Presentation on theme: "11/01/10 1 "Radio Astronomy and Satellite Communication, two N.J. first Whenever we touches history, events of the past belong to the present Electrical."— Presentation transcript:
11/01/10 1 "Radio Astronomy and Satellite Communication, two N.J. first Whenever we touches history, events of the past belong to the present Electrical Engineer Luis A. Riesco, IEEE Life Senior Member Consulted: 1. IRE Proceedings, yrs. 1932 & 1935 KG Jansky 2. My Brother KG Jansky an his discovery…yr. 1936 CM Jansky 94 th meeting A.A.Soc. 3. NASA Science educational publications 4. INFOAGE Museum and Partners Ocean Monmouth Radio Club OMARC and IEEE 5. The Evolution of RADIO ASTRONOMY, J.S. Hey 1973 Science History Publications 6. IEEE CENTENIAL JOURNAL, NJ Coast Section, 9 March 1984 7. THE INVISIBLE UNIVERSE, The Story of Radio Astronomy, Gerrit L. Verschuur 8. HIGHER FREQUENCY TECHNIQUES, Departments of the Army and Air Force, 1952 Copyrights by respective organizations and Ideas Unlimited, Corp. All copy rights reserved
11/01/10 2 Radiation from deep space detection PART 1 Radiation through space and back PART 2 We will recreate these New Jersey first into the present in such a way that you will understand how these science pioneers handled basic communication and space principles with hard work, determination and ingenuity. We will use decimal units as used in common practice.
11/01/10 3 Karl Guthe Jansky Early Family Life Father (born in Wisconsin) Cyril M. Jansky Dean of the college of Engineering U of Oklahoma Mother Nellie Moreau was of French and English descent. Dr. Karl Guthe physicist faculty Member Michigan U. important mentor to the father C. M. Jansky Who post graduated in Physics and Electrical Engineering. By then they have 2 children. When his third son arrived Oct. 22, 1905 was named after Karl Guthe the scientist and teacher whose guidance meant so much to his father. The perseverance with which Karl Guthe Jansky accumulated scientific data, objectivity and creativity ingenuity he demonstrated that his discovery were not accidental. His family life and background contributed much. Incitation of the contour Toynbee
11/01/10 4 Education and Employment Karl Jansky received his BS in Physics in 1927 U of Wisconsin. Nine years later received his Master in Physics from the same U. Karl applied for a position with Bell Lab in 1928. He was first turn down for physical reasons. His brother ten years previously had been member of the staff at Bell Labs. And frequented the Lab while member of the faculty U of Minnesota. He was in a position to argue with the Personnel Department and convinced them that Karl was a good risk. Certainly, Bell Telephone Labs and the world of science never had a reason to regret this decision C. M. Jansky (oldest son)
11/01/10 5 His project Yr. 1927 Bell Has created the first transatlantic telephone. The link was highly susceptible to electrical interference. Yr. 1930 Jansky was asked to locate the source of the interference. It is important to note that in the late 1920's and early 1930's, adequate instrumentation for his project and particularly for wavelengths as short as 14.6 meters, involved many new and unsolved problems Jansky had much help from research work results and from other engineers, but his genius made the discovery
11/01/10 6 Requirements to establish a communication We need a: Transmitter Receiver Transmission medium which allows the propagation of the signals from the transmitter to the receiver. Progress in the development and improvement of radio transmitters and receivers and antenna systems. However can do nothing to modify characteristics of the transmission medium on the ground and must be used as nature gives it. Today, pick a more favorable location (southern hemisphere), a space location, special nature astronomic events or man made.
11/01/10 7 Project Design The rotating antenna is a receiving array two wavelengths long made of ¾ in brass pipe, mounted on wheels with central pivot Driven by a chain from small motor making a complete synchronous rotation every twenty minutes. By the fall of 1930 (the system) was complete and in good working order. Bruce type broadside receiving array "About March, 1929, Karl Jansky began the design of a 14.5m (operated at14.6m) rototable, directional antenna system and the associated receiving apparatus. Scan the sky in all directions once every 20 minutes; it could also be pointed at different heights above the horizon. Known as Jansky's "merry- go-round," the antenna is believed to have been the largest of its type at the time. It operated at 20 MHz or 14.6 meters. He categorized the static into three different types: local thunderstorms, distant thunderstorms, and steady static. Jansky was able to establish that thunderstorms were the source of clicks and bangs. But he observed of the last type of static, as quoted in Mission Communications: The Story of Bell Laboratories, that it was "a very steady hiss type static, the origin of which is not yet known."
