est_ME2

50問 • 1年前

Loloysan

通報

問題一覧

The _____ ray passes through the axis of the fiber core.Select one:

Meridional

On which of the following signals does PLC operate on?

Digital

A traveling-wave tube (TWT) amplifies by virtue of

The absorption of energy by the signal from an electron stream

Why is a Yagi antenna often used for radio communications on the 20-metre band?

It helps reduce interference from other stations off to the side or behind

Ducts shall be supported with approved hangers at intervals not exceeding feet.

Which one is a causal system?

y(n) = 3x[n] - 2x[n - 1]

The spacing between the elements on a three-element Yagi antenna, representing the best overall choice, is _______ of a wavelength.

0.2

All causal systems must have the component of

Memory

Calculate the effective earth's radius if the surface refractivity is 301.

8493 km

A single mode fiber has refractive indices n1=1.50, n2 = 2.23, core diameter of 8μm, wavelength = 1.5μm cutoff wavelength = 1.214μm. Find the radius of curvature?

34 mm

The "doublet antenna" is the most common in the amateur service. If you were to cut this antenna for 3.75 MHz, what would be its approximate length?

38 meters (125 ft.)

What is the minimum spectrum allocation required by W-CDMA?

5 MHz

A system is said to be defined as non-causal, when

The output at the present depends on the input at time instant in the future.

A loss less line of characteristic impedance Z0 is terminated in pure reactance of -jZ0 value. VSWR is

infinity

Directors are used to increase ______ of the Yagi-Uda antenna.

Gain

Microwave frequencies are normally regarded as those in the range of

10 to 1000 GHz

The signal defined by the equations f(t) = 0 for t < 0, f(t) = E for 0 ≤ t ≤ a and f(t) = 0 for t > a is

a pulse function

A polarization maintaining fiber operates at a wavelength 1.2μm and have a modal birefringence of 1.8*10-3. Calculate the period of perturbation.

0.6 seconds

A magnetron is operated at a duty cycle of 0.001. It has a peak power output of 100 kilo-watts. Its average power is

100 watts

Effective noise temperature Te in terms of noise figure is ____

Te=To (F-1)

What kind of antenna feed line is made of two conductors held apart by insulated rods?

Open-conductor ladder line

A signal g(t) = A then g(t) is a

power signal

In a single-phase half-wave thyristor with R load and Vs = Vmsin(wt), the maximum value of the load can be given by

Vm/2

How much heat is produced by a human body?

100 W

A single mode fiber has mode field diameter 10.2μm and V = 2.20. What is the core diameter of this fiber?

10.1μm

Which of the following feeding has largest bandwidth?

Proximity Coupling

Assertion (A): If the duty cycle of chopper is low the current would not become discontinuous. Reason (R): If the time constant L/R of the load in chopper is low the current may become discontinuous.

A is correct but R is wrong

A single phase semiconverter is feeding a highly inductive load and has freewheeling diode across the load. The waveshapes of output voltage and output current.

are not similar

In a single phase full wave converter (M - 2 connection) feeding a highly inductive load, the firing angle for each thyristor is a in the respective half cycle. The period of conduction of each thyristor is

An energy signal has G(f) = 10. Its energy density spectrum is

100

A class A chopper has an input voltage of 200 V. Ton = 1.5 ms, and Toff = 4.5 ms. The duty cycle, average output voltage and ripple factor, respectively, are

0.25, 50 V and sqrt(3)

Coupling into and out of a traveling-wave tube can be accompanied by a

All of the above

In a frequency modulation transmitter, the _______ is located between the modulator and the frequency multiplier.

oscillator

A single phase full controlled bridge converter is connected to load having R = 0.4 £, E = 120 V, L = 0.2 mH, Vs = 230 V. The RMS value of the load current is 10 A for a firing angle of 53.21°. Find the input power factor.

0.5391 lag

Two thyristor of same rating and same specifications

may have equal or unequal turn on and turn off periods

What is one disadvantage of EDGE in comparison to HSCSD and GPRS?

Small coverage range

What is the low angle radiation pattern of an ideal half-wavelength dipole HF antenna installed parallel to the earth?

It is a figure-eight, perpendicular to the antenna

Which one of the following systems is causal?

y(t) = x(t-1) + x(t−2)

In a frequency modulation transmitter, the input to the speech amplifier is connected to the:

microphone

Klystron oscillators are most often used in the frequency range of

3000 to 30000 MHz

If the input power 100μW is launched into 6 km of fiber, the mean optical power at the fiber output is 2μW. What is the overall signal attenuation through the fiber assuming there are no connectors or splices?

16.98dB

What is the full form of MIDAS with respect to data acquisition package?

Maximum integrated data acquisition system

If k-factor is greater than 1, the array beam is bent

Towards the earth

The maximum usable range of the usual radar set (on any particular range setting) is determined by

The interval between transmitted pulses

How many directly driven elements do most Yagi antennas have?

One

In Laplace transform, multiplication by e-at in time domain becomes

translation by a in s domain

Which of the following is used to excite the antenna?

Feed line

Which conversion takes place when music is played from a memory card?

DAC

What should be the noise figure value at which the effective noise temperature equals to room temperature?

What type of interface does a DAQ (Data Acquisition) hardware creates?

