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 : 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 : What two main advantages of a parasitic array can be obtained by combining a reflector and a director with the driven element?
Last Answer : Increased gain and directivity.
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 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 : 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 : If the current ratios of the two or more elements must be held 5% and the phase angle to 3° the antenna is called a A. end fire array B. critical phased array C. broadband array D. wideband array
Last Answer : B. critical phased array
Description : What circuit is responsible in activating and deactivating adjacent antenna elements in a mobile satellite array? A. Radial divider B. Divider/combiner C. Radial combiner D. Radial multiplexer
Last Answer : A. Radial divider
Description : In a typical mobile satellite array antenna if three elements are activated, how many elements are deactivated? A. 3 B. 11 C. 5 D. 9
Last Answer : B. 11
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 : 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 : The parasitic array can be rotated to receive or transmit in different directions. What is the name given to such an antenna?
Last Answer : Rotary array.
Description : What is meant by the term radiation resistance for an antenna? A. The resistance in the trap coils to received signal B. An equivalent resistance that would dissipate the same amount of power as ... antenna C. The specific impedance of the antenna D. Losses in the antenna elements and feed line
Last Answer : B. An equivalent resistance that would dissipate the same amount of power as that radiated from an antenna
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 : The broadside array consists of a flat reflector and what other elements?
Last Answer : Two or more half-wave dipoles.
Description : What is the usual electrical length of a driven element in an HF beam antenna? A. ¼ wavelength B. ¾ wavelength C. ½ wavelength D. 1 wavelength
Last Answer : C. ½ wavelength
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 : What is antenna bandwidth? A. Antenna length divided by the number of elements B. The angle between the half-power radiation points C. The angle formed between two imaginary lines drawn through D. The frequency range over which an antenna can be expected to operate satisfactorily
Last Answer : D. The frequency range over which an antenna can be expected to operate satisfactorily
Description : What is meant by the term antenna bandwidth A. Antenna length divided by the number of elements. B. The angle between the half-power radiation points C. The frequency range over which and antenna ... perform well D. The angle formed between two imaginary line drawn through the ends of the elements
Last Answer : C. The frequency range over which and antenna can be expected to perform well
Description : An ungrounded antenna near the ground A. acts as a single antenna of twice the height B. is unlikely to need an earth mat C. acts as antenna array D. must be horizontally polarized
Last Answer : C. acts as antenna array
Description : A theoretical reference antenna that provides a comparison for antenna measurements. A. Marconi antenna B. Isotropic radiator C. Yagi-Uda array D. Whip antenna
Last Answer : B. Isotropic radiator
Description : ______ is an antenna array which is highly directional at right angles to the plane of the array? A. Broadside array B. End-fire array C. Turnstile array D. Log-periodic array
Last Answer : A. Broadside array
Description : _____ is an antenna with a number of half-wave antenna on it. A. Antenna array B. Tower C. Omni-directional D. Rhombic
Last Answer : A. Antenna array
Description : Which is a non-resonant antenna? A. Rhombic antenna B. Folded dipole C. End-fire array D. Yagi-Uda antenna
Last Answer : A. Rhombic antenna
Description : Which is the non-resonant antenna? A. Broadside Antenna B. Folded Dipole C. Rhombic antenna D. End fire array
Last Answer : C. Rhombic antenna
Description : It consists of a number of dipoles of equal size, equally spaced along a straight line with all dipoles fed in the same phase from the same source. A. Log-periodic antenna B. Yagi antenna C. End-fire array D. Broadside array
Last Answer : D. Broadside array
Description : What is the advantage of adding parasitic elements to a Yagi array?
Last Answer : Increased gain.
Description : Whichoneofthe followingterms doesnot applyto theYagi-Uda array? a. Good bandwidth b. Parasitic elements c. Folded dipole d.Highgain
Last Answer : d.Highgain
Last Answer : The number of parasitic elements in yagi antenna is 2.
