6. a) Derive the self and mutual impedance of two parallel Centers driven coupled
(4.5) dipole antennas.

b) Design an aperture antenna, with uniform illumination, so that the directivity is
maximized at an angle 30° from the normal to the aperture. Determine the

optimum dimension and its associated directivity when the aperture is

(4.5)
a) square
b) circular
Part C
7. a) Calculate the half-power beam width and directivity for the DolphTscebyscheff array
of lobe ratio 2608 for a spacing of between the (6) elements.
b) Derive the array factor of 90 °corner reflector. (6)

8. Why equiangular spiral antenna and log periodic antennas are called frequency independent

antennas. Explain their working. (12)

9. Design a broadside Dolph-Tschebyscheff array of 10 elements with spacing d between the
elements and with a major to minor lobe ratio of 26dB. Find the (12) excitation
coefficients and form the array factor.

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