# "Radio Astronomy and Satellite Communication, two N.J. first

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"Radio Astronomy and Satellite Communication, two N.J. first

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. 10/7/2010

Basic foundation originated in Europe Michael Faraday ( ) Electric magnetic field around a conductor James Clerk Maxwell ( ) Mathematical model for electromagnetic waves propagation Heinrich Hertz ( ) Demonstrated the existence of electromagnetic waves Guglielmo Marconi ( ) Built wireless apparatus and Patented in England US patents for elementary wireless apparatus has been granted to a number of researchers such as: Thomas A. Edison (1891) ; Oliver Joseph Lodge (1894); Nikola Tesla (1897) Worked at Edison Power Station then Joined Westinghouse and then started his own company. US Supreme Court overturned Marconi’s patent and in 1943 credited Tesla with the invention of Radio. However Marconi excel as businessman and soon became a world radio communication monopoly with Marconi’s Wireless Telegraph Company. Made demonstration to the British and US Navy and Transoceanic communication. Initial wireless technology used the spark gap principle before Hertz to Tesla, Marconi and others. The history of radio shows that the spark gap transmitter was the product of many people, often working in competition. Battery energy was transferred to a coil and a capacitor as a spark jumped the space oscillates and discharged into an antenna that irradiates a radio signal. 10/7/2010

The Circle as a Sine Wave Generator
Circle radius r=1 Axes x,y and z=time The 360 degree circle Wavelength λ Lambda, measured between any two repetitive points, such as crests, or repetitive zero crossing. Propagation through free space occurs at a velocity of nearly 300,000 km/sec. f is the frequency of oscillation in Hz/sec. c the velocity of propagation of electromagnetic radiation in m/sec. Then we have: c= f λ or λ m)=300/f(MHz) If you have several points, steps, or key ideas use multiple slides. Determine if your audience is to understand a new idea, learn a process, or receive greater depth to a familiar concept. Back up each point with adequate explanation. As appropriate, supplement your presentation with technical support data in hard copy or on disc, , or the Internet. Develop each point adequately to communicate with your audience. 10/7/2010

Electric and magnetic fields in an Electromagnetic wave
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Electromagnetic Spectrum
Microwave Bands f (GHz) λ (cm) L 30 –15 1 – 2 S C X K These are ballpark values 10/7/2010

Electrical wave generation
The capacitor is fully charged and there is no current passing through the coil. This situation is unstable and the capacitor spontaneously discharges via the coil, creating a current in it which is linked with a magnetic field. The energy stored in the capacitor (potential energy) is exchanged for the energy associated with the magnetic field and flowing current (kinetic energy) in the coil. In other words, the capacitor is the generator, and the coil is the load. The current flowing in the coil is at a maximum and so is the associated magnetic field. The capacitor is fully discharged. Unfortunately, because of this, at this very moment the power supply fails. The situation is unstable. The current flow ceases momentarily, the magnetic field gradually collapses, and a current is induced in the coil, passes out of the coil and charges up the capacitor. Kinetic energy is exchanged for potential energy, the above formula is effectively written the other way around, now the coil has become the generator and the capacitor has become the load. Since the impedances of coil and capacitor are conjugate, the maximum power is transferred from (transferred from, not consumed by!) one to the other at the condition of resonance. If there was no resistance in the circuit, this exchange or oscillation would continue indefinitely because the current and voltage are out of phase in each branch of the circuit and no power is consumed; the damping and decrement would be zero and the Q infinite. Some how this circuit deliver the oscillation and a Power Supply sustain the oscillation. If the resistance in a tuned circuit is negligible, then the resonant frequency is given by the well-known formula: f=1/2Pi Square root LC tes 10/7/2010

Radar astronomy is a technique of observing nearby astronomical objects by reflecting microwaves off target objects and analyzing the echoes. This research has been conducted for four decades. Radar astronomy differs from radio astronomy in that the latter is a passive observation and the former an active one. Radar systems have been used for a wide range of solar system studies. The radar transmission may either be pulsed or continuous. The strength of the radar return signal is proportional to the inverse fourth-power of the distance. Upgraded facilities, increased transceiver power, and improved apparatus have increased observational opportunities. 10/7/2010

