rf and microwave engineering two marks questions and answers

EC2403- RF and Microwave Engineering VII Semester ECE

Prepared by A.Devasena., Associate Professor., Dept / ECE

EC2403- RF AND MICROWAVE ENGINEERING

TWOMARKS QUESTIONS AND ANSWERS

UNIT I TWOPORT RF NETWORKS-CIRCUIT REPRESENTATION

1. What is insertion loss?

Insertion loss is a measure of the loss of the energy in transmission through a line or

device compared to direct delivery of energy without the line or device.

2. Why are S parameters used in microwaves?

The S parameters are used in microwaves because of the following characteristics

Increased stability at higher frequencies

Mismatch loss is less

Attenuation loss is less.

3. Specify the x- and frequency range and wavelength ( N/ D 2007)

The X- band frequency range : 8 – 12.5 GHz

The X-band wavelength : 3.7 – 2.4 cm

1. Specify the k-band frequency range and wavelength ( M / J 07)

The k-band frequency range : 18 – 26.5 GHz

The k-band wavelength 1.67- 1.13 cm

3. What is meant by symmetry of scattering matrix? ( a/ M 08)

Matrix of S is a symmetric matrix when the microwave device has the same

transmission characteristics in either direction of a pairs of ports.

Sij= Sji

4.Define – Scattering matrix

Scattering matrix is a square matrix which gives all the combinations of the power

relationships between the various input and output ports of a microwave junction.



5. Why are s parameters used in microwaves?

The S- parameters are used in microwave because of the following characteristics

Increased stability at higher frequencies

Mismatch loss is less

Attenuation loss is less

6. State the properties of S parameter. ( N / D 12)

The properties of S parameter are

It is always a square matrix of order ( n * n)

It is a unitary matrix

It is a symmetric matrix

Under perfect matched conditions, the diagonal elements of S parameter are

zero.

7.Define- Lossless Network

In lossless passive network, the power entering the circuit is always equal to power

leaving network which leads to the conservation of power.

8. Define- Straight Wire Inductance

When alternating current is applied in a wire medium, the magnetic field is alternatively

expanding and contracting. This produces an induced voltage in the wire that opposes any

change in the current flow. This opposition to change is called ‘ Straight Wire Inductance’.

9. Define – skin effect

As frequency increases, the electrical signals propagate loss inside the conductor.

Because of the current density increases to the perimeter of the wire and causes higher

impedance for the signal. This effect is known as skin effect.

10. State the different types of high frequency capacitors.

The different types of high frequency capacitors are

Parallel plate capacitor

Leaded capacitor

Perfect capacitor



11. State the different types of high frequency resistors.

The different types of high frequency resistors are

Carbon composite resistors

Metal film resistors

Thin film resistors

12. Define – Q factor

It is the measure of ability of an element to store energy and is equal to 2π times the

average energy stored to that of the energy dissipated per cycle.

13. Define – Two Port Network

A two port network has only two access ports, one for input or excitation and one for output

or response.

14. What are scattering coefficients?

The elements of scattering matrix are called scattering coefficients or scattering parameters.

15. Which one is called junction?

The point of interconnection of two or more devices is called a junction.

16. Define- Reflection Loss

The reflection loss is a measure of power loss during transmission due to the reflection of the

signal as a result of impedance mismatch.

17. What is the Zero property of S matrix?

It states that, “ for a passive lossless N- port network, the sum of the products of each term of

any row or any column multiplied by the complex conjugate of the corresponding terms of any

row or column is zero.

18. Define - Return Loss

The return loss is a measure of the power reflected by a line or network through a line.



19. What is wire?

A wire is the simplest element having zero resistance, which makes it appear as a short

circuit at DC and low AC frequencies.

20. What is a wave guide?

A waveguide is a hollow metal tube designed to carry microwave energy from one place to

another.

21. List the applications of waveguide twist.

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

Waveguide twists are helpful in converting vertical to horizontal polarizations or vice

versa.

22. What are the basic types of directional couplers?

Two hole directional coupler

Four hole directional coupler

Reverse coupling directional coupler

Bethe hole directional coupler.

UNIT –II RF amplifier Design & Matching Networks

1.Define – Unilateral Power Gain

When feedback effect of the amplifer is neglected ( i.e S12 = 0), the amplifier

power gain is known as unilateral power gain.

