ferrite antenna

FERRITE ANTENNA & SLOT ANTENNA

Rex Dancel U. NieblaApril Jeromee F. Sarmiento

FERRITE ANTENNA

The ferrite rod antenna is a form of RF antenna design that is almost universally used in portable transistor broadcast receivers as well as many hi-fi tuners where reception on the long, medium and possibly the short wave bands is required.

FERRITE ANTENNA

FERRITE ANTENNA

Ferrite rod antenna is also used in wireless application in areas such as RFID.

It as a type of Small Magnetic Loop (SML) antenna.

FERRITE ANTENNA

FERRITE ANTENNA

FERRITE ANTENNA BASICS

A coil is would around the ferrite rod and this is brought to resonance using a variable tuning capacitor contained within the radio circuitry itself.

FERRITE ANTENNA BASICSThe ferrite rod antenna operates using the high permeability of the ferrite material. This may be thought of as “concentrating” the magnetic component of the radio waves.

FERRITE ANTENNA BASICS

The fact that this RF antenna uses the magnetic component of the radio signals in this way means that the antenna is directive. It operates best only when the magnetic lines of force fall in line with the antenna.

FERRITE ANTENNA BASICS

Ferrite Rod Parameters

Ferrite rod antenna Q

One of the requirements for an efficient ferrite rod antenna is that it should have a high Q at the frequencies over which it operates

Ferrite Rod Parameters

Radiation resistance of a ferrite rod antenna

Placing the ferrite core in the coil has the effect of raising the radiation resistance by a factor of μ^2, and thereby bring the value into more acceptable limits.

KEY CHARACTERISTICS

Radiation Pattern:Vertical Polarization Bidirectional

Radiation Pattern:Horizontal Polarization Omnidirectional

ADVANTAGES

• More compact than the other forms of low or medium frequency RF antenna, as a result they are being used in applications such as RFID.

ADVANTAGES

• Reasonable level of radiation resistance. Hence, reduces the losses due to the resistance of the wire.

DISADVANTAGES

• The Q may be so high that the antenna filters away some of the required signal modulation.

DISADVANTAGES

• The dissipation in the ferrite makes the system unsuitable at a TX antenna.

• The µe value is only larger than the unity for small magnetic field levels.