Planning for an excelling and compelling career as an Antenna Engineer? Visit Wisdom jobs to look into the various Antenna jobs available along with the training and assessment material for improving your knowledge base and sample resumes for a winning job and Antenna interview questions.
Visit our Antenna job interview questions and answers pag e designed by our experts and also those collected from individuals who already attended Antenna jobs, for both freshers and experienced so as to make yourself acquainted with the nature of the interview. Answer : Antenna is a transition device or a transducer between a guided wave and a free space wave or vice-versa. Antenna is also said to be an impedance transforming device.
Question 2. Answer : Radiation pattern is the relative distribution of radiated power as a function of distance in space. It is a graph which shows the variation in actual field strength of the EM wave at all points which are at equal distance from the antenna. Question 3. Define Radiation Intensity? Answer : The power radiated from an antenna per unit solid angle is called the radiation intensity U watts per steradian or per square degree. The radiation intensity is independent of distance.
Question 4. Define Beam Efficiency? Question 5. Define Directivity? Answer : The directivity of an antenna is equal to the ratio of the maximum power density P q,f max to its average value over a sphere as observed in the far field of an antenna.
Antenna Array 2
Question 6. Answer : Effective aperture. Scattering aperture. Loss aperture.Ion propulsion system c. Liquid fuel d. Solar jet. The earth area covered by a satellite radio beam is known as …….
Lithium b. Leclanche c. Hydrogen d. Satellite launch sites are invariably located on Eastern seaboards to ensure that. Uplink b. Downlink c. Terrestrial d. A helical antenna is used for satellite tracking because of …………. Circular polarization b. Maneuverability c. Beamwidth d. Path loss c. Radiation loss d. Coverage b. Cost c. Access d. Increases b.
Decreases c. Remains the same d.
Multiple Choice Questions and Answers on Satellite Communication
None of the above. A satellite beam that covers almost Zone beam b. Hemispheric beam c. Spot beam d. Global beam. The signal from narrow-angle antenna was stronger than that from earth- coverage antenna by a factor of …………….
The angle subtended by earth at geostationary communication satellite is ………. The discussing sharing of a communication satellite by many geographically dispersed Earth station, DAMA means. Demand-Assigned Multiple Access b.
Decibel Attenuated Microwave Access c. Digital Analog Master Antenna d. Dynamically-Assigned Multiple Access.An antenna, when individually can radiate an amount of energy, in a particular direction, resulting in better transmission, how it would be if few more elements are added it, to produce more efficient output.
It is exactly this idea, which led to the invention of Antenna arrays. An antenna array can be better understood by observing the following images.
Observe how the antenna arrays are connected. An antenna array is a radiating system, which consists of individual radiators and elements.
Each of this radiator, while functioning has its own induction field. Therefore, the radiation pattern produced by them, would be the vector sum of the individual ones. The following image shows another example of an antenna array. The spacing between the elements and the length of the elements according to the wavelength are also to be kept in mind while designing these antennas.
The antennas radiate individually and while in array, the radiation of all the elements sum up, to form the radiation beam, which has high gain, high directivity and better performance, with minimum losses. Antenna Theory - Antenna Arrays Advertisements. Previous Page. Next Page. Previous Page Print Page.A 25 A source operating at MHz feeds a Hertizian dipole of length 4 mm situated at the origin.
Consider the point P 10, 30 o ,90 o. An antenna can be modeled as an electric dipole of length 4 m at 3 MHz. If current is uniform over its length, then radiation resistance of the antenna is.
A antenna located on the surface of a flat earth transmit an average power of kW. Assume that all the power is radiated uniformly over the surface of hemisphere with the antenna at the center. The time-average poynting vector at 50 km is. An L-band pulse radar has common transmitting and receiving antenna. The antenna having directive gain of 36 dB operates at 1. The object is km from the radar and its scattering cross section is 8 m 2. A transmitting antenna with a MHz carrier frequency produces 2 kW of power.
If both antennas has unity power gain, the power received by another antenna at a distance of 1 km is. A bistatic radar system shown in fig. To obtain a return power of 8 pW the minimum necessary radiated power is. An antenna is desired to operate on a frequency of 40 MHz whose quality factor is The bandwidth of antenna is. If its loss resistance is 1. An array comprises of two dipoles that are separated by the wavelength.
The dipoles are fed by currents of the same magnitude and phase. Login New User. Sign Up. Forgot Password? New User? Continue with Google Continue with Facebook. Gender Male Female. Create Account. Already Have an Account?Save my name, email, and website in this browser for the next time I comment. Tags: Uncategorized.
Related Posts. Leave a Reply Cancel reply Save my name, email, and website in this browser for the next time I comment. Leave this field empty. SONAR b. Subsurface communication c. Radio navigation d. Phase b. Frequency c. Amplitude d. Wave equation.
ELECTRONICS IMPORTANT MCQ PDF-Antenna & Wave Propagation 1
Sinusoidal b. Rectangular c. Square d. Solid bodies b. Ionized particles c. All of the above. Reflected b. Refracted c.
Radiated d. D-region b. Normal E-region c. Sporadic E-region d.SONAR b. Subsurface communication c. Radio navigation d. Phase b. Frequency c. Amplitude d. Wave equation. Sinusoidal b. Rectangular c. Square d. Solid bodies b.
Ionized particles c. All of the above. Reflected b. Refracted c. Radiated d. D-region b. Normal E-region c. Sporadic E-region d. Appleton region. Electric field intensity b. Magnetic field intensity c. Current density d. Power density. Impedance matching device b. Sensor of electromagnetic waves c. Metallic device for radiating or receiving radio waves.
For a charge with no motion b. For a charge oscillating in time motion d.The dipole antenna is cut and bent for effective radiation. The length of the total wire, which is being used as a dipole, equals half of the wavelength i.
Such an antenna is called as half-wave dipole antenna. This is the most widely used antenna because of its advantages. It is also known as Hertz antenna. The range of frequency in which half-wave dipole operates is around 3KHz to GHz.
This is mostly used in radio receivers. It is a normal dipole antenna, where the frequency of its operation is half of its wavelength. Hence, it is called as half-wave dipole antenna. The edge of the dipole has maximum voltage. This voltage is alternating AC in nature. At the positive peak of the voltage, the electrons tend to move in one direction and at the negative peak, the electrons move in the other direction.
This can be explained by the figures given below. Fig 1 shows the dipole when the charges induced are in positive half cycle.
Now the electrons tend to move towards the charge. Fig 2 shows the dipole with negative charges induced. The electrons here tend to move away from the dipole.
Fig 3 shows the dipole with next positive half cycle. Hence, the electrons again move towards the charge. The cumulative effect of this produces a varying field effect which gets radiated in the same pattern produced on it.
Hence, the output would be an effective radiation following the cycles of the output voltage pattern. Thus, a half-wave dipole radiates effectively. The above figure shows the current distribution in half wave dipole. The directivity of half wave dipole is 2. The radiation pattern of this half-wave dipole is Omni-directional in the H-plane. It is desirable for many applications such as mobile communications, radio receivers etc. The above figure indicates the radiation pattern of a half wave dipole in both H-plane and V-plane.
The radius of the dipole does not affect its input impedance in this half wave dipole, because the length of this dipole is half wave and it is the first resonant length. An antenna works effectively at its resonant frequencywhich occurs at its resonant length. Previous Page.