The speed of an object is measured by applying the Doppler principle. Object approaching the radar antenna, the frequency returned signal is greater than the frequency of the transmitted signal. Object is receding from the radar antenna, the returned frequency is less. Object is not moving relative to the antenna, the return signal will have the same frequency as the transmitted signal. Primary uses is in air traffic control, where airports use radar to track airplanes and for navigational and weather determination purposes. Military radar detects the enemy and guide defense weapons. Scientific study of the solar system. Used for basic orbit determinations measuring distance and speed versus time. Rendering data into a radar image. These techniques can also be applied from a spacecraft radar, flying past a solar system object or in orbit, around the object. With this new area of astronomy, hundreds of special bodies in the solar system have been studied by radar to map out their surface, measure their distance from earth, and to follow their orbits that allows present and future space travel landing and return 10/7/2010

Lt. Col. John H. DeWitt, Signal Corps Evans Signal Laboratory Director
Lt. Col. John H. DeWitt, Signal Corps Evans Signal Laboratory Director. W4ERI Born in Nashville, attended Vanderbilt University Engineering School for two years. Vanderbilt did not offer electrical engineering, so DeWitt dropped out in order to satisfy his interest in broadcasting and amateur radio. After building Nashville's first broadcasting station, in 1929 DeWitt joined the Bell Labs NY City, designing radio broadcasting transmitters.He returned to Nashville in 1932 as Chief Engineer of radio station WSM. 10/7/2010

State of the art and Project

“Radar was developed by men who were familiar with the ionospheric work. using widely-known scientific technique, which explains why the development of radar--took place simultaneously in several different countries." In September 1945, DeWitt assembled his team: Dr. Harold D. Webb, Herbert P. Kauffman, E. King Stodola, and Jack Mofenson. Dr. Walter S. McAfee, in the Laboratory's Theoretical Studies Group, calculated the reflectivity coefficient of the Moon. Members of the Antenna and Mechanical Design, Research Section, and other Laboratory groups. 10/7/2010

Basic equipment selection criteria
No attempt was made to design major components specifically for the experiment. The selection of the receiver, transmitter, and antenna was made from equipment already on hand, including a special crystal-controlled receiver and transmitter designed for the Signal Corps by radio pioneer Edwin H. Armstrong. Crystal control provided frequency stability, and the apparatus provided the power and bandwidth needed. The relative velocities of the Earth and the Moon caused the return signal to differ from the transmitted signal by as much as 300 Hz, a phenomenon known as Doppler shift. The narrow-band receiver permitted tuning to the exact radio frequency of the returning echo. 10/7/2010

As DeWitt later recalled: "We realized that the moon echoes would be very weak so we had to use a very narrow receiver bandwidth to reduce thermal noise to tolerable levels. We had to tune the receiver each time for a slightly different frequency from that sent out because of the Doppler shift due to the earth's rotation and the radial velocity of the moon at the time." 10/7/2010

Shortly after V-J Day, Lt. Col
Shortly after V-J Day, Lt. Col. DeWitt issued instructions to modify certain standard radar equipment for the moon investigation. Changes to allow us to send out a long pulse. The transmitter was driven as hard as possible so we could get considerably more power from it, and an ordinary telegraph key was connected in the circuit to turn it on and off. It was decided that a one-second pulse every four seconds would be satisfactory, so about ten minutes before moonrise I started to key the transmitter, for thirty minutes with no observable results. After operating for about ten days, it became evident that the TR system was not working satisfactorily The TR tubes were not protecting the receiver from the strong transmitted pulse. 10/7/2010

Engineers from the Antenna Design Section were called in.
J. Ruze, head of the section, and A. Kampinsky designed a system using quarter-wave step-up transformers on the 250-ohm line with open spark gaps on the ends of the quarter-wave TR and ATR. But the gaps would not last because of the unusually bang pulses, although normally they work very well on conventional radar sets where the pulses are very short and the average power is low. The next step was to design a mechanical TR system using an electro-mechanical keyer which bars on the transmission line, the keying being arranged that the shorting bars would have to be closed before the transmitter would go on.   But still we did not succeed in getting a response from the moon. 10/7/2010

