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Microwave Engineering MCQs Set-5

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1. If the characteristic impedance of a transmission line 50 Ω and reflection coefficient is 0.0126+j0.1996, then load impedance is:




2. If the normalized load impedance of a transmission line is 2, then the reflection co-efficient is:




3. The major advantage of single stub tuning over other impedance matching techniques is:




4. Shunt stubs are preferred for:




5. The two adjustable parameters in single stub matching are distance‘d’ from the load to the stub position, and _________




6. In shunt stub matching, the key parameter used for matching is:




7. For series stub matching, the parameter used for matching is:




8. For co-axial lines and waveguides, ________ is more preferred.




9. For a load impedance of ZL=60-j80. Design of 2 single-stub shunt tuning networks to match this load to a 50Ω line is to be done. What is the normalized admittance obtained so as to plot it on smith chart?




10. If the normalized admittance at a point on a transmission line to be matched is 1+j1.47. Then the normalized susceptance of the stub used for shunt stub matching is:




11. After impedance matching, if a graph is plot with frequency v/s reflection co-efficient of the transmission line is done, then at the frequency point for which the design is done, which of the following is true?




12. In series stub matching, if the normalized impedance at a point on the transmission line to be matched is 1+j1.33. Then the reactance of the series stub used for matching is:




13. If D=1.6 and B=2.8 for a 2 port network, then Y₁₁=?




14. The major disadvantage of single stub tuning is:




15. The major advantage of double stub tuning is:




16. In a double stub tuner circuit, the load is of _______ length from the first stub.




17. Double stub tuners are fabricated in coaxial line are connected in shunt with the main co-axial line.




18. Impedance matching with a double stub tuner using a smith chart yields 2 solutions.




19. All load impedances can be matched to a transmission line using double stub matching.




20. The simplest method of reducing the forbidden range of impedances is:




21. Stub spacing that are near 0 and λ/2 lead to more frequency sensitive matching networks.




22. The standard stub spacing usually used is:




23. If the length of the line between the first stub and the load can be adjusted, the admittance can be moved from the forbidden region.




24. A quarter wave transformer is useful for matching any load impedance to a transmission line.




25. Major advantage of a quarter wave transformer is:




26. If a narrow band impedance match is required, then more multi section transformers must be used.




27. The major drawback of the quarter wave transformer that it cannot match complex load to a transmission line cannot be overcome.




28. Complex load impedance can be converted to real load impedance by:




29. Converting complex load into real load for impedance matching has no effect on the bandwidth of the match.




30. If a single section quarter wave transformer is used for impedance matching at some frequency, then the length of the matching line is:




31. Quarter wave transformers cannot be used for non-TEM lines for impedance matching.




32. The reactances associated with the transmission line due to discontinuities:




33. If a load of 10Ω has to be matched to a transmission line of characteristic impedance of 50Ω, then the characteristic impedance of the matching section of the transmission line is:




34. Discontinuities in the matching quarter wave transformer are not of considerable amount and are negligible.




35. The overall reflection coefficient of a matching quarter wave transformer cannot be calculated because of physical constraints.




36. In the multiple reflections analysis method, the total reflection is:




37. If the first and the third reflection coefficients of a matched line is 0.2 and 0.01, then the total reflection coefficient if quarter wave transformer is used for impedance matching is:




38. To compute the total reflection of a multi-section transmission line, the lengths of the transmission lines considered are all unequal.




39. The total approximate reflection coefficient is a finite sum of reflection co-efficient of individual matching section of the matching network.




40. Using the relation for total reflection co-efficient certain designs of matching networks can be made as per practical requirements.




41. The passband response of a binomial matching transformer can be called optimum:




42. The passband response of a binomial matching transformer can be called optimum:




43. If a quality binomial matching transformer gives a good flat response curve, it is called “maximally flat”.




44. The response curve of a binomial matching transformer is plotted for each section of the matching network individually and then analyzed for optimum solution.




45. To obtain a flat curve in the response of a binomial multisection transformer, N-1 derivatives of │Г (θ) │are set to zero. This implies:




46. The condition │Г (θ) │=0 for θ=π/2 of a binomial multi section transformer corresponds to the:




47. In the plot of normalized frequency v/s reflection co-efficient for a binomial multisection filter, the curve has a dip at:




48. As the number of sections in the binomial multisection transformer increases the plot of normalized frequency v/s reflection co-efficient has a wider open curve.




49. A three section binomial transformer is used to match a 100Ω transmission line to a 50Ω transmission line. Then the value of the constant ‘A’ for this design is:




50. The major disadvantage of binomial multi section transformer is higher bandwidth cannot be achieved.