18 Questions
What is the maximum line-of-sight (LOS) distance between two antennas with heights hT and hR above the earth?
$2 RhT + 2 RhR$
Which type of communication uses skywave or skip propagation by reflecting or refracting radio waves back toward Earth from the ionosphere?
Ionospheric communication
Why are space waves suitable for very high-frequency waves and satellite communication?
They prevent loss of signal strength
What defines the structure of the ionosphere in terms of ionization and altitude?
Ultraviolet radiation absorption
In radio communication, what characterizes the ionospheric skip propagation?
Reflection from the ionosphere
What type of region is present in each ionized layer of the ionosphere with respect to ionization intensity?
Region of relatively dense ionization tapering off
What is the primary path of the space wave in direct wave propagation?
Directly from the transmitting antenna to the receiving antenna through the air
At what frequencies is communication essentially limited to Line of Sight (LOS) paths?
Above 40 MHz
What is the radio horizon of a transmitting antenna located at a height hT?
$2RhT$
Why must the receiving antenna be located within the radio horizon of the transmitting antenna in direct wave propagation?
To avoid signal blockage by obstacles
What happens to direct waves at frequencies above 40 MHz if the antennas are relatively smaller and placed at great heights above the ground?
They get blocked by the curvature of the Earth
In direct wave propagation, why does the receiving antenna need to be high enough to intercept Line of Sight (LOS) waves if the signal is to be received beyond the horizon?
To ensure effective communication over longer distances
What is the primary mode of propagation used for distances greater than 1000 km?
Sky wave
During daytime broadcast in the MF range (300 KHz - 3000 KHz), what type of propagation is relied upon?
Ground wave
At what frequencies do VHF waves operate?
4 m - 10 m wavelength
Why is communication beyond line-of-sight distance not appreciably possible in the HF range?
Space-wave propagation
Which range of frequencies can propagate as ground waves over short distances with negligible diffraction?
30 - 60 MHz
What factor determines the distance that UHF and SHF waves can travel?
Heights of transmitting and receiving antennas
Test your knowledge on antenna height calculation and Line of Sight (LOS) distance between two antennas. Learn about space wave propagation, satellite communication, and the significance of tower height in preventing signal attenuation.
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