radio receiver antenna

How Does A Radio Receiver Work

A radio receiver is simply a device, working electronically, that receives radio waves and transforms the waves into a usable form – usually sound or motion pictures. It may also be referred to as wireless or just as radio. The devices require an antenna to “catch” the radio waves that have been generated electronically using an electric current. Basically, an antenna is a simple wire in a particular length.

Two major components must be available for a successful radio transmission: transmitters and receivers. But exactly how do these components work? Keep reading to find out…

radio receiver circuit

Radio Transmitter

Radio transmitters have a couple of components that work in unison to give off radio waves which are later reproduced into meaningful digital data, video, or audio. The various elements of a radio transmitter are:

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  • Power supply: this provides the electricity that is needed to power the transmitters
  • Oscillator: this works by creating an AC at frequencies which are then transmitted by the transmitter. It generates a wave which is known as a carrier wave
  • Modulator: this works by adding meaningful data to the wave from the oscillator and can do so in two ways:
  • Amplitude modulation. Commonly referred to as AM in short. This method adds information to the carrier wave by slightly increasing or decreasing its intensity,
  • Frequency modulation. Commonly referred to as FM is short. This method adds information to the carrier wave by slightly increasing or decreasing its frequency.
  • Amplifier: this works by amplifying the wave from the modulator and increasing its power. A powerful amplifier results in a powerful broadcast
  • Antenna: this intercepts the amplified signals and turns them into radio waves which are applied to the receiver.

Radio Receivers

Radio receivers are the antagonist of radio transmitters. They work by capturing radio waves and processing them to extract the desired information only from the waves that vibrate at a specific frequency.

The most common type of radio receiver that we are familiar with is a broadcast radio receiver which produces a sound that has been transmitted via radio broadcasting. Although broadcast receivers are commonly referred to as radio, that doesn’t mean that their use is only limited to radios. Technological advancements have seen the receivers be widely applied in various electronic devices such as TVs, their remotes, modems, mobile phones, and other components of communications.

fm radio receiver

These are an important part of all electronics that use radio and may exist as a standalone device or within the electric circuit of another device.

The main components of a radio receiver are:

  • Antenna: this works by capturing radio waves. On exposure of the antenna to the waves, they induce a small AC to it. The antenna doesn’t discriminate – it captures waves of all frequencies and then sends them to the RF amplifier where they’re all amplified
  • RF amplifier: this is quite sensitive. It amplifies even weak signals received by the antenna so that they can undergo further processing
  • Tuner: this refers to circuits that extract signals of specific frequencies from a mixture of various signals of different frequencies.

When you’d like to listen to a specific radio channel, you use the tuner to select the signals for that particular channel from the mixture of signals. The tuner uses combined inductor and capacitor to form circuits that resonate at particular frequencies. This frequency is referred to as the resonant frequency and it works by blocking out any signals that are at a higher or lower frequency.

Tuning the radio refers to the act of adjusting the resonant frequency by changing the level of inductance in the inductor and the amount of capacitance of the capacitor.

  • Detector: this separates the audio signals from the carrier wave. The detector for AM signals comprises diodes that work by rectifying the AC signal. What remains after the diodes have their way with the AC signal is a direct current signal that gets fed into an amplifier.

The detector for FM signals works in a totally different manner and is quite sophisticated.

  • Audio amplifier:works by amplifying the weak signals that are received from the detector so that the listeners can hear the sounds. They do so using transistor amplifier circuits

The Working of Radio Receivers In a Nutshell

Radio receivers use electronic filters to separate the desired radio frequency from all the other frequencies that are picked up. Once the antenna has picked up the desired signals, the amplifier increases the signals’ power so that they can be processed some more. The final signal gotten by the end-user is gotten through demodulation. 

Note that there are many different types of radio receiver designs but they have more or less the same components that are found in most receivers.

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