Question 1
A major disadvantage of the lossless T-junction power divider is:
A. Not matched at all the ports
B. Low power output
C. Complex construction
D. None of the mentioned
View Answer
Answer: Option A
Explanation:
A T-junction hybrid cannot be matched at all the ports if the power divider is lossless. It can be matched only at 2 ports. This is one of the major disadvantages when they are to be used along with other microwave devices.
Question 2
A Wilkinson coupler designed can be operated at any frequency.
A. TRUE
B. FALSE
View Answer
Answer: Option B
Explanation:
The length of the branches of a Wilkinson coupler is all wavelengths dependent and hence Wilkinson coupler designed to operate at one frequency cannot be used to operate at another frequency.
Question 3
For an equal-split Wilkinson power divider of 50Ω system impedance, the characteristic impedance of quarter wave transmission line used is:
A. 70.7 Ω
B. 50 Ω
C. 100 Ω
D. None of the mentioned
View Answer
Answer: Option A
Explanation:
The characteristic impedance of a Z Ω system is given by √2*Z. hence, the characteristic impedance of 50Ω system is 70.7 Ω.
Question 4
If 10 watt is applied to the input port of a standard Wilkinson divider, then the sum of the power measured at the two output ports of the Wilkinson coupler is
A. 5 watt
B. 10 watt
C. 7.07 watt
D. 8 watt
View Answer
Answer: Option C
Explanation:
For a standard Wilkinson coupler, the output power is 3 dB less than the total input power in decibels. That is, 70.7% of the total input power is delivered to the output port.
Question 5
S12 curve of a Wilkinson coupler when plotted versus frequency is a line passing through origin.
A. TRUE
B. FALSE
View Answer
Answer: Option B
Explanation:
S12 gives the ratio of power at input port P1 to the power measured at port 2. Since the output power remains constant over a wide range of frequencies for a given input applied. Hence S11 is a curve parallel to X axis.
Question 6
The analysis of Wilkinson coupler is done using:
A. Even-odd mode analysis
B. Symmetry
C. S matrix approach
D. None of the mentioned
View Answer
Answer: Option A
Explanation:
Even-odd mode analysis is one of the simplest methods of analysis for Wilkinson coupler. This involves normalizing all impedances with the characteristic impedance of the transmission line used and carrying out some analysis.
Question 7
The plot of frequency v/s S11 parameter of a Wilkinson coupler has a dip at the frequency at which it is designed to operate.
A. TRUE
B. FALSE
View Answer
Answer: Option A
Explanation:
S11 parameter signifies the fraction of the power reflected back to port 1 when power is applied to port 1 of the coupler. Since the ports are matched at the frequency of design S11 is minimum and the curve has a dip.
Question 8
The plot of S23 v/s frequency has the same curve as that of S11 v/s frequency.
A. TRUE
B. FALSE
View Answer
Answer: Option A
Explanation:
When input is applied to port 1, output is measured at port 2 and port 3. S23 signifies the output at port 3 due to port 2 when input is applied at port 1. This parameter is minimum at the designed frequency.
Question 9
The Wilkinson power divider is a:
A. 2 port network
B. 3 port network
C. 4 port network
D. None of the mentioned
View Answer
Answer: Option B
Explanation:
Wilkinson power divider is a 3 port network; if it is used as a divider it has one input port and 2 output ports. If it is used as coupler, it has two input port and one output port.
Question 10
Wilkinson power divider is an equal split power divider.
A. TRUE
B. FALSE
View Answer
Answer: Option B
Explanation:
Wilkinson power divider can be used to divide power in any ratio, but the most commonly used configuration is the equal split power divider.