Electronics and Communication Engineering - Microwave Communication

26. 

For a circular wave guide

A. cutoff frequency for TE10 and TE01 modes are same
B. cutoff frequency for TE10 and TE01 modes are different
C. cutoff frequency for TE10 mode = twice the cutoff frequency for TE20 mode
D. cutoff frequency for TE10 mode = haf the cutoff frequency for TE20 mode

Answer: Option A

Explanation:

When a circular waveguide is rotated by 90°, the configuration remain the same.


27. 

In the given figure the reflected voltage wave after first reflection is

A. 18 V
B. -18 V
C. 30 V
D. -30 V

Answer: Option B

Explanation:

.


28. 

Assertion (A): A half wavelength line can be used as a 1 : 1 transformer.

Reason (R): The input impedance of a half wavelength line is equal to load impedance.

A. Both A and R are correct and R is correct explanation of A
B. Both A and R are correct but R is not correct explanation of A
C. A is correct but R is wrong
D. A is wrong but R is correct

Answer: Option A

Explanation:

Since a half wavelength line has an input impedance equal to load impedance, the impedance transformation ratio is 1:1.


29. 

The magnitudes of OC and SC input impedances of a transmission line an 100 Ω and 25 Ω. The characteristic impedance is

A. 25 Ω
B. 50 Ω
C. 75 Ω
D. 100 Ω

Answer: Option B

Explanation:


30. 

A loss less line is terminated in a circular lines are E lines

A. SWR = 0
B. SWE = 0
C. SWR is finite
D. SWR = ∞

Answer: Option C

Explanation:

= finite number and VSWR = finite number.