Feb 26 2009
Radio Detection and Ranging
On this day in history, two significant events happened with the usage of Radar. First, On February 26, 1935, the first radar system is demonstrated in England, tracking a Royal Air Force bomber. The invention of radar proved crucial to Great Britain’s defense in World War II.
The second event occurred on February 26, 1938 when radar was installed on the American passenger ship New York. This event proved that radar was a good use for ocean going vessels and the following year, the first battleship equipped with radar was placed into service.
Radio Detection and Ranging (Radar) was developed in the early 1900s when scientists and engineers invented a uni-directional ranging devices. Radar technology continued to improve through new designs and refinements in the 1920s and 1930s, leading up the first early warning and detection networks just prior to World War II.
The basic concept of how radar works is that a transmitter sends a radio signal out, it bounces off an object and is returned to the same point as the original signal. This out and back trip is then calculated and or displayed in various formats.
The very first radar, which never made it into production, was invented by Christian Huelesmeyer in 1904. His simple device was a spark gap that was aimed with an antenna and it would send out a signal, which would travel out to about 3km. The signal would bounce off a ship and would this ‘reflection’ would return and be picked up by a receiving antenna and sound a bell. This early device was designed to aid ships in avoiding collisions. In foggy and stormy weather, the device could be rotated to check for ships around the area. Naval operations were not that much interested in this and device and it did not make a go.
Today, one of the most popular forms of radar that everybody has seen is Doppler Weather Radar that you see on the nightly news weather reports. This special antenna resides in a white ball (looks like a huge golf ball) and it rotates 360 degrees. As the antenna rotates, it is transmitting a radio signal. This signal bounces off snow, rain, ice crystals, even insects and is returned to the receiving antenna. These radio waves are electronically converted into images to show precipitation and type, as well as the intensity. Doppler also shows the frequency change in the returning radio waves, the computer and software that processes this frequency change to show wind changes and directions.
Radar technology has come a long way since it was first discovered in the early 1900s. There are many types and variations that we did not cover in this short posting. In a future post, we will branch off and review and discuss specific types of radar and the applications it is used for. What applications can you think of that use radar?
