Advantages of Balun | disadvantages of Balun
This page covers advantages and disadvantages of Balun. It mentions Balun advantages or benefits and Balun disadvantages or drawbacks.
What is Balun?
• Balun is a device which connects balanced transmission line to unbalanced transmission line.
• Balun is the short form of Balanced-Unbalanced. It is the device which matches two different impedances. For example, balun transformer connects transmission feed line with antenna. In this application it converts impedance from 300 ohm to 75 ohm and vice versa. Here 300 Ohm is free space impedance and 75 ohm is coaxial line impedance.
The figure-1 depicts folded type of balun. It allows direct connection of a coax line to the dipole antenna.
There are various balun types which include Folded balun, sleeve balun, Split Coax Balun, Half wavelength balun, Candelabra Balun, Ferrite Core Balun,
Ferrite Candelabra balun, transformer balun, split tapered coax balun, microstrip balun etc.
Refer article on types of baluns with applications >> for more information.
As mentioned above there are two functions of balun transformer.
• Impedance transformation
• Balanced to unbalanced transmission
Benefits or advantages of Balun
Following are the benefits or advantages of Balun types used in various applications.
➨It helps in interfacing many types of antennas (dipoles, loops) which are balanced loads with their feeders which are unbalanced transmission lines (e.g. coax line).
➨They are used for proper connection of parallel line to a transceiver with 50 Ohm unbalanced output.
➨They prevent unwanted RF currents to flow into the third conductor of coaxial cable.
➨Transformer type balun will have electrically separate windings for inpur and output. This allows baluns to connect circuits which are elecrically incompatible. Hence these transformer baluns are also known as isolation transformers.
Drawbacks or disadvantages of Balun
Following are the drawbacks or disadvantages of Balun:
➨Certain type of baluns will provide high attenuation to the signal.
➨Its cost is high.
➨Certain balun types have complex geometry and hence it is difficult to manufacture.
➨The advantages and disadvantages vary based on different balun types. Hence one need to refer specific balun type for the same.