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95 Cards in this Set
- Front
- Back
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What are the United States cycles per second (CPS) frequency standards for electrical power?
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60 cps
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The concept that alternating current changes in magnitude and reverses its direction during each cycle is:
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what makes radio transmissions possible.
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At what point do magnetic fields around a wire no longer have time to collapse completely between alternations?
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10,000 cps
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Radio waves that travel near the earth's surface are called:
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ground waves
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Sky wave transmission is used for which type of communications?
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Long distance
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Direct waves are those that travel:
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through the air in a straight line.
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The earth's conductivity is determined by the type of:
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soil and water in the propagation path.
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Sky wave communications became possible when the:
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bending of the radio wave is great enough to return it to earth.
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The path undergoes a 180 degree phase shift is a:
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ground-reflected path.
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The angel at which a radio wave enters the ionosphere is known as the:
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angle of incidence.
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Frequencies higher than the critical frequency are:
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passed into space.
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The abbreviation FOT is derived from the term:
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Frequency of Optimum Transmission.
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Magneton splitting creates two waves called:
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ordinary and extraordinary.
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In dealing with sky/ground wave propagation, the area of silence where no signals are received is known as the:
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skip zone.
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Communications paths involving multiple refractions and/or reflections are called:
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multihop paths.
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Multi-path transmissions are extremely critical and should be avoided when transmitting:
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digital or data traffic.
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How many regions make up the atmosphere?
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5
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Scientists call the ionosphere an extension of the:
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Thermosphere.
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The recombination process is dependent on what?
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Time of day.
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Sunspots are disturbances:
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on the sun's surface.
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During what season do we have the wider range of critical frequencies and less absorption of all frequencies?
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Winter.
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Sunspots occur on an:
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11-year cycle.
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For the communications purposes, what is the usable frequency spectrum?
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From 3 Hz to 300 Ghz
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Near-vertical-incidence sky wave operations are most effective when you're using:
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lower HF frequencies.
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High frequency transmissions are normally conducted in which two operating modes?
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Single side band (SSB) and independent sidebands (ISB).
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What frequency band is most susceptible to jamming?
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High Frequency.
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The main very high frequency/ultra high frequency communications emphasis is on:
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air-ground communications.
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What communications development overcame the limited range problem of tropospheric scatter systems?
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Satellite communications.
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Why isn't very high frequency normally used for satellite communications?
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Ionospheric refraction can occur.
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Line of sight radio waves that are guided through the air between two layers of the atmosphere are known as:
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ducting.
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What types of satellite signals are very susceptible to free space loss?
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Ultra high frequency.
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What is the output of a radio frequency oscillator called when it is modulated?
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Carrier wave.
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What is the easiest way of controlling a continuous signal to represent intelligence?
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By use of a telegraph key.
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What basic requirements must a receiver meet?
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Collection, selection, detection and reproduction.
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The measure of a receiver's ability to reproduce the intelligence of a signal accurately is known as:
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fidelity.
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Mixing the radio frequency and the audio frequency in the modulator creates:
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four distinct frequencies.
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What are we more concerned with in military frequency modulation (FM) voice communications?
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Intelligence of the signal.
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The method of transmitting intelligence by shifting between two frequencies is known as:
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frequency shift keying.
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What type of transmission commonly uses frequency shift keying?
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Teletype.
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The synchronization of frequency hopping capable HAVE QUICK radio is accomplished through:
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time-of-day, word-of-day and net number.
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What type of signals are continuous waveforms that follow the amplitude and frequency variations of the intelligence they are carrying?
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Analog.
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What makes up a digital signal?
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Pulses and spaces.
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In this mode of operation, each end of the circuit can transmit and receive at the same time?
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Duplex.
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Which high power high frequency station below was not consolidated within the Scope Command System?
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Airways.
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The high frequency Global stations are connected to the centralized network control station at:
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Andrews AFB, Maryland.
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High frequency global operator's interaction with equipment is by way of:
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Mouse and keyboard.
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What system does automatic link establishment users send and receive E-mail messages?
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High frequency messenger.
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mally, how often are online encryption codes changed?
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Every 24 hours.
