Anna University Chennai 2005 B.E Electronics & Tele-Communication Engineering ./B.TECH :MICROWAVE ENGINEERING - Question Paper

B.E./B.TECH.DEGREE exam ,NOV/DEC 2005
VII -SEMESTER
MICROWAVE ENGINEERING

TIME :3 hrs
MAX MARKS :100


PART -A (10 X two = 20 MARKS)


1. Write down the ABCD parameters of a lossless transmission line.

2. State the 'PHASE SHIFTING' property of S- parameters

3. Stae the 2 parameters that define a directional coupler. describe them

4. compute the attenuation of a rotary vane attenuator if the angle of roatation is 34 degrees

5. What is TUNING with respect to microwave oscillators ? Name them

6. Drw the electronic admittance spiral of REFLEX KLYSTRON


7. Draw the equivalent circuits of pin diode under (a0 Reverse bias and (b) Forward bias

8. Which 2 phase angle make the voltage and current on A valanche transmit time device to be out of phase by 180 degrees?

9. Why is the SLOT located a the center of the SLOTTED SECTION?

10 elaborate LOW VSWR and HIGH VSWR and name the method followed to measure HIGH VSWR?

PART -B (5 X 16 =80)

11 (i) discuss the method of measuring impedence at microwavr frequencies

(ii) provide the relationship of LOADED and UNLOADED Q of a cavity

12 (a) (i) find the relationship of S parameters in terms of ABCD parameters

(ii) obtain the S parameters of an ideal transformer of turns ratio 1:n

OR
(b) A certain 2 -port microwave junction can be represented by the subsequent equivalent circuit. Determine the susceptance B and the turns ratio n of ideal transformer if the measurements provide S11= -(1 + j )/3 +j ,S22 = 1-j/3 +j


13(a) (i) From the 1st principle ,derive the scatttering matrix of an ideal directional coupler. Hence or otherwise write down [s] matrix of HYBRID COUPLER and MAGIC - T

(ii) What is the value of DIRECTIVITY of an ideal DIRECTIONAL COUPLER ? why?
OR
(b) (i) An isolator, with a charecteristic impedence of 50 ohms has forward and reverse losses of 0.9 dB and 32 dB respectivily. Its input and output VSWR's are 1.09 and 1.16 respectivily when it is terminated by a 50 ohms load. Determine its S parameters. presume zero phase components.

(ii) discuss how the inductances and capacitances can be varied using IRESES and SCREWS (posts)

14 (a) Derive the expression for the gain of a TWT

(b) Derive 'HULL CUT OFF' condition and 'HARTEE' condition of a cavity kind mgnetron

15 (a) (i) Derive 'Manley Rowe Relations '.

(ii) Use the above relations to obtain the poer gain of an UP CONVERTER and a DOWN CONVERTER

OR

(b) Write in detail the principle mechanism of operation and the application of IMPATT diode.

Earning:   Approval pending.