Antenna & Wave Propogation — Winter 2021

Write the different definitions of antenna. State and prove reciprocity theorem to antennas.

Define the following terms.(draw necessary figures and write equations if any)

Antenna efficiency ii) Radiation pattern iii) Gain and Directivity iv) FNBW and HPBW

Discuss

Dolph–Tchebysheff distribution for linear arrays. ii) Binomial arrays.

Derive an expressions for electric and magnetic components of a short dipole antenna if the spherical system is defined in r, θ and ϕ.

Derive an expression for radiation resistance of short dipole for far-field region. Prove that radiation resistance of half wave dipole antenna is 73 Ω.

Explain - Pattern Multiplication and show that it can be used to find the resultant pattern of a linear array.

Sketch the helical geometry with its associated dimensions showing relationship between circumference, spacing, turn length and pitch angle of helix. Also discuss different types of radiation modes

What is the importance of parabolic structure in antenna? Explain Casegrain feed method of parabolic reflector antenna.

Explain and design 3-element yagi-uda antenna.

In far field, for a small loop antenna derive field equations. Also derive radiated power resistance equation.

Explain Babinet’s Principle. Discuss it for complementary antenna.

Enlist the different types of lens antenna and explain in brief.

Explain measurement of radiation pattern antenna under test.

Explain the Different modes of Radio wave propagation.

Define the following terms.(draw necessary figures)

Skip distance (ii) Super refraction iii) Virtual height1

Give the geometry and discuss the performance of a Log periodic antenna. Derive the associated design equations.

Explain different types of horn antennas.2