2.What is the function of input and output matching networks?

Input and output matching networks are needed to reduce undesired reflections and

improve the power flow capabilities.

3. Define - Unconditional Stability

Unconditional stability refers to the situation where amplifier remains stable for any

passive source and load at the selected frequencies and bias conditions.



4. Define- Available power gain

Available power gain is defined as the power available from the microwave

network to that of the poer from the source.

5. What is meant by power gain of an amplifier? ( N / D 12)

Transducer power gain is defined as the ratio of power delivered to the load to

that of the power from the source.

6. Define – Noise Figure

Noise figure F is defined as the ratio of the input SNR to the output SNR

7. Name the types of magnetron.

There are three types of magnetron. They are

Split anode magnetron

Cyclotron- frequency magnetrons

Traveling wave magnetrons

8.What is the need for impedance matching networks? (N / D 11)

Matching networks can help stabilize the amplifier by keeping the source and load

impedances in the appropriate range. Input and output matching networks are needed to reduce

undesired reflections and improve the power flow capabilities.

9. Distinguish between O- type tubes and M-type tubes

O type tube M- type Tube

Accelerating electric field is in the same direction as the static magnetic field

Static magnetic field is perpendicular to the electric field.

Electron beam tranvels in straight line Electron beam travels in curved path

Klystron, TWT are some of the examples Magnetron is the example

10.Write the expression for noise figure of a two port amplifier ( N / D 11)

The generated noise of a two port network can be determined from the signal to noise

ratio ( SNR) from the input to the output.



11.What are the considerations in selecting a matching network? ( N / D 12)

Factors in the selection of matching networks are

Complexity of the system

Bandwidth requirement

Adjustability

Implementation

Maximum power delivery or transfer

Optimal efficiency

12. Why impedance matching is required? What are the other constraints required?

( M / J 13)

Matching networks can help stabilize the amplifier by keeping the source and load

impedances in the appropriate range. Matching network is important for the following

reasons.

Maximum power loss is in the feed line

Maximum power delivery or transfer

Improving the S/N ratio of the system

13. Define Transducer Power Gain

Transducer power gain is nothing but the gain of the amplifier when placed between

source and load.

14. What are the parameters used to evaluate its performance of an amplifier? ( N / D 12)

Gain and gainflatness ( in dB)

Operating frequency and bandwidth ( in Hz)

Output power (in dB)

Power supply requirements ( in V and A)

Noise figure ( in dB)

15. Define – Operating Power Gain

The operating power gain is defined as the ratio of the power delivered to the load (Pl) to

the power supplied to the amplifier



16. State the various types of waveguide stub.

The various types of waveguide stub are

E – Stub

H- Stub

E-H tuner

17. Mention the purpose of resistors.

The purpose of resistors are as follows:

In transistor bias networks, to establish an operating point.

In attenuators, to control the flow of power

In signal combiners, to produce a higher output power

In transmission lines, to create matched conditions

18. What is an inductor?

A wire is wound (or coiled) in such a manner so as to increase the magnetic flux linkage

between the turns of the coil. The increased flux linkage increases the wire’s self inductance.

19. State the different types of high frequency resistors.

The different types of high frequency resistors are

Carbon composite resistors

Metal film resistors

Thin film resistors



UNIT III – MICROWAVE PASSIVE COMPONENTS

1. What is the need for waveguide twist?


2. How a faraday rotation isolator can be constructed by using ferrite rod? ( N / D 08)

Isolators can be made by inserting ferrite rod along the axis of a rectangular waveguide.

3. Define - Coupling factor

Coupling factor is a measure of how much of the incident power is being sampled.

4. Define – Isolator

An isolator is a two port non-reciprocal device which produces a minimum attenuation in

the wave in one direction and very high attenuation in the opposite direction.

5. What is meant by hybrid junction?

A hybrid junction is a four- port network in which a signal incident on any one of the port

devices between two output parts with the remaining port being isolated.

6. What are the basic types of directional coupler? ( N / D 09)

The basic types of directional coupler are

Two- hole directional coupler

Four-hole directional coupler

Reverse coupling directional coupler

Bethe coupler.

7. Name some uses of waveguide tees.

It is used to connect a branch or section of the waveguide in series or parallel with the

main waveguide transmission line for providing means of splitting and also of combining

power in a waveguide system.



