Description : How does the gain of a parabolic dish type antenna change when the operating frequency is doubled? A. Gain does not change B. Gain is multiplied by 0.707 C. Gain increases 6 dB D. Gain increases 3 dB
Last Answer : C. Gain increases 6 dB
Description : An antenna with very high gain and very narrow beamwidth. A. Helical antenna B. Discone antenna C. Horn antenna D. Parabolic dish antenna
Last Answer : D. Parabolic dish antenna
Description : Part of a microwave link can be approximated by free space conditions. The antenna gain are each 40 dB, the frequency is 10 GHz, and the path length is 80 km. Calculate the receive power for a transmitted power of 10 W? A. 0.871 μW B. 871 μW C. 0.871 mW D. 871 nW
Last Answer : A. 0.871 μW
Description : What is the characteristic impedance of a single wire with a diameter d= 0.25 mm placed at the center between grounded parallel planes separated by 1 mm apart. The wire is held by a material with a velocity factor of 0.75. A. 85 Ω B. 63 Ω C. 50 Ω D. 75 Ω
Last Answer : D. 75 Ω
Description : What is the free space loss, in dB, between two microwave parabolic antennas 38.0 kilometer apart operating at 7.0 GHz? A. 145.6 dB B. 138.5 dB C. 135.5 dB D. 140.89 dB
Last Answer : D. 140.89 dB
Description : A dipole antenna requires to be fed with 20 kW of power to produce a given signal strength to a particular distant point. If the addition of a reflector makes the same field strength available with an input power of 11kW ... Gain referred to this particular dipole). A. 4.75 B. 2.6 C. 1.81 D. 4.24
Last Answer : B. 2.6
Description : What is the effective radiated power of a repeater with 75 watts transmitter power output, 5 dB feedline loss, 4 dB duplexer and circulator loss, and 6 dB antenna gain? A. 37.6 W B. 237 W C. 150 W D. 23.7 W
Last Answer : A. 37.6 W
Description : What is the effective radiated power of a repeater with 75 watts transmitter power output, 4 dB feedline loss, 3 dB duplexer and circulator loss, and 10 dB antenna gain? A. 600 W B. 75 W C. 18.75 W D. 150 W
Last Answer : D. 150 W
Description : What is the typical gain of a rhombic antenna? A. Between 15 to 60 B. Between 20 to 90 C. Between 50 to 75 D. Between 10 to 25
Last Answer : A. Between 15 to 60
Description : A dipole antenna requires to be feed with 20 kW of power to produce a given signal strength to a particular distant point. If the addition of a reflector makes the same field strength available with an input power of 11 ... ( Gain referred to this particular dipole) A. 4.24 B. 1.81 C. 4.75 D. 2.6
Last Answer : D. 2.6
Description : For high degree of workability , the compaction factor is (a) 0.65 (b) 0.75 (c) 0.85 (d) 0.95
Last Answer : (d) 0.95
Description : One of the following is very useful as a multiband HF receiving antenna. A. Parabolic antenna B. Elementary doublet C. Log-periodic D. Square loop
Last Answer : C. Log-periodic
Description : A special horn antenna consisting of a parabolic cylinder joined to a pyramidal horn. A. Hoghorn B. Cass-horn C. Pyramidal horn D. Conical horn
Last Answer : A. Hoghorn
Description : What antenna can be used to minimize the effect of Faraday rotation of polarization? A. Dipole B. Parabolic C. Helical D. Rhombic
Last Answer : C. Helical
Description : ECE Board Exam March 1996 A type of an underground antenna is a/an __________ antenna. A. Hertz B. isotropic C. parabolic D. Marconi
Last Answer : A. Hertz
Description : What is the common up-converter and down-converter IF for microwave communications? A. 60 MHz B. 80 MHz C. 120 MHz D. 70 MHz
Last Answer : D. 70 MHz
Description : Which of the following is not a common microwave application? A. Radar B. Data transmission C. Space communications D. Mobile radio
Last Answer : D. Mobile radio
Description : A microwave communications system space loss calculation formula is A. 92.4 + 10 log f +20 log d B. 94.2 + 10 log f +20 log d C. 92.4 + 20 log f +20 log d D. 94.2 + 20 log f +20 log d
Last Answer : C. 92.4 + 20 log f +20 log d
Description : ECE Board Exam March 1996 It is a spacecraft placed in orbit around the earth carrying onboard microwave receiver and transmitting equipments. A. Fiber optic equipment B. Communications satellite C. Wireless radio system D. Coaxial cable syste
Last Answer : B. Communications satellite
Description : Determine the gain of a 6 ft. parabolic dish operating at 1800 MHz. A. 30 dB B. 11.2 dB C. 15.5 dB D. 28.17 dB
Last Answer : D. 28.17 dB
Description : Which does not use vertical polarization antenna? A. AM Broadcasting B. FM Broadcasting C. Mobile Communications D. Satellite Communications
Last Answer : B. FM Broadcasting
Description : Which of the following frequencies is normally used for distress and safety communications? A. 4209.5 kHz B. 490 kHz C. 518 kHz D. 2174.5 kHz
Last Answer : D. 2174.5 kHz
Description : Referred to as a ferrite device that can be used in lieu of a duplexer to isolate a microwave transmitter and receiver when both are connected to the same antenna. A. Isolator B. Circulator C. Coupler D. Diode.
