The Invention of Radar

Experimental radar antenna, US Naval Research Laboratory, Anacostia, D. C., from the late 1930s (photo taken in 1945)
Experimental radar antenna, US Naval Research Laboratory, Anacostia, D. C., from the late 1930s (photo taken in 1945)

Intro

RADAR (Radio Detection and Ranging) is a method of detecting objects and measuring distances by using electromagnetic waves to detect, locate, and track objects. It works by sending out pulses of radio waves and then listening for the echoes that bounce off objects in the environment. By measuring the time that it takes for these echoes to return, the range (distance) to the object can be calculated. Radar is used to detect aircraft and ships, measure precipitation and wind speed, and map the surface of the Earth.

The invention of radar has revolutionized the way we navigate and interact with the world around us. It was first developed in the early twentieth century by a British physicist named Sir Robert Watson-Watt, and has since become an invaluable tool for navigation, surveillance, and defence.

The Telemobiloskop

The origins of radar can be traced back to the late 1800s, when several scientists began experimenting with radio waves. Experiments conducted in the late 19th century by Heinrich Hertz, showed that radio waves are reflected off of metal objects.

One of the first experiments in this field was conducted by Christian Hülsmeyer in 1904, when he used a device called Telemobiloskop (sometimes written French-style, Télémobiloscope) to send out radio waves and measured their reflections when they bounced back from objects.

Christian Hülsmeyer - The inventor and his Telemobiloskop
Christian Hülsmeyer – The inventor and his Telemobiloskop

He patented this device in Germany, the UK and in the USA. This device was the world’s first radar.

A successful demonstration on the Rhine proved the technical function of the method. However, due to the inadequacies of high-frequency components at that time, no outstanding ranges were achieved. While this was an important step in the development of radar, it did not lead to any practical applications at the time.

The Telemobiloskop - the First early Radar
The Telemobiloskop – the First early Radar

The Invention of Radar

Serious development work in radar began in the early 1930s, but radar’s fundamental ideas originated with Hertz’s classic experiments with electromagnetic radiation conducted during the late 1880s.

Before the invention of radar technology in 1935, the job of the ‘listener’ was designed to act as an acoustic early warning system against raids. In wartime in the 1900s, pre-radar listeners would listen to approaching enemy aeroplanes and listen for the sound of engines approaching from the skies. Pre-radar had the capability of picking up sounds at a long distance and were tasked with signalling and monitoring events.

The invention of radar is credited to Sir Robert Alexander Watson-Watt, who in 1935 proposed the idea of using radio waves to detect aircraft. He built a prototype radar system and tested it in the UK, where it successfully detected an incoming aircraft. This marked the first practical use of radar, and it was soon adopted by the military for aircraft detection and tracking.

Sir Robert Alexander Watson-Watt
Sir Robert Alexander Watson-Watt

Shortly before World War II began, the British built a network of radar stations on England’s coastline using the designs of Sir Robert Watson-Watt. In February 1935, Watson-Watt demonstrated the first practical radio-based aircraft detection system to a Committee of the Ministry of Air. On April 2, 1935, Robert Watson-Watt was granted a patent on a radio apparatus to detect and localize an aircraft, more work was needed before the first radar system was developed that could detect planes 40 miles away.

The first workable unit built by Robert Watson-Watt and his team
The first workable unit built by Robert Watson-Watt and his team

Sir Robert Alexander Watson-Watt was appointed Director of Radio Research at the British National Physical Laboratory in 1935, where he completed his studies for a radar system which would be capable of locating aircraft. Robert Alexander Watson-Watt realized, while refining his radar device, that radio waves could be used for much more than detecting storms. Radar had been developed over the years, with contributions from a number of sources, but it was Robert Alexander Watson-Watt who designed the first set put to practical use.

Without question, radar gave the British an element of surprise over the Germans in the Second World War, and the consequences would have been unthinkable without it. His contribution to the war effort was such that he was knighted in 1942.

Memorial plaque commemorating Robert Watson-Watt and Arnold Wilkins
Memorial plaque commemorating Robert Watson-Watt and Arnold Wilkins – Memorial at the Daventry site of the first successful RADAR experiments. 52.195982°N 1.050121°W

Evolution of Radar

Radar technology quickly evolved in the following decades, with improvements in the range, accuracy, and resolution of radar systems. The first radar jobs were mainly focused on detecting and tracking aircraft, but soon radar was used to monitor storms, guide ships, and even detect objects in outer space.

Commercial marine radar antenna. - Animated GIF showing a rotating waveguide antenna of a typical X band marine radar on a ship. It radiates a narrow vertical fan-shaped beam of microwaves perpendicular to the antenna bar, along the water surface. The rotating antenna scans the water surface surrounding the ship out to the horizon. The microwaves reflect off any ships present and some return to the antenna, causing a "blip" to be displayed on the radar screen.
Commercial marine radar antenna. The rotating antenna radiates a vertical fan-shaped beam – Animated GIF showing a rotating waveguide antenna of a typical X band marine radar on a ship. It radiates a narrow vertical fan-shaped beam of microwaves perpendicular to the antenna bar, along the water surface. The rotating antenna scans the water surface surrounding the ship out to the horizon. The microwaves reflect off any ships present and some return to the antenna, causing a “blip” to be displayed on the radar screen.

A practical technology, it would go on to play an important role in the Second World War and subsequent conflicts. The development of systems capable of producing brief pulses of radio energy was a key advancement which allowed the development of modern radar systems.

True radar, like Britain‘s Chain Home Early Warning System, which provides directional information about objects at shorter distances, was developed in the following two decades. The cavities magnetron produced a compact short-wave radio source and allowed the fighter command to spot approaching enemy aircraft, from far away.

Chain Home radar installation at Poling, Sussex, 1945 - On the left are three (originally four) in-line 360ft steel transmitter towers, between which the transmitter aerials were slung, with the heavily protected transmitter building in front. On the right are four 240ft wooden receiver towers placed in rhombic formation, with the receiver building in the middle.
Chain Home radar installation at Poling, Sussex, 1945 – On the left are three (originally four) in-line 360ft steel transmitter towers, between which the transmitter aerials were slung, with the heavily protected transmitter building in front. On the right are four 240ft wooden receiver towers placed in rhombic formation, with the receiver building in the middle.

Today, radar is used for a variety of purposes ranging from air traffic control to surveillance and weather prediction. Advances in technology have enabled radar systems to detect smaller objects, operate at longer ranges, and even take advantage of new types of signals. This has allowed radar to become an indispensable tool for many industries and applications.

In conclusion, radar is an invention that has changed the way we interact with our environment. Its invention in the early twentieth century marked a major milestone in the development of modern technology, and its evolution over the years has enabled it to become an essential tool in navigation, surveillance, and defence.

6 thoughts on “The Invention of Radar 1935

  1. Very interesting write-up and I like how you organized the sections with an index. Your site is very nice! Robert sounds very interesting. I do remember reading a biography on him and couldn’t help but think how much Radar has changed things.

    1. Thanks 😘

      I started doing indexes in all posts not long after I finally figured out the design and layout.
      I figured it makes it easier to read. And some of them are really long. So if you don’t read it in one sitting is easier to find where you left of

      1. It also helps to for mobile readers because I mostly read on my phone and always am scrolling accidentally or refreshing. So often do loose my place but it’s easy to find when I know what section I left off. Love you design.

  2. Um objeto mutio inteligente que ajuda aos navegadores e ate mesmo outros tipos, é um site muito interessante q aborda fatos surpreendentes, e historias q nao conheciamos

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