ESAT RHM2 - PART 4
301. Reference line is also called:
A. Rest position
B. Normal line
C. origin
D. source
302. Waves that are neither transmitted nor absorbed, but are reflected from the surface of the medium they encounter.
A. Refraction waves
B. Diffraction waves
C. Transmission waves
D. Reflection waves
303. The changing of direction as a wave leaves one medium and enters another medium of a different density.
A. refraction
B. diffraction
C. transmission
D. reflection
304. The condition produced when the frequency of vibrations are the same as the natural frequency (of a cavity). The vibrations reinforce each other.
A. synchronized
B. In phase
C. resonant
D. flat
305. A diamond-shaped antenna used widely for long-distance, high-frequency transmission and reception.
A. Rhombic antenna
B. Delta antenna
C. Y antenna
D. Loop antenna
306. Why are HF scatter signals usually weak?
A. Propagation through ground waves absorbs most of the signal energy
B. Only a small part of the signal energy is scattered into the skip zone
C. The F region of the ionosphere absorbs most of the signal energy
D. Auroral activity absorbs most of the signal energy
307. That portion of the radiation which is directly affected by the surface of the earth is called:
A. Tropospheric wave
B. Ionospheric wave
C. Inverted wave
D. Ground wave
308. When is the ionosphere most ionized?
A. Dawn
B. Midnight
C. Midday
D. Dusk
309. For radio signals, the skip distance is determined by the:
A. Power fed to the final
B. Angle of radiation
C. Type of transmitting antenna used
D. Height of the ionosphere and the angle of radiation
310. The usual effect of ionospheric storms is to:
A. Produce extreme weather changes
B. Cause a fade-out of sky- wave signals
C. Prevent communications by ground wave
D. Increase the maximum usable frequency
311. Which two types of radiation from the sun influence propagation?
A. Subaudible and audio-frequency emissions
B. Polar region and equatorial emissions
C. Infra-red and gamma-ray emissions
D. Electromagnetic and particle emissions
312. The angle at which the receiving antenna must be aimed to capture the scattered energy of tropospheric scatter.
A. Beaming angle
B. Receive angle
C. Scatter angle
D. Angle of acceptance
313. Objects that produce their own light.
A. Electroluminescent body
B. Bioluminescent body
C. Incandescent body
D. self-luminous body
314. A circuit that acts as a low impedance at resonance.
A. Series resonance
B. series-parallel resonance
C. Parallel resonance
D. LC
314. A circuit that acts as a low impedance at resonance.
A. Series resonance
B. series-parallel resonance
C. Parallel resonance
D. LC
315. A transmission line that has a terminating impedance equal to 0.
A. Open circuited line
B. Load terminated line
C. Matched line
D. Short circuited line
316. The flow of ac current near the surface of a conductor at rf frequencies.
A. Surface effect
B. Faraday’s effect
C. Skin effect
D. Miller effect
317. What usually happens to radio waves with frequencies below the maximum usable frequency (MUF) when they are sent into the ionosphere?
A. They are changed to a frequency above the MUF
B. They are completely absorbed by the ionosphere
C. They are bent back to the earth
D. They pass through the ionosphere
318. On which amateur frequency band is the extended-distance propagation effect of sporadic-E most often observed?
A. 160 metres
B. 20 metres
C. 6 metres
D. 2 metres
319. What type of radio-wave propagation allows a signal to be detected at a distance too far for ground-wave propagation but too near for normal skywave propagation?
A. Short-path skip
B. Sporadic-E skip
C. Scatter
D. Ground wave
320. A zone of silence between the point where the ground wave becomes too weak for reception and the point where the sky wave is first returned to earth.
