QUESTIONS: ANSWERS:What provides an alternative at microwave frequencies and it isessentially a pipe through which an electromagnetic wave travels? WaveguideWaveguides operate essentially as ______. high-pass filterIt has no radiation loss. WaveguideWhat do you call of the electrical energy that can propagate along a waveguide? modesIt is more than one mode propagating at a time. multimode propagationWhat limits the usefulness of waveguides with pulsed signals and other types of modulation? dispersionSingle mode propagation can achieved by using only the mode with the lowest cutoff frequency. This mode is called? dominant modeWhat is the actual speed at which a signal travels down the guide? group velocityWhat describes the variation pf phase along the wall of the guide,and is the rate at which the wave appears to move along the wall phase velocityof the guide, based on the way the phase angle varies along thewalls?What is the impedance of free space?

1. probeWhat are the 3 basic ways to launched a wave down a guide? 2. loop

3. HoleWhat do you call of the method using a probe resembling a quarter-wavelenght monopole antenna and the probe couples to the electric filed in the guide, and it therefore ahould locate probe couplerat an electric-filed maximum?It is used to couple with the magnetic filed in guide. loopIt is the third way of coupling energy, is simply to put a hole in the waveguide, so that the electromagnetic energy can propagate holeinto or out of the guide from the region extirior to it.It is characterized by their insertion loss, coupling and directivity. directional couplersWhat do you call of the amount by which the signal in the mainguide is attenuated? inserion lossThe _____ specification gives the amount by which the signal in the main gain is greater than that coupled to the secondary couplingwaveguide.What refers to the ratio between the power coupled to the secondary guide, for the signal traveling in the 2 possible directivitydirections slong the main guide?_____ and _____ like waveguide, have a crtical frequency. striplines and microstripsIt is carefully designed for gradual bends, resembles plumbing and is just a tricky to install. rigid waveguideIt is used for awkward installation. flexible waveguideWhat is the most common components used with ordianry transmission line and which allows one line to branch into two? teeThe _____ , the signal will be in phase at the two inputs, while H-plane teethe ______ produces two out-of-phase signals. E- plane teeWhat is the other name for H-plane tee? shunt teeWhat is the other name for E-plane tee? series teeIt is the combination of E-plane and H-planes tees. hybrid or magic teeTo launched a series of waves in a short section ofguide called? cavityWhat is a type of frequency meter that consist of a cavity with adjustable plunger? wavemeterIt uses a carbon flat thatcan be inserted to greater or lesser extent into the waveguide. flap attenuatorIt is rotated so that the electrical filed is perpendicular to itssurface, little loss occur, but when the field runs along the rotating vanesurface of the vane, a much larger current is induced, causing greater loss.The carbon insert is designed to dissipate the energy in the terminating load ofguide without reflecting it. the waveguideWhat is useful in microwave components that is generally Isolators and use ferrites in their operation? circulators

CHAPTER XVII: Microwave Devices

377Ω

QUESTIONS: ANSWERS:What is the device that allows the signal to pass in one directionand it can be used to shield a source from a mismatched load? isolatorWhat device is very useful that allows the separation of signals? circulatorsIf a ferrite is subjected to a magnetic filed from a permanent magnet, the electron spins experienced a phenomenon called? processionWhat do you call of the phenomenon that causes the polarizationof waves of certain frequencies to change as they move through Faraday rotationthe ionosphere?

on the length of the ferriteThe amount of phase shift depends? and the strenght of the dc

magnetic field to which it issubjected.

What so you call of the design in which the emitter and the base? "interdigital"It is designed to reduce capacitance to a minimum. "fingers"Gallium arsenide is _____than the silicon and is preferred in microwave applications. "faster"The Gunn devic, also known as the _____ is one of the simpler TEDtransit-time devices. transferred electron device What is the other name for Gunn Device? Gunn diodeIt has two terminal, it has no junction, however, but is just a Gunn diodeslap of N-type gallium arsenide.Who discovered the negative resistance? J. B GunnWhen was the negative resistance discovered? 1963It has a large electric field formed in the material and moved toward the positive terminal. It forms when there is a small region domainwith an electric field greater than in the rest of the material, possibly due to somelocal impurity.In this mode the devised is biased in the negative resistance LSAregion but, the voltage swing is such that the device moves out limited-space-charge-of this region once per cycle, so that the domain is quenched. accumulation