Part of the solution The head of the Research section of the Laboratory, E. K. Stodola, W3IYF, Dr. Harold Webb and J. Mofensen, now part of the moon-radar group, decided that: If two antennas could be mounted side by side on the same tower the additional 6 db. gain that, could be realized in the two-way system would be an advantage. Engineers from the Mechanical Design Section were consulted. Under the able direction of J. Zorowritz this rather difficult feat was accomplished. According to the reciprocity theorem, the transmitting and receiving patterns of an antenna are identical at a given wavelength 10/7/2010

Now instead of 32 dipoles we had 64. The phasing of the dipoles was done by F. Haacke, P. Hartman and F. Elacker, ex. W2DMD. During the time that the new antenna was being assembled and installed it was decided to utilize the narrowest band-pass possible in the receiver, to design an electronic keyer and sweep generator in order to operate a nine-inch cathode ray oscilloscope, and to measure the receiver sensitivity. Test results found that 0.04 micro volts would equal the receiver noise, showing that the receiver was many times more sensitive than our previous ham receivers - although it should be noted that the band-width used (about 50 cycles) is much too narrow for voice communication (20 to 20,000 Hz) At 2.7 m (111 Mhz) wavelength the antenna utilized ground reflection in order to increase the gain of the aerial beam, which was fixed at low elevation. 10/7/2010

Tentative wiring configuration as per site description. Ing Luis A
Tentative wiring configuration as per site description. Ing Luis A. Riesco NOTE: In 1971 the Army destroyed documentation and “Camp Evans history went up in smoke” InfoAge Evidently a quick draft based on multiple dipoles amateur radio antennas configuration To my surprise one panel wired in the same fashion HIGHER FREQUENCY TECHNIQUES, Page 117 Departments of the Army and Air Force, 1952 open 10/7/2010

Antenna Pattern and Considerations
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. For this antenna the beam width of the array is approximately 15 deg at the half power point, with the first three lobes spaced approximately 3 deg in elevation. 9. “The SCR-270 in Japan” page 11 Fig 85, shows the “Expected vertical coverage diagram” For the 100 Kw Pk Pwr radar with a Westinghouse water cooled WL-530 tube. The antenna pattern for the “Final experimental version” was 500 KW Pk Pwr with two air cooled Triodes JAN6C21 using the same antenna the only difference is the distance in miles. It was concluded that: Since the diameter of the moon subtends roughly one half degree of arc, most of the power transmitted does not illuminate the target, a serious waste of power. The transmitter was driven as hard as possible to get considerably more power from it, and reach the moon with the first lobe as instructed. The rate of rise of the moon along its ecliptic is 1 degree of arc every 4 minutes, which allowed roughly 40 minutes of observation as the moon intercepted the first three lobes of the antenna. Bending effects path through the ionosphere exist, but no precise measurement of this effect has yet been made. 10/7/2010

How to reach the moon and detect a back signal Free space radar equation #1
Basic formula for maximum distance at which a radar set can detect targets as function of peak transmitter power, radio frequency of the transmitted signal, duration of the signal, receiver noise figure, and target echoing area. These constants, among others, are concisely summarized in the: Form #1 r is the radar range at which a signal may be detected, Pt is the transmitter power during the pulse, Go, the transmitting antenna power gain, Ao the absorption area of the receiving antenna, o’ the effective echoing area of the target, Pr the power of a barely discernible signal, 10/7/2010

Theoretical Considerations
On the same basis as Pt. The power gain due to ground reflections (not considered in the free space equation)increases the range of the system by a factor of 2. This is equivalent to a power gain of 12 db. In the case of a target as large as the moon (2160 miles diameter), calculations showed that in order to receive an echo from the whole hemisphere of the moon at once, a pulse width greater than seconds was required. This set a lower limit on the transmitter pulse width which corresponds to an optimum bandwidth of 50 Hz for the receiver. Propagation studies indicated that electromagnetic waves at a frequency of 110 Mz were capable of penetrating the ionosphere, and because of availability of equipment, a radar set operating at Mz was chosen for the experiment. The effect of Earths Upper Atmosphere on Radio Signal Atmospheric Windows of EM radiations 10/7/2010

