Microwaves (Satellite Comms) PDF

**I. IDENTIFICATION** **[Satellite]** 1. It is a celestial body that orbits around a planet such as the moon is a satellite to the Earth. **[Transponder?]** 2. It is a satellite radio repeater of which any satellite may have many. **[Satellite Bus]** 3. It includes control mechanisms that support...

**I. IDENTIFICATION** **[Satellite]** 1. It is a celestial body that orbits around a planet such as the moon is a satellite to the Earth. **[Transponder?]** 2. It is a satellite radio repeater of which any satellite may have many. **[Satellite Bus]** 3. It includes control mechanisms that support the payload operation in a satellite system. **[Moon]** 4. It was the first passive satellite used by the US Navy to successfully transmit the first message in 1951. **[Explorer I]** 5. An active satellite launched by the Americans that transmitted telemetry for nearly 5 months in 1957. **[Johannes Kepler]** 6. He discovered the laws that govern satellite motion. The laws of planetary motion describe the shape of the orbit, the velocities of the planet, and the distance a planet is with respect to the sun. **[Eccentricity]** 7. The measure of the deviation of the path of an orbiting body from a true circle. **[Prograde Satellite Orbit]** 8. The term used to describe the type of Earth orbit when the satellite is orbiting in the same direction as Earth\'s rotation at an angular velocity greater than that of the Earth. **[Geostationary Satellites]** 9. Satellites that orbit in a circular pattern with an angular velocity equal to that of the Earth, an orbital time of 24 hours, same as the Earth. **[Inclined Orbits]** 10. An orbital pattern that virtually encompasses all Earth orbits except those that travel directly above the equator or directly over the North and South poles. **[Lines of Nodes]** 11. The line joining the ascending and descending nodes through the center of the Earth. **[Equatorial Orbits]** 12. An orbital pattern that occurs when the satellite rotates in an orbit directly above the equator, usually in a circular path. **[Mount Chimborazo]** 13. In the early 1800s, this 20,700-foot mountain in Ecuador was erroneously thought to have the highest point on the planet. However, because of the equatorial bulge, it proved to be the farthest point from the center of the Earth. **[Station-keeping]** 14. It is the term used to describe when ground controllers must periodically adjust the satellite positions to counteract these forces, if not the excursion would build up at a rate between 0.6° and 0.9° per year. **[Arthur C. Clarke]** 15. He was the first one to suggest the existence of a geosynchronous orbit in 1945 and proposed its use for communications satellites. **II. TRUE OR FALSE** **[FALSE]** 1. In astronomical terms, a satellite is a space vehicle launched by humans and orbits the Earth or other celestial body. **[FALSE]** 2. In Kepler\'s Law of Harmonics, the planet moves faster near the Sun, so the same area is swept out in a given time as at larger distances, where the planet moves more slowly. **[FALSE]** 3. Geosynchronous satellites can provide reliable communications to approximately 100% of the Earth\'s surface. **[TRUE]** 4. In an elliptical orbit, the speed depends on the height the satellite is above the Earth. The speed is greater when it is closer to the Earth. **[FALSE]** 5. When the satellite is orbiting in the same direction as the Earth with an angular velocity less than that of the Earth, it is said to have a retrograde orbit. **[FALSE]** 6. 