Kraków 2013-05-02
Outline of the history of navigation. The beginnings of radio technology.
In the previous chapters on navigation in the period 1918-1939, we presented the most important problems of the development of commercial aviation and the navigation associated with it. As we have shown, the progress was enormous. Aviation, and with it navigation, developed evolutionarily and systematically. Unfortunately, this development was halted by the outbreak of World War II by the German plague and their Muscovite brothers, for the second time. Civilian aircraft were used by the military. Instead of bringing development to humanity, they sowed destruction and death. Factories building commercial, sports and tourist aircraft had to switch to building fighters, attack aircraft, bombers and reconnaissance aircraft.
Could navigation and related communications develop under such conditions? Of course not. In Europe, passenger and cargo traffic was completely suspended. All airlines suspended their operations or were militarized. Even in the US, which was not directly involved in warfare, cargo and passenger traffic (after the attack on Pearl Harbor on December 7, 1941) decreased by 85%. It is not true that the development of war technology pushes civilization forward. Quite the opposite. It regresses man, triggers the lowest instincts in him and makes him think – How to deprive another person of freedom with everyday objects, or even how to kill him? It is not true that World War II led to the development of radar stations. It is not true that pressurized aircraft cabins were developed during the war. And such examples can be multiplied. However, it is true that World War II led to the development of the atomic (nuclear) bomb.
Radar station.
A radar station is commonly called a radar. We will return to the etymology of this word. The history of radar begins at the end of the 19th century. At that time, many scientists worked on phenomena accompanying electricity and vacuum tubes. One of them was Nikola Tesla. In 1887, he was able to produce cathode radiation strong enough to observe its negative impact on living beings. In 1892, Nikola Tesla proved that with the help of cathode radiation, it is possible to observe the interior of the human body and record it on a photographic plate. Later, these rays were called X-rays. These studies and those of other scientists proved that it is possible to produce a type of wave that is penetrable through some materials and not through others.
Important discoveries and inventions:
In 1880, American professor John Trowbridge used the conductivity of water to achieve communications between ships and shore stations.
In 1882, Dolbear received a patent for a “wireless inductive transmission and reception system” using an induction coil and a receiver. This patent was confirmed in 1886.
In 1885, Germanic physicist Heinrich Hertz conducted experiments to practically verify the theory of the electromagnetic field developed by James Clerk Maxwell and published in 1864.
In 1885, Thomas Alva Edison patented a system of communication by electrostatic induction between two stations containing antennas placed on masts. He patented the invention.
In 1888, Hertz produced, transmitted, and detected radio waves, about 5 and 50 cm long. He found that these waves were reflected from various objects and focused them using reflectors.
In 1890, English engineer John Ambrose Fleming published a paper describing the operation of an electron tube, the so-called diode.
In 1890, Nikola Tesla patented his transformer, which became the basis for many early radio transmitting devices.
In 1891, French physicist Édouard Branly invented the coherer, a device that could detect radio waves.
In 1893, Tesla conducted research on a wireless information transmission system. The object was a remote-controlled boat floating on the Hudson River.
In 1894, Oliver Lodge repeatedly demonstrated a system for radio transmission of information with a coherer-based receiver during public lectures. He also used Morse code during the presentation.
In 1896, Alexander Popov, a Muscovite, established communication using an electromagnetic telegraph key and Morse code between two buildings at a distance of 250 m and transmitted the first radiogram. He also noticed that objects placed in the path between the transmitter and the receiver can interrupt the flow of an electromagnetic wave. Similar discoveries were made by other scientists and researchers, even in the 19th century.
In 1896, a remote-controlled radio boat, built by Wilson and Evans, floated on the Thames.
In 1897, Marconi received a British patent for his wireless telegraph system. He demonstrated his devices publicly for the first time. In the Bristol Channel, he achieved communication at a distance of about 36 kilometers. He gained the support of important British institutions: the post office and the navy.
In 1897, Lodge patented the principles of tuning the transmitter and receiver to the same frequency. This is the fundamental basis of radio transmission. Antenna systems were also developed.
In 1900, Tesla proposed a system for detecting moving objects using radio waves (radar), or theoretically developed radar.
