1. a) Define the following antenna terminologies.
i) Antenna field zones
ii) Effective height
iii) Effective Aperture
08
b) Determine the directivity of the following source.
i) u = um cos3 θ
ii) u = um
sin θ sin2ф
06
c) Determine the effective aperture and directivity of a linear λ/2 dipole Antenna.
06
2. a) Derive an expression for the resultant field of an array of N isotropic source and obtain the
condition for operating it as
i) Broad side array
ii) End fire array
08
b) Explain the concept of principle of pattern multiplication with an example.
06
c) Obtain the field equation for a linear uniform array of 6 isotropic point sources spaced λ/2
distances apart. The power is applied with equal amplitude and in phase. Also find FNBW.
06
3. a) Derive an expression for the field components of a short dipole starting with expressions of
electric potential and vector magnetic potential. Also determine the far field components.
12
b) Determine the radiation resistance of a λ/2 dipole.
08
4. a) Derive the expression for the field strength E ф and H θ in far field for small loop.
08
b) Explain Bobinet’s Principle with illustration.
05
c) Write note on patch or micro strip antenna. 07
PART-B
5. a) Explain the following design parameters of a helical antenna.
i) Beam width
ii) Axial ratio
iii) Impedance
06
b) Design a yagi- uda Six element antenna for operation at 500 MHZ with folded dipole feed.
What are the lengths of
i) Reflector element
ii) Driven element
iii) Four director element
iv) Between reflector and driven element
v) Between director element.
06
c) Explain the working of log periodic antenna.
6. a) Explain the working of corner reflector and plasma Antenna with figure.
10
b) Explain the antennas used for terrestrial mobile communication system.
10
7. a) An Antenna located at the surface of the earth is used to receive the signals transmitted by
another antenna located at a height of 80mt from the spherical surface of the earth.
Calculate the optical and radio horizon if =-39/kmt .
06
b) In tropospheric propagation, show that radius of curvature of path is a function of the rate
of change of dielectric constant with height and explain the duct wave propagation.
08
c) Explain the ground wave propagation by means of
i) Surface waves
ii)Diffraction
06
8 a) For ionospheric layers, derive the expression for conductivity and relative permittivity as a
function of electron density and angular frequency.
08
b) Define the terms
i) Critical frequency fC
ii) Skip distance Dskip
iii) Maximum usable frequency fMUF. Obtain the relation for Dskip in term of fC and fMUF.
08
c) Ionospheric wave is reflected from E layer with virtual height 100kmt and from F layer with
virtual height 300kmt. Determine the single-hop distance for each layer
i) Antenna field zones
ii) Effective height
iii) Effective Aperture
08
b) Determine the directivity of the following source.
i) u = um cos3 θ
ii) u = um
sin θ sin2ф
06
c) Determine the effective aperture and directivity of a linear λ/2 dipole Antenna.
06
2. a) Derive an expression for the resultant field of an array of N isotropic source and obtain the
condition for operating it as
i) Broad side array
ii) End fire array
08
b) Explain the concept of principle of pattern multiplication with an example.
06
c) Obtain the field equation for a linear uniform array of 6 isotropic point sources spaced λ/2
distances apart. The power is applied with equal amplitude and in phase. Also find FNBW.
06
3. a) Derive an expression for the field components of a short dipole starting with expressions of
electric potential and vector magnetic potential. Also determine the far field components.
12
b) Determine the radiation resistance of a λ/2 dipole.
08
4. a) Derive the expression for the field strength E ф and H θ in far field for small loop.
08
b) Explain Bobinet’s Principle with illustration.
05
c) Write note on patch or micro strip antenna. 07
PART-B
5. a) Explain the following design parameters of a helical antenna.
i) Beam width
ii) Axial ratio
iii) Impedance
06
b) Design a yagi- uda Six element antenna for operation at 500 MHZ with folded dipole feed.
What are the lengths of
i) Reflector element
ii) Driven element
iii) Four director element
iv) Between reflector and driven element
v) Between director element.
06
c) Explain the working of log periodic antenna.
6. a) Explain the working of corner reflector and plasma Antenna with figure.
10
b) Explain the antennas used for terrestrial mobile communication system.
10
7. a) An Antenna located at the surface of the earth is used to receive the signals transmitted by
another antenna located at a height of 80mt from the spherical surface of the earth.
Calculate the optical and radio horizon if =-39/kmt .
06
b) In tropospheric propagation, show that radius of curvature of path is a function of the rate
of change of dielectric constant with height and explain the duct wave propagation.
08
c) Explain the ground wave propagation by means of
i) Surface waves
ii)Diffraction
06
8 a) For ionospheric layers, derive the expression for conductivity and relative permittivity as a
function of electron density and angular frequency.
08
b) Define the terms
i) Critical frequency fC
ii) Skip distance Dskip
iii) Maximum usable frequency fMUF. Obtain the relation for Dskip in term of fC and fMUF.
08
c) Ionospheric wave is reflected from E layer with virtual height 100kmt and from F layer with
virtual height 300kmt. Determine the single-hop distance for each layer
No comments:
Post a Comment