# Which of the following statements is true regarding end-fire array?

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Which of the following statements is true regarding end-fire array?

(a) The necessary condition of an ordinary end-fire array is β=±kd+nπ

(b) The phase excitation difference is zero

(c) Same input current is fed through the array, but the phase excitation is varies progressively

(d) Maximum radiation occurs at normal to the axis of array

I have been asked this question in an interview.

I'd like to ask this question from End Fire Array in chapter Antenna Array of Antennas

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The correct choice is (c) Same input current is fed through the array, but the phase excitation is varies progressively

Easy explanation: For end-fire array:

Phase excitation difference β=±kd

Maximum radiation occurs along the axis of the array that is at θ=0° or 180°.

Even though same input current s fed to the arrays of equal magnitude, the phase vary progressively along the line to get the unidirectional pattern.

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