Impact Avalanche andWhat does the acronym IMPATT stands for? Transit TimeIt has a PN-junction and in fact, it is often afour-layer device. IMPATT

Trapped Plasma AvalancheWhat does TRAMPATT stands for? Triggered TransitIt can operate with still higher power (about 100 W in the pulsedoperation) efficiency levels, bu its expensive, requires complex TRAMPATTcircuitry and is noisier than the IMPATT.It use a means of providing a capacitance that can be changedby varying the voltage that reverses the bias of the diode. Varactor DiodeWhat is the other name for Varactor diode? step-recovery or snap diodeIt is operated with forward bias for most ot the cycles of fundamentals. step-recovery or snap diodeWhat do you call of the sphere that can be used in placed YIGof a resonant cavity as a microwave resonant circuit? Yttrium-iron-garnetWhat do you call of the resonant cavity that is made of a solidslab ofa dielectric materials such as alumina? dielectric resonatorsIt was invented in 1972 and is the oldest microwave tube designand its variations are high-power, fixed-frequency oscillators, not magnetronnoted for stability or ease of modualtion but simple,rugged andrelatively efficient (about 40% and 70%).What is the common application of magnetron? radar transmitterWhat is the rate at which the electrons move around the cathode? cyclotron frequencyWhat is the other name for magnetron? cross-field tubeThe movement of the wave around the tube at the rate much slower than the speed of light? slow-wave structureThe cathode that reduces the life of the tube and lower efficienry. bombardmentThe power average over time of magnetron (or any other device that generates pulse) is the power in the pulses, which is peak valuegenerally called?What is the preffered tube for high-power, high stability amplifi-cation of signals at frequencies from UHF to about 30GHz? klystron

QUESTIONS: ANSWERS:reflex klystron

What are the two different types of klystron? multicavity klystronWhat is produced in the conventional manner by a hot cathode? linear beam tubeIt is caused by the interaction between the electric field at the bunching or input cavity and the electron in the beam. velocity modulationWhat can be used as a moderate-power amplifier or with modifi- TWTcations, as an oscillator? travelling-wave tubeThe inner conductor of the coaxial line sometimes referred as? probeWhat is an acronym RADAR stands for? radio detection and rangingRadar requires that a transmitter emit a signal using a directionalantenna toward some object called? targetWhat reflects from the target and is received at a later time? pulseIt is defined as the area of a perfectly conducting plate, facingthe source, that would reflect the same amount of power toward radar cross sectionthe receiver.It is when the radar cannot distinguish between the target and much a closer one. ambiguityThe transmmited pulse has a finite pulse duration also called? pulse widthWhat causes the frequency effect of the echo to differ from thatof the transmitted signal when there is relative motion between Doppler Effectthe radar and the target. Along the line joining the two?What can measure only the velocity component along a line thatjoins the source and the target? Doppler radarWhat allows the velocity of target, as well as its position and direction, to be estimated? Doppler techniqueThe whole process can be made much more efficient by installinga transmitter-receiver called? transponderAs _____ increases into gigahertz range, sistributed capacitanceand inductance become very imporatnt everywhere in the circuit. frequencyWhat do you call of a very practical means of transmitting electri-cal energy at microwave frequencies, as they have much lowerlosses than coaxial cable and they are not very useful at lower Waveguidesfrequencies because they must be too large in cross section?Two velocities must be calculated. The _____ which is lowerthatn the speedof the light, is the speed at which the signal group velocity andtravel down the guide. The _____ , which is greater than the pahse velocityspeed of the light, is used for calculating the wavelenght inthe guide.

using probes, loopHow can be the power be coupled into and out of the waveguides? and holes in the waveguidesIt has a special properties that make them just as useful at microwave frequencies as at lower frequencies. Ferrites

circulators, isolators What are some of the applications of Ferrites? attenuators and resonatorsAt _____ conventional active components such as tubes and transistors suffer from excessive carrier transit time as well as micowave frequencystray capacitance and inducdtance.The _____ in the microwave region allow antennas to built with high gain and narrowbandwidht. short wavelenght

Pulse RadarWhat are the 2 radar systems? Doppler RadarIt works by reflecting pulses from a target, whose distance isgauged at the time taken for pulse to return. Pulse RadarWhat estimates the velocity of a target by measuring the difference in frequency between transmitted and received signals? Doppler RadarIn a klystron, a cavity that velocity modulates the electron beam. buncherIt is the velocity modulation. bunchingIn a klystron, a cavity that removes some of the energy from theelectron beam and transfers it in the form of microwave energy catcher

to the output.

