An Introduction to Ferrite Rod Antenna

Overview

Ferrite rod antennas are tiny magnetic loop antennas that are utilised in AM
broadcast transistor radios for medium and long waveband reception as well as
RFID applications. It is constructed using a ferrites rod or bar and contains a coil
coiled around the ferrite rod using a variable tuning capacitor in the radio
electronics.

How does Ferrite Rod Antenna work?

Its performance and frequency responsiveness are limited due to losses in the ferrite
core. As a result, the antenna functions at frequencies ranging from 2 to 3 MHz.

A ferrite rod antenna is mostly used to receive lower frequency transmissions ranging
from 50hz to 50khz. It functions as transmitting antennas for applications that require
minimal power and efficiency. If the power levels are high, the ferrite rod may
experience heat dissipation problems.

The tiny size and convenience, on the other hand, contribute to its advantages and raise
its demand for RFID applications.

Design

The antenna may also be constructed using other parameter combinations. As a
result, a shorter and broader coil with more turns can provide the same output
voltage as a longer and thinner coil with fewer turns and greater magnetic
permeability.

Because each arrangement will employ various materials, the price may vary.
The major goal is to deliver a target output voltage and power while keeping
restrictions like physical size and Q factor in mind. This might assist you in
determining the optimum configuration that has the lowest cost and meets all
design limitations.

Ferrite Rod Antenna Parameters

The two most significant characteristics of a ferrite rod antenna are the tuned
circuit's 'Q' and the radiation resistance. These characteristics govern where the
antennas can be used as well as the design of the circuits that utilise them.

Importance of The ‘Q’ Parameter

The 'Q' or Quality parameter of the circuit design in which the ferrite rod antenna coil is
positioned is a significant issue. To perform efficiently, the circuit must have a high Q at
the frequencies where the antenna would operate.

If the frequency is a few hundred kHz, a medium permeability material will be put in the
ferrite rod antenna to assist maintain a Q value of 1000 or so. At this point, the antenna
must be tuned to function at a higher frequency.

Because the magnetic circuit is open, the Q value of the ferrite core in the rod will
likewise be bigger than the material value. This number is proportional to the maximum
operational distance.

How is it useful for Radiation Resistance?

If the antenna is not ferrite, it has a small loop that is less than a wavelength in
length and has a low radiation resistance. As a result, the losses caused by wire
resistance would be exceedingly large.

To address this, a ferrite core is put in the coil to boost the radiation resistance
of the ferrite rod antenna. This lowers the radiation resistance and reduces
resistive losses caused by the wire.

Continue…

While the ferrite rod is helpful for increasing radiation resistance in antennas, it
introduces additional losses. The energy necessary to alter the magnetic
alignment in the granular structure of the ferrite core is absorbed by the ferrite.

If the frequency is increased, the number of changes increases, and hence the
losses increase. As a result, ferrite rod antennas are only employed at low
frequencies and not at higher frequencies.

Conclusion

In terms of efficiency, frequency, and tuning, a ferrite rod antenna is a solid
choice. Their popularity and demand as RF antennas for portable radios is
increasing worldwide.

Alisha Coils & Transformers designs Ferrite Rod Antennas using quality and new
technology to give our customers with customised solutions. Our strength is
in-house ferrite core manufacturing, which allows us to assure product quality
and timely delivery.

Thank You

If you need more assistance, you can feel free to connect with our experts who
will take you through our wide range of ferrite products available for several
applications. Contact us to learn more.

[email protected] www.cosmoferrites.com

+91-11 4939 8800