# Microwave Engineering Questions and Answers – Ferrite Phase Shifters

This set of Microwave Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Ferrite Phase Shifters”.

1. ______ is a device that produces a phase shift of a required amount of the input wave.
a) Phase shifter
b) Attenuator
c) Resonator
d) None of the mentioned

Explanation: Ferrite phase shifter is a two port component that provides a variable phase shift by changing the bias field of the ferrite. Microwave diodes and FETs can also be used to implement phase shifters.

2. Phase shifters are used in _______ where the antenna beam can be steered in space by electronically controlled phase shifters.
a) Phased array antennas
b) Dipole array antennas
c) Slot antennas
d) Patch antennas

Explanation: Phase shifters are used in phased array antennas where the antenna beam can be steered in space by electronically controlled phase shifters. Phase shifters can be of two types, Reciprocal phase shifters and non reciprocal phase shifters. These are chosen as per the application requirement.

3. Reciprocal phase shifters give different phase shift in different direction.
a) True
b) False

Explanation: Reciprocal phase shifters are those devices which give the same phase shift in either direction. That is, either if port 1 or port 2 of the phase shifter is used as input port, the phase shifts at the output remains the same.

4. If a ferrite slab provides a phase shift of 48⁰/ cm, then the length of the ferrite slab required to produce a phase shift of 180⁰ is:
a) 4 cm
b) 3.75 cm
c) 4.5 cm
d) 3.5 cm

Explanation: The given ferrite slab provides a phase shift of the 48⁰/ cm. hence the length of the required ferrite slab is 180/45, the required length is 3.75 cm.

5. If a ferrite slab provides a phase shift of 48⁰/ cm, then the length of the ferrite slab required to produce a phase shift of 90⁰ is:
a) 2.44 cm
b) 1.88 cm
c) 4.5 cm
d) 3.5 cm

Explanation: The given ferrite slab provides a phase shift of the 48⁰/ cm. hence the length of the required ferrite slab is 90/45, the required length is 1.88 cm.

6. Gyrator is a device that produces a phase shift of ____ between the input and output.
a) 90⁰
b) 180⁰
c) 45⁰
d) None of the mentioned

Explanation: Gyrator is a device that produces a phase shift of 180⁰ between the input and output of the gyrator. This is a special case of the ferrite phase shifter which gives a constant phase shift and cannot be changed.

7. The scattering matrix of a gyrator is:
a) Symmetric
b) Skew symmetric
c) Identity matrix
d) Null matrix

Explanation: The scattering matrix of a gyrator is Skew symmetric. This is because of the 180⁰ phase shift that occurs in the device.

8. Ferrite phase shifters have more advantages over FETs and diodes in using them in microwave integrated circuits.
a) True
b) False

Explanation: Even though PIN diode and FET circuits offer a less bulky and more integratable alternative to ferrite components, ferrite phase shifters are cost effective; have high power handling capacity and power requirements.

9. A gyrator can be made a passive device by certain design methods so that they do not affect the power levels of the circuit in which they are used.
a) True
b) False

Explanation: The gyrator can be implemented as a phase shifter with a 180⁰ phase shift; bias can be provided with a permanent magnet, making the gyrator a passive device.

10. If a ferrite slab produces a phase shift of 0.836 rad/ cm, then the length of the slab required to produce a phase shift of 135⁰ is:
a) 2.81 cm
b) 3 cm
c) 2 cm
d) 3.4 cm

Explanation: Converting the given phase shift from radian scale to degree scale, the produced phase shift is 48⁰/ cm. To produce a phase shift of 135⁰, the required length is 135/45 this is equal to 2.81 cm.

Sanfoundry Global Education & Learning Series – Microwave Engineering.
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