8. List the applications of waveguide twist.


Waveguide twists are helpful in converting vertical to horizontal polarizations or vice versa.

9. Why magic tee is referred as E-H tee?

Magic Tee is constructed by E-plane Tee and H plane Tee perpendicular to each other.

Therefore magic tee is referred to as E-H tee.

10. What is meant by directivity of directional coupler? ( A / M 08)

The directivity of directional coupler is defined as the ratio of forward power P r to the

back power Pb and expressed in dB.

11. What are the basic parameters to measure the performance of a directional coupler?

( N / D 2008)

The basic parameters to measure the performance of directional coupler are

Coupling coefficient

Directivity

Insertion loss

Isolation.

12. What is H- plane Tee?

An H- plane Tee is a waveguide Tee in which the axis of its side arm is parallel to the H-

field of the main arm.

13. Define a microwave junction

The point of interconnection of two or more microwave devices is called microwave

junction.

14. What is E-plane Tee?

An E- plane tee is a wave guide tee in which the axis of its side arm is parallel to the H-

field of the main arm.



15. Why bends are used?

Bends are used to alter the direction of propagation in a waveguide system. The reflection

due to the bend is a function of its radius.

16. Define – Gradual twists

The gradual twists changes the plane of polarizations in a continuous order.

17. Define- Non Reciprocal Devices

Non reciprocal devices are defined as devices having different forward and reverse

propagating characteristics.

18. State the properties of ferrites.

Ferrites exhibits strong magnetic ability

Ferrites exhibits high resistivity compared with copper in microwave

Ferrites exhibits non- reciprocal property.

19. What is sum arm?

In a H- plane tee, if two input waves are fed into port1 and port2 of the collinear arm, the

output wave at port3 will be in phase and additive. Because of this, the third phase is called as

sum arm.

20. Write the applications of magic tee?

The applications of magic tee are

For the measurement of impedance

As a duplexer

As a mixer

As an isolator



21. Write the types of ferrite device.

Three types of non reciprocal ferrite devices which make use of faraday rotation in

microwave system are Gyrator, Isolator, circulator.

22. List the applications of cavity resonator.

Cavity resonators find applications as a wave meter

As an echo box for testing of a radar transmitter

As tuned circuits in UHF tubes

In microwave oscillators like reflex klystron and magnetrons.

23. Define – Difference Arm

In E- plane Tee, the power out of port3 is proportional to the difference between

instantaneous power entering from port1 and port 2. Therefore, this third port is called as

difference arm.

24. Write the applications of circulator.

A circulator can be used as a duplexer for a radar antenna system. Two or three port

circulators can be used in tunnel diode or parametric amplifiers.

25. What is a circulator?

A circulator is a multiport junction in which the wave can travel from one port to the next

immediate port in one direction only. They are useful in parametric amplifiers.,tunnel diode,

amplifiers and duplexer in radar.

26. Name some uses of isolators.

Isolators are generally used to improve the frequency stability of microwave generators

such as klystrons and magnetrons in which the reflection from the load affects the generating

frequency.



27. What is a gyrator?

It is a two port device that has a relative phase difference of 180˚ for transmission from

port1 to port2 and no phase shift for transmission from port2 to port1.

28. Define – Faraday Rotation Isolator

Isolators can be made by inserting ferrite rod along the axis of a rectangular waveguide.

Here the isolator is called as faraday rotation isolator.

UNIT IV MICROWAVE SEMICONDUCTOR DEVICES

1. High reliability What are M- type tubes? ( A / M 08)

M- type tubes are crossed field devices where the static magnetic field is perpendicular to

the electric field. Here the electrons travel in the curved path.

2. State the advantages for microwave IC’s ( A / M 08)

The advantages for microwave IS’s are

Low package density

Small size and less weight

Different transmission structures are possible.

3. What is the other name of O- type tube? ( N /D 07)

The other name for O- type tube is linear tube or rectilinear beam tube.



4.Differentiate tunnel diode from normal P-N diode

Tunnel diode PN diode

Doping levels at P and N sides are very high Doping levels at P and N sides are very normal

It exhibits negative resistance characteristics It exhibits positive resistance characteristics

Low noise Moderate noise

Preferred semi conductor – GaAs Preferred semiconductor – Ge and Si

5. What is HEMT ( N / D 11)

The field effect transistor (FET) which is made using a hetero-junction is called High

electron Mobility transistor(HEMT)

HEMT has higher frequency of operation

HEMT has low noise figure

6. What is MESFET? (( N / D 07)

When the FET is constructed with a metal- semiconductor Schottky- barrier diode, the

device is called a Metal Semiconductor Field Effect Transistor.

