1. Microwave frequencies typically range from:
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Explanation:
Microwaves are a form of electromagnetic radiation with frequencies ranging from about 3 GHz up to about 30 GHz, falling between radio waves and infrared waves in the electromagnetic spectrum.
2. The component in microwave systems that generates microwave energy is called:
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Explanation:
An oscillator in microwave systems is the component responsible for generating microwave frequency signals, often using a magnetron or a Gunn diode.
3. The main advantage of microwave communication over conventional radio wave communication is:
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Explanation:
Microwave communication offers higher bandwidth, which translates to a higher data transfer capacity compared to conventional radio waves.
4. In microwave communication, line-of-sight is crucial because:
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Explanation:
Microwave communication requires line-of-sight between transmitting and receiving antennas because microwaves travel in straight lines and cannot easily bend over the horizon or around obstacles.
5. A common application of microwaves in everyday life is:
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Explanation:
Microwave ovens are a common household appliance that uses microwaves to heat and cook food quickly.
6. Which waveguide mode is most commonly used in microwave communication?
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Explanation:
In microwave communication, the Transverse Electromagnetic (TEM) mode is most commonly used as it supports the propagation of the signal with both electric and magnetic fields perpendicular to the direction of the wave.
7. What is the primary purpose of a circulator in microwave systems?
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Explanation:
A circulator is a passive device used in microwave systems to control the direction of signal flow, typically routing microwave signals from one port to another in a sequential manner.
8. In satellite communication, the frequency band used for downlink is generally:
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Explanation:
In satellite communication, the downlink frequency (from satellite to earth) is generally lower than the uplink frequency (from earth to satellite) to avoid interference between the signals.
9. What causes fading in microwave communication?
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Explanation:
Fading in microwave communication is primarily caused by atmospheric conditions and multipath reflection, where the signal takes multiple paths to reach the receiver, resulting in phase cancellations.
10. The most common antenna used in microwave communication is:
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Explanation:
The parabolic dish antenna is widely used in microwave communication because of its ability to focus microwave signals into a narrow beam, providing high directivity and gain.
11. In a microwave transmission, multipath fading is caused by:
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Explanation:
Multipath fading in microwave transmission occurs when the direct signal interferes with signals that have been reflected off buildings, mountains, or other surfaces, causing phase cancellation.
12. A RADAR system primarily utilizes microwaves for:
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Explanation:
RADAR (Radio Detection and Ranging) systems use microwaves to detect the location and speed of objects by transmitting microwave signals and analyzing the reflected waves.
13. The component that converts microwave energy into electric current is called a:
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Explanation:
A microwave diode, such as a Schottky diode, is used to convert microwave energy into electric current, especially in microwave detection and mixing applications.
14. Which phenomenon limits the effective range of microwave line-of-sight communication?
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Explanation:
The Earth's curvature limits the effective line-of-sight range of microwave communication, as microwaves travel in straight lines and the Earth's surface is curved.
15. In microwave communication, the term 'attenuation' refers to:
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Explanation:
Attenuation in microwave communication refers to the loss of signal strength as it travels through the medium, which can be caused by various factors like absorption, scattering, and free-space loss.
16. The process of mixing a microwave signal with a local oscillator signal to produce intermediate frequencies is known as:
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Explanation:
Heterodyning is the process of mixing a signal with a local oscillator signal to convert a microwave signal to a lower intermediate frequency, commonly used in the signal processing of radar and communication systems.
17. A major challenge in designing microwave circuits is:
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Designing microwave circuits presents the challenge of maintaining high-frequency stability, as microwave components are sensitive to variations in frequency.
18. The primary function of a duplexer in a microwave radar system is to:
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Explanation:
A duplexer in microwave radar systems allows the same antenna to be used for both transmitting and receiving signals simultaneously by switching between the transmitter and receiver.
19. Waveguides in microwave communication are used to:
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Explanation:
Waveguides are physical structures used to guide and transmit microwave signals with minimal loss by confining the electromagnetic waves in one dimension.
20. The frequency range of Extremely High Frequency (EHF) microwave band is:
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The Extremely High Frequency (EHF) microwave band encompasses frequencies from 30 GHz to 300 GHz. It is used in specialized communication and radar applications.
21. The primary advantage of using higher frequencies in microwave communication is:
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Explanation:
Higher frequencies in microwave communication offer higher bandwidth, which translates to a greater data transfer capacity, enabling more information to be transmitted in a given time.
22. A horn antenna in microwave communication is used for:
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Explanation:
A horn antenna is used in microwave communication to focus the microwave signal into a narrow beam, enhancing directivity and gain.
23. In microwave communication, 'fading' refers to:
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Explanation:
Fading in microwave communication refers to the variation or deterioration in signal strength, often caused by atmospheric conditions such as rain, fog, or multipath interference.
24. The 'Faraday rotation effect' impacts microwave communication by:
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Explanation:
The Faraday rotation effect can impact microwave communication by rotating the plane of polarization of the microwave signal as it passes through the ionosphere, potentially affecting signal reception.
25. In satellite microwave communication, the satellite functions primarily as a:
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Explanation:
In satellite microwave communication, the satellite functions as a relay station that receives microwave signals transmitted from an earth station, amplifies them, and retransmits them back to another location on earth.