This set of Wireless & Mobile Communications Multiple Choice Questions & Answers (MCQs) focuses on “Paging System”.
1. A helical antenna is used for satellite tracking because of _____
a) Circular polarization
Explanation: In helical antenna, the diameter and pitch of the helix are comparable to a wavelength. The antenna functions as a directional antenna radiating a beam off the ends of the helix. It radiates circularly polarized radio waves. These are used for satellite communication.
2. Repeaters inside communications satellites are known as _______
Explanation: A communications satellite’s transponder is the series of interconnected units that form a communications channel between the receiving and the transmitting antennas. It is mainly used in satellite communication to transfer the received signals.
3. _______ is the geographical representation of a satellite antenna radiation pattern.
Explanation: The geographical representation of a satellite’s antenna radiation pattern is called a footprint or footprint map. In essence, a footprint of a satellite is the area on Earth’s surface that the satellite can receive from or transmit to.
4. The smallest beam of a satellite antenna radiation pattern is _______
a) Zone beam
b) Hemispheric beam
c) Spot beam
d) Global beam
Explanation: The size of the antenna that generates these beams on earth is related directly to the peak gain at the center of the spot beams and the smallest spot beam size. The spot beams are typically defined by the contours at 3 or 4 dB down from the peak power at the center of the beam.
5. _________ detects the satellite signal relayed from the feed and converts it to an electric current, amplifies and lowers its frequency.
a) Horn antenna
c) Satellite receiver
d) Satellite dish
Explanation: LNA detects the satellite signal relayed from the feed and converts it to an electric current, amplifies and lower its frequency. The most common device used as an LNA is tunnel diode.
6. A satellite signal transmitted from a satellite transponder to earth’s station is _________
Explanation: In satellite telecommunication, a downlink is the link from a satellite down to one or more ground stations or receivers, and an uplink is the link from a ground station up to a satellite.
7. __________ is a loss of power of a satellite downlink signal due to earth’s atmosphere.
a) Atmospheric loss
b) Path loss
c) Radiation loss
Explanation: The path loss is the loss in signal strength of a signal as it travels through free space. This value is usually calculated by discounting any obstacles or reflections that might occur in its path.
8. Which of the following is the point on the satellite orbits closest to the Earth?
Explanation: The point where satellite is closest to the Earth is known as the perigee. Here, the satellite moves at its fastest. The high point of the orbit, when the satellite is moving the slowest is called the apogee.
9. What kind of battery panels are used in some advance satellites?
a) Germanium based panels
b) Silicon based panel
c) Gallium Phosphate solar panel array
d) Gallium Arsenide solar panel array
Explanation: Gallium Arsenide solar panel arrays are used for battery panels in some advanced satellites. These new types of cells allow smaller solar arrays to be used on future space missions.
10. A satellite battery has more power but lighter ________
Explanation: Lithium batteries have more power and are lighter in weight. Any mass that could be saved by the use of lighter batteries would allow a corresponding increase in the amount of useful payload equipment.
11. INTELSAT stands for ________
a) Intel Satellite
b) International Telephone Satellite
c) International Telecommunications Satellite
d) International Satellite
Explanation: INTELSAT is a communications satellite services provider. INTELSAT operates a fleet of 52 communications satellites, which is one of the world’s largest fleet of commercial satellites.
12. The frequency of Ku band for satellite communications is ______
a) 6/4 GHz
b) 14/11 GHz
c) 12/14 GHz
d) 4/8 GHz
Explanation: The Ku band is a portion of the electromagnetic spectrum in the microwave range of frequencies ranging from 11.7 to 12.7GHz. (downlink frequencies) and 14 to 14.5GHz (uplink frequencies).
13. The most common device used as an LNA is ________
a) Zener diode
b) Tunnel diode
d) Shockley diode
Explanation: The LNA must provide a relatively flat response for the frequency range of interest, preferably with less than 1 dB of gain variation. The most common device used as an LNA (low noise amplifier) is tunnel diode. It is a highly sensitive, low-noise device.
Sanfoundry Global Education & Learning Series – Wireless & Mobile Communications.
To practice all areas of Wireless & Mobile Communications, here is complete set of 1000+ Multiple Choice Questions and Answers.