11/01/10 8 Jansky Antenna Scan the sky in all directions once every 20 minutes, it could also be pointed at different heights above the horizon. It operated at 20 MHz or 14.6 meters.
11/01/10 9 What is left today: Antenna Historical Marker, Holmdel, N.J. LOCATION: Far behind the giant transistor shaped water tower behind what was once a reflection pond of the abandoned Bell Labs facility, 101 Crawfords Corner Road, Holmdel NJ 07733 Bell Labs facility, 101 Crawfords Corner Road, Holmdel NJ 07733 http://www.hmdb.org/marker.asp?marker
11/01/10 10 Antenna Directional Pattern The fundamental characteristics of an antenna are its Gain and the half power beamwidth (HPBW) angular separation between the half power points on the antenna radiation pattern, where the gain is one half the maximum value. This is where the electric field intensity equals 0.707= 1/sqr2 of the main beam maximum field E intensity.
11/01/10 11 Receiver Short wave field strength measuring set of double detection. The out put connected to trough a long time constant ckt to a LN recorder, which auto- change the gain every 10 sec. intervals to keep the output of the receiver constant. During 9 sec. charges 100 microF condenser proportionally to the static. Battery B charges the condenser in opposite direction. The battery B and resistances are adjusted for condenser voltage zero. Then S is closed mechanically by a cam from the recorder. Thus the condenser every 1 sec. discharges and LN record the static.
11/01/10 12 Recorded Storms 7-10 Yr. 1931 Aug 27 Severe Local TS Same Severe Local TS Long Wave Rec, pk 63 dB Rec. Comparison Passed S to NE Sept 2 S traveling twrd Rec from W to N to NE Sept 14 Several rapid Small S Passing NE X Credit Justin MU
11/01/10 13 Recorded Storms 11-12 Yr. 1931 Two storms same day from S passed rec. SE SEPT. 26, 1931 OCT. 8, 1931 Storm approaches rec. from the W and split part to the N and part to S of rec. Credit Justin MU Intensity in DB above 1 micro V/m for 1 KC Band With
11/01/10 14 Recorded Static Hiss 13-14 Yr 1932 The static of the third group causing a hiss, is readily distinguish from ordinary static. is readily distinguish from ordinary static. Probably does not originate in T areas. Direction of arrival changes gradually thru the day and dies out in the middle of the night NW. And static from NE begins to be recorded. The process repeats day after day. Feb 24, 1932 Curve 1. Day light Hrs. direction of the Sun w/Rec. Dec. to p/Jan Curve 2. Jan to Feb however gradually shifted preceding the Sun 1Hr. Curve 3. Since Dec 21 the Suns ray getting more perpendicular at Rec., as sun rise occur earlier and earlier each day.
11/01/10 15 Recorded Static Hiss direction, and origin early conclusions Horizontal scale 60min/12/hr=5min/hr Peak every 5min/hrx4=20min/hr Intensity in micro V /m per 1Hz BW The intensity of this static is never high at no time exceeds 0.39 microV /m per 1Hz BW, however, its presence during otherwise quiet periods is unmistakable. Some how associated with the position of the sun. It may be that the static come directly from the sun or, more likely, it may come from a sub-solar point on the earth As per IRE but Harald Friis cautioned him proposing extraterrestrial source in case he should probed wrong.
11/01/10 16 Directional Studies of Atmospherics at High Frequencies Jansky Karl G. Proceedings IRE, Vol. 20, p 1920, 1932 Jansky discovered three static sources: Nearby storms and Distant storms Fig. 7-12 The third static source came from an unknown origin. Fig. 13-14 Jansky discovered that it appeared four minutes earlier each day, which corresponded to the 23 Hr 56, sidereal day of the stars, different from Earth 24Hr day rotation. This meant that the stars emitted energy as radio waves, as well as light waves. In conclusion, data have been presented which show the existence of electromagnetic waves in the earth's atmosphere which apparently come from the direction that is fixed in space. The data obtained give for the coordinates of this direction a right ascension of 18 hours and a declination of -10 degrees. Karl Jansky concluded that the hiss static came from the center of the Milky Way and tried to correlate data and realized that some early data was recorded daylight savings time. He applied the correction and found that his previous data tended to still further support his discovery pointing Sagittarious. Fortunately the 11 year cycle solar activity was at a minimum then the ionosphere was transparent to 20 MHz at night. Extended extreme of the Atmospheric window of EM radiation for this solar activity.
