MCQOPTIONS
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MCQOPTIONS
This section includes 161 Mcqs, each offering curated multiple-choice questions to sharpen your Microwave Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
HEMT used in the microwave circuit is a: |
| A. | Source |
| B. | High power amplifier |
| C. | Detector |
| D. | Low noise amplifier |
| Answer» E. | |
| 102. |
In both the sequential-lobing and conical-scan tracking techniques of radar, the measurements of angular errors in two orthogonal coordinates (azimuth and elevation) require that a minimum of: |
| A. | Three pulses be processed |
| B. | Two pulses be processed |
| C. | Four pulses be processed |
| D. | Only one pulse be processed |
| Answer» D. Only one pulse be processed | |
| 103. |
Noise temperature (T) and gain (G) are two important parameters of satellite antennas. Which one of the following antennas has the largest G/T radio? |
| A. | Parabolic reflector |
| B. | Cassegranian antenna |
| C. | Pyramidal horn antenna |
| D. | Dipole antenna |
| Answer» D. Dipole antenna | |
| 104. |
When electromotive waves travel along a metallic waveguide in which there is a discontinuity due to some lossy material field in a small length and the other end is terminated with a matched load, the discontinuing will cause: |
| A. | Progressive waves throughout the line |
| B. | Standing waves on the generator side and progressive waves on the matched load line |
| C. | Progressive waves on the generator side and standing waves on the load side. |
| D. | Standing waves throughout the line |
| Answer» B. Standing waves on the generator side and progressive waves on the matched load line | |
| 105. |
Wave guides are pressurised above normal atmospheric pressure for: |
| A. | Increasing their power handling capacity |
| B. | Improving the conductivity of their walls |
| C. | Preventing higher order modes from propagating |
| D. | Varying the wave impedence |
| Answer» D. Varying the wave impedence | |
| 106. |
In TWT, attenuator is put: |
| A. | At the beginning |
| B. | In the middle |
| C. | At the end |
| D. | Anywhere |
| Answer» B. In the middle | |
| 107. |
Microwave antenna aperture efficiency depends on: |
| A. | Feed pattern |
| B. | Antenna aperture |
| C. | Surface losses |
| D. | Low side lobe level |
| Answer» C. Surface losses | |
| 108. |
The kinetic energy of the beam remains uncharged in the interaction between an electron beam and RF wave in a: |
| A. | Multi-cavity klystron |
| B. | Crossed field amplifier |
| C. | Travelling-wave tube |
| D. | Gyrotron |
| Answer» D. Gyrotron | |
| 109. |
In parametric amplifiers, used in microwave communication systems, the amplification is limited by: |
| A. | Type of biasing |
| B. | A maximum limit of 10 |
| C. | Pump energy |
| D. | Frequency of operation |
| Answer» D. Frequency of operation | |
| 110. |
Consider the following statements relating to problem of mounting the bolometer in a waveguide for microwave power measurement. |
| A. | 1, 2 and 3 are correct |
| B. | 1, 3 and 4 are correct |
| C. | 2, 3 and 4 are correct |
| D. | 1, 2 and 4 are correct |
| Answer» E. | |
| 111. |
Consider the following statements: Laser is an acronym for light amplification by stimulated emission of radiation. In comparison to LED, it has: |
| A. | (i), (iii) and (iv) are correct |
| B. | (i), (ii) and (iii) are correct |
| C. | (i) and (iii) are correct |
| D. | (i), (ii) and (iv) are correct |
| Answer» B. (i), (ii) and (iii) are correct | |
| 112. |
Ionospheric preparation is not possible for microwaves because: |
| A. | Microwaves will be fully absorbed by the ionospheric layers |
| B. | There will be an abrupt scattering in all directions |
| C. | Microwaves will penetrate through the ionospheric layers |
| D. | There will be dispersion of microwave energy |
| Answer» D. There will be dispersion of microwave energy | |
| 113. |
To increase the radar range of ground and surface targets to see well beyond the normal radar horizon, the electromagnetic wave propagation adopted is: |
| A. | Ionospheric scatter |
| B. | Tropo scatter |
| C. | Ground wave propagation |
| D. | Duct |
| Answer» C. Ground wave propagation | |
| 114. |
The front end of an amplifier chain in a microwave communication system is kept immersed in liquid nitrogen to: |
| A. | Dissipate heat generated by amplifier |
| B. | Expand its noise figure |
| C. | Improve its noise figure |
| D. | Reduce the distortion produced by the amplifier |
| Answer» D. Reduce the distortion produced by the amplifier | |
| 115. |
