Antennas and wave Propagation (EC-602) - Important Questions

What is retarded potential, how does it account for finite propagation speed, how does it differ from static potential, and why is it important for radiation / antenna theory?

Derive the radiated electric and magnetic field components of an alternating current element / oscillating electric dipole.

Explain the working principle of a quarter-wave monopole antenna, derive the radiation pattern expression, and discuss its applications.

Explain the directional characteristics / properties of dipole antennas.

Explain the effect of ground conductivity and permittivity (earth) on the vertical radiation patterns of antennas.

Define antenna gain, classify its types, and explain the relation between gain, directivity, efficiency and effective aperture.

Explain linear antenna arrays. Derive the array factor for an N-element uniform linear array and discuss the effect of spacing, amplitude and phase on the radiation pattern.

Explain the construction, operation, characteristics and radiation pattern of a Yagi-Uda antenna, including the roles of reflector and directors and its use for TV reception.

Explain the construction and working principle of a log-periodic antenna and how its structure enables wideband operation.

Explain the construction, axial and normal modes, radiation pattern and applications of a helical antenna.

Define and explain MUF, LUF and skip distance in sky wave propagation and their relevance to long-distance communication.

Explain the variation of field strength with height in space wave propagation and discuss the phenomenon of super-refraction and its effect on signal transmission.

Explain the construction and radiation mechanism of a microstrip antenna along with its advantages and disadvantages.

Describe slot antennas and derive the radiation pattern of a rectangular slot in an infinite ground plane.

Write short notes on any two of the following: (i) Tropospheric scattering and its effect on radio wave propagation (ii) Modes of propagation - ground, sky and space wave (iii) Effects of environment on radio wave propagation.