QUESTIONS: ANSWERS:What do you call of the space in which microwaves can resoanteby means of in-phase reflections from the walls? cavityWhat do you call of the device with three or more ports that allows an input to one port to emerge only at the next port in circularorder?In a klystron or travelling wave tube, the element that receivesthe electron beam; in a conventional tube,this element is called collectoranode.What do you call of the microwave tuve in which the electric and the magnetic field are at right angles? crossed-field tubeWhat is the device that launches or receives a wave in a transmission lines or waveguides in one direction? directional couplerIt is a variation of velocity as a function of frequency in a wave-guide or medium. dispersionIn a semiconductor, a concentration of charge. domainWhat do you call of the change in frequency that occurs when a wave reflects from a moving objects? Doppler EffectWhat is a lens that is stepped to reduce its size? Fresnel lensWhat do you call of the speed of transmission of the signal alonga waveguide? group velocityIt is a slab of N-type gallium arsenide that can operate as an oscillator or amplifier by means of domain information. Gunn DeviceWhat do you call of the combination of E-plane and H-plane tees? hybridWhat is a juntion device that can operate as an oscillator or amplifier, by means of avalanche breakdown? IMPATT diodeWhat is a waveguide device that has low loss one direction andhigh loss in the other? isolatorWhat is a type of a linear-beam microwave tube that uses velocityof modulation of the electron beam? klystronWhat do you call of a microwave tube in which electrons travelin a straight line down the length of the tube? linear-beam tubeIt is a crossed-filed microwave tube oscillators in which electronscircles around the cathode under the influenced of the magnetic magnetronfield.It is a microwave transmission lines constructed on a printed-circuit board, consisting of a single condutor on one side of the microstripboard and ground plane on the other side.Conventionally, electromagnetic radiaton in the range aboveapproxiamtely 1 GHz. microwaveWhat is the speed ofelectrons drift in conductor or semi-conductor? mobilityIn a waveguide what is a specific configuration of electric andmagnetic fields that allows a wave to propagate? mode(s)What is the apparent speed of speed of propagation along a waveguide based on a distance between wavefronts along the phase velocitywalls of the guides?What do you call of the three-layer diode (P-intrinsic-N) thatcan be used as a switched and an attenuator at microwave PIN diodefrequencies?In a feerite, what is the rotataion of the axis of rotation of the electrons? precessionWhat is the equivalent size of the target, in terms of perfectly conducting flat plate oriented toward the receiver? radar cross sectionIn a microwave,what do you call of any device that causes a wave to propagate at less than the speed of the light, so that slow-wave structurethe electron beam and the wave move at approximately the samespeed.What do you call ofmicrowave transmission line that consist

of conductor inside a circuit board, working against two ground striplineplanes, one on the top on the bottom of the board?In a radar, it is the object whose range, direction, and / orvelocity is to be measured. targetWhat is a combination of a transmitter-receiver? transponder

QUESTIONS: ANSWERS:What do you call of the variations of IMPATT designed for highpower operation? TRAMPATT diodeWhat do you call of a linear beam microwavetube in which an TWTelectron beam gives up energy to a slow-wave structure? Travelling-wave-tubeIt is a metal object threaded into a waveguide to add capacitanceor inducatance. tuning screqIt is a hollow structure that has no center conductor but allowswaves to propagate down its length. waveguidesIt is a type of ferrite. Yttrium-iron-garnet. YIG

QUESTIONS: ANSWERS:Terrestrial microwave links are useful for? short-range communicationRepeaters are used for? long-range systemsWhat propagation does a microwave system use? Line-of-sight propagationMicowave sytems use line-of-sight propagation and require repeaters approximately every _____ , depending on the terrain. 40 KmCare must be taken to keep the micowave beam well above Signal loss due to obstacles on the ground to avoid? diffraction_____ and _____ must be chosen to give a satisfactory carrier transmitter power andpower-to-noise ratio systems. antenna gain

Energy per bit noiseIn digital system, the equivalent specification is the? density ratio._____ is common with microwave signals. It can be overcomeby using either frequency or space diversity. FadingWhat does analog microwave system use? FM or SSB

