**CS/B.Tech/Even/ECE/6th Sem/EC-604A/20142014**

Antenna Theory & Propagation

Time Allotted: 3 Hours Full Marks : 70

The figures in the margin indicate full marks.

Candidates are required to give their answers in their own words as far as practicable.

GROUP – A

(Multiple Choice Type Question)

1. Choose the correct alternatives for any ten of the following: 10x1=10

i) The induction field of short current element varies as

a) 1/

b) 1/r

c) 1/

d)

ii) The radiation resistance of a/2 antenna in free space is given by

a) 377 ohms

b) 73 ohms

c) 36.5 ohms

d) None of these

iii) Fields are said to be elliptically polarized if their magnitudes are

a) Equal & they are in phase

b) Equal & they differ in phase by

c) Unequal 7 they differ by

d) Not equal but they are in phase

iv) The current distribution in half-wave dipole is

a) Constant

b) Sinusoidal

c) Triangular

d) None of these

v) An antenna has a gain of 40db at a frequency of 300 Mhz.The effective area of the antenna in

square meter is

a) 796

b) 10000

c) 2500

d) 3183

vi) Circularly polarized antenna is

a) Dipole

b) Helical