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What device allows the secure terminal equipment secure voice and data capabilities to be accessed?
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Crypto-card.
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This self-contained terminal has two independent modems?
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KY-99
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Stand-alone high frequency transceivers are more often found in what type of stations?
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Deployable.
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Which high frequency radio has frequency-hopping capability?
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RF-5000
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The PRC-150 is what type of radio?
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A multi-band tactical radio.
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Which auxiliary equipment is capable of automatic link establishment?
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RF 7210A
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Which tag will one used for turning in condemned radio equipment?
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DD Form 1577 or 1577-1 (RED TAG)
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Which tag is used to indicate the equipment is serviceable?
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DD Form 1574 or 1574-1 (YELLOW TAG)
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What determines the time period required for each orbit of a satellite?
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Altitude.
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This orbit satellite is an orbit that is equal in speed to the earth's rotation?
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Synchronous.
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The angle between the orbit and the equator is the:
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Inclination.
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Any definite position of a satellite is a:
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Incercept point.
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The footprint depends on the satellite's orbit, inclination, and:
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antenna beamwidth.
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What are two types of satellite orbital control?
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Attitude control and station keeping.
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What orbital control procedure keeps a satellite in a desired position?
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Station keeping.
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What are two types of active satellites?
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Real-time and delay.
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Which of these satellite communications systems is not composed of satellites?
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Air Force Satellite Communications System.
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The operational Military Strategic and Tactical Relay Satellite System satellite constellation consists of how many satellites?
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5
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Which is not a segment of Military Strategic and Tactical Relay Satellite?
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Control.
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With what system is the LST-5B interoperable?
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Ultra High Frequency Satellite Communications.
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This radio can provide one channel of either Ultra High Frequency or Very High Frequency Amplitude Modulation voice communications?
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TRC-176
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Tactical units for inter and/or intra-site communications and forward operating base local area command and control communications use:
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Lamdn Mobile Radio.
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This ground mobile terminal is installed on 40-foot trailers and provides mobile command and control support to the Commander of US Strategic Command?
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TRC-194
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What guide allows an operator to pinpoint a satellite's position in space?
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Equatorial satellite antenna pointing guide.
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Use of a hilltop or tower locations does what to the line-of-sight range?
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Increases.
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A resonant antenna effectively radiates a radio signal for frequencies close to its designed frequency, usually within range of plus or minus what percent?
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2
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If the design frequency of a resonant antenna is 10 MHz, what will be its frequency range?
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9.8 to 10.2 MHz
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The actual range of frequencies within the antenna's bandwidth is called the:
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frequency range.
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The lowest frequency at which an antenna resonates is known as its:
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fundamental frequency.
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Areas in which no antenna radiation pattern passes through are called:
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nulls.
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Which antenna radiates radio energy in a circular pattern?
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Omni-directional.
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What device is used with vertical antennas to improve their efficiency?
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Ground radials.
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What two devices are used to increase reflecting characteristics of the ground?
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Counterpoise and ground radial.
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Common antennas used with the GRA-4 masts are the whip and long-wire, but one we cannot includeis the:
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rhombic.
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How many metal mast sections are used with the GRA-4?
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16
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Insulators are metals that confine radio frequency energy to just the antenna wire. Plastic and glass have the best insulating properties, but you can also use:
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wood.
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Which is a portable vertical antenna assembly often used as a mast to support other antennas?
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GRA-4
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Why do you avoid interconnecting loops when you repair broken antenna wire?
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They create noise in the receiver.
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What type of materials act as the best insulators?
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Plastic and glass.
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What is a common fixed station antenna?
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Long-periodic.
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The rhombic antenna's greatest disadvantage is its:
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size.
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The MILSTAR antennas have three different types of antenna beams, they are the earth coverage, agile, and:
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Spot beam.
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What type of satellite antenna radiates a circularly polarized signal?
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Helical.
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What type of directivity does the whip antenna provide?
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Omni-directional.
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What type of antenna is needed to communicate with several stations located in different areas?
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Omni-directional.
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What is one of the simplest and most functional antennas in use?
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Half-wave dipole.
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Radio sets are left on 24-hours a day in a jungle environment to:
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prevent short circuits.
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