*-distribution of televisionWhat are some of the applications of microwave systems? broadcasting

*-internet service *-two-way systems

It is the signal-to-noise ratio in the receiver at a point before thedetector? carrier-to-noise ratioWhat ist the deviation of wave as it passes as obstacle or passes through a small surface? diffractionWhat do you call of the use of more than one frequency or transmission path, to improve systems reliabilty diversityin the presence of fading?It is the energy received in the time taken to transmit one bit. energy per bitWhat is the variation field strenght over time due to changesin propagation conditions? fadingIt is the region neart an object in which diffraction effects aresignificant. Fresnel ZoneIt is a single transmission path from transmitter to receiver. hopAbrupt variations in the timing of a digital signal. jitterWhat is the network using microwaves for two-way transmission LMDSof telephony, television and high-speed data? Local Multipoint

Distribution SystemsIt is the Terrestrial Microwave system for the distribution of MMDSthe televission, Internet, and telephone services to businesses Multichannel multipointand residences. distributon systemIt is a receiver-transmitter combination that amplifies and retranasmit a signa. repeaterWhat so you call of the map showing sufacefeatures, including the elevation of the terrain? topographic Map

CHAPTER XVIII: Terrestrial Microwave Communication System

QUESTIONS: ANSWERS:It has the advantage over the terrestrial modes when mobile-or point-to-point communication is required. Satellite CommunicationMost commincations satellites are ______ to simplify trackingrequirements. geostationaryLow-earth-orbit are coming into increasing use, especially for the shorter distance int themobile communications, because? satellites results in stronger

signaltelevision

What are the common appilcations of Sattelite? telephonyand data communicatio

When satellites is to be used with digital signals only, improved Using signal processing performance can be obtained by? in the satellite_____ television broadcasting via satellite is rapidly increasing Digital its performance. Direct-to-home televisionIt is especially useful for telecommunication in remote areas where tereestrial cellular systems are prohibitedly expensive Satellitesor impossible to build.The orbital period of a satellite in a circular orbit depends? on its

distance from the earth, Satellites orbits are classified according to their distance from Low earth orbit LEOthe earth. Medium earth orbit MEO

Geostationary earth orbit GEO_____ appear stationary at a point above the equator. Geostationary satellitesSystems using satellite in lower orbits have lower path loss and But require more satellitesshorter propagation times. for real0time coverageCurrent satellites systems for mobile communication use either? GEO or LEO satellitesOnly the latter systems allow handheld _____. transceiverWhat is the point farthest from earth in a satellite orbit? apogeeWhat is a structure that orbits the earth and was built by humans? artificial satelliteWhat is the naturalsatellite? moonWhat is a satellite transponder design that receives signals andtransmits them at higher power at different frequency, without bent-pipe configurationany other processign?In Satellite telephony, a group of satellites coordianted in such away as to provide continous communication. ConstellationsIt is a radio or optical connection directly between satelliteswithout going through an earth stations. crosslinkIt is a transmission of signals form a satellite from the earth'sstations. downlinkWhat do you call of the satellite obit tht is entirely above theequator? equatoraial orbitWhat is the change in the direction of polarization of signals passing through the ionosphere? Faraday rotationFor a microwavereceiver, the ratio, expressed in decibels, of gain to noise temperature figure of meritIt is a depiction of signal strenght contours from a satellite transmitter on the earth. footprintsIt is a satellite orbit in which the satellite appears to remain stationary at a point above the equator. geostationary orbitWhat is a satellite orbit in which the satellite's period of revolutionis equal to the period of rotation of the earth? geosnchromous orbitIt is an antenna beam on a geostationary satellite but is any other processign. hemispher beamIt is an artificial satellite orbitting the earth at an amplitude less LEOthan about 1500 Km. low-earth-orbitIt is a satellite in orbit at a distance above the earth surface MEOof approximately 8000 to 2000 Km. medium-earth-orbitWhat do you call of any artificial satellite that is not geostationary? orbital satelliteWhat is the point closest to the Earth in a satellite orbit? perigee

