solution for rf modelling and antennas(a) a radio link has 15 watt transmitter connected to an...

Mumbai University EXTC (Semester -V)

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Solution for RF Modelling and Antennas

May 2016

Index

Q.1)

a) …………………………………………………………………………. 2-3

b) …………………………………………………………………………. 4-5

c) …………………………………………………………………………. 5-7

d) …………………………………………………………………………. 8

Q.2)

a) …………………………………………………………………………. 9-12

b) …………………………………………………………………………. 13-14

Q.3)

a) …………………………………………………………………………. 14-15

b) …………………………………………………………………………. 15-19

Q.4)

a) …………………………………………………………………………. 19-21

b) …………………………………………………………………………. 21-25

Q.5)

a) …………………………………………………………………………. 25-29

b) …………………………………………………………………………. 29-33

Q.6)

a) …………………………………………………………………………. 34-35

b) …………………………………………………………………………. 36- 39

c) ………………………………………………………………………….39-40

d) …………………………………………………………………………. 40-41



Q 1) Attempt All (20)

(a) Explain the hazards of Electromagnetic Radiation.

Ans :- Electromagnetic Radiation (EM Radiation or EMR)

Biological effects :-

a) Thermal effects :-



b) Non – thermal effect :-

c) Dosimetry :-



(b) Explain the radiation mechanism of antenna with single wire system.

Ans :- single wire as a Source of Radiation



(c) Explain the use of Richard transformation and Kuroda’s Identity in RF filter

design. Ans :- Filter Implementation



Richard’s Transformation :-

Kuroda’s Identities :- a) Unit Elements



b) Use of Kuroda’s Identities :-



(d) Derive an expression for array of two isotropic sources with same amplitude and in phase. (05)

Ans :-



Q2) (a) Explain the RF behaviour of resistor, capacitor and inductor. (10)

Ans :- (A) RF behaviour of resistor

(i) Carbon Composition Resistor

Electrical Equivalent :-



(ii) Wire Wound Resistor :-




(iii) Metal Film Resistor :-

(ii) Thin Film Chip Resistor :-

(B) RF Behaviour of a Capacitor



(C) RF Behaviour of a Inductor :-




(b) Discuss the design procedure for filter using image parameter method.(10) Ans :- Image Parameter Method

Image Impedances (Zi )

Image Impedances in terms of ABCD Parameters :-



Q3) (a) Design a maximally flat LPF with a cut off frequency of 2GHz.The generator

and load impedance is 50Ω with 15 dB insertion loss at 3 GHz with discrete LC components. (10)



Ans :-

Applying both impedance and frequency transformation :-

(b) Derive an expression for array factor of N element linear array, where all

elements are equally fed and spaced. Also find the expression for the



position of principle maxima, nulls and secondary maxima. (10)

Ans :-

a) Expression for Field :-



b) Array Factor :-



c)

d)



Q4) (a) A radio link has 15 watt transmitter connected to an antenna of 2.5 m2

effective aperture at 5 GHz .The receiving antenna has an effective aperture of 0.5 m2 and is located at 15 km line of sight distance from transmitting antenna .Assume lossless antennas .Find power delivered to the receiver.



Ans :-



(b) Derive an expression for E field and H field of infinitesimal dipole antenna. Ans :-



Q5) (a) What is the folded dipole antenna ? Draw its typical structure and explain

working mechanism .Give its advantages. Ans :



(b) What is Dolph-Chebyshev array? Explain the steps involved in design of

Dolph-Chebyshev array. (10)

Ans :-



Q6) (a) Ground effects on Antenna . Ans :-



(b) Log periodic Antenna .

Ans :-



(c) Loop antenna. Ans :-



(d) Horn antenna. Ans :-

solution for rf modelling and antennas(a) a radio link has 15 watt transmitter connected to an...

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