11/01/10 17 Karl Jansky pointing at the Galactic emission Ursa Major, Ursa Minor Polaris Cassopeia As he realized the extraterrestrial nature of the statics BELL LAB WAVES TRACED TO The CENTER OF THE MILKY WAY NBC broadcasted issue a press release the next day NYT head line NEW RADIO JANKYS STAR NOISE
11/01/10 18 Electrical Disturbances Apparently of Extraterrestrial Origin" Before the Washington meeting of the International Scientific Radio Union held in April 1933, Karl Jansky presented his paper in which he stated his conclusion as to what the data showed. In the title of his paper note the word, "Apparently". This illustrates a modesty which I am sure astronomers, physicists and all true scientists understand and appreciate. Brother C. M. Jansky
11/01/10 19 KARL GUTHE JANSKY 1928-1932 Work lead the discovery which laid the foundation for the science of radio astronomy, contains many lessons for those of us in the fields of either pure or applied science, and particularly for students or young people who hope to become scientists.
11/01/10 20 Jansky's discoveryin 1933 were of great influence on the later development of the new study of radio astronomy One was Grote Reber, who singlehandedly built a radio telescope in his back yard in 1937 and did the first systematic survey of radio waves from the sky. Grote Reber, The second was John Kraus, who, after World War II, started a radio observatory at Ohio State U. and wrote a textbook on radio astronomy, which was the "bible" for radio astronomers.John Kraus,
11/01/10 21 KARL GUTHE JANSKY 1905-1950 Karl did not live long enough to see the unbelievably result of his early discovery He is now recognized as the father of radio astronomy. He deserved but never got the Nobel prize for his discovery Harald T. Friis
11/01/10 22 Amazing History of World Radio Telescopes from Jansky-1932, Reber-1938 to 1995-2015 International race into the Cosmos http://www.eso.org/sci/facilities/alma/science/papers/alma-series/course-two.pdf
11/01/10 23 Sociology in Jansky Innovation 1 Karl Jansky was astute enough. Not only to make the discovery, but also to appreciate its cientific significance. However, depite the publiation of his results and despite of interest from theorists and astrophysicists his discovery did not persuade a single professional astronomer to change their experimental strategy and adopt the new technique Eventualy Bell assigned him to a different projects but not working in interstellar waves anymore. It was left to an amateur, Grote Reber an Electronic Engineer follow up his discovery, building the first worlds dish telescope in his backyard, superating many difficulties; surveyed the galatic back ground radiation and created the first radio map of the universe and confirmed Janskys claim. Reber submitted his paper to the Astrophysical Journal, but there was no one qualified to review the paper. In January 1988 article in The Toronto Star, "The astronomers couldn't understand the radio engineering and the radio engineers couldn't understand the astronomy." The editor decided to publish the paper without a review and it finally appeared in June of 1940. It took several years before his results warranted serious attention by professional astronomers. Harald T. Friis became a leading research scientist with the Bell System, eventually holding 25 patents, including one for the famous horn-reflector antenna of microwave systems first used in satellite communication. Highly regarded as a teacher of other scientists, Friis also supervised the work of the late Karl Jansky, founder of radio astronomy. There was a major controversy on this matter.
11/01/10 24 GROTE REBER Call W9GFZ Over 60 DX Jansky was then assigned to work on other projects at Bell Laboratories and never had the opportunity to continue his work on stellar radio waves. Reber read Jansky's work in the Proceedings of the IRE journal and was determined to continue his work. He built the first radio telescope in the backyard of his home and, for a decade, he was the only radio astronomer in the United States. Recorded radio signals at different wavelengths and created the first radio map of the universe. Maped the Milky Way. And confirmed Jansky's claim that the static was strongest at Sagittarius, the center of the universe. He also detected strong signals from other constellations, namely Cygnus, Cassiopeia, Canis Major, and Puppis. Reber published his initial findings in the Proceedings of the IRE
11/01/10 25 Back Yard Radio Telescope In the 1930s Reber applied for jobs with Karl Jansky at Bell Labs and with astronomical observatories to study cosmic radio waves, but none of them were hiring at the time, since it was in the middle of the great depression. Reber decided to study radio astronomy on his own. The telescope was constructed by Grote Reber in 1937 in his back yard in Wheaton, Illinois (a suburb of Chicago). He built the telescope at his own expense while working full time for a radio company in Chicago. This shows the telescope as it was in Wheaton, Ill. The mirror, made of sheet metal 31.4 feet in diameter, focuses radio waves to a point 20 feet above the dish. The cylinder contains the radio receiver which amplifies the faint cosmic signals by a factor of many million, making them strong enough to be recorded on a chart. The wooden tower at the left is used for access to the receiver. Reber built a parabolic dish reflector because this shape focuses waves to the same focus for all wavelengths. This principle had been used for a long time by astronomers for design of optical telescopes, to avoid chromatic aberration. Reber knew that it would be important to observe a wide range of wavelengths of radiation from the sky in order to understand how the radiation was being produced. A parabolic reflector is usable over a wide wavelength range.
