RF Antenna Interview questions and answers

This page covers top RF Antenna interview questions and answers will help interviewee pass the job interview for RF Antenna engineer job position. This RF Antenna questions are written by specialists in RF Antenna domain.

Question -1: What is the function of RF Antenna ?
Answer -1: The main function of RF antenna is to radiate EM waves in the desired direction into the air and to receive EM waves from the air into the RF receiver circuits. This is achieved by impedance transformation between antenna ports and air medium. Air has impedance of about 377 Ohm.

Question -2: Mention difference between Near Field Region and Far Field Region of antenna.
Answer -2: • The region close to the antenna (i.e. upto 2*D²/λ) is known as near field region. Here D indicates antenna diameter and λ indicates wavelength. The near field region is further divided into reactive region (upto 3λ) and fresnel region (above 3λ and upto 2*D²/λ).
• The region above 2*D²/λ is known as far field region. This region is also referred as Fraunhofer region.

Question -3: Mention difference between linear polarization, circular polarization and elliptical polarization.
Answer -3:
Linear polarization : In this polarization, amplitude of E field varies at radio frequency rate and direction is constant.
Circular polarization : In this polarization, amplitude of E field is constant and its direction rotates synchronously with radio frequency.
Elliptical Polarization : In this polarization, amplitude and direction of E field varies synchronously with radio frequency.

Question -4: Explain terms related to antenna radiation pattern.
Answer -4: The common terms associated with antenna radiation pattern are main lobe, side lobes, 3 dB beamwidth, squint, Bore sight and so on. Let us understand definition of these terms.
Main lobe : Direction of lobe having larger field strength than other parts.
Side lobes : Parts of pattern other than main lobe are called side lobes.
Bandwidth : Frequency range over which antenna can transmit/receive EM waves is called its bandwidth.
3 dB beamwidth : Range between two points which are located at one half of maximum power on the radiation pattern is called 3 dB beamwidth.
Squint : Main beam of radiation pattern is shifted from its normal position. This degree of shift is called squint.
Bore sight : The direction where there will be maximum gain is called bore sight.

Question -5: What is G/T of an RF antenna ?
Answer -5: It is referred as figure of merit of antenna. It is expressed as ratio of antenna gain and system noise temperature.
➨ G/T in dB/K = Receiver Antenna Gain - 10*Log (System Noise Temperature)

Question -6: Mention common types of RF antenna and describe their functions.
Answer -6: Refer types of antenna which mention different antenna types with their functions.

Question -7: Mention Parabolic Reflector Antenna Gain Equation.
Answer -7: Following is the gain equation for parabolic reflector antenna.

Question -8: Which Antenna is used for TV signal transmission and reception ?
Answer -8: Different indoor and outdoor antenna types are used for TV signal reception. Indoor antennas include loop antenna and half wave dipole. Outdoor antennas include Yagi antenna, log periodic antenna and phased array antenna. Now-a-days parabolic dish antenna has become very popular for satellite TV channel receptions.

Question -9: What is the difference between antenna efficiency and antenna directivity ?
Answer -9: Ratio of total radiated power to input power of antenna is called efficiency.
Ability of antenna to focus energy in particular direction while transmitting and receiving is called directivity.

Question -10: What is the relation between wavelength and frequency of Electromagnetic wave ?
Answer -10: Following equation denotes relation between wavelength and frequency.

Question -11: What is the difference between dBi and dBd ?
Answer -11: dBi refers to calculation of gain of antenna compare to isotropic radiator. dBd refers to calculation of directional gain compare to dipole antenna.

Question -12: What are the different types of cell tower antennas ?
Answer -12:Refer Cell Tower Antenna types >> for more information.

This set of RF Antenna interview questions and answers are useful for freshers and experienced level of job positions. Refer following links on RF Antenna for more information.

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