CHAPTER 20: Satellite Communications

QUESTIONS: ANSWERS:What is a satellite orbit passing over the north and south poles? polar orbitWhat so you call of the time taken for a signal to travel throughspace from the transmitter to receiver? propagation timeIn a Satellite system what do you call of the focus beam of energy that covers a relatively small area on the earth, spot beamproduced by a high gain antenna on the satellite.What is the process of adjustiong the orbit of geostationary satellite so that it appears to remain stationary above the station-keepingpoint on the earth?In digital communication, the use of this device to receive one or more data packets, store them, and retransmit them later at store-and -forward techniquea given time.In a satellite communication what do you call of the tracking andadjusting the position of a directional antenna on the ground, trackingso that it always points at the satellite?In a satellite communication what do you call of a repeaterlocated on the station? transponderIt is a transmission of signals from an earth station to a satellite uplink

QUESTIONS: ANSWERS:Utilize the line of sight path which means the 2 Microwave antennas should see each other. Communication

SystemA graph wherein the terrain in which the microwave beam Radio Pathshould traverseNo obstructuion. Line of SightThe microwave beam barely touches the obstruction. Grazing PathThe microwave beam is hindered by an obstruction. Obstructed PathUnder this condition, the radius of the earth appears to the microwave beams to be longer than the true radius. Standard Condition (k=4/3)

Under this condition results in an effective flattering of Super Standard Condition the equivalent earth’s curvature. The unusual refill condition Sub- standard Condition (k<4/3)The least or the weakest signal the receiver could accept Sensitivity Thresholdto be considered satisfactory.A margin for fading, an allowance in dB in case the RSL Fade Marginencounters fadingThe difference between the normal output power of a transmitter System Gainand the minimum input power required by a receiver.Intercepts, amplifies and retransmits the signal. Active RepeatersBounces the signal from 1 direction to another. Passive RepeatersIt is amplified, demodulated, amplified in the baseband Baseband Repeatersfrequency and remodulated.Improve noise performance. IF Heterodyne RepeatersAmplification is provided directly at microwave frequency. RF Heterodyne RepeatersFlat metal type used to reflect microwave signals. BillboardUses two standard antenna dishes directly joined by a short Back to Back Passivelength of waveguides.The measure of a unilateral antenna’s directional Beamwidthproperties of directivity.The portion of plane surface near the antenna perpendicular to Aperture of a unidirectional the direction of maximum radiation passes through which antennathe major part of the radiation passes.

Near Field (Fresnel Region)3 main regions of a parabolic antenna: Far Field (Fraunhoffer Region)

Transition ZoneA method of utilizing 2 or more receivers to reduce fading or increase reliability of the system. Diversity ReceptionSignal is transmitted on 2 different frequencies Frequency DiversitySignal is transmitted on 2 different paths. Space DiversityUsing dual polarization. Polarization DiversityA special combination of frequency and space diversity Hybrid DiversityA combination of a reflector mounted on a tower Periscope Arrangementand the parabolic antenna below.A non-metallic covering in a parabolic antenna for protection against strong wind velocity. RadomeA metal wrapped around the antenna aperture to eliminate side lobes which may cause interference. ShroudAn electron tube in which the electrons are periodically bunched Klystronby electric fields.A diode vacuum tube used as a microwave oscillator in radar and microwave ovens to produce powers up to the megawatt Magnetronrange.A microwave power amplifier with very wide bandwidth. Travelling Wave TubeA microwave power amplifier based on the magnetron and Crossed-filled Amplifierlooking very much like it.A hybrid combination of klystron driver and TWT output Twystronsection in tandem with the same envelope.A multicavity klystron with interconnected multigap cavities. Extended Interaction Amplifier

ADDITIONAL INFORMATION: Microwave

QUESTIONS: ANSWERS:Consists of flat metallic ground planes separated by a thickness of dielectric in the middle of which a thin metallic strip has been Striplineburned.Has the advantage over stripline in being simpler construction and easier integration with semiconductor devices, lending itself Microstripwell to printed circuit and thin film techniquesUse solid piezoelectric materials at frequencies in the VHF and UHF regions. Surface Acoustic Wave DevicesA microwave semiconductor device use to generate microwave Gunn Diodeenergy.A single hollow metallic conductor either rigid or flexible which transfers electromagnetic energy from 1 point to another. Waveguide3 Types of waveguide: Rectangular

EllipticalCircular

The configuration in which the energy propagates thru waveguide. ModeThe electric field is always perpendicular to the direction Transverse Electricof the propagation.The magnetic field is always perpendicular to the direction Transverse Magneticof the propagation.Types of modes: Dominant Mode

