B.TECH - Semester 6 antenna and wave propagation Question Paper 2019 (jun)
Practice authentic previous year university questions for better exam preparation.
Sample Questions
- Define radiation resistance. Derive the expression for radiation resistance of short dipole.
- Define directivity. Derive the expression for directivity.
- A thin dipole antenna is $\lambda / 15$ long. If its loss resistance is $15 \Omega$, find the radiation resistance and efficiency.
- Derive the expression for electric field intensity of array of two isotropic point sources of equal amplitude and phase.
- Write a note on binomial arrays.
- Compare V antenna and inverted V antenna.
- Explain with necessary diagram principle of operation of parabolic dish antenna.
- What is critical frequency. Derive the expression for it.
- Explain skip distance.
- A high frequency radio link has to be established between two points at a distance of 2500 km on earth's surface. Considering the ionospheric height to be 200 km and its critical frequency 5 MHz , calculate the MUF for the given path. ( $\mathbf{1 0}...
- Derive the expression for electric field and magnetic field due to short dipole. 10
- (a) Explain far field and near field regions of an antenna. 5
- (b) Define radiation resistance, Derive the expression for radiation resistance of short dipole. 5
- (a) A transmitting antenna having an effective height of 61.4 metres, takes a current of 50 Amp at a wavelength of 625 metres. Find
- (i) Radiation resistance (ii) Power radiated (iii) Antenna efficiency for a total antenna resistance of $50 \Omega$.
- (b) Explain the following terms of an antenna
- (i) Effective area (ii) Effective length Module - II
- Design a 8 element broadside array of isotropic sources of $\lambda / 2$ spacing between elements. The pattern is optimum with a side lobe 26 dB down the main lobe maximum.
- Derive the expression for electric field due to array of $n$ isotropic point sources of equal amplitude and spacing fed by same phase. Draw radiation pattern also.
- Explain with neat diagram Helical antenna and its modes of operation.
- Define virtual height and MUF. Derive the expression for both. 10
- (a) Explain duct propagation in detail. 6
- (b) Write a note on VLF and ELF propagation in sea water. 4
- (a) Explain ionospheric abnormalities in detail. 7
- (b) Calculate the value of frequency at which electromagnetic wave must be propagated through the D-region with an index of refraction of 0.5 and an electron density of $3.24^{*} 10^{4}$ electrons $/ \mathrm{m}^{3}$.