29 4-45.   Adding more elements to a collinear antenna array produces which of the following effects? 1.   Increased gain 2.   Decreased gain 3.   Decreased directivity 4.   Mismatched impedances 4-46.   What is the maximum number of elements ordinarily used in a collinear array? 1.   One 2.   Two 3.   Three 4.   Four 4-47.   Constructing a collinear array with elements longer than 1/2 wavelength has which of the following effects on antenna characteristics? 1.   Increased gain 2.   Decreased gain 3.   Increased frequency range 4.   Decreased frequency range 4-48.   In a two-element collinear array, maximum gain is obtained when the center-to-center spacing between the ends of the elements is approximately what electrical distance? 1.   Wavelength 2.   0.15 wavelength 3.   0.5 wavelength 4.   0.75 wavelength 4-49.   Compared with collinear arrays, broadside arrays have which of the following advantages? 1.   Sharper tuning 2.   Broader bandwidth 3.   Broader frequency response 4.   Less coupling between dipole 4-50.   Optimum gain is obtained from a broadside array when the spacing of its elements is which of the following distances? 1.   One-half wavelength 2.   One-quarter wavelength 3.   Greater than one-half wavelength 4.   Slightly less than one-quarter 4-51.   An end-fire array physically resembles the collinear array except that it is more compact. What disadvantage does the endfire array possess? 1.   It has lower gain 2.   It has low radiation resistance 3.   It has loose coupling 4.   Each of the above 4-52.   What is the range of electrical spacing between the elements of an end-fire array? 1.   3/4 to 1   wavelength 2.   1/2 to 3/4 wavelength 3.   1/4 to 1/2 wavelength 4.   1/8 to 1/4 wavelength 4-53.   The end-fire array produces what type of lobes, if any, along the axis of the array? 1.   Minor lobes 2.   Major lobes 3.   None 4-54.   Assuming that the elements are correctly spaced, the directivity of an end-fire array may be increased by which of the following actions? 1.   Increasing the frequency 2.   Decreasing the frequency 3.   Decreasing the number of elements 4.   Increasing the number of elements