How it Works

How does the radio at your home, work?

Radio has been popular in the 90s and is quite infamous now. The popularity of mobile phones now can be analogs to radios then. In this blog, let’s dig deep into the working of the radios.

What is a Radio?

Radio is an electronic device. It uses radio waves to send music, news, and other programming. Radio is also used for transferring data in coded form. And also to provide sound and television signals.

History of Radio

Now, let’s see the history of radio. The narrative of radio’s beginnings is one of the many overlapping technologies colliding. Hertz discovered Electromagnetic waves. Marconi invented wireless telegraphs, which allowed for one-way communication. De Forrest created an audio vacuum tube. The convergence of these and other advancements resulted in a breakthrough. Radio broadcasting started on Christmas Eve in 1906.

In March 1922, the Atlanta Journal granted the call letters WSB to the first commercial radio station in the South. The “Voice of the South,” was transmitted on two frequencies, one for entertainment and the other for news and market information, from the fifth floor of the Journal building. The Journal offered instructions on how to make crystal-set receivers in the weeks coming up to the station’s launch.

Most stations did not have regular programming schedules, in the beginning, transmitting for less than 8 hours each day. Listeners in the “invisible audience” might hear a combination of news, music, and commentary from the presenters. The “invisible audience” grew over the next two years as three extra stations launched.

When Mercer University established WMAZ (Macon) in 1922, it was used to broadcast sermons and addresses by theology students. WPAX (Thomasville) began broadcasting phonographs from the owner’s garage in the same year, using a microphone next to a Victrola. In 1923, WGST (Atlanta), a project of Georgia School of Technology’s electrical engineering school, became Georgia’s fourth radio station.

Now, as we are aware of the historic development of the radio, let’s shift our focus on the working of the radio. And for understanding the working of radio let’s see more about the radio waves.

Radio waves

Radio waves are a form of electromagnetic radiation. That finds uses in communication technology including television, mobile phones, and radios.

The electromagnetic (EM) spectrum contains a minor part of the radio-frequency spectrum. There exist many sub waves in the electromagnetic spectrum. They are Radio waves, microwaves, infrared (IR), visible light, ultraviolet (UV), X-rays, and gamma-rays are frequent terms.

These are organized on the basis of wavelength and energy and frequency. The wavelength, energy, and frequency are one and the same for the organization of the EM waves.

Radio waves have the longest wavelengths in this EM spectrum. Ranging from 0.04 inches to more than 62 miles. They also have the lowest frequencies. Ranging from roughly 3,000 cycles per second (3 kHz) to over 300 billion hertz (3 gigahertz).

The radio spectrum is a finite resource that is sometimes likened to agriculture.

How does Radio works?

Electromagnetic waves find use in transmission and receiving in radio. A radio signal is an electronic current that travels back and forth at a high rate. This field is sent outward from a transmitter by an antenna. Which is picked up by a receiver and converted into the sounds heard on the radio.

The power (amplitude) of the signal is modulated to generate the sounds in AM (Amplitude Modulation) radio. The speed (frequency) of the broadcast is adjusted in FM (Frequency Modulation) radio. When you listen in to your radio, the dial number displays the kilo or megahertz at which the signal is transmitted.

The frequency of a radio transmission refers to how rapidly the waves in the field rise and fall. Hertz is the unit to measure the number of wave cycles per second. Kilohertz is the unit to measure AM radio, whereas megahertz is the unit to measure FM radio . The signal’s range, or how far it can go, is affected by the station’s power.

Materials used

Today’s radio consists of an antenna printed circuit board, resistors, capacitors, coils and transformers, transistors, integrated circuits, and a speaker. A plastic enclosure holds all these components. A small diameter insulated copper wire twisted around a ferrite core makes up an internal antenna.

An external antenna is made up of a series of metal tubes that move into each other. A copper-clad design is attached to a phenolic board on the printed circuit board. The cabling from component to component is known as the copper pattern. It replaces much of the wire used in older radios. The flow of electricity is limited by resistors.

A carbon film is printed on a cylindrical substrate and is housed in a plastic (alkyd polyester) container with copper wire leads. Capacitors store electrical charge and allow alternating current to pass across an electrical circuit while blocking direct current flow. Two extended aluminum foil electrodes are encased in a plastic or ceramic container with copper wire leads in fixed capacitors and are insulated by polypropylene film.

A set of fixed aluminum plates and a set of spinning aluminum plates with an air insulator make up variable capacitors. Coils and transformers serve the same purpose. Their job is to insulate a circuit while also transmitting energy from one to the other. They are made up of two or more sets of copper wire coils that are either coiled on an insulator or mounted side by side with air between them as the insulator.

Transistors, whether germanium or silicon, are contained in a metal chassis with copper wire leads. A transistor is a device that controls how much electricity flows across a circuit. Thousands of resistors, capacitors, and transistors are packed into a small and compact container known as a chip. The chip is housed in a plastic box with metal tabs for attaching to a PCB.


The radiofrequency amplifier, mixer, variable frequency oscillator, intermediate frequency amplifier, detector, and audio amplifier are only a few of the specialized electrical circuits that make up a radio.

The radiofrequency amplifies and boosts a radio broadcast transmitter’s signal. To generate an intermediate frequency, the mixer takes the radio signal and mixes it with another signal produced by the radio’s variable frequency oscillator. The radio’s tuning knob is the variable frequency oscillator.

The intermediate frequency amplifier amplifies the generated intermediate frequency. The detector receives this intermediate signal and transforms the radio signal into an audio signal. The audio amplifier boosts the signal before sending it to the speaker or earbuds.

All these circuits are put on a single circuit board in the simplest AM/FM radio. The majority of these circuits can fit on a single integrated circuit. The volume control (a variable resistor), tuning knob (a variable capacitor), speaker, antenna, and batteries can all be found on or in the radio’s casing.

Manufacturing of radio

There is no single method for producing a radio.

A single circuit board is encased in a plastic casing in the simplest radio. Many circuit boards or modules are placed in an aluminum enclosure in the most complicated radio.

Printed circuit boards, which are proprietary, can be made in-house. Robots do the majority of the production tasks. Printed circuit boards and component installation on the printed circuit board are examples. The printed circuit board and controllers are mounted into the enclosure by hand, as are some soldering processes.

  1. A thin copper film is glued to one or both sides of the blank printed circuit board, which is made of glass epoxy resin. Over the copper film, a light-sensitive photoresist film is applied. Over the photoresist coating, a mask containing the electrical circuitry is applied. UV light is used to expose the photoresist film. The picture on the photoresist is developed and transferred to copper film. During etching, the unexposed portions disintegrate, resulting in a printed circuit on the board.
  2. Resistors, capacitors, transistors, integrated circuits, and coils are smaller electronic components are soldered in holes on the printed circuit board. These tasks can be carried out by humans or robots.
  3. Larger components, such as the power transformer, speaker, and antenna, are attached by screws or metal spring tabs on the PCB or cabinet.
  4. The radio can be housed in either a plastic or an aluminum housing. Pellets are melted and injected into a mold to create plastic casings. A metal press is used to form aluminum casings from sheet aluminum. The antenna, speaker, power transformer, volume, and frequency controls are all external components that are not located on the printed circuit board and are attached to the enclosure using screws, rivets, or plastic snaps. The printed circuit board is then screwed or snapped into place in the casing.