HOW RADIO WORK - Part 1 - 15/4/2009

How Radio Works

by Brain, Marshall. "How Radio Works." 07 December 2000. HowStuffWorks.com. 16 April 2009.

Inside this Article

1. Introduction to How Radio Works
2. The Simplest Radio
3. A (Slightly) More Elaborate Radio

4. Radio Basics: The Parts
5. Radio Basics: Real-life Examples
6. Simple Transmitters
7. See more »

   7. Simple Transmitters: Make Your Own
   8. Transmitting Information
   9. Receiving an AM Signal
   10. The Simplest AM Receiver
   11. Antenna Basics
   12. Antenna: Real-life Examples
   13. Lots More Information
   14. See all Radio articles

Radio Image Gallery

Radio waves control everything from wireless networks to garage door openers. See radio pictures.

"Radio waves" transmit music, conversations, pictures and data invisibly through the air, often over millions of miles -- it happens every day in thousands of different ways! Even though radio waves are invisible and completely undetectable to humans, they have totally changed society. Whether we are talking about a cell phone, a baby monitor, a cordless phone or any one of the thousands of other wireless technologies, all of them use radio waves to communicate.

Here are just a few of the everyday technologies that depend on radio waves:

• AM and FM radio broadcasts
• Cordless phones
• Garage door openers
• Wireless networks
• Radio-controlled toys
• Television broadcasts
• Cell phones
• GPS receivers
• Ham radios
• Satellite communications
• Police radios
• Wireless clocks

The list goes on and on... Even things like radar and microwave ovens depend on radio waves. Things like communication and navigation satellites would be impossible without radio waves, as would modern aviation -- an airplane depends on a dozen different radio systems. The current trend toward wireless Internet access uses radio as well, and that means a lot more convenience in the future!

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­The funny thing is that, at its core, radio is an incredibly simple technology. With just a couple of electronic components that cost at most a d­ollar or two, you can build simple radio transmitters and receivers. The story of how something so simple has become a bedrock technology of the modern world is fascinating!

In this article, we will explore the technology of radio so that you can completely understand how invisible radio waves make so many things possible!

The Simplest Radio

Radio can be incredibly simple, and around the turn of the century this simplicity made early experimentation possible for just about anyone. How simple can it get? Here's an example:

• Take a fresh 9-volt battery and a coin.
• Find an AM radio and tune it to an area of the dial where you hear static.
• Now hold the battery near the antenna and quickly tap the two terminals of the battery with the coin (so that you connect them together for an instant).
• You will hear a crackle in the radio that is caused by the connection and disconnection of the coin.

By tapping the terminals of a 9-volt battery with a coin, you can create radio waves that an AM radio can receive!

Your battery/coin combination is a radio transmitter! It's not transmitting anything useful (just static), and it will not transmit very far (just a few inches, because it's not optimized for distance). But if you use the static to tap out Morse code, you can actually communicate over several inches with this crude device!