This set of Microwave Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Dielectric Resonators”.
1. A dielectric material in the form of a small cube or disc can be used as a resonator.
a) true
b) false
View Answer
Explanation: A dielectric material in the form of a small cube or disc can be used as a resonator. It has the same operating principles as that of a rectangular waveguide resonator and a circular waveguide resonator.
2. Dielectric resonators use materials that are less lossy.
a) true
b) false
View Answer
Explanation: Dielectric resonators use materials that are less lossy and have high dielectric constant, ensuring that most of the fields will be contained in the dielectric.
3. The major disadvantage of dielectric resonators is:
a) complex construction
b) field fringing
c) requirement of high dielectric constant
d) none of the mentioned
View Answer
Explanation: The major disadvantage of dielectric resonators is field fringing or leakage from sides and ends of a dielectric resonator. This leakage of field energy results in high loss.
4. One of the most commonly used dielectric materials is:
a) barium tetratetanate
b) titanium
c) teflon
d) none of the mentioned
View Answer
Explanation: Materials having dielectric constant in the range of 10-100 are used in dielectric resonators and one more required characteristic property is low loss. Barium tetratetanate has all these properties. Hence it is most commonly used.
5. The resonant frequency of a dielectric resonator cannot be mechanically tuned.
a) true
b) false
View Answer
Explanation: By using an adjustable metal plate above the resonator, the resonant frequency can be mechanically tuned. As it has these desirable features, it is mostly used in integrated microwave filters and oscillators.
6. If a dielectric resonator has a dielectric constant of 49, then the reflection coefficient of the dielectric resonator is:
a) 0.5
b) 0.75
c) 0.1
d) 0.7
View Answer
Explanation: Reflection co-efficient of a dielectric resonator is given by (√∈r-1)/ (√∈r-1). Given that dielectric constant is 49, the reflection coefficient is 0.75.
7. Q factor does not exist for dielectric resonator.
a) true
b) false
View Answer
Explanation: Q factor exists for a dielectric resonator .it is defined as the ratio of the energy stored in the dielectric to the energy dissipated and other losses that may occur.
8. The approximate loaded Q due to dielectric loss for a dielectric resonator given the loss tangent is 0.0001 is:
a) 1000
b) 500
c) 2000
d) 10000
View Answer
Explanation: Loaded Q due to dielectric loss for a dielectric resonator is given by the reciprocal of the loss tangent. Taking the reciprocal of loss tangent, loaded Q due to dielectric loss is 1000.
9. The direction of propagation is in z direction outside the dielectric in the resonator.
a) true
b) false
View Answer
Explanation: In a dielectric resonator, the direction of propagation can occur along the Z direction in the dielectric at resonant frequency but the fields are cutoff in the air region around the dielectric.
10. A dielectric resonator is considered to be closed at both the ends.
a) true
b) false
View Answer
Explanation: For all analysis purpose, a dielectric resonator is considered to be of a short length L and termed as dielectric waveguide open at both the ends.
Sanfoundry Global Education & Learning Series – Microwave Engineering.
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