’t guaranteed even when a balun is recommended, so you can frequently leave it out.
What size balun do I need?
The overall length of the multi-band dipole antenna should be shorter than one-half wavelength as shown in Table 1. For best efficiency, ladder line feed and a good antenna tuner with balanced connections are required. The ideal balun is a 1:1 ratio DX Engineering special application tuner balun.
Why do we need balun?
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.