Higher Order ModeThe lowest frequency that will propagate thru a waveguide while operating in a particular mode. Cut-off FrequencyVelocity of the waves as they propagate thru the waveguide. Group VelocityVelocity with which the wave changes phase. Phase VelocityThe wavelength of the traveling wave which propagates down Guide Wavelengththe waveguide.Principal effect is to lower the value of the cut-off wavelength. Ridged WaveguidesWaveguide sections capable of bending, twisting, stretching Flexible Waveguidesor vibration.Methods of Exciting Waveguides: Antennas

Slot CouplingDirect Coupling

QUESTIONS: ANSWERS:Some of the first communications satellites were designed to operate operate in a passive mode. Instead of actively Significant milestone in transmitting radio signals, they served merely to reflect signals Satellite Communicationthat were beamed up to them by transmitting stations on the ground. Moon was the first passive satellite used 385,000 km away, 1940’s-1950orbits in 28 days.The U.S navy conducted the “Earth Moon Earth” (EME) means bounce experiments using the moon as a passive reflector and 1954succeeded in transmitting messages between distant points.Russia launched “SPUTNIK 1” the first active satellite, which transmitted telemetry information for three weeks on the same 1957year at the USA, launched the “EXPLORER 1” and transmitted information for 5 months.AT&T launched the “TELSTAR 1” the first duplex satellite 1962transmission.AT&T launched “TELSTAR H” telephone, TV, fax, 1963and data transmission.COMSAT launched the “EARLY BIRD” which transmitted messages to five (5) earth stations with 66 telephone circuits 1965using EDM techniques.The National Development Company and POTC established the DOMSAT ushering satellite technology to the 1966Philippines.PHILCOMSAT installed the first earth station at the foot of Sierra Madre Mountains-Mount Pinugay, Baras, Rizal. 1967Western Union launched the “WESTER” for TV and data transmission. 1974Indonesia launched its first satellite “PALAPA A-1”. 1976India launched its first satellite “INSAT-C”; Russia launched the “OKEAN” for remote sensing. 1988Thailand launched its first satellite “THAICOM-1”. They also launched the “Microsatellite Program” through 1993United NASA and GE.Mabuhay Philippines Satellite Corporation launched Aguila IIthe first Philippines satellite. 1997A spacecraft placed in orbit around the earth which carries on board microwave receiving and transmitting equipment (repeater) Satellite capable of relaying signals from one point on earth to the other points.A radio repeater in the sky. TransponderA ground based station to control its operations, and a user network of earth stations that provide the Ground Base Stationfacilities for transmission and reception of communication traffic through the satellite systems.A communications path formed between two or more ground stations transmitting and receiving radio Satellite Link communications traffic via satellite.The portion of the satellite communications link involving the transmission of traffic from the ground station up to the satellite. UplinkThe portion of a satellite communications link involving the transmission of traffic from the Downlinksatellite to the earth terminal.Refers to the satellite orientation with respect to earth. Satellite AttitudeMonitoring of ecological situation (ocean, communication, deforestation) sea surface dynamics, etc. Remote SensingDisaster prediction and early warning. Weather ForecastingForecasting of meteorological effects of eliminate on agricultural Agricultural Production production. ForecastingMilitary espionage/surveillance operations by remote satellite monitoring. Intelligence/ Surveillance

ADDITIONAL INFORMATION: Satellite Communications

QUESTIONS: ANSWERS:Satellite based electronic navigation. NavigationSatellite based electronic navigation. Search and RescueInternational TV broadcasting, telepaging, cellular, telephony, Telecommunication/video conferencing, etc. Tele broadcastingInteractive educational broadcast for simultaneous instructions among several classrooms throughout the globe. Interactive EducationAstroplanics a biological experiments, etc.. Sea researchA satellites velocity (speed at which it would travel straight line). PayloadThe gravitational force between the satellite and the earth. BusActual user information conveyed through the system. Passive SatelliteIncludes control mechanisms that support the payload operation. Active SatelliteA communications satellite not equipped with electronic devices to retransmit communications. Such satellite acts only as 3-axis Stabilizer reflector of radio waves.A satellite equipped with electronic devices to receive, amplify, convert and retransmit signals. Non-Synchronous or OrbitalUse angular momentum of its spinning body to provide roll Prograde Orbitand yaw stabilization.Body remains fixed relative to earths surface while an internal subsystem provides roll and yaw stabilization Retrograde Orbit

