Antenna theory and design fianl exam.docx

Question N1 - An antenna, in addition to radiating or receiving energy, is also used to \_\_\_\_ energy in some directions and suppress in others. a\) Dissipate b\) Generate noise c\) accentuate Question N2 - A radiator having equal radiation in all directions is referred to as a: a\) directi...

Question N1 - An antenna, in addition to radiating or receiving energy, is also used to \_\_\_\_ energy in some directions and suppress in others. a\) Dissipate b\) Generate noise c\) accentuate Question N2 - A radiator having equal radiation in all directions is referred to as a: a\) directional radiator b\) isotropic radiator c\) guided radiator Question N3 - If charge is moving with constant velocity, radiation can be created by \_\_\_. a\) smooth wires b\) bent wires c\) infinite length wires Question N4 The range of frequencies within which the performance of an antenna, with respect to some characteristic, conforms to a specific standard is referred to as \_ a\) bandwidth b\) beamwidth c\) loop Question N4 The angular separation between two identical points on an amplitude pattern of an antenna is referred to as the: a\) bandwidth b\) beamwidth c\) loop Question N5 - The minimum radial distance to the far field region for an antenna of maximum length of D is equal to: a\) D\^2/lambda b)2\*D\^2/lambda c)4\*d\^2/lambda Question N5 An aggregate of individual discrete radiating elements (antennas) in an electrical and geometrical arrangement is referred to as a \_\_\_. a\) continuous source b\) wave guide c\) array Question N6 The radiation lobe containing the direction of maximum radiation is referred to as the: a\) minor b\) Major c\) black Question N6 The radiation lobe opposite to the major lobe is called \_\_\_ a\) minor b\) back c) Question N7 The normalized power pattern of antenna is represented as U(𝜃)=sin (𝜃). Then HPBW of antenna is equal to: a\) 30 b\) 60 c\) 120 d\) 180 Question N7 The normalized power pattern of antenna is represented as U(𝜃)=sin\^2 (𝜃). Then HPBW of antenna is equal to a\) 90 b\) 60 c\) 120 Question N8 The ratio of the radiation intensity of an antenna to the radiation intensity of an isotropic source is defined as the: Answer: Directivity correct always Question N8 The ratio of the radiation intensity in a given direction from the antenna to the radiation intensity averaged over all directions is defined as the: Answer: Directivity correct always Point: 1.0 Question N9 The maximum directivity (dimensionless) of elementary electric dipole with uniform current distribution is: a\) 1.5 b\) 4 c\) 1.64 Question N9 The maximum directivity (dimensionless) of a half-wavelength dipole, with an idealized sinusoidal current distribution, is: a\) 1.5 b\) 4 c\) 1.64 Question N10 The total maximum directivity is also defined as Do = 4\*Pi/WA where WA is referred to as the: a\) Beam efficiency b\) Radiation efficiency c\).... Question N10 The ratio of the gain to the directivity of an antenna is defined as the: a\) beam efficiency b\) Radiation efficiency Question N11 The imaginary parts of the input impedance of an antenna are referred to as the: a\) reflection resistance b\) radiation resistance c\) Radiation reactance Question N11 The real parts of the input impedance of an antenna are referred to as the: a\) reflection resistance b\) radiation resistance c\) Radiation reactance Question N12 In MKS, the units of Intensity are: a\) watts/meter b)watts/unit solid angle c)watts/meter squared Question N12 In MKS, the units of radiation dentinsity are: a\) watts/meter b)watts/unit solid angle c)watts/meter squared Question N13 The polarization of an electric field with two components orthogonal to each other and to the direction of propagation, of the same amplitude, and with a 90 deg phase difference is: a\) circular b\) linear Question N13 The polarization of an electric field that has two orthogonal components transverse to the direction of propagation and a 0 