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RF Modelling and Antennas : Question Paper May 2013 - Electronics & Telecomm. (Semester 5) | Mumbai University (MU)
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## RF Modelling and Antennas - May 2013

### Electronics & Telecomm. (Semester 5)

TOTAL MARKS: 80
TOTAL TIME: 3 HOURS
(1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Assume data if required.
(4) Figures to the right indicate full marks.
1 (a) Draw the lumped element circuit model for a transmission line. Derive the expression for voltage and current travelling waves.(5 marks) 1 (b) Explain simplified Ebers-Moll model for forward active mode of a transistor.(5 marks) 1 (c) Explain current flow in p-n junction and give the expression for Idiff in terms of diffusion constant and Vdiff in terms of doping concentration. (5 marks) 1 (d) Discuss terminations used for microstrip lines.(5 marks) 2 (a) Prove the first three Kuroda s Identities by computing appropriate ABCD matrices. (10 marks) 2 (b) Explain construction and functionality of HEMT. (10 marks) 3 (a) Discuss power considerations in transmission line when
i) Source and Load impedances are matched
ii) Load impedance is matched and source mismatched.
(10 marks)
3 (b) Explain with equivalent circuits the RF behavior of resistor,inductor and capacitor. (10 marks) 4 (a) Explain Insertion loss, Ripple factor and bandwidth in relation to filter design. Why ideal filter response cannot be realised?(10 marks) 4 (b) if Z0=50Ω, plot the following impedances on Smith Chart.
23+j42Ω, 12-j109Ω, 72+j42.5Ω & 115-j22Ω