Interview Questions.

Question 1. What Is Microwave Engineering?

Answer :

Microwave engineering is the study and design of microwave circuits , components , and systems. Fundamental standards are carried out to evaluation , design and dimension strategies in this discipline.The quick wavelengths involved distinguish this field from digital engineering . This is because there are exclusive interactions with circuits, transmissions and propagation characteristics at microwave frequencies.

Question 2. Define S-matrix And Its Properties?

Answer :

In a microwave junction there's an interplay of three or extra additives.There could be an output port, further there can be mirrored image from the junction of different ports. Totally there can be many aggregate, these are represented easily using a matrix known as S matrix.

Properties of s- matrix:

it possess symmetric houses sij=sji
it possess unitary property
[s][s]*=[i]
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Question 3. Write The Applications Of Microwave Engineering?

Answer :

Following are the packages of microwave engineering:

Antenna benefit is proportional to the electrical length of the antenna. At better frequencies, greater antenna advantage is consequently viable for a given physical antenna length, which has vital outcomes for enforcing miniaturized microwave structures.
More bandwidth may be found out at better frequencies. Bandwidth is critically vital due to the fact available frequency bands in the electromagnetic spectrum are being unexpectedly depleted.
Microwave alerts tour by line of sight are not bent by way of the ionosphere as are decrease frequency signals and therefore satellite tv for pc and terrestrial communique hyperlinks with very high capacities are possible.
Question four. Why Is S-matrix Used In Mw Analysis?

Answer :

Matrix is utilized in MW evaluation to overcome the trouble which happens when H,Y & Z parameter are used in excessive frequencies.

Microwave Engineering Tutorial
Question 5. What Are The Advantages Of Abcd Matrix?

Answer :

The blessings of ABCD matrix are as follows-

They are used in strength transmission strains
They are beneficial in case of cascade networks.
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Question 6. What Are Junctions ? Give Some Example?

Answer :

A microwave circuit consists of several microwave devices connected in a few way to obtain the desired transmission of MW signal. The interconnection of two or extra microwave may be appeared as MW junction.

E.G.: TEE, HYBRID RING

Question 7. What Are Non-reciprocal Devices ?Provide Two Examples?

Answer :

The devices that are having the homes that the ahead characteristics are not equal to the opposite traits are called non-reciprocal gadgets.

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Question 8. What Are The Applications Of Reflex Klystron?

Answer :

The main applications of a reflex klystron are as follows:

Signal supply in MW generator
Local oscillators in receivers
It is used in FM oscillator in low power MW hyperlinks.
In parametric amplifier as pump supply.
Question 9. What Is The Purpose Of Slow Wave Structures Used In Twt Amplifiers?

Answer :

Slow wave systems are unique circuits which might be used in microwave tubes to reduce wave pace in a positive direction so that the electron beam and the signal wave can engage. In TWT, because the beam can be extended only to velocities which can be about a fragment of the velocity of light, slow wave structures are used.

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Question 10. Give Two Examples For Two Port Junctions?

Answer :

Following are the 2 examples of  port junctions:

The junction of  rectangular publications of unequal top
A symmetrical junction which includes two comparable square guides joined by way of an Intermediate manual of more width.
Question eleven. What Is Microwave?

Answer :

Electromagnetic waves having frequencies among 1 GHz to three hundred GHz (it may be three hundred MHz to three hundred GHz) are referred to as microwaves.

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Question 12. What Are The Properties Of Microwaves?

Answer :

Microwave are unidirectional. This method that after an antenna transmits microwaves, they travel in one direction. That is why microwave propagation is line of sight (LOS) propagation. They aren't contemplated by means of ionosphere. High frequency microwaves can not penetrate an item like wall.

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Question thirteen. What Are The Merits And Demerits Of Microwaves?

Answer :

Due to above properties  microwaves have following blessings and disadvantages:

Due to line of sight propagation, a couple of antennas can be  aligned without interfering with another pair of aligned antennas.
Due to extensive frequency bandwidth, high facts switch price is feasible.
Due to line of sight propagation, it can be transmitted long distance. But a problem is faced due to its penetration homes.It can't be switch inside a bound area. Also its transformation has barriers like hills trees, mountains, earth curvature and so on. That is why we need repeaters or tall towers for lengthy distance transmission.
As they're no longer contemplated via ionosphere, they can be used for area transmission.
Question 14. What Are The Applications Of Microwave?