Pr Minimum perceptible receiver power #2 and Noise Figure #3
Due to the relative velocities of the earth and the moon, the returned signal may differ from the transmitted signal by 300 Hz Doppler frequency shift. In using a highly selective receiver whose final mixer is tuned to receive the pre calculated frequency of an echo return from the moon, the receiver rejects any signal returned at any other frequency. To reduce the noise contribution of the receiver, a high gain, low noise figure preamplifier was connected between the antenna and the receiver. The minimum perceptible received power Pr # calculating NF Form. # Form. #3 E2/4R maximum available signal power at the receiver input terminals in watts E is the signal voltage at the antenna terminals. R is the effective impedance in ohms. KTB is the maximum available noise power at the receiver input K is Boltzman's constant, 1.37 X joules per degree Kelvin T temperature in degrees Kelvin, chosen, at 300 degrees B is the noise bandwidth of the receiver in Hz/sec For this receiver B is 57 Hz/sec 10/7/2010

Antenna effective gain
For a one to one ratio Form # 3 gives signal power to noise power of 1.48 X watts, taking the effective noise figure (NF)of the receiver as 7 db. The best antenna available at this frequency was a 32 horizontal dipole array utilized by the SCR-271 early warning radar. Two of these arrays 64 dipoles were secured side by side and mounted on a 30m (100 ft) tower. Calculations show that the array had now a power gain of 152 times that of a single half wave dipole antenna. Since the effective gain of a single dipole is 1.64 times that of an isotropic radiator, the value of G is given as 1.64 X 152 or power gain 250 times a single half wave dipole 10/7/2010

Receiving effective range
The absorption area A, of the receiving antenna is calculated from substituting the value of G, previously given, Ao = X square miles. Substitution of these values in the free space radar equation gave a maximum range of 573,500 miles The effective range of the equipment was more than twice that needed to receive echoes from the moon. 10/7/2010

Efective area of the target #3 Summarizing
The remaining constant to be determined before solving Eq. 1 is o Calculations of the reflectivity coefficient made by Walter McAfee of the Theoretical Studies Group, assuming zero conductivity and a dielectric constant of six for the moon, resulted in the figure The effective echoing area is this figure multiplied by the projected area of the moon, Pi d2/4 where d is the lunar diameter. This gave an effective echoing area of (2160)2 (3.1416)/4 or 647,000 square miles r is the radar range at which a signal may be detected…573,500 Mi or Km Pt is the transmitter power during the pulse……..30 Kw Go, the transmitting antenna power gain……… 250 Ao the absorption area of the receiving antenna…522.1 X 10-7 square miles. o the effective echoing area of the target……….647,000 square miles Pr the power of a barely discernible signal……..20 dB above thermal noise 10/7/2010

Maximum receiving range considerations
This calculation of the signal strength of the returned echo checked closely with observations and indicated that no appreciable attenuation occurs in free space. By adding the power gain due to ground reflection, a further excess of power of 12 db or a range of 1,140,000 mi or1,843,460 Km. Which meant that according to calculations, the received signal should be about 20 db above thermal noise. 2 10/7/2010

When radio wave reaches the ionosphere
The electric field in the wave forces the electrons in the ionosphere into oscillation at the same frequency as the radio wave. Some of the radio-frequency energy is given up to this resonant oscillation. The oscillating electrons will then either be lost to recombination or will re-radiate the original wave energy. Total refraction can occur when the collision frequency of the ionosphere is less than the radio frequency, and if the electron density in the ionosphere is great enough. Critical frequency is the limiting frequency at or below which a radio wave is reflected by an ionospheric layer at vertical incidence. If the transmitted frequency is higher than the plasma frequency of the ionosphere, then the electrons cannot respond fast enough, and they are not able to re-radiate the signal. It is calculated as shown below: where N = electron density per cm3 and fcritical is in MHz. 10/7/2010

