How RF Amplifiers Work

By Tyler Lacoma

Radio Signals

When radio signals originate, especially from some type of input microphone system (such as a walkie-talkie or radio station system), they are only weak electric currents. Often a small diaphragm will translate sound's pressure waves into movement, which is then transmitted into distortions in an electrical current.

The problem is that this electric current is far too weak to be transmitted through the air--the entire point of radio waves. In order to change this low-power electronic signal into a powerful radio signal that can sent to a transmitter and broadcast through an antennae, an RF amplifier is used to give the signal a needed boost.

RF Amplification

Like all amplifiers, the RF amplifier takes the distortions in the radio signal and distorts them even further, making the small differences large differences that can be sent and picked up more easily. The problem with this process is that the more distorted the signal becomes, the less chance the frequency will stay clear, becoming more and more different from its original electrical current.

To solve this problem, amplifiers spend most of their energy ensuring that every part of the signal is replicated faithfully as it is enhancing and transferred to a much higher-power system.

RF Amp Devices

The primary device responsible for the signal enhancement is known as a triode, or a diode with one added part--a control grid. The control grid affects on the electric charge flows through the diode, and by applying small voltage variations in the current passing through, the triode can make large changes in the strength and behavior of the current.

Of course, this is a very basic description of the process: modern RF amplifiers employ entire circuit boards to make sure the signal is given maximum strength with as little signal distortion as possible. Today, these amplifiers are used no only in radio towers, walkie-talkies, and specialized communication devices, but also in every cell phone and cell phone tower.