InterviewSolution

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This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.

51.	Why can we not use sky waves for navigation?(a) Low power(b) More noise(c) Unpredictable path(d) Not economicalI had been asked this question during an internship interview.This key question is from Radio Propagation and Noise Characteristics topic in section Terrestrial Radio Navigation System of Avionics
Answer» Right answer is (C) UNPREDICTABLE path The best I can explain: The sky waves makes some types of long range communication possible, but is of less value to navigation system because it’s transmission path is unpredictable. A rough location where the sky waves might GET reflected can be determined by SNELL’s law.

52.	What is the maximum limit on the frequency that can be used for ground wave communication?(a) 6MHz(b) 2MHz(c) 5MHz(d) 3MHzThe question was posed to me by my school principal while I was bunking the class.Question is taken from Radio Propagation and Noise Characteristics in portion Terrestrial Radio Navigation System of Avionics
Answer» Correct OPTION is (d) 3MHz The explanation is: Up to 3MHz, an appreciable AMOUNT of energy FOLLOWS the CURVATURE of the earth and are called as the GROUND wave. Above 3MHz, the radio waves do not follow the curvature of the earth and are used for a line of sight communication.

53.	What type of polarization is used for ground waves?(a) Vertical polarization(b) Right circular polarization(c) Horizontal polarization(d) Left circular polarizationThis question was addressed to me during an interview.The question is from Radio Propagation and Noise Characteristics topic in division Terrestrial Radio Navigation System of Avionics
Answer» RIGHT answer is (a) Vertical polarization Best explanation: At lower FREQUENCIES, along the surface of the earth, vertical polarization is universally USED. This way minimum SIGNAL is radiated into the GROUND.

54.	The factor by which a receiver fails to reach the theoretical internal noise limit is known as ________(a) Noise factor(b) Noise(c) Coefficient of noise(d) Noise figureThe question was asked during an interview.Asked question is from Radio Propagation and Noise Characteristics in section Terrestrial Radio Navigation System of Avionics
Answer» The correct answer is (d) Noise figure For EXPLANATION: The factor by which a receiver FAILS to reach the theoretical internal noise limit is OFTEN expressed as a ratio, in DECIBELS, and is known as the noise figure. It can also be described as the ratio between the noise POWER output of a practical receiver and the noise power output of an ideal receiver.

55.	The ratio of terminating impedance to the power density of the incident wave is called as?(a) Maximum effective aperture(b) Maximum allowable power(c) Directivity(d) GainThe question was posed to me in a job interview.Origin of the question is Radio Propagation and Noise Characteristics in portion Terrestrial Radio Navigation System of Avionics
Answer» Right OPTION is (a) Maximum effective aperture To explain I would say: Maximum effective aperture is defined as the ratio of TERMINATING IMPEDANCE to the POWER density of the incident wave. It is also CALLED the effective area of an antenna and is given by Dλ/4π.

56.	Received radio energy is a function of the area of the receiving antenna.(a) True(b) FalseThis question was posed to me in an international level competition.This intriguing question originated from Radio Propagation and Noise Characteristics topic in portion Terrestrial Radio Navigation System of Avionics
Answer» The correct option is (a) True The best explanation: The RECEIVED radio energy is a function of the area of the RECEIVING antenna. If the transmission is omnidirectional, the received energy is proportional to the area of the receiving antenna DIVIDED by the area of the sphere of radius equal to the DISTANCE from the transmitter.