7. State the limitations of bipolar devices at high frequencies. ( N / D 09)

The limitations of bipolar devices at high frequencies are

Unstable beyond k band frequency

Higher noise level

Voltage gain is less compared to other transistors

8. State Gunn effect. ( A / M 08)

When the electric field is varied from zero to threshold value, the carrier drift velocity is

increased from zero to maximum, when the electric field is beyond the threshold value of 3000

V/ cm , the drift velocity is decreased and the diode exhibits negative resistance.



9. State the transferred electron effect. ( N / D 12)

When GAAs is biased above a threshold value of the electric field, it exhibits a negative

differential mobility. The electrons in the lower energy band will be transferred into the higher

energy band. This behavior is called transferred electron effect.

10. What are the materials that exhibit Gunn effect?

The materials exhibiting Gunn effect are

Gallium Arsenide

Indium phosphide

Cadmium telluride

Indium arsenide.

11. What are the modes available in negative resistance devices?

The modes available in negative resistance devices are

Voltage controlled mode

Current controlled mode

12. What are the major disadvantages of IMPATT diodes? ( N / D 08)

The major disadvantages of IMPATT diodes are

Avalanche process makes the IMPATT diode noisy

Poor noise figure of 30 dB

Low efficiency due to induced electron current

13. State any two applications of parametric amplifier. ( M / J 07)

The applications of parametric amplifier are in

Space communication systems

Radio telescopes

Tropo- receivers.



14. State the advantages of parametric amplifiers.( N / D 11)

The advantages of parametric amplifier are

Thermal noise in parametric amplifiers is less

Stability is high at higher frequencies

Noise figure is in the range of 1- 2 dB

15. State the different types of lithography. ( A / M 08)

The different types of lithography are

Electron- beam lithography

Ion- beam lithography

Optical lithography

X- ray Lithography

16. State the various MMIC fabrication techniques.

The various MMIC fabrication techniques are

Diffusion and ion implementation

Oxidation and film deposition

Epitaxial growth

Lithography

Etching and photo resist deposition

17. Define - Saturated Drift Velocity.

Maximum velocity of charge carriers in a semiconductor is called saturation drift

velocity.

18. Describe tunneling phenomenon.

When the doping level is increased, the depletion region reduces. Due to thin depletion

region, even for very small forward bias, many carriers penetrate through the junction and appear



at the other side. This phenomenon of penetration of carriers through the depletion region is

known as tunneling.

19. Define – Homo- Junction Transistor

When the transistor junction is joined by two similar materials such as silicon- to silicon

or germanium-to-germanium, it is called a homo junction transistor.

20. What do you mean by hetero junction transistor?

When the transistor junction is joined by two different materia ls such as Ge to GaAs, then

it is called a homo junction transistor.

21. What are the applications of tunnel diode?

The applications of tunnel diode are

Relaxation oscillator

Microwave oscillator

Storage device

Pulse generator

High speed switching networks

22. What are the key characteristics of tunnel diode?

The key characteristics of a tunnel diode are its negative resistance region.

23. List the advantages of tunnel diode.

The advantages of tunnel diode are

Low cost

Low noise

High speed

Low power consumption

24. List the disadvantages of tunnel diode.



The disadvantages of tunnel diode are

Low output voltage swing

No isolation between input and output.

25. Define - Varactor Diode

Varactor diodes are p-n junction diodes which provide a voltage variable junction in

microwave circuits when reverse biased.

26. Write the types of waveguide cavity resonators

The types of waveguide cavity resonators are

Rectangular cavity resonator

Circular cavity resonator

27. Mention the applications of IMPATT diodes.

The applications of IMPATT diodes are

Microwave generators

Modulated output oscillators

Receiver local oscillators

Parametric amplifier pumps

IMPATT diodes are also suitable for negative resistance amplification.

28. Explain plasma function in TRAPATT diode.

During the operation of the diode, a high field avalanche zone propagates through the

depletion region and fills the layer with dense plasma of electrons and holes which get trapped in

the low field region behind the zone.