deg or multiples of 180 deg phase difference is: a\) ellibtical b\) linear c\) circular Question N14 The ratio of the available power at the terminals of a receiving antenna to the power density of a plane wave incident on the antenna is referred to as the: a\) effective area b\) effective length Question N14 The ratio of open-circuit voltage at the terminals of antenna to the magnitude of electric field strength in the direction of the antenna polarization is defined as the: a\) effective area b\) effective length Question N15 If the current I on antenna is increased in 10 times, its electric field at the observation point is \_\_\_: a\) Decreased in 10 times b\) Increased in 10 times c\) remains unchanged Question N15 If the current I on antenna is decreased in 10 times, its electric field at the observation point is \_\_\_: a\) remains unchanged b\) decreased in 100 times c\) decreased in 10 times Question N16 If the current I on antenna is increased in 10 times, its radiation density at the observation point is \_\_\_: a\) decreased in 10 times b\) decreased in 100 times c\) increased in 100 times Question N16 If the current I on antenna is decreased in 10 times, its radiation density at the observation point is \_\_\_: a\) decreased in 100 times b\) decreased 10 times Question N17 If the distance R from the antenna to the observation point is decreased in 10 times, its electric field at the observation point is \_\_\_: a\) increased in 10 times b\) increased in 100 times c\) decreased in 10 times Question N17 If the distance R from the antenna to the observation point is increased in 10 times, its radiation density at the observation point is \_\_\_: a\) decreased in 10 times b\) decreased in 100 times c\) increased in 10 times d\) increased in 100 times Question N18 The radiation resistance of a very small (L= lambda/25) dipole with triangular current distribution is \_\_\_: a\) 80\*(pi)\^2\*)L/lambda)\^2 b\) 20\*(pi)\^2\*(L/lambda)\^2 c\) 40\*(pi)\^2\*)L/lambda)\^2 Question N18 The radiation resistance of an infinitesimal dipole, with an idealized uniform current distribution, is: a\) 60\*(pi)\^2\*(L/lambda)\^2 b\) 20\*(pi)\^2\*(L/lambda)\^2 c\) 80\*(pi)\^2\*(L/lambda)\^2 Question N19 The polarization of a far-zone field of an infinitesimal dipole is \_\_: a\) circular b\) linear c\) square Question N19 The polarization of a far-zone field of a small loop is \_\_: a\) circular b\) linear c\) squar Question N20 - The input impedance of a linear dipole \_\_\_\_\_ as the length of the dipole increases from very small to one wavelength a\) increase b\) decrease c\) I don't know Question N20 The maximum directivity of a linear dipole \_\_\_\_\_\_as the length of the dipole increases from very small to one wavelength a\) increases b\) decrease c\) remain unchanged Question N21 The directivity of a very small electrical loop is equal to: a\) 4 b\) 2 c\) 1.5 Question N21 The directivity of a very small electrical loop is the same as that of \_\_\_ a\) Infinitesimal linear dipole b\) lambda linear dipole Question N22 The radiation resistance of a very small loop of radius lambda/25, with idealized uniform current distribution is: a-1ohm b- less than 1 ohm c- the same as the dipole 73 ohm d- greater than 1 ohm Question N22 The input impedance of a lambda/2 dipole, with an idealized sinusoidal current distribution, is (Ohm): a\) 50+j 100 b\) 73 + j 42.5 Question N23 The maximum directivity of antenna is related to its maximum effective area by: a\) D0=(4\*pi/lambda\^2)\*Aem b\) D0=(lambda\^2/(4\*pi/))\*Aem c\) D0=(4\*pi/lambda)\*Aem Question N23 The maximum effective area of antenna is related to its maximum directivity by: a\) lambda/(4\*pi)\* D0 b\) lambda\^2 / 4\*pi c\) lambda \*pi /lambda \^2 Question N24 - The maximum directivity of antenna is related to its beam solid angle by: a\) D0=WA/4\*pi b\) WA=4\*PI/D0 Question N24 The beam solid angle of antenna can be found via its maximum directivity by: a\) WA=4\*pi/D0 