Andhra University 2007 B.E Microwave Engineering - Question Paper

First ques. is compulsory
ans any 4 out of the remaining ques.
All ques. carry equal Marks
1)
a)List any 2 applications of Mixer.
b)what is Re-entrant cavity?
c)Give the principle of working of Magnetron
d)List any 2 properties of scattering matrix
e)List any 2 Fabrication techniques used for MIC
f)what is LSAmode of operation in a GUNN diode?
g)State any 2 applications of Tunnel diode.

2
a)what is magic tree?explain
b)An air filled circular wave guode has a radius of 3cm and is used as a respmatpr fpr TEo.,mode at 10GHz by placing 2 perfectly conduction plates at its 2 ends. Determine the minimum distance ranging from the 2 end planes.

3)
a)Describe the advantages and disadvantages of parameteric devices.
b)A KV-band IMDTS diode has a pulsed operating voltage of 100v and a pulsed operating current of 0.9 A. The efficiency is about 10%.Calculate
i)the o/p power
ii) The duty cycle if the pulse width is 0.01 ns and the frequency is 16GHz.

4)a)A reflex Klystron operates at the peak mode of n=2 with beam voltage:V0=300V m beam current ofI0=20mA; signal voltave(V1)=40V. Determine
i)the i/p powe in watts
ii)the o/p power in watts
iii)the efficiency

b)Describe the principle and operation of a normal circular magnetron and lists its characteristics.

5)
a) Derive 'S' matrix for a directional coupler
b)A GaAs MOSFET balanced amplifier with 2 large couplers gas the subsequent parameters
Sparameters S11a=S11b
S22a=S22b
i/p signal power Pin=200mW
power gain of every GaAs chip . Gain =10dB.Determinei)i/p GOIP USWR ii)the o/p power in watts iii)the linear o/p power gain in dB

6)
a) List the basic characteristics needed for an ideal substrate material in the case of MICs
b)Describe the basic fabrication techniques used for MIC:epitaxy , diffusion, deposition and etching

7)a)Explain how do you measure VSRW<10
b)How directivity is measured and discuss with the help of a neat sketch?

8)write short notes on any 3 of the following:
a)frequency measurement
b)Tunnel diode
c)microwave filters
d)any 2 microwave applications

Earning:   Approval pending.