Electronics and Communication Engineering - Microwave Communication

21. 

Which of the following parameters is negligible in transmission lines?

A. R
B. L
C. C
D. G

Answer: Option D

Explanation:

Shunt conductance can be neglected in most of calculations.


22. 

The width of a radio beam from a 1 m diameter parabolic antenna at 10 GHz is about

A. 100°
B. 50°
C.
D.

Answer: Option C

Explanation:

.


23. 

The diagram to show distance time history of electrons in klystron amplifier is called

A. apple gate diagram
B. asynchronous diagram
C. bunching diagram
D. velocity modulation diagram

Answer: Option A

Explanation:

Applegate diagram is distance time plot.


24. 

Impedance level of Impatt diodes is generally lower than that of Gunn diodes

A. True
B. False

Answer: Option A

Explanation:

An Impatt diode has n+ - p - i - p + structure and is used with reverse bias.

It exhibits negative resistance and operates on the principle of avalanche breakdown.

Impatt diode circuits are classified as broadly tunable circuit, low Q circuit and high Q circuit.

The impedance of Impatt diode is a few ohms. The word Impatt stands for Impact Avalanche Transit Time diode.

The features of Impatt diode oscillator are : frequency 1 to 300 GHz, Power output (0.5 W to 5 W for single diode circuit and upto 40 W for combination of several diodes), efficiency about 20%.

Its applications include police radar systems, low power microwave transmitter etc.


25. 

A quarter wave line open circuited at far end behaves as

A. inductance
B. L and C in parallel
C. capacitance
D. L and C in series

Answer: Option D

Explanation:

A quarter wave line o.c. at far end behaves as a series tuned circuit.