Description : Why is the number of elements used in a collinear array limited?
Last Answer : As more elements are added, an unbalanced condition in the system occurs which impairs efficiency.
Description : What is the maximum number of elements ordinarily used in a collinear array?
Last Answer : Four.
Description : How can the frequency range of a collinear array be increased?
Last Answer : By increasing the lengths of the elements of the array.
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 : 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 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 : The broadside array consists of a flat reflector and what other elements?
Last Answer : Two or more half-wave dipoles.
Description : What is the advantage of adding parasitic elements to a Yagi array?
Last Answer : Increased gain.
Description : As the spacing between elements in a broadside array increases, what is the effect on the major lobes?
Last Answer : They sharpen.
Description : When more than two elements are used in a broadside array, how are the elements arranged?
Last Answer : Parallel and in the same plane.
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 : The Yagi antenna is an example of what type of array?
Last Answer : Multielement parasitic array.
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 : 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 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 : To maintain the required balance of phase relationships and critical feeding, how must the end-fire array be constructed?
Last Answer : Symmetrically.
Description : Where does the major lobe in the end-fire array occur?
Last Answer : Along the major axis
Description : What are some disadvantages of the end-fire array?
Last Answer : Extremely low radiation resistance, confined to one frequency, and affected by atmospheric conditions.
Description : What is the ratio of the maximum radiation intensity to the average radiation intensity? A. Aperture gain B. Directivity gain C. Transmission gain D. Power gain
Last Answer : B. Directivity gain
Description : The directivity pattern of an isotropic radiator is A. a figure-8 B. a sphere C. a unidirectional cardioid D. a parabola
Last Answer : B. a sphere
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 : 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 : 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 : ______ is the measurement of a unilateral antenna properties of directivity A. Phase angle B. Antenna gain C. Beamwidth D. Bandwidth
Last Answer : C. Beamwidth
Description : What determines the ability of radar to determine the bearing to a target? A. Speed of light B. Speed of target C. Antenna directivity D. Frequency of signal
Last Answer : C. Antenna directivity
Description : Themaindisadvantage ofthe two-hole directional coupleris a. low directional coupling b. poor directivity c. high SWR d.narrowbandwidth
Last Answer : d.narrowbandwidth
Description : Define the following terms related to antennas; (i) Antenna resistance (ii) Directivity (iii) Antenna gain (iv) Power density
Last Answer : Antenna Resistance - The resistance of an antenna has two components: 1. Its radiation resistance due to conversion of power into electromagnetic waves 2. The resistance due to actual losses in the ... the transmitter power divided by the surface area of a sphere (4πR2) at that distance.
Description : Define the following terms: (i) Polarization (ii) Antenna gain (iii)Antenna resistance (iv)Directivity
Last Answer : i) Polarization:- It is defined as the direction of electric field vector in the EM wave radiated by the transmitting antenna. ii) Antenna Gain:- Antenna gain is defined as the ratio of ... in only one direction in which the radiation is maximum. That is directivity = Max. directive gain
Description : An antenna has a radiation resistance of 72 Ω a loss resistance of 8 Ω and a power gain of 16. Find efficiency and directivity.
Last Answer : An antenna has a radiation resistance of 72 Ω a loss resistance of 8 Ω and a power gain of 16. Find efficiency and directivity.
Last Answer : A higher directivity is specified by High gain low BW.
Description : Write a C++ program to accept array of five elements, find and display smallest number from an array.
Last Answer : #include<iostream.h> #include<conio.h> void main() { int a[5],smallest,i; clrscr(); cout<<" Enter array elements:"; for(i=0;i<5;i++) cin>>a[i] ... } } cout<<endl<<"Smallest number="<<smallest; getch(); }
Description : What minimum number of non-zero non-collinear vectors is required to produce a zero vector? -General Knowledge
Last Answer : The answer is '3'
Last Answer : answer:
Description : What minimum number of non-zero non-collinear vectors is required to produce a zero vector?
Last Answer : 3
Description : Python: How to get the indices of several elements in a list or numpy array at once? -Web-Development
Description : Python : How to find the indices of elements in a sublist in a list or numpy array -Web-Development
Description : How to compute percentile of the Python array elements -Web-Development
Description : Python : compute z-score for elements of an array -Web-Development
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 : 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 mobile satellite array has usually how many elements? A. 6 B. 88 C. 12 D. 14
Last Answer : D. 14
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 : How can you sort the elements of the array in descending order?
Last Answer : By calling Sort() and then Reverse() methods.
Description : Suppose that data is an array of 1000 integers. Write a single function call that will sort the 100 elements data [222] through data [321].
Last Answer : quicksort ((data + 222), 100)
Description : Whichoneofthe followingterms doesnot applyto theYagi-Uda array? a. Good bandwidth b. Parasitic elements c. Folded dipole d.Highgain
Last Answer : d.Highgain
Description : Accept data for five students and display it. Write a C++ program to displya sum of array elements of array size n.
Last Answer : #include<iostream.h> #include<conio.h> void main() { int arr[20],i,n,sum=0; clrscr(); cout<<"\nEnter size of an array:"; cin>>n; cout<<"\nEnter ... ; } cout<<"\nSum of array elements is:"<<sum; getch(); }