APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
Course Name: MICROWAVE AND ANTENNAS
PART A
1 a) Define Radiation resistance, HPBW, and effective length of an antenna
b) Derive the expressions for far field pattern Electric and Magnetic fields of a short dipole
excited with constant current. Derive expression for directivity of the short dipole antenna.
2 a) Explain antenna temperature.
b) Derive reciprocity theorem for antennas.
3 a) Explain the procedure involved in the radiation gain measurement of antenna
b) Explain how the input impedance of an antenna is measured
PART B
4 Derive expression for array factor of N isotropic sources for end-fire array. Derive expression
for major lobe, minor lobes, and Nulls of the array.
5 a) Design a 5 element Dolph-Chebyshev array with peak side lobe level 19.5dB
b) Explain the working of V antenna
6 a) Explain the working of a parabolic dish antenna. Write down the expression for gain,
HPBW and BWFN
b) Explain the working of a rhombic antenna and it uses.
PART C
7 (a) Explain the working of a log periodic dipole array and explain its design steps.
b) Explain ground wave propagation
8 a) Explain axial mode helical antenna. Write down the expression for gain, HPBW, BWFN
and radiation resistance of axial mode helical antenna.
b) Neglecting the effect of earth’s magnetic field derive expression for refractive index of
ionosphere.
9 Derive expression for line-of-sight distance and received field strength for space wave
propagation