b\) WA=2\*Pi/D0 Question N25 The radiation resistance of a very small loop with N closely spaced turns with an idealized uniform current distribution is: a\) 20\*pi\^2(C/lambda)\^4\*N b\) 20\*pi\^2(C/lambda)\^4\*N\^2 c\) 20\*pi\^2(C/lambda)\^4\*N\^4 Question N25 The radiation resistance of a very small loop with an idealized uniform current distribution is: a\) (80π\^2 \* (r\^4) \* N) / (3λ\^2) b\) 80\*pi\^2(C/lambda)\^2 Question N26 Maximum effective area of a very small loop of constant current is \_\_\_ than physical area of the loop a\) equal b\) large c\) smaller Question N26 Maximum effective area of a very small loop at the same frequency is \_\_\_ than that of an infinitesimal dipole a\) equal b\) large c\) smaller Question N27 To increase the bandwidth of a wire dipole antenna, its diameter should \_\_ Answer: be increased Point: 1.0 Question N27 To decrease the bandwidth of a wire dipole antenna, its diameter should \_\_ a\) be increased b\) be decreased Question N28 The half-wavelength dipole at a frequency f=30 MHz should have a length close to: a\) 0.5 m b\) 1 c\) 5 Question N28 The half-wavelength dipole at a frequency f=300 MHz should have a length close to: a\) 0.5 m b\) 1 c\) 5 Question N29 The maximum directivity of antenna with HPBWs Θ1d=15 deg,Θ2d=27.5 deg, is about \_\_\_ (use Kraus' formula) a\) 200 b\) 400 c) Answer: 200 Point: 0.0 Question N29 Antenna array, which radiation maximum is directed normal to the axis of the array, is referred to as \_\_ array a\) end-fire b\) broadside Question N30 Maximum Effective area of a small loop at a frequency of 300 MHz is about \_ Answer: 1.2 m\^2 Point: 0.0 Question N30 Maximum Effective area of a small loop at a frequency of 30 MHz is about \_ a\) 1.2 m\^2 b\) 12 m\^2 Question N31 Antenna array, which radiation maximum radiation is along the axis of the array, is referred to as \_\_ a\) broadside b\) scanning c\) end-fire Question N31 Antenna array, which radiation maximum radiation is directed normal to the axis of the array, is referred to as \_\_ a\) scanning b\) end-fire array c\) Broadside array Question N32 End-fire uniform antenna array with a progressive phase beta=-kd has a radiation maximum \_\_\_ of array a\) opposite to the axis b\) along the axis c\) normal to the axis Question N32 End-fire uniform antenna array with a progressive phase beta=+kd has a radiation maximum \_\_\_ of array a\) along the axis b\) opposite the axis c\) normal to the axis Question N33 Directivity of a a linear, broadside, uniform array of isotropic elements can be calculated as: Answer: b Point: 0.0 Question N33 Directivity of a linear, ordinary end-fire, uniform array of isotropic elements can be calculated as: a\) D0= 2\*N\*(d/lambda) b\) D0= 4\*N\*(d/lambda) c\) D0=1.805\*\[4\*N\*(d/lambda)\] Question N34 Directivity of a linear, end-fire, uniform array of 5 isotropic elements (N = 5) with a separation of λ∕4 (d = λ∕4) between the elements is \_\_\_ Answer: 5 Point: 1.0 Question N34 Directivity of a linear, broadside, uniform array of 20 isotropic elements (N = 20) with a separation of λ∕4 (d = λ∕4) between the elements, is \_\_ a\) 5 b\) 40 c\) 10 Question N35 Input impedance of antenna Answer: \`impedance presented signals as its terminal,which helps implenting the voltage. Uploaded File N1 Point: 0.00 Question N36 Elementary electric dipole and its characteristics Answer: Elementary electric dipole seperates the both charges negative and positive it defined as a group or couple of +q and -q the characteristics that it signal direction goes from negative to postive,and it helps implenting the net netural source. Point: 0.00 Question N37 Yagi-Uda antenna (construction and operation principle) Answer: Its an Directional Antenna that is used in television reciept and radio. Construction : 1)Driven Element 2)Refractor 3)Director 4)Boom operation Principal : its a directional Antenna so it recieve and transmit effectively on a specific Direction. 14 correct 20 uncorrect