100% of the Earth\'s surface can be covered with a single satellite in an Inclined Orbit such that every location on Earth lies within the radiation pattern of this satellite twice each day. **[FALSE]** 7. Two satellites in a Clark orbit separated by 120 in longitude can provide communications over the entire globe except the Polar Regions. **[TRUE]** 8. The location of a satellite is expressed in terms of longitude and latitude but is only identified by a point on the surface of the Earth directly below it and must fall on the equator; this is known as subsatellite point. **[TRUE]** 9. In a Geosynchronous satellite, there is a delicate balance between acceleration, speed and distance that will exactly balance the effects of centrifugal force and the gravitational forces. **[TRUE]** 10. A footprint is known as the geographical representation of a satellite antenna\'s radiation pattern. **III. MULTIPLE CHOICE** 1\. The following are satellite subsystems except for a. b. c. d. 2\. It is the actual user information conveyed through the satellite transmission system a. b. c. d. 3\. The high and low points of a satellite\'s orbit are called, respectively: a. b. c. d. 4\. The velocity required by a satellite to stay in its orbit: a. b. c. d. 5\. The surface on the Earth that is \"covered\" by a satellite is called its: a. b. c. d. 6\. The height of geosynchronous orbit above the equator is about: a. b. c. d. 7\. \"Station-keeping\" refers to: a. b. c. d. 8\. An antenna is aimed by adjusting the two \"look angles\" called: a. b. c. d. 9\. LEO stands for: a. b. c. d. 10\. In a satellite system, Johannes Kepler stated that \"the square of the periodic time of orbit is proportional to the cube of the mean distance between the primary and the satellite\". This is also known as: a. b. c. d. 11\. In a satellite system, Johannes Kepler stated that \"the satellite a. b. c. d. 12\. In a satellite system, Johannes Kepler stated that \"the satellite a. b. c. d. 13\. In a frequency reuse technique of increasing satellite channel capacity of corresponding transponders how do you control the antenna used to prevent interference. A. B. C. D. 14\. What does the term "apogee" refer to when applied to an Earth satellite? a. b. c. d. 15\. A point on the satellite orbit known to be the closes location to the surface of the Earth. a. b. c. d. 16\. The direction of maximum gain of the Earth station antenna a. b. c. d. 17\. The center of the mass of the two-body system and in always centered **Barycenter** 18\. The point where the orbit crosses the equatorial **Ascending node** 19\. The first active satellite which transmitted **Sputnik I** 20\. Launched by NASA in 1958 and the first artificial satellite **Score** 21\. In 1960, it **Echo** 22\. The first transponder type satellite that transmitted about 3 watts of power and lasted only 17 days in 1960. **Courier** 23\. The first active satellite to simultaneously receive and trans **Telstar I** 24. **Telstar II** 25. **Syncom I** 26. **Early Bird or Intelstat** 27. **Molniya or Lightning** 28. **Anik or Little Brother** 29. **Westar** 30. **Satcom** 1. **Answer: Farthest Point** 2. **Answer: Apogee** 3. **Answer: Barycenter** 4. **Answer: Courier 1B** 5. **Answer: Telstar 1** 6. **Answer: Telstar 2** 7. 8. 9. 10. 11. 12. 13. **IV. COMPUTATIONS** 1\. Titan, the largest moon of Saturn has a mean orbital radius of 1.22x10^9^m. The orbital period of Titan is 15.95 days. Hypenon, another moon of Saturn, orbits at a mean radius of 1.18x10^9^m. Use Kepler\'s 3^rd^ Law of Planetary Motion to predict the **ORBITAL PERIOD** of Hyperon in days 2\. Determine the **RECEIVED SIGNAL STRENGTH** at the satellite an Earth station is transmitting 7W of power using a parabolic antenna with a gain of 45 dBi, operating at 4 GHz, the path length is 40,000 km and the satellite receiver gain is 10 dBi. 3\. It is often claimed that the Ku-band (12 GHz) is better than the C-band (4 GHz) for TVRO reception because a parabolic antenna of a given diameter has higher gain at higher frequency. Though the gain is undoubtedly higher, what is the **DIFFERENCE IN PATH LOSS** to find out if there is really a net improvement in the signal strength obtained for a given receiving antenna? 4\. If the average distance of the Earth from the Sun is 1 Astronomical Unit, what is the **ORBITAL PERIOD** of planet Venus (in years) if its average distance from the Sun is 40.121 A.U. following Kepler\'s 3rd Law on planetary motion. 5\. Earth has an orbital period of 365 days and the mean distance from the Sun is 1.495x10^8^km. The planet Pluto\'s mean distance from the Sun is 5.890x10^9^km. Using Kepler\'s 3rd Law, calculate Pluto\'s **ORBITAL PERIOD** in Earth days.  **V. ENUMERATION** 1. 2.