JNTU B.Tech III ANTENNAS AND WAVE PROPAGATION Previous Question Paper (May/June - 2019 - R13)

Define reciprocity theorem applicable to antennas.

A directional antenna requires to radiate 200W where as the isotropic antenna requires to radiate 2.6kW to produce the required power density at the receiver. Find the directive gain of directional antenna.

Derive the radiation characteristics of horn antenna.

Explain the tuning mechanism and bandwidth variation in Yagi Uda antenna.

Discuss about various types of microstrip antenna.

Differentiate deep dishes from the shallow dishes. List their relative merits and demerits.

What are the advantages of Binomial Array?

An EFA composed of λ/2 radiators with axis at right angles to the line of array required to have a power gain of 20. Determine the array length and width of major lobe between the nulls.

What is horizon? Differentiate between radio horizon and optical horizon.

Explain the mechanism by which waves are bent back by ionosphere layer with the aid of snells law.

Define the effective length of a linear antenna for transmitting. Upon what factors does it depend?

Assume a sinusoidal current distribution on a centre fed thin straight half wave dipole. Derive the equations of all field components.

A thin dipole is λ/15 long. If it has a loss resistance of 1.5Ω calculate its (i) Directivity (ii) Effective aperture area (iii) Beam solid angle (iv) Radiation resistance (v) Gain

Derive the expressions for radiation fields of half wave dipole. Using these expressions find the total power radiated by it.

Draw the sketch of Yagi Uda antenna and sketch the E-pane and H-lane radiation patterns.

Describe the current distribution and radiation pattern of a folded dipole antenna. Find the input impedance of folded dipole and explain why the antenna has higher bandwidth.

Derive the construction and basic principles of operation of a helical antenna under (i) Normal mode of operation (ii) axial mode of operation

A 10 turn right handed helical antenna has a diameter of 100 mm and 70 mm turn spacing. It is being operated at 1GHz. Find the HPBW, gain, polarization state.

Explain the principle of operation of cassegrain feed with neat sketches.

Differentiate flat sheet and corner reflector antennas.

Explain the transmission model analysis of microstrip antenna.

Design a rectangular microstrip antenna using RT Duroid substrate with dielectric constant of 2.2, h=0.15cm so as to radiate at 10GHz.

What is BSA? What are the conditions to achieve it? Derive the expression for directivity.

Consider a two element linear array. Derive the expression for electric field. Plot the radiation pattern by performing case study for different phase shift of currents fed to the elements.

Derive Friss transmission formula. Explain its importance in antenna measurement.

Describe various techniques for antenna gain measurement.

Distinguish between ground wave propagation and ionospheric propagation.

Explain the following terms with diagrams (i)Duct propagation (ii) Skip zone.

Calculate the transmission path distance for an ionospheric transmission that utilize a layer of height 200km. The angle elevation of antenna beam is 200. Earth radius can be around 6370km.

Write a note on tropospheric propagation.