ASSIGNMENT 6-10 ( UNIT – 2 )

ASSIGNMENT – 6

a. Hemispheric Power pattern of Unidirectional Antenna

b. Unidirectional Cosine Power Pattern

c. Bidirectional Sine Power Pattern

d. Bidirectional Sin2 Power Pattern

e. Unidirectional Cos2 Power Pattern

4. Show that directivity for unidirectional operation is 2(n+1) for an intensity variation of

U = Um Cosn θ.

5. Write a short note on Antenna Arrays. Mention the factors on which the resultant pattern

depends.

ASSIGNMENT – 7

6. Differentiate between BSA and EFA

7. Draw the Radiation Pattern for the following –

8. Derive an expression for electric field intensity of array of n isotropic sources with equal

amplitude and spacing and having a given phase difference.

9. Explain the principle of Pattern Multiplication.

ASSIGNMENT – 8

10. Obtain the electric field intensity of non-isotropic but similar point sources.

11. Obtain the Radiation Pattern for four sources forming a uniform BSA with a spacing of

λ/2.

12. Obtain BWFN and HPBW for BSA and EFA.

13. Explain Hansen Woodyard condition for increased directivity.

14. Four sources have equal magnitude and are spaced apart by half wavelength. Maximum

field is to be in line with sources. Plot the field pattern for the array, given

ASSIGNMENT – 9

15. Find BWFN for uniform EFA and extended EFA. Given – (i) n=4 (ii) d=λ/2

16. The principle lobe width of uniform 10 elements of BSA was observed to be 300 at a

frequency of 30MHz. estimate the distance between the individual elements of the array.

17. A Uniform linear array consists of 16 isotropic sources with a spacing of half wavelength

and phase difference of . Calculate HPBW and aperture.

18. The main lobe width of 8 elements of BSA was observed to be 450 at a frequency of

20MHz. estimate the distance if N=8.

ASSIGNMENT – 10

19. An EFA is composed of elements with the axis at right angles to the line of the array is

required to have a power gain of 20. Calculate the array length and width of the major

lobe between the nulls.

20. Calculate the exact and approximate BWFN for BSA, given n=4 and d= λ/2.

21. A BSA operating at 200cm wavelength consists of 4 dipoles spaced λ/2 apart and having

Rr=73 ohms. Each element carries radio frequency in same phase and has an amplitude

of 0.5A. Calculate Radiated Power and BPBW.

22. Complete the field pattern and find BWFN and HPBW for a linear uniform array of 6

isotropic sources spaced λ/2. Assume the power applied to be equal in amplitude and in

phase.

23. An array of 4 isotropic antennas is placed along a straight line. Distance between the

elements is λ/2. The peak is to be obtained in the direction from the axis of the array.

What should be the phase difference between the adjacent elements? Compute the

pattern and find BWFN and HPBW.