In 1901, Landell de Moura, a Brazilian priest, publicly demonstrated the radio transmission of a human voice for the first time (at a distance of 8 kilometers, in São Paulo).
In 1904, Engineer Christian Hülsmeyer patented in England, a ship obstacle avoidance and navigation system based on a device using radio wave reflection (radar) called the Telemobiloscope.
In 1904, Marconi signed an agreement with the Cunard Line to equip their ships with radiotelegraph communication systems.
In 1904, American engineer Frank Sprague invented the printed circuit.
In 1904, American engineer Harry Shoemaker designed radio-controlled torpedoes.
In 1905, Fessenden launched the first radio channel – a radiophonic transmission of speech and music. This was how the first radio station was created.
In 1906, American physicist Lee de Forest invented the triode, a three-electrode tube with the ability to amplify a signal. It enabled the rapid development of radio technology. This tube became the basis of electronics for half a century.
In 1907, the Dane Valdemar Poulsen transmitted music using his 1 kW spark transmitter with an antenna 60 m high. The broadcast was audible at a distance of 600 km.
In 1910, W.R. Ferris transmitted the first radio telegram from an airplane.
In 1910, T. Baker demonstrated a method of transmitting a photographic image using radiotelegraphy.
In 1911, A. Blondel presented a radio-controlled airplane.
In 1912, Sinding and Larsen carried out a radio transmission of a television signal using three channels: one for sound, another for the image and a third for synchronizing the image and sound.
In 1913, the transmission of constant time signals from the Eiffel Tower in Paris for the purposes of maritime navigation was launched.
In 1914, engineer Hammond used directional loop antennas to build a radio direction finder for maritime navigation.
In 1915, AT&T Company transmitted the human voice by radio across the Atlantic. The signal transmitted from Washington was heard in Hawaii and Paris.
In 1919, Robert Watson-Watt patented shortwave radar.
In 1919, the first regular radio broadcast began in Pittsburgh, USA.
In 1920, C.E. Prince installed radiotelephone transmitters on airplanes.
The examples cited show that the originator and visionary of the radiolocation station can be considered Nikola Tesla, a brilliant and at the same time mad scientist. Many of his ideas have materialized, but many are still waiting to be developed. Without a doubt, Nikola Tesla was recognized as the creator of radio, winning a lawsuit against Guglielmo Marconi after his death. Guglielmo Marconi used 17 of Nikola Tesla’s patents in his radio. When writing about Nikola Tesla, it is hard not to mention that he did not receive the Nobel Prize, which is further proof of the lack of objectivity of the Royal Swedish Academy.
Nikola Tesla proved that electromagnetic waves have properties identical to light waves, and differ only in frequency. He also showed that electromagnetic waves can be reflected by metal objects. He proved that they are refracted when passing through a prism made of a dielectric. He discovered waves that were called X-rays. He implemented the ideas of alternating current (alternating current), which turned out to be more advantageous than direct current.
In 1907, Nikola Tesla put forward a project to use ultra-short radio waves, in the form of very short pulses, with a power of several thousand kilowatts, to detect Germanic submarines. The level of radio technology at that time did not allow for the generation of pulses of such power, but most of today’s radars are pulse radars.
Work in the USA.
During the Great World War, military scientists in the USA worked intensively on the development of wireless communication. They used both low and high frequencies. One of them was Hoyt Taaylor and Leo C. Young. In 1919, fate brought them together. In 1922, they observed that ships passing on the Potomac River caused random fluctuations in radio waves between a radio transmitter and a receiver placed on opposite banks. Today, such a device would be called a bistatic radar, with a continuous wave. The term bistatic means that the transmitter and receiver of the radar are placed in different places, even several dozen kilometers away.
This discovery (its one hundred percent repeatability) resulted in the establishment of a special Radio Department, headed by Hoyt Taaylor, and Leo C. Young, one of its leading scientists.
The first was a simple device used to jam radio waves. With its help, it was possible to detect an object (ship, plane), but its course, position or speed could not be determined. In December 1934, an apparatus was built to detect an aircraft at a distance of one mile (1.6 km), flying over the Potomac River. Although the detection range was small and the indications on the oscilloscope monitor were unclear, the validity of these assumptions was demonstrated. The work led to the construction of a radar project, with a frequency of 200 MHz. In 1930, an American radar detected a flying aircraft for the first time.
