Radar (Part II): The History of Radar

RADAR (Radio Detection And Ranging) is a tool that makes use of radio waves to tell you information about your surroundings. Radio waves are sent through a transmitter, bounce off of various objects, and the strength at which they return tells you how far they traveled and what they bounced off of. For a more detailed explanation of how radar works, see Part I.

But people don’t just go around bouncing radio waves off of things, so how was radar first discovered? What made it into the incredibly powerful tool it is today?

The answer is (as it is to a surprisingly high number of questions) war.

Our story starts in the late 1800s with someone called Heinrich Hertz. He conducted an experiment that conclusively proved that electromagnetic waves exist. Why is this important? Before his experiment, visible light was the only section of the electromagnetic spectrum (a fancy phrase for all the kinds of energy waves) that we knew existed. Once Hertz proved that there were other, invisible forms of energy, the doors were blown open for research into gamma waves, microwaves, and (you guessed it) radio waves. For his research, the scientific unit of frequency (a type of measurement used for waves) was called Hertz, because once you pioneer something cool, you’re allowed to stick your name on it. (I wonder if articles about radar can be called Isabelles)

That’s about as far as he got. His research would later be picked up in the middle of World War II. Some background-- on one side were the Axis powers: Germany, Italy, and Japan. On the other side were the Allied powers: the USA, Britain, France, and Russia. There were tons of other countries involved, but those were the big seven.

Now, remember the metal bucket in the dirt from the last article? The airplanes and submarines of WW2 were a lot like that metal bucket: hidden (behind clouds or water instead of dirt) and really, really important to find before they attacked your city. The problem was, no one had a reliable way to “see” these threats until it was too late-- it’s hard to see planes behind clouds, let alone at night, and the deeper a submarine, the more invisible to the naked eye. They needed a solution, something that could look right through clouds and water and darkness as if they weren’t there.

Sir Robert Watson-Wattis is often credited as the person who found that solution. In 1935, he began experimenting on whether radio waves from airplanes could be detected (spoiler: they could). He then won a patent and went on to create the Chain Home network, one of the first early warning radar systems in the world!

The Chain Home network was a series of radar transmitters and dishes that would flood the area with radar signals. The deluge of signals would bounce off of anything in the air and back to the radar dish, to be collected and sent to a computer and analyzed. This system was revolutionary in its potential: no people didn’t have to wait and stare at the sky with telescopes, hoping that any planes wouldn’t find cloud cover.

After the Chain Home system, lots of other types of radar began popping up during World War II. The US had their LORAN (LOng RAnge Navigation) which helped the world. In Germany, the Wurzburg Radar was detailed enough to distinguish British and German planes.

Even after the war, these technological marvels didn’t just fade away. The LORAN isn’t used much today and has been mostly replaced by GPS. On the other hand, the GCA (Ground Controlled Approach) is still used today to help air traffic controllers guide planes to the airstrip, and the Wurzburg radar is used for astronomy.

Instead, it turns ever further. In the early 1940s, people were able to transmit radio waves at higher frequencies. This was important because low radio waves need really big antennas and dishes to capture the signal. Smaller dishes led to the creation of the Cavity Magnetron in the UK, which helped inspire the laser, radio astronomy, and even the transistor.

In recent years, radar has undergone improvements that Robert Watson-Wattis could only have dreamed of.

This, however, is not where the story ends. Radar is as fascinating and as open for progress as the night sky. Try it out, and who knows what we might get back?

Heinrich Hertz

Picture Credit: Britannica