Microwave Engineering Lab Viva Questions 5

1. If all ports of a lossless reciprocal junction is matched, the device must work as a

a) Magic Tee

b) Directional Coupler

c) Either a or b

d) Cannot be specified

Answer : [c] Either a or b

2. A Wilkinson power divider is designed with a quarter wave line having characteristic impedance 50 Ohm. What should be the value of the shunt resistance?

a) 100

b) 50

c) 141.42

d) 70.71

Answer : [d] 70.71

3.

(i) The output impedance of any Wilkinson power divider will be the input characteristic impedance Z0

(ii)Isolation is possible between all the output ports of N-way Wilkinson power divider.

a) Only (i) is true

b) Only (ii) is true

c) Both (i) and (ii) are true

d) Both (i) and (ii) are false

Answer : [b] Only (ii) is true

4. In a switch, the DC block should have _____ impedance and the RF choke should have ____ impedance at high frequency

a) Very Low, Very High

b) Very High, Very Low

c) Very Low, Very Low

d) Very high, Very high

Answer : [a] Very Low, Very High

5. A PIN diode shunt switch having forward resistance Rd is installed on a line with characteristic impedance Z0. The insertion loss due to the switch is

Answer : -20 log (2Zd/(2Z0+Zd))

6. If a directional coupler is fed from port 1 the directivity D of the coupler is the

Answer : 10 log (P3/P4)

7. For an unequal Wilkinson-type power divider with a power ratio K:1 the value of the shunt resistance is

Answer : Z0(K+(1/K))

8. The relation between coupling(C) , directivity(D) and isolation(I) of a directional coupler is

a) D=C-I

b) I=C-D

c) C=I-D

d) C=D+I

Answer : [c] C=I-D

9. Wilkinson-type power divider is

a) Lossless and Reciprocal

b) Matched at all ports and Reciprocal

c) Reciprocal and Lossless

d) Lossless, Reciprocal and matched at all ports

Answer : [b] Matched at all ports and Reciprocal

10. Which one of the following devices is frequency dependent?

a) Magic T

b) Directional coupler

c) Wilkinson Power divider

d) None of these

Answer : [a] Magic T