It can also be mentioned that since 1930, in the USA, work was carried out on methods of detecting aircraft using their acoustic waves and infrared radiation. The latter topic was particularly interesting. It was wanted to use the thermal radiation emitted by aircraft engines or their on-board equipment, possibly using high-power ground reflectors, emitting infrared radiation (using filters) and receiving reflected waves from the flying aircraft.
Experiments with pulse radar were continued. First of all, the receiver was improved to handle short pulses. In June 1936, the first prototype of the KLR radar system, operating at 28.6 MHz, enabled detection of aircraft from a distance of up to 25 miles (40 km). The radar was based on low-frequency signals (at least by today’s standards), and thus required large antennas, which was impractical for a ship or aircraft. In October 1936, further successful experiments were carried out. The transmitter and receiver were placed on the coast of the USA. The transmitter was 1 mile away from the receiver. On December 14, 1936, it was possible to detect aircraft flying to and from New York from a distance of 7 NM (11 km).
In 1937, the first radar operating on board a ship was built. In 1939, serial production of radars installed on board US NAVY ships began. The name “radar” was coined by US Navy officers F.R. Furth and S.M. Tucker. It was an acronym for the first letters of the words: Radio Detection And Ranging, which means detecting and determining the range using radio. The English version of this abbreviation is Radio Aids for Defense And Reconaissance, which means radio aids for defense and reconnaissance. After 1945, this abbreviation began to be explained with the words; Radio Direction And Range or Radio-Angle Direction And Range. In Poland, the name Radiolocation Station was used, until 1989. Then the Western name Radar was adopted. If the radar was used only for aiming, it was called a radiolocation sight.
In 1923, the Frenchman M. Bravel used a rotating antenna to determine the direction of objects. The invention was extremely important. Thanks to it, it was possible to determine your position in the field by targeting sources of electromagnetic radiation with known coordinates. This was the beginning of radio-location.
Work in the UK.
The adventurous attitude of the Germans, during the interwar period, led to the idea of using radar in Great Britain as a warning device against sea or air invasion. Bistatic radar was not very suitable for this. So the idea of monostatic radar was developed. The second direction of work was to generate electromagnetic waves in the direction of the high frequency range. The English managed to modernize the microwave lamp capable of generating electromagnetic field energy, of high frequency and high power. The British later made their invention available to the Americans.
In England, the name of Sir Robert Watson-Watt is best known. The problem arose when in 1933, the Germans democratically elected Hitler as their leader. Great Britain began to seriously fear a repeat of the situation of 1914. In 1934, the Air Ministry appointed a commission under the chairmanship of Sir Henry Tizard. The prospect of heavy bombers bombing civilian areas of the British Isles caused concern in the government. Artillery support seemed inadequate. Germanic bombers would only need 20 minutes to carry out an attack that British fighter planes would not have time to repel. At that time there was a rumour that the German army already had a super weapon using radio waves capable of destroying cities and people. In the UK the question was asked at that time – Is it possible to create radio waves capable of causing the death of the crew of an approaching enemy aircraft? This question was born in the Scientific Research Department of the Air Ministry in January 1935. The matter was taken up by Sir Robert Watson-Watt’s team, who carried out analyses and calculations and showed that it was possible, but not in the current state of technology. One of the employees, Arnold Wilkins, noticed, however, that appropriate stationary equipment would be able to detect an approaching aircraft, although it would not destroy it, and would not even let the crew know that it had been detected (targeted). The program was not discontinued, but its design was changed.
On February 12, 1935, Sir Robert Watson-Watt sent a secret memo of the proposed system to the Air Ministry. In it, he proposed building a system for detecting and locating aircraft by radio methods. Although it was not as exciting as the Germanic death rays, the concept had a future. Before the Air Ministry could provide funding, they asked for a demonstration of the possibilities and proof that radio waves would detect an approaching aircraft. The demonstration was carried out on February 26, 1935. The facility was one of the BBC’s shortwave radio stations in Daventry. Two antennas were placed about 10,000 m away so that the waves reflected from the aircraft could be received as a stronger signal and displayed on a CRT display. This was what is now known as passive radar. The experiment used a Heyford Handley Page aircraft, which flew the exact route it had been instructed to fly several times. Each pass produced a clear signal and the experiment was a success. There was a hundred percent repeatability of the experiment. The purpose of the experiment was so secret that only three people knew about it; Sir Robert Watson-Watt, Arnold Wilkins and one person from the Air Ministry. On April 2, 1935, Sir Robert Watson-Watt received a patent for a radio device for detecting and locating aircraft. In May 1935, the program was transferred to the Orford Ness facility. In June 1935, aircraft detection was achieved at a distance of 27 km, which was already a sufficient range. But already in December 1935, a detection distance of almost 100 km was achieved.
