Description : The antenna effective height is ____ to ____ of the actual height. A. ½ to 2/3 B. ½ to ¾ C. ¼ to 2/3 D. ¼ to ¾
Last Answer : A. ½ to 2/3
Description : ECE Board Exam March 1996 SSB transmission requires only ______ of the bandwidth for a DSBFC transmission. A. ¼ B. 2/3 C. ½ D. ¾
Last Answer : C. ½
Description : In the case if Marconi antenna, the actual length if the radiating element is A. one-half wavelength B. one-quarter wavelength C. one wavelength D. one-eight wavelength
Last Answer : B. one-quarter wavelength
Description : Which of the following improves antenna directivity? A. Driven element B. Reflector element C. Director element D. Parasitic element
Last Answer : D. Parasitic element
Description : What is a driven element of an antenna? A. Always the rearmost element B. Always the forwardmost element C. The element fed by the transmission line D. The element connected to the rotator
Last Answer : C. The element fed by the transmission line
Description : The sewers A. Must be of adequate size to avoid over flow B. Must flow under gravity ½ to ¾ full C. Must be laid at least 2 to 3 m deep to collect /water from the basements D. All the above
Last Answer : ANS: D
Description : What is the value for centrifugal torque for maximum power transmission in belt drives a) ½ maximum torque b) 2/3 maximum torque c) ¾ maximum torque d) None of the above
Last Answer : d) None of the above
Description : Which of the following is not a valid size of a Floppy Disk? A) 8? B) 5 ¼? C) 3 ½? D) 5 ½?
Last Answer : Answer : D
Description : Accuracy of elevation of various points obtained from contour map is limited to (A) ½ of the contour interval (B) ¼ th of the contour interval (C) rd of the contour interval (D) th of the contour interval
Last Answer : (A) ½ of the contour interval
Description : If the focal spot to film distance is increased from 20cm to 40cm, the intensity of radiation is reduced by: a. ½ b. ¼ . c. 1/3 d. 1/5
Last Answer : b. ¼ .
Description : If the focal spot to film distance is increased from 20cm to 40cm, the intensity of radiation is reduced by: A. ½ B. ¼ C. 1/3 D. 1/5
Last Answer : B. ¼
Description : Oxadiazon has a half life of 60 days, so after 120 days the concentration will be a). ½ b). ¼ c). 1/3 d). 1/5
Last Answer : b). ¼
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 : The antenna efficiency of an HF grounded vertical antenna can be made comparable to that of a half-wave antenna A. By installing a good ground radial system B. By isolating the coax shield from ground C. By shortening the vertical D. By lengthening the vertical
Last Answer : A. By installing a good ground radial system
Description : The advantage of using top loading in a shortened HF vertical antenna is A. lower quality factor B. greater structural strength C. higher losses D. improved radiation efficiency
Last Answer : D. improved radiation efficiency
Description : How can the antenna efficiency of an HF grounded vertical antenna be made comparable to that of a half-wave antenna? A. By lengthening the vertical B. By installing a good ground radial system C. By shortening the vertical D. By isolating the coax shield from ground
Last Answer : B. By installing a good ground radial system
Description : If an antenna is too short for the wavelength being used, the effective length can be increased by adding: A. capacitance in series B. inductance in series C. resistance in parallel D. resistance in series
Last Answer : B. inductance in series
Description : The reflector and director of an antenna array are considered as A. Parasitic elements B. Transcendental elements C. Feed-points D. Driven elements
Last Answer : A. Parasitic elements
Description : A type of array antenna which consists of one half-wave driven dipole, one reflector and one director A. Hertzian dipole B. Yagi-uda C. Broadside collinear D. Log periodic dipole array
Last Answer : B. Yagi-uda
Description : Increasing the electrical length of an antenna means A. add an inductor in parallel B. add a capacitor in series C. add an inductor series D. add a resistor is series
Last Answer : C. add an inductor series
Description : What is the effect of adding a capacitor in series with an antenna? A. The antenna’s resonant frequency will increase B. The antenna’s resonant frequency will decrease C. The antenna will be physically 5% longer than its electrical length D. A capacitor is never added in series with an antenna
Last Answer : A. The antenna’s resonant frequency will increase
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 : Actual height of antenna should be at least A. one wavelength B. half wavelength C. quarter wavelength D. three-fourth wavelength
Last Answer : C. quarter wavelength
Description : In order to get maximum radiation to all surrounding points in the horizontal plane, the antenna used is a A. vertical loop B. vertical quarter-wavelength rod C. array which includes parasitic elements D. a horizontal Hertz dipole
Last Answer : B. vertical quarter-wavelength rod
Description : A shunt-fed quarter-wavelength Marconi antenna A. has maximum RF impedance to ground at its feedpoint B. has a current null at its feedpoint C. has a zero DC resistance to ground D. has zero RF resistance to ground
Last Answer : C. has a zero DC resistance to ground
