People often confuse TV antennas with ham radio antennas and this is often because some ham radio antennas, known as Yagis or directional antennas, resemble the classic television aerial.
You cannot use a standard TV antenna as a ham radio antenna without modifications to the antenna and the transformer and cables that feed into it. If you simply connect a TV antenna to a ham radio station and attempt to transmit then you’ll probably damage your ham radio set.
TV antennas are used to receive signals from TV broadcast stations
It’s important to remember that a television antenna is a passive device that picks up the electromagnetic waves from the air and sends them to the TV set for conversion into a picture and all it does is receive signals.
In contrast, a ham radio antenna is an active device which helps in converting electrical energy from your transmitter to electromagnetic energy so that it can be radiated for others to receive.
The principles behind the functions of a TV antenna and a ham radio antenna of this type are very similar, in that they operate in a directional manner with focus in a certain direction.
This directional aspect can improve signal strength and detection and, in the case of a ham radio station, transmission also.
However, this is where the similarities end as the technical characteristics of TV antennas are not the same as those used by ham radio.
Can a TV antenna be modified to use as a ham radio antenna
In standard form use of a TV antenna with a ham radio transceiver would most likely result in damage to the radio due to mismatches between the antenna and the radio.
It is perfectly possible to modify a TV antenna to suit the requirements of a ham radio set but this would need changes to the coaxial cables, transformer and, most likely the actual beams of the antenna.
Ham radio operators tend to be practical individuals who enjoy experimentation and many would simply build their own directional ( Yagi ) antenna rather than reconfigure an old TV aerial.
TV antennas are the wrong size for ham radio use
If you were to compare a standard TV antenna to a ham radio yagi antenna then you would see a significant size difference.
This is nothing to do with space but is related to the wavelength of the radio waves that both receive.
Ham radios operate at different frequencies to those that are used by TV and even the highest ham radio UHF frequency is lower than that used by TV.
It may be possible to receive some signals on a ham radio by using a standard TV antenna – but they would likely be weak and tuning could be challenging.
TV antennas have a different impedance
TV antennas are usually designed for 75 ohm coaxial cables. Ham radio antenna cables use 50 ohms and there is often a mismatch when the signal enters the ham radio set.
The 75 ohm system can be easily modified to work with 50 ohms but changing the impedance of a TV antenna will affect how it works.
For this reason, most radio amateurs would use directional ( Yagi ) antenna designs for their ham radio stations rather than using a TV antenna.
TV antennas are designed to receive horizontal polarized waves
Most TV signals are transmitted with the end of the aerial pointing vertically and the transmission is horizontal polarized – compared with vertical polarization for most ham radio frequencies.
Vertical polarization offers a number of advantages including a better signal penetration through buildings and foliage and there is also less chance of electrical interference affecting the signals.
Final Words
If you’re looking to buy a TV antenna for your ham radio, keep in mind that antennas intended for use with televisions are not suitable.
Instead of wasting time and possibly money in trying to adapt a TV aerial for ham radio use, you would be better off building a new antenna designed for use with ham radios or buying a purpose made antenna for use with your radio set.
Remember that transmitting into a poorly matched antenna, such as an unmodified TV antenna, could damage your transceiver and leave you with an expensive repair.
Read Next
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- What does QRP mean in ham radio?