The first radars were set up at a centre near Orford Ness and at Bawdsey Manor. Sir Robert Watson-Watt’s team created the devices using existing and available components. Thanks to this, work progressed very quickly and mass production was possible. The radars were placed on towers. This resulted in a system of 5 long-range CH (Chain Home) radars on the east coast of Great Britain, which was in operation from December 1935. The first full tests proved unsuccessful. Not because of the radar’s shortcomings, but because of the complicated information transmission system, which resulted in the fighters being in the air after the bombers had already made a mock attack. As a result of further work, a command and control system for air defence was created, which had not previously existed anywhere in the world. At its centre was a map room, to which all information flowed and from where all orders were issued. In 1937, the results were so encouraging that it was decided to set up another 17 radars in a system of permanent radar towers along the east and south coasts of England. This system played a key role in the Battle of Britain. By the end of World War II, the system had over 50 radar stations.
The German army knew about the development of the Chain Home system, but they thought it was designed to provide long-range communication with naval ships. They tried to test the system using the Zeppelin LZ 130 airship, which wrongly confirmed the theory, which suited the British. What’s more, during World War II, the Germans assessed that British radars were there, but not working. The reason for this mistake was their unawareness that UK radars were already working at higher frequencies, which the Germans did not record.
The greatest achievement of Sir Robert Watson-Watt’s team was the construction of a cavity magnetron, an electron tube that generated precise radio waves of very high frequency.
As early as 1936, Sir Robert Watson-Watt’s team was working on an on-board radar for bomber aircraft. Scientists have estimated that in the air, the airborne radar should have a mass of less than 90 kg (200 lb), a volume of less than 216 liters (8 ft3), and a transmitting power of 500 watts. We will mention that to establish radio communication at a distance of up to 40 km, a power of 1 watt is enough, and with a directional antenna, the distance increases to 100 km.
Work in France.
The third country that achieved considerable success in radiolocation was France. Since 1927, French physicists had been experimenting with magnetometers and other devices emitting electromagnetic waves. They were constantly trying to materialize a system that was consistent with the principles developed by Tesla. They managed to obtain waves with a length of 16 cm. In 1934, they filed a patent application for a device for detecting obstacles using continuous radiation of ultra-short wavelengths, generated by a magnetron. The device measured azimuth and distance, but not on a screen, but using pointing devices. Tests were carried out on the sea coast and on ships. Ships were detected from a distance of 10-12 NM. Due to insufficient funds, the research dragged on and until the outbreak of World War II, the system was not introduced into service. At the same time, in 1938, intensive work was carried out in France on radars for detecting flying aircraft. It was possible to achieve an excellent detection result, as much as 55 km (34 NM). Further work was already underway during World War II. However, it was too late to create a defense and detection system. The French had no choice but to share their achievements with their allies (UK and USA).
World War II.
The Germans, together with their Muscovite brothers, started World War II. As a result, instead of developing radar systems, the Germans rested on their previous achievements. In the USA and UK, on the other hand, radar stations were still being improved. It was possible to reduce the size of the device, and especially the antenna itself, which allowed the radar to be placed on board the aircraft. This is how the airborne radar was born.
The technological progress forced by warfare led to the construction of radars mounted on ships. They were used to detect enemy ships and correct artillery fire. This is how the radar sight was born, which later found its way on board fighter planes. When using airborne radars, it was noticed that the radar screen showed a faint but faithful image of the terrain below the aircraft. This phenomenon was used to build the British H2S radar, designed to accurately designate targets for bomber aircraft. This radar was one of the most closely guarded secrets until the end of the war.
Written by Karol Placha Hetman