Description : A one-quarter wavelength shunt-fed vertical Marconi antenna A. has maximum radiation in a vertical direction B. must have a horizontal receiving antenna for the best reception C. must use a receiving antenna for the best reception D. must have a vertical receiving antenna for the best reception
Last Answer : D. must have a vertical receiving antenna for the best reception
Description : Which of the following antennas receive signals in the horizontal plane equality well from all directions? A. Horizontal Hertz antenna B. Vertical loop antenna C. Vertical Yagi antenna D. A vertical antenna which is a quarter-wavelength long
Last Answer : D. A vertical antenna which is a quarter-wavelength long
Description : A simple half-wavelength antenna radiates the strongest signal A. at 45 degrees to its axis B. parallel to its axis C. at right angles to its axis D. at 60 degrees to its axis
Last Answer : C. at right angles to its axis
Description : An antenna which is one-tenth wavelength long A. Hertzian dipole B. Loop antenna C. Marconi antenna D. Elementary doublet
Last Answer : D. Elementary doublet
Description : A transmitted signal 5 meters in wavelength is received by an antenna coil having a 50-Ω resistance and a 0.01 H inductance. What is the capacitance of the tuner shunting the antenna coil at this point? A. 0.704 fF B. 0.704 μF C. 0.704 nF D. 0.704 mF
Last Answer : A. 0.704 fF
Description : What is the seventh harmonic of a 100 MHz quarter wavelength antenna? A. 14.28 MHz B. 107 MHz C. 149 MHz D. 700 MHz
Last Answer : D. 700 MHz
Description : What is driven element? A. Always the rearmost element B. Always the forward most element C. The element fed by the transmission line D. The element connected to the rotator
Description : Comparing the signal strength arriving at the driven element from the desired direction to the signal strength reaching the driver from the opposite direction. A. Directivity B. Sensitivity C. Beamwidth D. Front-to-back ratio
Last Answer : D. Front-to-back ratio
Description : When a beam of light enters one medium from another, which quantity will not change? a. Direction b. Speed c. Frequency d. Wavelength
Last Answer : c. Frequency
Description : Quantity that do not change when a beam of light enters on e medium to another. A. Frequency B. Wavelength C. Direction D. Speed
Last Answer : A. Frequency
Description : The smallest beam of a satellite antenna radiation pattern A. Zone beam B. Hemispheric beam C. Spot beam D. Global beam
Last Answer : C. Spot beam
Description : The angle of elevation of the antenna beam is 20°. Calculate the transmission-path distance for an ionospheric transmission that utilizes a layer of virtual height 200 km. Use flat-earth approximation. A. 966 km B. 2100 km C. 1100 km D. 405 km
Last Answer : C. 1100 km
Description : Refers to a type of beam antenna which uses two or more straight elements arranged in line with each other. A. Dipole antenna B. Yagi antenna C. Whip antenna D. Rhombic antenna
Last Answer : B. Yagi antenna
Description : What is the electrical wavelength of a 500 MHz signal? A. 60 centimeters B. 6 meters C. 0.06 meter D. 60 meters
Last Answer : A. 60 centimeters
Description : The parasitic element of an antenna system will A. decrease its directivity B. increase its directivity C. give the antenna unidirectional properties D. both B and C
Last Answer : D. both B and C
Description : Known as the technique for adding a series inductor at or near the center of an antenna element in order to cancel the capacitive reactance of an antenna. A. Dipole B. Center loading C. Reflector D. loading coil
Last Answer : D. loading coil
Description : In what range of frequencies are most omnidirectional horizontally polarized antennas used? A. VHF, UHF B. VLF, LF C. SH, EHF D. MF, HF
Last Answer : A. VHF, UHF
Description : Indicate the false statement. A. HF mixer are generally noisier than HF amplifiers. B. Impulse noise voltage is dependent on bandwidth C. Thermal noise is independent of the frequency at which is measured. D. Industrial noise is usually of the impulse type.
Last Answer : B. Impulse noise voltage is dependent on bandwidth
Description : What frequency band is referred to as the metric waves? A. VHF B. UHF C. HF D. SHF
Last Answer : A. VHF
Description : What is the channel spacing for MF-HF voice frequencies? A. 2.8 kHz B. 500 Hz C. 3.5 kHz D. 3 kHz
Last Answer : D. 3 kHz
Description : Where does the AM broadcast band located in the spectrum band? A. HF band B. VHF band C. LF band D. MF band
Last Answer : D. MF band
Description : Highest frequency that can be used for skywave HF communications between two given points on earth. A. Gyro frequency B. Maximum usable frequency C. Critical frequency D. Virtual frequency
Last Answer : B. Maximum usable frequency
Description : Which frequency band is the standard AM radio broadcast? A. HF B. UHF C. MF D. VHF
Last Answer : C. MF
Description : What would be the physical length of a tpical coaxial transmission line that is electrically one-quarter wavelength long at 14.1 MHz? A. 20 meters B. 3.51 meters C. 2.33 meters D. 0.25 meter
Last Answer : B. 3.51 meters
Description : What is actual length in feet of a one-half wavelength of a coax with a velocity factor of 0.59 at 26 MHz? A. 11.16 B. 40.29 C. 42.46 D. 46.28
Last Answer : A. 11.16