Rotate around the earth in low altitude elliptical or circular Geostationary or pattern GeosynchronousWhen a satellite orbits in the same direction as that of the Equatorial Orbitearths rotation.When a satellite orbits in the opposite as the earths rotation but as an angular velocity less than of the earth. Polar OrbitOrbit in a circular pattern with an angular velocity equivalent to that of earth remain in a fixed in respect to a given point in earth with an orbital time of about 24 hours (a sidereal Inclined Orbit day = 23 hrs. 56 sec.).Rotation about the earth’s equator, usually for geosynchronous communications satellite. OrbitRotation over the North and South Poles, used for non-communications mission such as weather and surveillance Ascending Nodeobservation.Rotation creating as angle between the equatorial a polar plane. It is not suitable for global network. Descending NodeThe path of a celestial body or satellite in “unpowered flight”. ApogeePoint where the orbit crosses the equatorial plane going Perigeefrom south to north.Point where the orbit crosses the equatorial plane going Eccentricityfrom north to south.The highest point of the orbit or it is the point in an earth earth satellite orbit, which is farthest away from Major Axisthe earth.The point in an earth satellite orbit, which is closest in the earth. Minor AxisA number between zero and one which describe the shape pf an ellipse. Mean Distance

The longer axis of the ellipseElliptical Orbits: The shortest axis of the ellipse

The average distance from the center of the earth.

The orbit of any planet is an ellipse with the sun at one focus. First LawEvery planet moves so that its radius sector sweeps over equal Second Law areas in equal intervals of time. (Law of Areas)The square of the periods of revolution of any two planets is to each other as the cubes of their Third Law respective mean distances from the sun. (Law of Periods)Space shuttles carry some satellites into space, but rockets that fall into the ocean after their fuel is spent launch Launching the Satellite most satellite.Once a satellite is placed into a stable orbit, it can remain there for a long time without further adjustment.

QUESTIONS: ANSWERS:Provides the power for those vehicles that lifted the satellite into orbit. Rocket motors do not depend on the Rocket Motorsatmosphere for oxidizing or burning fuel. They classify as solid or liquid propellant motors.Works on principle similar to small gunpowder rockets used for fireworks displays. It contains gas fuel, a combination Solid Propellant Rocketsof combustible Carries two tanks outside the combustion chamber, one for fuel and the other for the oxidizer. Liquid Propellant RocketsPortion of satellite link which receives processes and transmits communications between the earth Earth Stationand a satellite.Converts input baseband signal to FM, QAM IF. IF modulatorConverts IF to RF carrier frequency IF-RF microwave Up ConverterProvides adequate input sensitivity and output power propagate. High Power AmplifierLimits bandwidth. Output Bandpass FilterMicrowave repeaters carried communication satellite. Receive, amplify, converts frequency and retransmit signals. TransponderLimits input noise power to LNA. Bandpass FilterHigh sensitive, low noise device usually a tunnel diode Low Noise Amplifier (LNA)or parametric amplifier.Mixer/bandpass filter combination which converts RF-IF RF-IF DownConverterPrimarily dictated by the external and internal noise sources that contribute to the noise system temperature and Choice of Frequencyby the existence of spectral windows for which signal attenuation is small.Immune to atmospheric noise but requires large antennas. The most commonly used band. C BandImmune to terrestrial jamming but sensitive to atmospheric conditions such as transient noise. Ku-BandThe strongest signal and higher data rate capability. It is directional and has spot footprint coverage. Ka-BandEach is assigned a longitude spaced between 3-6 degrees in the arc approximately 22,300 miles above Spacingthe equator.Positions depend on frequency bandwidth to avoid interference. Terrestrial microwave transmission operates on different frequency Frequency Allocationrange then does of satellites, so there is no interference.Band of frequencies available for an earth station to transmit to a satellite in space. Uplink frequency is always Uplink Bandhigher than the downlink frequency.Band of frequencies for a satellite to transmit to an earth station. Downlink BandTechnique employed in order to conserve electron\magnetic frequencies resources. Frequency ReuseThe use of the same frequency beamed towards different geographic areas on earth multiple spot beam antennas. Multiple Coverage AreasSending different information signals using vertical or horizontal electromagnetic polarization. This is similar to polarization Dual Polarizationdiversity to improve system liability.Geographic representations of a satellites radiation pattern with contour lines representing limits of Footprintequal receive power density.Beams concentrate the radiated power in a very small geographic area. Spot CoverageCovers less than 1/3 of earth’s surface. Zonal CoverageCovers approximately 1/3 of earth’s surface using a 17° . Earth CoveragebeamwidthCovers the whole world. GlobalCovers selected regions such as Pacific, Atlantic, etc.. RegionalCovers domestic or national territory. National/Domestic

