What is a Ferrite Rod Antenna?

What is a Ferrite Rod Antenna?

Ferrite Rod brings back nostalgic memories of childhood when it was shown to me inside our old transistor radio by none other than my father, who was neither an electronics expert nor an amateur radio operator. Ferrite rod antenna is a small magnetic loop antenna used in medium and short wave radios of yester years. A variable capacitor was used to tune in the radio station in broadcast receivers. As the number of persons listening to medium and shortwave broadcasts have come down, the requirement for such radios also have  come down. But ferrite rod antennas have found a new use in Radio Frequency Identification (RFID) applications. The presence of ferrite rod within the tuning coil greatly enhances the reception of radio signals.

Ferrite rod aerial, ferrite loop antenna, and loopstick aerial are other names for a ferrite rod antenna. The  Creative Commons Attribution-Share Alike 3.0 Unported picture of ferrite rod antenna in the illustration from Wikipedia shows two coils wound on a single ferrite rod, one for long wave and another for medium wave. Though ferrite rod antennas perform better than a simple coil wound on an air core former, they are definitely inferior to external antennas. In amateur radio, ferrite rod antennas find their place in Amateur Radio Direction Finding, popularly known as Fox Hunt! Sometimes a very small loop wound on a ferrite rod may be used to find out the hidden transmitter in a Fox Hunt, especially while closing in on the transmitter location. That is because there is a sharp null along the loop axis. When the loop axis is aimed directly at the transmitter, the target signal almost vanishes. Anybody who has used the transistor radios of yester years with a ferrite rod antenna would have experienced this while turning the radio towards and away from the radio station.