Propagation and Antenna

Define an antenna. Explain the radiation mechanism and conditions of a single wire antenna that can radiate electromagnetic waves or not.

State the reciprocity theorem and compensation theorem for an antenna system.

Write short notes on: (Any Three) [3x3] (a) Retarded time (b) Patch antenna (c) Radio duct (d) Knife edge diffraction

What are broadside and endfire arrays? Derive an expression for the total field in case of two isotropic point sources with equal amplitude and opposite phase.

What are broadside and endfire arrays? Derive an expression for the total field in case of two isotropic point sources with equal amplitude and opposite phase.

Define the following antenna parameters: (a) Fractional Bandwidth (FBW) (b) Power flux density (PFD)

Explain the following antenna parameters with necessary derivations: (a) Fractional Bandwidth (FBW) (b) Antenna Gain (G)

List the main characteristics of UHF band. Explain the construction, working principle and characteristics of Log-periodic antenna with necessary diagram.

Explain the working principle, construction, advantages and application of V antenna. Sketch radiation patterns of both types of V antennas.

What is a travelling wave antenna? Draw the structure, radiation pattern and explain the working function of an axial mode helix antenna.

Design a 5 element Yagi-Uda antenna for receiving UHF band of frequency range from 540 MHz to 548 MHz Assume the driven element is a half-wave folded dipole and take spacing between elements $0.15{\lambda }_c$.

What are the major features of corrugated horn antenna? How does a helical antenna radiate in axial mode? Explain with necessary diagrams.

Sketch the current distribution and radiation pattern of center fed vertical dipole for following lengths.

Define a critical frequency $f_{(CRT)}$. Derive an expression for the relation between skip distance and maximum usable frequency ($f_{MUF}$) in SW propagation assuming that the Earth is Flat.

What is a direct wave propagation? Explain the different factors that affect the space wave propagation.

Describe space wave propagation and derive the expression for the maximum line-of-sight (LOS) distance between transmitting and receiving antennas.

List the major characteristics of MW and VHF radio propagation system.

A parabolic reflector antenna having the antenna efficiency $85\%$ is designed for $3\text{ GHz}$ resonant frequency with $2.5\text{ dB}$ wavelength loss. Find out the antenna diameter if effective isotropic radiated power (EIRP) is calculated $46\text{ dBW}$ and transmitting power is $500\text{ watt}$.

Derive the Friis transmission equation and find out the free space path loss from the equation that is equal to $22+20\log (R/{\lambda }_c)$ in dB where $R$ is distance between transmitting and receiving antennas and ${\lambda }_c$ is wavelength of the frequency being used.

A ground station located at $42.7^{\circ }$ N latitude and $108.3^{\circ }$ E longitude need to establish a Ku-band uplink to a GEO satellite positioned at $128^{\circ }$ E longitude. The satellite's receiver has a G/T of $4.8$ dB/K and the desired $C/N_o$ is $107$ dBHz. The ground station employs a parabolic antenna with a diameter of $7.8$ m, $a^n$ antenna efficiency of $75\%$ and waveguide loss of $1.6$ dB. Determine the minimum transmit power that the ground station must provide to achieve the required $C/N_o,accounting$ for the actual Earth-satellite slant distance.

Derive the Friis transmission equation for free space communication and also find out free space loss for 6 GHz and 14 GHz frequencies for 36,500 km line-of-sight distance (R).

Explain the principle of light propagation through a fiber with necessary diagrams. Derive the relation between numerical aperture and acceptance angle.

Write short notes on: (any four) [4x3] a) Marconi Antenna b) Friis equation and path loss in case of free space propagation c) Knife edge diffraction phenomenon d) NA for meridional rays in optical fiber e) Radio frequency spectrum

Define attenuation in optical fiber communication. Explain the different types of attenuation and discuss the main factors that affect it.

Write short notes on: Knife edge diffraction

Derive the formula to establish the relationship between maximum usable frequency ($f_{MUF}$) and skip distance (D) assuming earth is flat.

Explain the construction, working principle and characteristics of Log-periodic antenna with necessary diagram.

What is a linear array? Differentiate between a broadside array and end firearray.

List the main properties of antenna. Explain the major required conditions for a simple conductor to be a good antenna.

State the reciprocity theorem and compensation theorem for an antenna system.

What is a travelling wave antenna? Explain the working principle and main features of V-antenna with necessary diagrams.

Define a critical frequency $f_{(CRT)}$. Derive an expression for the relation between skip distance and maximum usable frequency ($f_{MUF}$) in SW propagation assuming that the Earth is Flat.

Write short notes on (Any Two): [2x2] (a) Smart Antennas (b) Duct propagation (c) Knife edge diffraction

Explain the construction, working principle and characteristics of Log-periodic antenna with necessary diagram.

A parabolic reflector antenna having the antenna efficiency $85\%$ is designed for $3\text{ GHz}$ resonant frequency with $2.5\text{ dB}$ wavelength loss. Find out the antenna diameter if effective isotropic radiated power (EIRP) is calculated $46\text{ dBW}$ and transmitting power is $500\text{ watt}$.