Imagine stretching your hands to capture pictures, words, and other information then transmitted to a receiver. Literally, that’s what antennas do: they receive, convert, and broadcast radio waves from or to an electrical receiver. Often referred to as receivers or aerials, antennas are part of the technological developments that make it possible to listen to radios, watch televisions, or operate telephone systems.
Antennas exist in different sizes and shapes and pose a significant challenge to electrical systems users and novice electrical engineers when fixing a problem in their systems. This guide covers how antennas work – but first, take a close look at what is a radio wave.
Radio waves consist of right-angled fields – electrical and magnetic fields. These electromagnetic fields oscillate at specific frequencies (at a standard speed of 300 million m/s in free space), with electrical fields traveling perpendicular to magnetic fields. As obstacles appear in the path of frequency due to the increasing distance, the fields weaken in speed leading to low or no signals to the electrical systems.
How Antennas Work
Antennas operate through three stages:
- Generation of a radio wave;
- Application of a voltage to the antenna, which creates the electromagnetic fields;
- And induction of desired voltage into the receiver in the form of electric current.
Stage One: At the transmitter, the antenna captures people sounds, programs, pictures, and other information and convert them into electrical energy. This is possible, for instance, through the use of microphones to generate sound waves at the station.
Stage Two: In the antenna, the electrical energy is transformed into radio waves, and a voltage applied to the waves depending on the desired travel distance. The transformation occurs when the electrons in the atoms jiggle inside the antenna thereby creating electromagnetic radiations (radio waves).
While traveling with the speed of light, the electromagnetic fields in the radio waves carry the electrical signals along the way.
Stage Three: Finally, the receiver of electronic systems (radios or TVs) convert the radio waves into electric current through the jiggling of electrons. The current, in the form of a signal, is decoded electronically into sound and pictures.
Remember, it started with programs (sound and pictures) at the radio or television stations, then transmission of the programs in the form of radio waves through the antenna, and finally, reconversion of radio waves into the programs. These programs are what you hear or see when you turn on your electrical system.
While radio waves travel at the speed of light, it is relevant to note that these fields differ in wavelength. This is why most modern radios have two antennas, and indoor TVs have dipoles – to effectively capture different wavelengths. Modern phones, on the other side, have compact in-built antennas – a development of earlier versions with visible antennas.