Frequency and angle considerations
The Maximum Usable Frequency (muf ) is defined as the upper frequency limit that can be used for transmission between two points at a specified time. where α = angle of attack, the angle of the wave relative to the horizon, and sin is the sine function. The cutoff frequency is the frequency below which a radio wave fails to penetrate a layer of the ionosphere at the incidence angle required for transmission between two specified points by refraction from the layer. 10/7/2010

Temperature profile a high altitudes
Above 100 km is the thermosphere and ionosphere where the temperature increases from 200 K at 100 km to 500 K at 300 km. Basically at the bottom it is 200K. At the top it is 500K. K is in Kelvin. Celsius it would be -73 ºC to 227 ºC. ………………K..Substract –273.15=Centigrade Fahrenheit it would be ºF to ºF…………K 10/7/2010

Summarizing all calculations
r is the radar range at which a signal may be detected 573,500 Mi or Km Pt is the transmitter power during the pulse……..30 Kw Go, the transmitting antenna power gain……… 250 Ao the absorption area of the receiving antenna…522.1 X 10-7 square miles. o’ the effective echoing area of the target……….647,000 square miles Pr the power of a barely discernible signal……..20 dB above thermal noise 10/7/2010

The "bedspring" mast antenna
The two antennas from SCR-271 stationary radars were positioned side by side to form a 64-dipole array aerial, mounted on a 30m (100-ft) tower. Originally RCA design, remarkable for BW and absence of secondary lobes. The antenna had only azimuth control It was impractical an equatorial mechanism. No prevision has been made to incline the antenna in elevation. Hence, experiments were limited to the rising and setting of the Moon. “This condition of observation is the worst possible (due to the long path through the atmosphere and the consequent possibility of trapped radiation) has been recognized” (Courtesy of the U.S. Army Communications-Electronics Museum, Ft. Monmouth, New Jersey.) 10/7/2010

The Transmitter, Receiver, Keyer and Indicator
Transmitter Conventional: At KHz x24x9= 111,5 MHz (MC) Receiver Non conventional. Designed by Major E. H. Armstrong for another purpose selected, as met the requirements of power and BW. All the receiver is frequency controlled, with four mixer stages which heterodyne the radio frequency signal to of 180 cps. The first three injection frequency and the final radio frequency are derived from multiples common crystal oscillator, a high degree of frequency stability is achieved in the system essential to permit tuning the highly selective receiver to the frequency of the echo signal accomplished in the final heterodyne stage. Keying: A low level multiplier stage conduct by driving its cathode negative for the duration of the transmitted pulse .25 sec on every 4 sec Initially keying performed mechanically by a relay, but been replaced by an electronic keyer controllable between to 0.2 seconds 10/7/2010

Jack Mofenson, adjusts the position on the transmission line of the waveform monitoring stub
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Lt. Col. John H. De Witt at the Power Transmitter Stage.
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Triode JAN6C21 Power Transmitter Stage
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Year New Moon. First Quarter. Full Moon
Year New Moon First Quarter Full Moon Last Quarter Jan :30 P Jan : Jan : Jan :00 10/7/2010

The first echoes from the moon were received at moonrise on January 10, 1946
11:48 A.M. they aimed the antenna at the horizon and began transmitting. The first signals were detected at 11:58 A.M., and the experiment was concluded at 12:09 P.M., when the Moon moved out of the radar's range. The modified radio receiver was an audible 180 cycle beat note occurring 2.5 seconds after transmission. Although numerous observations have been made, both at moonrise and moonset, echo returns do not occur after every transmission. The radio waves had taken about 2.5 seconds to travel from Hearth to the Moon and back, a distance of over 800,000 km. Camp Evans Audio, scroll down to “Project Diana - Radar Makes Round Trip to the Moon” 10/7/2010