Last Answer : B. Circulator
Description : The advantage of periscope antenna in microwave A. Minimize interference to and from other neighboring stations B. Shorten waveguide link C. Reduce tower height D. All of these
Last Answer : B. Shorten waveguide link
Description : It is a measure of the microwave power radiated from an antenna as a function of angular direction from the antenna axis. A. Antenna pattern B. Polarization C. Beamwidth D. Sidelobes
Last Answer : C. Beamwidth
Description : Respiratory quotient of an average mixed diet is about (A) 0.65 (B) 0.7 (C) 0.75 (D) 0.85 MINERAL METABOLISM 201
Last Answer : Answer : D
Description : The specific gravity of petrol is about a. 0.65 b. 0.75 c. 0.85 d. 0.95
Last Answer : ANSWER b. 0.75
Description : What is the gain of an antenna over a half-wavelength dipole when it has 6 dB gain over an isotropic radiator? A. 6.0 dB B. 8.1 dB C. 3.9 dB D. 10.0 dB
Last Answer : C. 3.9 dB
Description : Gain of an isotropic antenna A. -1 dB B. 1 dB C. 0 dB D. 2 dB
Last Answer : C. 0 dB
Description : How does spatial isolation technique in satellite communications avoid interference? A. Use of different polarity antennas B. Use of different types of antennas C. Employment of highly directional spot-beam antennas D. Use of low gain antennas
Last Answer : C. Employment of highly directional spot-beam antennas
Description : What is the time delay introduced by a 75-ft coaxial cable with a dielectric constant of 2.3? A. 1.54 ns B. 11.5 ns C. 115.6 ns D. 1156 ns
Last Answer : C. 115.6 ns
Description : Type of emission produced by one of the early radio transmitter in trains of damped RF ac waves where its oscillator is coupled to a long wire antenna, normally used in radio telegraph and having sidebands on its carrier. A. Digital emission B. Key emission C. Cycle emission D. Spark emission
Last Answer : D. Spark emission
Description : Type of antenna which is normally used for satellite tracking service. A. Omni B. Helical C. Yagi D. Dipole
Last Answer : B. Helical
Description : 52 Scythians (Sakas) invaded the Gandharan region in: A. 65 BC B. 75 BC C. 85 BC D. 95 BC
Last Answer : ANSWER: B
Description : The ordinary and maximum tolerance limit of sound by human being is – (1) 50 db to 70 db (decibel) (2) 60 db to 80 db (decibel) (3) 65 db to 75 db (decibel) (4) 70 db to 85 db (decibel)
Last Answer : (2) 60 db to 80 db (decibel) Explanation: Normal speech is about 60 dB (decibels). A dangerous sound is anything that is 80 dB or higher which can lead to hearing loss. At 70 dB or ... the risk of harm to healthy ears is negligible. Listening to sound above 80 decibels can cause profound deafness.
Description : Carbon percentage (by weight) in crude petroleum may be about (A) 65 (B) 75 (C) 85 (D) 95
Last Answer : (C) 85
Description : Percentage of water in buffalo milk is:- a. 65-67 % b. 70-75 % c. 80-85 % d. 87-90 %
Last Answer : d. 87-90 %
Description : A trader sells 145 m of cloth for Rs 12325 at the profit of Rs 10 per metre of cloth. What is the cost price of 1 m of cloth? 1. Rs 65 2. Rs 75 3. Rs 95 4. Rs 85
Last Answer : 2. Rs 75
Description : About ____ percent of the proteins of white flour are relatively insoluble. a. 55 c. 75 b. 65 d. 85
Last Answer : d. 85
Description : The ordinary and maximum tolerance limit of sound by human being is (1) 50 db to 70 db (decibel) (2) 60 db to 80 db (decibel) (3) 65 db to 75 db (decibel) (4) 70 db to 85 db (decibel)
Last Answer : 60 db to 80 db (decibel)
Description : What is transit time (time delay) of a 50-ft length transmission line of the above problem? A. 50 ns B. 100 ns C. 75 ns D. 65 ns
Last Answer : C. 75 ns
Description : ECE Board Exam March 1996 The K-factor under normal atmospheric conditions in a microwave radio data profile calculation is equal to ___________. A. 2/3 B. 0 C. 4/3 D. Infinity
Last Answer : C. 4/3
Description : The effect of adding parasitic elements of a Hertz dipole is to A. make the antenna more omnidirectional B. reduce its resonant frequency C. increase the antenna’s power gain D. All of these
Last Answer : C. increase the antenna’s power gain
Description : The purpose of stacking elements on an antenna. A. Sharper directional pattern B. increased gain C. Improved bandpass D. All of these
Last Answer : D. All of these
Description : What is the gain, in dB of a helical antenna with diameter of λ/3, 10 turns at pitch of λ/4, used at 100 MHz? A. 16 B. 41.1 C. 31.4 D. 1.25
Last Answer : A. 16
Description : The power fed to a two-bay turnstile antenna is 100 watts. If the antenna has a 2 dB power gain, what is the effective radiated power? A. 317 watts B. 158 watts C. 200 watts D. 400 watts
Last Answer : B. 158 watts
Description : _____ of an antenna is a measure of how the antenna concentrates its radiated power in a given direction. A. Efficiency B. Power C. Gain D. Polarization
Last Answer : C. Gain
Description : What is the gain of isotropic antenna? A. 10 B. 1 C. 10 D. 100
Last Answer : B. 1
Description : How will you increase the gain of an antenna? A. By adding several antennas in parallel B. By focusing the radiated energy in one desired direction C. By making antenna rods thicker D. By making the antenna size larger
Last Answer : B. By focusing the radiated energy in one desired direction
Description : An antenna with unity gain A. Rhombic B. Half-wave dipole C. Isotropic D. Whip
Last Answer : C. Isotropic