QUESTIONS: ANSWERS:FixedMobile

Satellite Types as to Services Offered: BroadcastingMaritime

AeronauticalPoint-to-point

MilitaryAmateur

ExperimentalThe product of the total antenna radiated power and its gain. Total Transmit PowerThe ratio between the Noise Power and the product of the Bandwidth and Boltzmann constant. Equivalent Noise TemperatureTotal noise power normalized to 1 hertz bandwidth. Noise DensityInvolves action necessary to position, tract, monitor and command the satellite during the course of its operational life it involves supervising and monitoring the establishment, Satellite Controlreconfiguration and control of each required link through the satellite transponder in accordance with the desire parameters.Required in a communications satellite for initial orientation and for all subsequent adjustment so that the antenna will constantly Orientationview the earth and the solar cells will w\view the sun.Required in a communications satellite for initial orientation and for all subsequent adjustment so that the Position Controlantenna will constantly view the earth and the solar cells will w\view the sun.Altitude control of a vehicle about any or all of its axes(roll, pitch and yaw) projects for axial, radial axis Orientation Control correctionsOperates on the principle that the direction of the spin axis of a rotating body tends t remain fixed inertial space. Spin StabilizationRequires no, power or expandable mass once deployed and allows more of satellite electrical power and weight for Gravity Gradient Stabilizationcommunications purposes.The control routing necessary to keep the satellite in position Station KeepInvolves actions necessary to assure that requires circuits between all authorized users are established maintained and restore satisfactorily, a function performed by technical control Circuit Controlfacilities personnel.Refers to the way a communications system uses a satellite Access techniquestransponder.In communication satellites, those satellites so equipped that they may function as a portion of a communications link Multiple Accessbetween more than one pair of ground stations simultaneously.Refers to the satellite output power that is lost due to the the necessity for backing off on earth station radiated power to avoid generating excessively high intermodulation Multiple Access Back-offproducts in the satellite. Its range from 1 to 2 dB.A satellite transponder is divided into smaller frequencies hand segments where cash segment is assigned to use for his Frequency Division uplink or downlink frequency. Multiple AccessA given number of available voice hand channels from each earth station are assigned dedicated Pre-assigneddestinations.Voice band channels are assigned on “As-needed” basis. Demand AssignedA master station “polls” other station sequentially. Polling

A central computer located at the master station coordinates the status of channels. Random AccessUses a processor controller at each earth station accessing the system. All earth stations in the network monitor the status Random Access Distributed information by means of digital wire circuit. Control

QUESTIONS: ANSWERS:Single channel per carrier PCM Access Demand Assignment SPADEEquipment. Time Division Multiple AccessWorks in the time domain and is TDMAapplicable to digital systems because information storage is required.A technique in which a message received from earth termed is held held in storage until the satellite is in view of Store and Forwarda second earth terminal at which time the message in transmitted.Spread spectrum multiple accessing has no restrictions on time or bandwidth. CDMAIs a form of CDMA where a digital code is used to continually change the frequency of the carrier. Frequency HoppingInternational Maritime Satellite Organization Recommended by the panel of experts commissioned by the IMCO. They consider the introduction pf satellite INMARSATcommunications to the maritime sphere with the aim of improving communications with ships particularly for safety and distress purposes.International Maritime Satellite Consortium founded in 1964 at Washington D.C by COMSAT of the United States, Overseas INTESLSATTelecommunications Commission of the Australia and nine other world communications agencies. Ship to shore and shore to ship communications via dedicated geostationary satellite system, providing high quality telephony, MARISATdata and telex/telegraphy circuits.A satellite remains in orbit until its velocity decreases as the gravitational force pulls it down into a relatively dense part of the Falling from orbitatmosphere.