29. What are the advantages of microwave transistors?

Microwave transistors are miniaturized designs to reduce device and package parasitic

capacitances and inductances and to overcome the finite transit time of the charge carriers in the

semiconductor materials.



30. Name the surface geometries available in microwave power transistors.

Three geometries are available. They are

Interdigitated

Overlay

Matrix

31. Mention the applications of Gunn diode amplifier.

Gunn diodes have been used in conjunction with circulator coupled networks in the

design of high level wideband transferred electron amplifiers that have a voltage gain bandwidth

product in excess of 10dB for frequencies from 4 to 16 GHz.

32. What is the need of diffusion and ion implantation?

Diffusion and ion implantation are the two processes used in controlling amounts of

dopants in semiconductor fabrications.

33.Write the types of epitaxy.

The types of epitaxy are

Vapour-phase epitaxy (VPE)

Molecular- beam epitaxy (MBE)

Liquid- phase epitaxy

34. Why monolithic technology is not well suitable for microwave integrated circuits?

Monolithic technology is not well suited for microwave integrated circuits,because the

processing difficulties, low yields and the performance have seriously limited their

applications.

35. What is Lithography?

Lithography is the process of transferring patterns of geometric shapes on a mask to a

thin layer of radiation sensitive material, which is known as resist, for covering the surface of a

semiconductor wafer.

36. Name the circuits used in hybrid MMICs.



Three general types of circuits can be utilized for hybrid MMICs. They are

Distributed micro strip lines

Lumped- element

Thin-film circuits

UNIT V- MICROWAVE TUBES AND MEASUREMENTS

1. State any two sensors used to measure the power. (N / D 09)

Barretter

Thermistor

2. What is bolometer? ( M / J 07)

Bolometer is a power sensor whose resistance changes with temperature as it absorbs

microwave power. Examples: Barretter, Thermistor.

3. What are the possible errors occur in measurement of standing wave ratio? (N / D 12)

The possible errors occur in measurement of standing wave ratio are

V max and Vmin may not be measured in the square law region of the crystal detector.

Probe thickness and depth may produce reflections in the line.

Residual VSWR arises due to mismatch impedance.

Harmonics and spurious signals from source cause measurement errors.

4. State the demerits of single bridge power meter. ( N / D 08)

The demerits of single bridge power meter are

The change of resistance due to a mismatch at the microwave input ports results in

incorrect reading.



The thermistor is sensitive to changes in the ambient temperature resulting in false

reading.

5. What is the principle by which high power measurements could be done by calorimetric

method? ( A/ M 08)

Direct heating method

Indirect heating method.

6. State any four limitations of conventional tubes at high frequencies. ( N / D 11)

The limitations of conventional tubes at high frequencies are

Lead inductance effects

Inter-electrode capacitance effects

Transmit angle effects

Gain bandwidth product limitation.

7. Define - Insertion Loss ( M / J 14)

Insertion loss is a measure of the loss of the energy in transmission through a line or

device compared to the direct delivery of energy without the line or device.

8. Distinguish between thermistor and barretter.

Barretter Thermistor

Barretter has a positive temperature coefficient.

i.e resistance increases with temperature.

Thermistor has negative temperature

coefficient

They are less sensitive They are more sensitive

They need less bias current They need more bias current

Barretters are usually operated at 100 ohms. Thermistors are operated at 100 ohm to 200

ohms.



9. What are the drawbacks of using power meter with single bridge?

The change of resistance due to a mismatch at the microwave input port results in

incorrect reading. The thermistor is sensitive to changes in the ambient temperature in false

reading.

10. Name two methods to measure impedance.

Slotted line

Reflectometer.

11. What is meant by microwave resonators?

Microwave resonators are tunable circuits used in microwave oscillators, amplifiers,

wave meters and filters. At the tuned frequency the circuit resonates where the average energies

stored in field. the electric And magnetic purely real.

12. What are the classifications of power measurements?

The classifications of power measurements are

Low power(less than 10mW)

Medium power ( from 10mW to 10 W)

High power ( > 10 W)

13.Define - Microwave Sensor

The microwave power meter consists of a power sensor, which converts the microwave

power into energy. The corresponding temperature rise provides a change in the electrical

parameters resulting in an output current in low frequency circuitry and indicates the power.

