# N-element Linear Array MCQ’s

This set of Antenna Multiple Choice Questions & Answers (MCQs) focuses on “N-element Linear Array”.

1. Normalized array factor of N –element linear array is ________
a) $$\frac{sin(Nᴪ/2)}{Nᴪ/2}$$
b) $$\frac{cos(Nᴪ/2)}{Nᴪ/2}$$
c) $$N\frac{sin(ᴪ/2)}{ᴪ/2}$$
d) $$N\frac{cos(Nᴪ/2)}{Nᴪ/2}$$

2. Which of the following expression gives the nulls for the N- element linear array?
a) $$θ_n=cos^{-1}⁡(\frac{λ}{2πd}[-β±\frac{2πn}{N}])$$
b) $$θ_n=sin^{-1}⁡(\frac{λ}{2πd}[-β±\frac{2πn}{N}])$$
c) $$θ_n=cos^{-1}⁡(\frac{λ}{2πd}[-β±\frac{πn}{N}])$$
d) $$θ_n=cos^{-1}⁡(\frac{λ}{2πd}[β±\frac{2πn}{N}])$$

3. Which of the following statement is true?
a) As the number of elements increase in array it becomes more directive
b) As the number of elements increase in array it becomes less directive
c) Point to point communication is not possible with more number of array elements
d) There is no uniform progressive phase shift in linear uniform array

4. Maximum value of array factor for N-element linear array occurs at ______
a) $$θ_m=cos^{-1}⁡(\frac{λ}{2πd}[-β±2πm])$$
b) $$θ_m=cos^{-1}⁡(\frac{λ}{2πd}[β±2πm])$$
c) $$θ_m=sin^{-1}⁡(\frac{λ}{2πd}[-β±2πm])$$
d) $$θ_m=sin^{-1}(\frac{λ}{2πd}[-β±2πm])$$

5. Find the Nulls of the N-element array in which elements are separated by λ/4 and phase difference is 0?
a) $$θ_n=cos^{-1}⁡(\left[±\frac{4n}{N}\right])$$
b) $$θ_n=cos^{-1}⁡(\left[±\frac{2n}{N}\right])$$
c) $$θ_n=sin⁡(\left[±\frac{4n}{N}\right])$$
d) $$θ_n=sin^{-1}⁡(\left[±\frac{4n}{N}\right])$$

6. The radiating pattern of single element multiplied by the array factor simply gives the ___________
a) Pattern multiplication
b) Normalized array factor
c) Beamwidth of the array
d) Field strength of the array

7. Find the maximum value of array factor when elements are separated by a λ/4 and phase difference is 0?
a) θm=cos-1⁡(4m)
b) θm=sin-1⁡(4πm)
c) θm=cos-1⁡(4πm)
d) θm=sin-1(2m)

8. Find the Nulls of the 8-element array in which elements are separated by λ/4 and phase difference is 0?
a) $$θ_n=cos^{-1}⁡(\left[±\frac{n}{2}\right])$$
b) $$θ_n=cos^{-1}⁡(\left[±\frac{n}{4}\right])$$
c) $$θ_n=sin^{-1}⁡(\left[±\frac{n}{2}\right])$$
d) $$θ_n=sin^{-1}⁡(\left[±\frac{n}{4}\right])$$

9. Condition for the half power width of the Array factor is given by ___________
a) $$\frac{Nᴪ}{2}=±1.391$$
b) $$\frac{Nᴪ}{2}=±3$$
c) $$\frac{Nᴪ}{2}=±0.5$$
d) $$\frac{Nᴪ}{2}=±1$$

10. The maximum of the first minor lobe of array factor occurs at 13.46 dB down the maximum major lobe.
a) True
b) False

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