Answer :

They are used in several applications. Some of these are:

Communication (astronomy, satellite tv for pc, WLAN, cell,cell, radar, TV and so on)
Remote sensing and navigation (prediction/tracking/guidence- site visitors manipulate, climate, missile, aircraft and many others)
Medical packages (cautery imaging, heart stimulation, remedy and many others)
Question 15. What Are The Reasons For Using Microwave In Communication?

Answer :

Wider bandwidth because of better frequency
Better decision because of smaller wavelength
Higher pace of operation
Higher antenna gain (length reducing)
As the production of  frequency in microwave range by way of natural resources are less , it is extra to be had and less crowed frequency spectrum. 
Lower interference due to decrease sign crowding.
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Question 16. What Is Velocity Of Microwave?

Answer :

All electromagnetic wave has speed of light. (Light,microwave,radio wave, infrared ray all are electromagnetic wave).

Question 17. What Is Microwave Systems?

Answer :

A microwave machine generally consists of a transmitter subsystem, consisting of a microwave oscillator, waveguides, and a transmitting antenna, and a receiver subsystem that includes a receiving antenna, transmission line or waveguide, a microwave amplifier, and a receiver.

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Question 18. What Is Pointing Theorem?

Answer :

It states that the total complex energy fed into a volume is equal to the algebraic sum of the energetic power dissipated as warmness, plus the reactive power proportional to the distinction among time-common magnetic and electric energies saved in the extent, plus the complex power transmitted across the surface enclosed with the aid of the quantity.

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Question 19. What Are Boundary Conditions?

Answer :

There are 4 primary regulations for boundary situations on the surface among two exceptional substances:

The tangential components of electric field depth are continuous across the boundary.
The everyday additives of electrical flux density are discontinuous at the boundary by way of an amount same to the surface-fee density on the boundary.
The tangential additives of magnetic subject depth are discontinuous at the boundary with the aid of an amount equal to the surface-contemporary density on the boundary.
The ordinary components of magnetic flux density are non-stop across the boundary.
Question 20. Why Uniform Wave Is A Tem Wave?

Answer :

A uniform aircraft wave is a wave whose magnitude and segment are both consistent. Electromagnetic waves in loose space are standard uniform aircraft waves. The electric powered and magnetic fields are collectively perpendicular to every other and to the direction of propagation of the waves. The phases of the two fields are continually in time section and their magnitudes are usually consistent. The saved energies are equally divided between the 2 fields, and the energy waft is transmitted by using the two fields inside the direction of propagation. Thus a uniform plane wave is a transverse electromagnetic wave or a TEM wave.

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Question 21. What Is Non-uniform Wave ?

Answer :

A non-uniform aircraft wave is a wave whose amplitude (not phase) may additionally vary inside a plane everyday to the direction of propagation. Consequently, the electric and magnetic fields are no longer in time section.

Question 22. What Is Wave Propagation In Free Space?

Answer :

The electromagnetic wave being propagated in loose area near the surface of the earth is split into  elements: 

Ground wave: Classified as direct wave, earth-contemplated wave and floor wave
Sky wave or ionosphere wave. 
Question 23. What Are The Properties Of Tem Modes In A Lossless Medium?

Answer :

Its cutoff frequency is zero.
Its transmission line is a -conductor system.
Its wave impedance is the impedance in an unbounded dielectric.
Its propagation consistent is the regular in an unbounded dielectric.
Its section speed is the velocity of light in an unbounded dielectric.
Transmission & Distribution Interview Questions
Question 24. What Is Terminated Line?

Answer :

A transmission line terminated in its function impedance Zo is called a well terminated line. Otherwise it's miles referred to as an improperly terminated line.

Electronic Communications Interview Questions
Question 25. What Is Dominant Mode?

Answer :

The mode having the bottom resonant frequency.

Question 26. What Is Microwave Junction?

Answer :

The point of interconnection of  or greater microwave gadgets is referred to as a junction. Commonly used microwave junctions encompass such waveguide tees because the E-plane tee, H -plane tee, magic tee, hybrid ring (rat-race circuit), directional coupler and the circulator.

Question 27. What Is Tee Junction?

Answer :

In microwave circuits a waveguide or coaxial-line junction with 3 independent ports is typically known as a tee junction.

MCSE Interview Questions
Question 28. What Is E-plane Tee (series Tee)?

Answer :

An £-aircraft tee is a waveguide tee in which the axis of its facet arm is parallel to the E subject of the principle manual.

Question 29. What Is H-aircraft Tee (shunt Tee)?

Answer :

An H-plane tee is a waveguide tee in which the axis of its side arm is "shunting" the E area or parallel to the H discipline of the primary manual.

Question 30. What Is Magic Tees (hybrid Tees)?