Sociology in Diana Experiment 2
History on High officer to Subordinate relationship shows some cases that low level military in some countries are not authorize to give directives to superior officers. Pearl Harbor wrong data interpretation and faliure to verification shows: The first wave of Japanese planes numbered more than 180. Although U.S. radar operators saw the massive formation nearly a full hour before the attack began, they raised no alarm, because they mistook the planes for a group of U.S. bombers expected to arrive from California around the same time. This mistake happened in spite of the fact that the planes seen on the radar were coming from the wrong direction and were much more numerous than the expected bomber fleet. De Witt developed a team work in a Management by Design Objective environment. Motivated his staff. In some cases they made test run experimentation with not failure report. However he always was in control of the project. His instructions shows that driving hard the equipment was able to considerably exceed the return radar pulse requirements. Calculations and measurement trusted and verified. The signal transmission and moon eco reception met the project objectives. After celebration, pictures, films and PR activity the team work continue until, Some time later the Army, concluded however, that nothing of military use would come of this work and ended the experiments.  At the Naval Research Laboratory, Mr. James H. Trexler saw that the moon reflections might be useful in relaying military communications and got his project funded. 10/7/2010

Lt. Col. De Witt’s Experiment were of great influence on the later development of Earth Moon Earth (EME) communications Mr. Trexler's idea for a communications relay capability using the moon Project Pamor (Passive Moon Relay) was funded by the Naval Security Group. With NAVSECGRU funding, Trexler's development teams built a 60-foot-diameter antenna (actually a reflector-shaped hole in the ground), at Stump Neck, Maryland, and with NRL in-house funding proceeded to experiment with T&R of signals off the moon.  1951- The feasibility study of using moon reflections communications was successful 1954- On July 25th, using a 100-watt 220-megahertz communications transmitter, NRL transmitted the first voice messages via the EME path.  1955- On November Transcontinental communications were demonstrated teletyping messages from Washington DC to San Diego; two months later NRL conducted transoceanic communications EME between Washington DC and Hawaii. 1956-The Chief of Naval Operations directed the establishment of the Communication Moon Relay (CMR) system for transmission of teletype and facsimile messages between Washington DC and Hawaii. Using 84-foot-diameter dish antennas-one for transmitting, the other for receiving. Transmitter at the U.S. Naval Radio Station, Annapolis, Maryland, Receiver at Cheltenham, Maryland.  The Hawaiian facilities at Opana and Wahiawa on the island of Oahu.  10/7/2010

Test results verification and predictions
1946 January 10th –The experiment was daily repeated three days and eight days by the end of the month. 1946 January 24-Until then The War Department withheld announcement of the success. A press release explained: "The Signal Corps was certain beyond doubt that the experiment was successful and that the results achieved were pain-stakingly [sic] verified." As DeWitt recounted years later: "We had trouble with General Van Deusen our head of R&D in Washington. When my C.O. Col. Victor Conrad told him about it over the telephone the General did not want the story released until it was confirmed by outsiders for fear it would embarrass the Sig[nal]. C[orps].“ Two outsiders from the Radiation Laboratory, George E. Valley, Jr. and Donald G. Fink, arrived and, with Gen. Van Deusen, observed a moonrise test of the system carried out under the direction of King Stodola. Nothing happened. DeWitt explained: "You can imagine that at this point I was dying. Shortly a big truck passed by on the road next to the equipment and immediately the echoes popped up. I will always believe that one of the crystals was not oscillating until it was shaken up or there was a loose connection which fixed itself. Everyone cheered except the General who tried to look pleased." Several years later, the Signal Corps erected a new 50-ft (15 meters) Diana antenna 108-MHz transmitter for ionospheric research, lunar echo studies and the tracking of the Apollo launches. The implications of the Signal Corps experiment were grasped by the War Department, although Newsweek cynically cast doubt on the War Department's predictions by calling them worthy of Jules Verne. Time reported that Diana might provide a test of Albert Einstein's Theory of Relativity. In contrast to the typically up-beat mood of Life, both magazines were skeptical, and rightly so; yet all of the predictions made by the War Department, including the relativity test, have come true in the manner of a Jules Verne novel. END PART 2 10/7/2010

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