RF Waveguide Interview Questions and Answers

This page covers top RF Waveguide interview questions and answers to help interviewees pass job interviews for RF Waveguide engineer positions. These RF Waveguide questions are written by specialists in the RF Waveguide domain.

Question -1: What is the function of an RF waveguide?

Answer -1: It is a hollow metallic conductor used to carry high-frequency or microwave-frequency signals. It usually comes in two different shapes: rectangular and circular. It is one of the many transmission mediums used to transfer EM energy from one point to another, such as coaxial cable, optical fiber, and wired lines. Waveguides typically operate from 300 MHz to 300 GHz frequency range.

Question -2: What is the dominant mode of a waveguide? Mention the dominant mode for rectangular and circular waveguides.

Answer -2: A waveguide passes EM waves above a particular cutoff frequency. Various TM and TE modes are supported in an RF waveguide. The mode with the lowest cutoff frequency is known as the dominant mode.

• A rectangular waveguide supports the dominant mode TE10.
• A circular waveguide supports the dominant mode TE11.

Question -3: What is the difference between TE mode and TM mode?

Answer -3:

• TE mode: Referred to as Transverse Electric wave mode, where the E-field is completely transverse to the waveguide, meaning perpendicular to the broad dimension of the waveguide.
• TM mode: Referred to as Transverse Magnetic wave mode, where the H-field is completely transverse to the waveguide, meaning perpendicular to the broad dimension of the waveguide.

They are used as EM wave propagation inside rectangular waveguides.

Question -4: Mention various devices used for impedance matching in a waveguide.

Answer -4: Metallic objects such as posts/screws, irises, E-H tuners, single stub tuners, double stub tuners, and probes are used as impedance-matching devices. They are used to eliminate standing waves.

Question -5: What are the benefits or advantages of RF waveguides?

Answer -5: Following are the advantages of RF waveguides.

• Passes EM mode propagation with minimum losses.
• EM waves are shielded in a metal structure and are immune from outside RF interference.
• Offers high power-handling capacity.

Question -6: What are the drawbacks or disadvantages of RF waveguides?

Answer -6: Following are the disadvantages of RF waveguides.

• Not suitable for lower frequency transmission.
• Bulky in size and heavy in weight.
• Rigid waveguides are not flexible.
• They support a narrow band of operation.
• TEM mode is not possible.

Question -7: What is the function of waveguide Tees such as E-plane tee, H-plane tee and magic tee.

Answer -7:

• E-Plane Tee : A waveguide junction where the output is split or combined in the electric field (E-field) plane, acting as a series-type power divider.
• H-Plane Tee : A waveguide junction where the output is split or combined in the magnetic field (H-field) plane, functioning as a parallel-type power divider.
• Magic Tee : A hybrid waveguide junction that combines both E-plane and H-plane tees, enabling power division with phase differences, commonly used in mixers and balanced circuits.

Question -8: Where are waveguide bends, twists, and flanges used?

Answer -8: They are used for joining two or multiple waveguide structures for various reasons. Bends (i.e., E-bends and H-bends) are used to prevent reflections within the bend length. Twists and flanges are also used for the same reasons.

Question -9: What is the function of a waveguide mode suppressor?

Answer -9: Modes other than the desired ones are undesirable, causing power dissipation. The devices used to suppress undesired modes in a waveguide are known as waveguide mode suppressors.

Question -10: What is the function of a waveguide isolator?

Answer -10: An isolator is basically a two-port and non-reciprocal device that produces minimum attenuation to E-M waves in one direction and maximum attenuation to the waves in the other direction. Hence, it is placed between the source and the load so that all the power is transmitted from the source to the load, and no reflection is fed back in the other direction. An isolator designed for RF waveguide structure is known as a waveguide isolator.

Question -11: What is the function of a waveguide switch?

Answer -11: The device which usually interfaces with two input waveguide ports and one output port; but actively guide EM waves from one input port to the output port is called waveguide switch.

Question -12: What is the function of a waveguide coupler?

Answer -12: The device which couples the EM Signal from main path of the waveguide to some other path for testing or some other purpose is known as waveguide coupler.

This set of RF Waveguide interview questions and answers are useful for freshers and experienced level of job positions.