Answer :

A magic tee is a mixture of the £-aircraft tee and H -aircraft tee.  The magic tee is typically used for mixing, duplexing, and impedance measurements.

Question 31. How To Use Waveguide Corners, Bends, And Twists?

Answer :

These are usually used to alternate the route of the waveguide via an arbitrary angle.

Question 32. What Is Waveguide Twist?

Answer :

Waveguide twists are used to exchange the plane of polarization of a propagating wave.

Question 33. What Is Directional Couplers?

Answer :

A directional coupler is a four-port waveguide junction. Several forms of directional couplers exist, including a two-hole directional coupler, 4-hole directional coupler, reverse-coupling directional coupler (Schwinger coupler), and Bethe-hollow directional coupler.

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Question 34. What Is Hybrid Couplers?

Answer :

Hybrid couplers are interdigitated microstrip couplers along with four parallel striplines with trade strains tied collectively.  Hybrid couplers are regularly used as additives in microwave systems or subsystems together with attenuators, balanced amplifiers, balanced mixers, modulators, discriminators, and segment shifters.

Question 35. What Is Microwave Isolators?

Answer :

An isolator is a nonreciprocal transmission tool that is used to isolate one element from reflections of different additives inside the transmission line.

Question 36. Why Isolator Is Uniline?

Answer :

An best isolator absolutely absorbs the electricity for propagation in one path and offers lossless transmission within the opposite path. Thus the isolator is generally called uniline.

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Question 37. How Does Isolator Increase Frequency Stability ?

Answer :

Isolators are usually used to enhance the frequency stability of microwave generators, including klystrons and magnetrons, wherein the reflection from the load impacts the generating frequency. In such cases, the isolator placed between the generator and cargo prevents the meditated energy from the unrivaled load from returning to the generator. As a end result, the isolator maintains the frequency balance of the generator.

Question 38. What Is Non Reciprocal Devices?

Answer :

Non reciprocal gadgets are described as devices having special forward and reverse propagating traits.

Question 39. What Is Cavity Resonator?

Answer :

It is a metal enclosure that confines the electromagnetic strength. Some cavity resonators:  rectangular-cavity resonator, circular-cavity resonator, and reentrant-cavity resonator etc.

Question 40. What Is The Need Of Quality Factor Q?

Answer :

Quality element Q that is a degree of the frequency selectivity of a cavity.

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Question forty one. What Is The Function Of Input And Output Matching Networks?

Answer :

Input and output matching networks are had to reduce undesired reflections and enhance the energy go with the flow abilities.

Question 42. What Is Transferred Electron Effect?

Answer :

When GAAs is biased above a threshold price of the electric field, it well-knownshows a bad differential mobility. The electrons in the lower strength band could be transferred into the higher energy band. This behavior is called transferred electron impact.

RF Engineer Interview Questions
Question 43. What Is Saturated Drift Velocity?

Answer :

Maximum speed of charge providers in a semiconductor is called saturation flow velocity.

Question forty four. What Is Homo- Junction Transistor?

Answer :

When the transistor junction is joined by means of two similar materials such as silicon- to silicon or germanium-to-germanium, it is known as a homo junction transistor.

Question forty five. What Is Hetero Junction Transistor?

Answer :

When the transistor junction is joined by way of two extraordinary substances together with Ge to GaAs, then it is called a homo junction transistor.

Question forty six. What Is The Need Of Diffusion And Ion Implantation?

Answer :

Diffusion and ion implantation are the two techniques used in controlling amounts of dopants in semiconductor fabrications.

Question 47. What Is Insertion Loss?

Answer :

It is a measure of the loss of the strength in transmission through a line or device as compared to the direct delivery of energy without the line or device.

Question 48. What Is Unconditional Stability?

Answer :

It refers to the state of affairs wherein amplifier remains strong for any passive source and load at the selected frequencies and bias situations.

Question forty nine. What Is Available Power Gain?

Answer :

Available electricity gain is defined because the strength to be had from the microwave community to that of the product from the source.

Question 50. What Is Power Gain Of An Amplifier?

Answer :

It is described as the ratio of strength delivered to the weight to that of the strength from the supply into an amplifier.

Question fifty one. What Is Reflection Loss?

Answer :

The reflection loss is a degree of power loss at some stage in transmission because of the reflection of the signal because of impedance mismatch.

Question 52. What Is Zero Property Of S Matrix?

Answer :

It states that, “ for a passive lossless N- port community, the sum of the goods of every time period of any row or any column expanded by way of the complicated conjugate of the corresponding phrases of any row or column is 0”.