Description : All elements in a beam _____ antennas are in line A. collinear B. yagi C. broadside array D. log-periodic
Last Answer : A. collinear
Description : A mobile satellite array has usually how many elements? A. 6 B. 88 C. 12 D. 14
Last Answer : D. 14
Description : Where are the current nodes in a half-wave antenna? A. At the ends B. At the center C. Three-quarters of the way from the feed point toward the end D. One-half of the way from the feed point toward the end
Last Answer : A. At the ends
Description : Where are the voltage nodes in a half-wave antenna? A. At the ends B. Three-quarters of the way from the feed point toward the end C. One-half of the way from the feed point toward the end D. At the feed point
Last Answer : D. At the feed point
Description : A final amplifier of a radio transmitter draws 250 mA of plate current when the plate supply voltage is 1400 volts. If the plate circuit efficiency is 80% and the transmitter is connected to an antenna having a feed impedance of 70 ohms, ... at the feed-point? A. 4.0 A B. 2.2 A C. 1.25 A D. 2.0 A
Last Answer : D. 2.0 A
Description : _________ detects the satellite signal relayed from the feed and converts it to an electric current, amplifies and lower its frequency. A. Horn antenna B. LNA C. Satellite receiver D. Satellite dish
Last Answer : B. LNA
Description : If a transmission line has a power loss of 6 dB per 100 feet, what is the power at the feed point to the antenna at the end of a 200 foot transmission line fed by a 100 watt transmitter? A. 70 watts B. 50 watts C. 25 watts D. 6 watts
Last Answer : D. 6 watts
Description : Refers to one of the front end circuit of a VHF TV superheterodyne receiver which is usually a separate circuit coupled to the mixer. A. Antenna feed B. AGC C. RF amplifier D. Local oscillator
Last Answer : D. Local oscillator
Description : How can intermodulation interference between two transmitters in close proximity reduced or eliminated? A. Through installing a band-pass filter in the antenna feed line B. Through installing terminated circulator ... high driving power D. By installing a low-pass filter in the antenna feed line
Last Answer : A. Through installing a band-pass filter in the antenna feed line
Description : Where the voltage node of a half-wave antenna does exists? A. At feed point B. Near the center C. At center D. Near the feed point
Last Answer : A. At feed point
Description : The main function of a communications satellite is a/ an A. repeater B. reflector C. beacon D. observation platform
Last Answer : A. repeater
Description : Which of the following is the basic component of a communications satellite receiver? A. On-board computer B. Reflector C. Telemetry D. Transponder
Last Answer : D. Transponder
Description : Stacking antenna elements A. increases sensitivity to weak signals B. will suppress odd harmonics C. decrease signal to noise ratio D. increases selectivity
Last Answer : A. increases sensitivity to weak signals
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 : Stacking elements in a transmitting antenna system A. increases the field strength at the receiving antenna B. increases the directivity of the transmitter antenna C. decrease the size of the lobe in the radiation pattern D. both A and B
Last Answer : D. both A and B
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 : Horn-Fed Cassegrain reflector antenna
Last Answer : Design Horn-Fed Cassegrain reflector antenna for operating frequency, gain, beam width, dish ... Provide proper citations and references in write-up
Description : ECE Board Exam March 1996 An antenna that is circularly polarized is the ____________. A. parabolic reflector B. helical C. Yagi-uda D. small circular loop
Last Answer : B. helical
Description : What are the disadvantages of the parasitic array?
Last Answer : Their adjustment is critical and they do not operate over a wide frequency range.
Description : hat two factors determine the directivity pattern of the parasitic array?
Last Answer : Length of the parasitic element (tuning) and spacing between the parasitic and driven elements.
Description : What illumination factor is normally considered in computing parabolic antenna gain in microwave communications? A. 0.54 B. 0.65 C. 0.75 D. 0.85
Last Answer : A. 0.54