11/01/10 27 Rebers ANTENNA NRAO Moved to NRAO Green Bank, WV
11/01/10 28 REBERs way His radio maps of space have shown that the radio sky is brighter at longer wavelengths than shorter wavelengths. He believes that this is due to photons losing energy as they travel through space, while proponents of the Big Bang theory see this as a sign of a receding galaxy. Reber has given many lectures on why he does not believe in the Big Bang theory and many astronomers disagree with him. However, he is accustomed to being alone in his beliefs and is waiting for an opportunity to test them. In the 1950s, Reber sought a field that seemed neglected by most other researchers and turned his attention to cosmic radio waves at very low frequencies (1-2 MHz, or wavelength 150-300 meters). Waves of these frequencies cannot penetrate the Earth's ionosphere except in certain parts of the Earth at times of low solar activity. One such place is Tasmania, where Reber lived for many years. He died in Tasmania on December 20, 2002.
11/01/10 29 What produces the radio emission? The process that produces the emission can be deduced from the spectrum, i.e., the graph of how power changes with frequency. Reber found that the radio power was weaker at higher frequencies, contrary to what was predicted by the theory of thermal radiation. This theory applies to the light from stars, or any hot object such as molten iron or stove burners, and predicts that the radio emission increases at higher frequencies. But Reber found just the opposite relation for the Milky Way. Some other, "non-thermal", process had to be at work. It was not until the 1950s that a Russian physicist, V.L.Ginzburg, worked out the theory of synchrotron radiation, which explains the observed radio spectrum. Synchrotron radiation results from electrons moving at speeds close to the speed of light in magnetic fields. Our galaxy is full of high speed charged particles, including electrons, known as "cosmic rays". We now believe that these particles were blasted into interstellar space as a result of supernova explosions. This is the origin of most of the radio radiation from the Milky Way that Jansky and Reber measured. Stars, Galaxies, Sun, the Planets and many other objects radiate not only light waves, but also strong radio signals. Some objects transmit only radio waves and will be for ever invisible to the human eye. The radio astronomer does not transmit signals, he only tunes in a passively mode, those coming from space.
11/01/10 30 Our solar system is one of billions in the MW galaxy. The MW galaxy is one of billions in the universe. The MW is about 100,000 light yrs in diameter and 3,000 light yrs in width. It is believed to contain more than three hundred billion stars. Total mass of six hundred billion times the gross mass of the Sun There are believed to be more than one100 billion galaxies within the universe. Individual galaxies are separated by distances in excess of millions of light yrs. Intergalactic space, is filled with an unsubstantiated plasma matter of an average density less than one atom per cubic meter. ` Outer Arm Perseus Arm Sagittarious Arm Scatum-Crux ArmSun The MILKY WAY A GSFC artist's impression of our home galaxy Edited Luis
11/01/10 31 The Jansky power flux unit The unit used by radio astronomers for the strength (or flux density) of radio sources is the jansky (symbolic form, Jy). The jansky is equal to one-hundredth of one-trillionth of a trillionth of a watt per square meter per hertz. ( Hz detector band of the receiver) One Jansky is defined as 10 -26 watt/(meter 2 Hertz), a very small flux indeed. [This equation, expressed in English: one Jansky is equal to ten to the minus twenty-six watts per square meter per hertz.] Note that in accordance with the SI (System International) notation, the unit jansky is not capitalized when written out but it is capitalized when in its symbol form (Jy). This convention is followed whenever a unit is named after a person. Thus, we have the watt (symbol W), the hertz symbol (Hz), both named after persons, but the meter (symbol m) because the meter is not named after a person. Typical strong radio sources have strengths of 10 Jy to 100 Jy Weaker radio sources are measured in mJy
11/01/10 32 Repeating Janskys Experiment NRAO - Green Bank WV, 1995-1996 It was Grote Reber's idea to build a copy of Jansky's antenna and locate it at the entrance to the National Radio Astronomy Observatory as an historical monument. Insisted that it be an accurate replica which resulted in a usable antenna with similar properties to the original. The replica was completed in September of 1964. Receiver and Data acquisition systems have been added which are more modern than Jansky's, the antenna itself, including the feed and drive system. http://www.gb.nrao.edu/~fghigo/JanskyAntenna/RepeatingJansky_memo10.pdf End Part 1