Interface between a computer and signal

elex1

elex1

elex2

elex2

ME1 & ME2_ ELEX

Loloysan · 100問 · 1年前

ME1 & ME2_ ELEX

ME1_Math

ME1_Math

Math2

Math2

ME1 & ME2_MATH

Loloysan · 100問 · 1年前

ME1 & ME2_MATH

rc2_elex

rc2_elex

rc3_elex

rc3_elex

geasME1

geasME1

geasME2

geasME2

GEAS_ME1 & ME2

Loloysan · 100問 · 1年前

GEAS_ME1 & ME2

est_ME1

est_ME1

est_ME1 & ME2

Loloysan · 100問 · 1年前

est_ME1 & ME2

100問 • 1年前

Loloysan

問題一覧

The _____ ray passes through the axis of the fiber core.Select one:

Meridional

On which of the following signals does PLC operate on?

Digital

A traveling-wave tube (TWT) amplifies by virtue of

The absorption of energy by the signal from an electron stream

Why is a Yagi antenna often used for radio communications on the 20-metre band?

It helps reduce interference from other stations off to the side or behind

Ducts shall be supported with approved hangers at intervals not exceeding feet.

Which one is a causal system?

y(n) = 3x[n] - 2x[n - 1]

The spacing between the elements on a three-element Yagi antenna, representing the best overall choice, is _______ of a wavelength.

0.2

All causal systems must have the component of

Memory

Calculate the effective earth's radius if the surface refractivity is 301.

8493 km

A single mode fiber has refractive indices n1=1.50, n2 = 2.23, core diameter of 8μm, wavelength = 1.5μm cutoff wavelength = 1.214μm. Find the radius of curvature?

34 mm

The "doublet antenna" is the most common in the amateur service. If you were to cut this antenna for 3.75 MHz, what would be its approximate length?

38 meters (125 ft.)

What is the minimum spectrum allocation required by W-CDMA?

5 MHz

A system is said to be defined as non-causal, when

The output at the present depends on the input at time instant in the future.

A loss less line of characteristic impedance Z0 is terminated in pure reactance of -jZ0 value. VSWR is

infinity

Directors are used to increase ______ of the Yagi-Uda antenna.

Gain

Microwave frequencies are normally regarded as those in the range of

10 to 1000 GHz

The signal defined by the equations f(t) = 0 for t < 0, f(t) = E for 0 ≤ t ≤ a and f(t) = 0 for t > a is

a pulse function

A polarization maintaining fiber operates at a wavelength 1.2μm and have a modal birefringence of 1.8*10-3. Calculate the period of perturbation.

0.6 seconds

A magnetron is operated at a duty cycle of 0.001. It has a peak power output of 100 kilo-watts. Its average power is

100 watts

Effective noise temperature Te in terms of noise figure is ____

Te=To (F-1)

What kind of antenna feed line is made of two conductors held apart by insulated rods?

Open-conductor ladder line

A signal g(t) = A then g(t) is a

power signal

In a single-phase half-wave thyristor with R load and Vs = Vmsin(wt), the maximum value of the load can be given by

Vm/2

How much heat is produced by a human body?

100 W

A single mode fiber has mode field diameter 10.2μm and V = 2.20. What is the core diameter of this fiber?

10.1μm

Which of the following feeding has largest bandwidth?

Proximity Coupling

Assertion (A): If the duty cycle of chopper is low the current would not become discontinuous. Reason (R): If the time constant L/R of the load in chopper is low the current may become discontinuous.

A is correct but R is wrong

A single phase semiconverter is feeding a highly inductive load and has freewheeling diode across the load. The waveshapes of output voltage and output current.

are not similar

An energy signal has G(f) = 10. Its energy density spectrum is

100

A class A chopper has an input voltage of 200 V. Ton = 1.5 ms, and Toff = 4.5 ms. The duty cycle, average output voltage and ripple factor, respectively, are

0.25, 50 V and sqrt(3)

Coupling into and out of a traveling-wave tube can be accompanied by a

All of the above

In a frequency modulation transmitter, the _______ is located between the modulator and the frequency multiplier.

oscillator

0.5391 lag

Two thyristor of same rating and same specifications

may have equal or unequal turn on and turn off periods

What is one disadvantage of EDGE in comparison to HSCSD and GPRS?

Small coverage range

What is the low angle radiation pattern of an ideal half-wavelength dipole HF antenna installed parallel to the earth?

It is a figure-eight, perpendicular to the antenna

Which one of the following systems is causal?

y(t) = x(t-1) + x(t−2)

In a frequency modulation transmitter, the input to the speech amplifier is connected to the:

microphone

Klystron oscillators are most often used in the frequency range of

3000 to 30000 MHz

16.98dB

What is the full form of MIDAS with respect to data acquisition package?

Maximum integrated data acquisition system

If k-factor is greater than 1, the array beam is bent

Towards the earth

The maximum usable range of the usual radar set (on any particular range setting) is determined by

The interval between transmitted pulses

How many directly driven elements do most Yagi antennas have?

One

In Laplace transform, multiplication by e-at in time domain becomes

translation by a in s domain

Which of the following is used to excite the antenna?

Feed line

Which conversion takes place when music is played from a memory card?

DAC

What should be the noise figure value at which the effective noise temperature equals to room temperature?

What type of interface does a DAQ (Data Acquisition) hardware creates?

Interface between a computer and signal