A. Skip zone
B. Skip distance
C. Quiet distance
D. Scatter distance
321. Pertaining to sounds capable of being heard by the human ear.
A. supersonic
B. ultrasonic
C. sonic
D. subsonic
322. Reception of radio waves by two or more antennas spaced some distance apart.
A. Space diversity
B. Frequency diversity
C. Receiver diversity
D. Quad diversity
323. The entire range of electromagnetic waves.
A. bandwidth
B. Dynamic range
C. MUF
D. spectrum
324. The range of electromagnetic waves that stimulate the sense of sight.
A. Visible spectrum
B. Light spectrum
C. Infrared spectrum
D. Electromagnetic spectrum
325. The entire range of electromagnetic waves arranged in order of their frequencies
A. Visible spectrum
B. Light spectrum
C. Infrared spectrum
D. Electromagnetic spectrum
326. Insulator used with transmission lines and antennas to keep the parallel wires separated.
A. spreader
B. isolator
C. rod
D. All of the above
327. The ratio of the maximum (voltage, current) to the minimum (voltage, current) of a transmission line. Measures the perfection of the termination of the line.
A. Γ
B. SWR
C. Velocity factor
D. εr
328. Short section of a transmission line used to match the impedance of a transmission line to an antenna. Can also be used to produce desired phase relationships between connected elements of an antenna.
A. Q section
B. Quarterwave transformer
C. balun
D. stub
329. Speed greater than the speed of sound.
A. supersonic
B. ultrasonic
C. sonic
D. subsonic
330. The condition in which warm air is formed above a layer of cool air that is near the earth's surface.
A. climate
B. ducting
C. aurora
D. Temperature inversion
331. Musical sounds are also called:
A. notes
B. tones
B. tones
B. tones
332. A device designed to guide electrical energy from one point to another.
A. Transmission line
B. transmitter
C. receiver
D. Coaxial cable
333. A type of substance that transmits almost all of the light waves that fall upon it.
A. opaque
B. transparent
C. translucent
D. All of the choices
334. The portion of the atmosphere closest to the earth's surface, where all weather phenomena take place.
A. ionosphere
B. stratosphere
C. mesosphere
D. troposphere
335. The peak of the negative alternation (maximum value below the line).
A. trough
B. summit
C. zenith
D. crest
336. A type of antenna used in VHF communications that is omnidirectional and consists of two horizontal half-wave antennas mounted at right angles to each other in the same horizontal plane.
A. End fire
B. broadside
C. turnstile
D. delta
337. A parallel line consisting of two wires that are generally spaced from 2 to 6 inches apart by insulating spacers
A. Twin lead
B. Twisted pair
C. Coaxial cable
D. 2 wire open line
338. Sounds above 20,000 Hertz.
A. supersonic
B. ultrasonic
C. sonic
C. sonic
339. Another name for the flat or nonresona
A. Tuned line
B. Untuned line
C. Fixed line
D. Unfixed line
340. The rate at which a disturbance travels through a medium.
A. ripple
B. Refractive index
C. Velocity factor
D. velocity
341. The part of a radiation pattern that is radiated in the vertical plane.
A. Horizontal pattern
B. Vertical pattern
C. azimuth
D. All of the choices
342. Another name of end feed method:
A. Current feed method
B. Impedance feed method
C. Center feed method
D. Voltage feed method
343. Another name for Beverage antenna.
A. Long wire antenna
B. Beer antenna
C. Wave antenna
D. Delta antenna
344. A continuous series of waves with the same amplitude and wavelength
A. Complex wave
B. Wave train
C. Astable pulse
D. Clock pulses
345. A hollow metal tube used as a transmission line to guide energy from one point to another.
A. isolator
B. iris
C. waveguide
D. circulator
346. A multielement parasitic array. Elements lie in the same plane as those of the endfire array.
A. Log periodic
B. Marconi
C. Yagi
D. broadside
347. Input end is also called:
A. Generator end
B. Load end
C. end
D. All of the choices
348. Output end is also called:
A. Generator end
B. Load end
C. end
D. All of the choices
349. Lumped impedance tuning is also called:
A. stubbing
B. tuning
C. loading
D. All of the choices
350. Omnidirectional can also be thought of as:
A. unidirectional
B. biderectional
C. non-directional
D. All of the choices
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