14. Name the method used for high power microwave measurements.

High power microwave measurements can be conveniently done by the calorimetric

method which involves conversion of the microwave energy into heat in a fluid and then

measuring of the dissipating medium.

15. What do you mean by thermocouple sensor?

A thermocouple sensor is a junction of two dissimilar metals or semiconductors. It

generates an emf when two ends are heated up differently by absorption of microwaves in a thin



film tantalum- nitride resistive load deposited on a Si substrate which forms one electrode of the

thermocouple. This emf is proportional to the incident microwave power to be measured.

16. What do you mean by slotted line?

Slotted line is a fundamental tool for microwave measurements. Slotted line consists of a

section of waveguide or coaxial line with a longitudinal slot. The slot is roughly 1 mm wide and

allows an electric field probe to enter the waveguide for measurement of the relative magnitude

of field at location of the probe.

17.Distinguish between low frequency measurements and microwave measurements.

Low frequency measurements Microwave measurements

At low frequency it is convenient to measure

voltage and current and use them to calculate

power

At microwave frequencies the amplitudes of

the voltage the amplitudes of the voltages and

current on a transmission line are the functions

of a distance and are not easily measurable

At low frequency, circuits are lumped

elements.

At microwave frequencies, the circuit elements

are distributed.

18. Mention the application of two cavity.

The applications of two cavity are as follows

Used in troposphere scatter transmitters

Satellite communication ground stations

Used in UHF TV transmitters

Radar transmitters

19. What is drift space?

The separation between buncher and catcher grids is called as drift space.

20. Define – Velocity Modulation



The variation in electron velocity in the drift space is known as velocity modulation.

21. Define – Reflex klystron

The reflex klystron is an oscillator with a built in feedback mechanism. It uses the cavity

for bunching and for the output cavity.

22. What is TWTA?

A traveling wave tube amplifier ( TWTA) circuit uses a helix slow- wave non resonant

microwave guiding structure. It is a broadband device.

23. What is the need of Quality factor Q?

Quality factor Q which is a measure of the frequency selectivity of a cavity.

24. Give the comparison between TWTA and klystron amplifier.

TWTA Klystron Amplifier

It is a non resonant wave circuit It is a resonant wave circuit ( Linear O type

device)

Waveband band device due to traveling wave

structures

Narrow band device

Traveling wave structures are used throughout

the system.

Using cavities for input and output circuits.

25. Write the applications of TWT

The applications of TWT are

Medium power satellite

High power satellite transponder output

Radar transmitters.



26. What are the advantages of TWT?

The advantages of TWT are

Bandwidth is large

High reliability

High gain

High duty cycle.

27. What are the drawbacks available in klystrons?

The drawbacks available in klystron are

Klystrons are essentially narrow banded devices

In klystrons and magnetrons, the microwave circuit consists of a resonant structure which

limits the bandwidth of the tube.

28. What is the role of slow wave structures in TWT? ( M / J 13)

Slow- wave structures are special circuits that are used in microwave tubes to reduce the

wave velocity in a certain direction so that the electron beam and the signal wave interact.

29. State any four high frequency limitations? ( N / D 11)

Conventional vacuum triodes, tetrodes and pentodes are less useful signal sources at the

frequencies above 1 GHz due to

Lead- inductance

Interelectrode- capacitance effects

Transit- angle effects

Gain bandwidth product limitations.

30. What are the errors possible sin voltage standing wave ratio measurements?

( N / D 12), ( M / J 13)

Vmax and Vmin may not be measured in the square- law region of the crystal detector.



The probe thickness and depth penetration may produce reflections in the line and also

distortion in the field to be measured.

Any harmonics and spurious signals from the source may be tuned by the probe to cause

measurement error.

A residual VSWR of slotted line arises due to mismatch impedance between the slotted

line and the main line.

31. Why magnetron is called a cross field device?

In magnetron, the dc magnetic field and dc electric field are perpendicular to each other

and hence magnetron is called as cross field device.

32. Write a short notes on negative resistance magnetron.

Negative- resistance magnetrons ordinarily operate at frequencies below the microwave

region. This type of magnetron uses a static negative resistance between two anode segments but

has low efficiency and is useful only at low frequencies ( < 500 MHz)

rf and microwave engineering two marks questions and answers

Documents

matrix of s

s parameters

s parameters

frequency increases

symmetric matrix

x band frequency range

microwave device

unitary matrix