What is the purpose of a 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.
How does a balun work?
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. Common-mode chokes are also used as baluns and work by eliminating, rather than ignoring, common mode signals.
What is the main purpose of a balun in an RF system?
The concept of a balun is based around a transformer, and its main function as a balun is to isolate the direct connection between the balanced antenna or feeder and the unbalanced coaxial feeder.
What is the purpose of a 1 1 balun?
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.
What is balun in transmission line?
A balun is a form of transformer that goes from an unbalanced signal to a balanced signal. The unbalanced, or “single-ended” signal can be microstrip or stripline; the key characteristic is that one of the two conductors is clearly grounded.
How do CCTV baluns work?
The passive balun is non-powered and just converts the unbalanced to balanced signals so it’s possible to transmit the camera analog signals over the Cat5e cable. An active balun is powered and can convert and boost the unbalanced signal to balanced signals and transmit it to long distances over the Cat5e cable.
Does a balun reduce noise?
Whilst a balun is usually associated with reduced unwanted transmission line radiation (eg. from the feedline and power cord), a balun can also help minimise unwanted noise picked up by your feedline. There are many sources for design and construction of simple baluns on the internet.
What is a balun in RF?
The balun (a contraction of balanced-unbalanced) is a two-port component placed between a source and load when a differential, balanced RF functional block must connect to a single-ended, ground-referenced one. Baluns are not new or even relatively recent components.
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.
What is the difference between a balun and a choke?
Counterexample: an inductor in a matching network is not a choke, but the same inductor, used to filter RF from a DC power supply, could be called a choke. A balun is any device designed to connect a balanced source to an unbalanced load or vice-versa.
What is RF transformer?
An RF transformer is an electromagnetic device that sits between two or more circuits and uses changes of electric signals and the principle of induction in a conductor to produce a varying magnetic field (flux) that couples energy through to another conductor.
What is the difference between a balun and an UNUN?
A Balun is used to match a balanced line to an unbalanced line. An Unun is used to match an unbalanced line to another unbalanced line. This is a 4:1 Current Balun. The only difference between the Unun and Balun is how you connect the feed line.