A disadvantage of microstrips with respect to stripline circuit is that the former: |
| A. | Do not let themselves to be printed-circuit techniques |
| B. | Are more likely to radiate |
| C. | Are bulkier |
| D. | Are more expensive and complex to manufacture |
| Answer» E. | |
| 116. |
Consider the following statements regarding feed which is the Key component of a reflector antenna as it has a decisive bearing on the overall-performance: |
| A. | 1, 2 and 3 |
| B. | 1 and 2 |
| C. | 2 and 3 |
| D. | 1 and 3 |
| Answer» B. 1 and 2 | |
| 117. |
A calorimetric measurement for average power of a signal gave a value of 400 W. The value was interpreted for peak power as 0 5 mW. Then the duty cycle of the signal is: |
| A. | 0 08% |
| B. | 8% |
| C. | 40% |
| D. | 80% |
| Answer» B. 8% | |
| 118. |
Radiation from a helical antenna is: |
| A. | Plane polarised |
| B. | Partially plane polarised |
| C. | Circularly polarised |
| D. | Elliptically polarised |
| Answer» D. Elliptically polarised | |
| 119. |
(A) In an oscillation zone of reflex klystron an increase in the reflector voltage results in lighter oscillation frequency. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true but R is not a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» C. A is true but R is false | |
| 120. |
In microwave radar, pulse repetition frequency is used to resolve range and doppler ambiguities using: |
| A. | CW radar |
| B. | Pulsed radar |
| C. | Moving target indicator |
| D. | Pulse-doppler radar |
| Answer» D. Pulse-doppler radar | |
| 121. |
A loss-less line having characteristic impedance Z0 is terminated in a pure reactance of value jZ |
| A. | 10 |
| B. | 2 |
| C. | 1 |
| D. | Infinite |
| Answer» E. | |
| 122. |
Guide wavelength ( |
| A. | <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td><td rowspan="2"> = </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td><td rowspan="2"> </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td></tr><tr><td style="text-align: center;"> <sup>2</sup><sub>g</sub></td><td style="text-align: center;"> <sup>2</sup><sub>0</sub></td><td style="text-align: center;"> <sup>2</sup><sub>c</sub></td></tr></table> |
| B. | <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td><td rowspan="2"> = </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td><td rowspan="2"> </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td></tr><tr><td style="text-align: center;"> <sub>0</sub><sup>2</sup></td><td style="text-align: center;"> <sub>g</sub><sup>2</sup></td><td style="text-align: center;"> <sub>c</sub><sup>2</sup></td></tr></table> |
| C. | <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td><td rowspan="2"> = </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td><td rowspan="2"> &plus; </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td></tr><tr><td style="text-align: center;"> <sub>c</sub><sup>2</sup></td><td style="text-align: center;"> <sub>c</sub><sup>2</sup></td><td style="text-align: center;"> <sub>g</sub><sup>2</sup></td></tr></table> |
| D. | <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td><td rowspan="2"> = </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td><td rowspan="2"> &plus; </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td></tr><tr><td style="text-align: center;"> <sub>g</sub></td><td style="text-align: center;"> <sub>0</sub></td><td style="text-align: center;"> <sub>c</sub></td></tr></table> |
| Answer» B. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td><td rowspan="2"> = </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td><td rowspan="2"> </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td></tr><tr><td style="text-align: center;"> <sub>0</sub><sup>2</sup></td><td style="text-align: center;"> <sub>g</sub><sup>2</sup></td><td style="text-align: center;"> <sub>c</sub><sup>2</sup></td></tr></table> | |
| 123. |
A microstrip line on alumina substrate ( T = 9) has a zero thickness strip of width, w = 3 mm. Substrate thickness h = 0 5 mm. Assuming TEM wave propagation and negligible fringing field, the characteristic impedance of the line will be approximately: |
| A. | 10 |
| B. | 21 |
| C. | 26 |
| D. | 50 |
| Answer» C. 26 | |
| 124. |
In microwave power measurements using bolometer, the principle of working is the variation of: |
| A. | Inductance with absorption of power |
| B. | Resistance with absorption of power |
| C. | Capacitance with absorption of power |
| D. | Cavity dimensions with heat generated by the power |
| Answer» C. Capacitance with absorption of power | |
| 125. |
Double the minimum method is relevant to the measurement of: |
| A. | Low attenuation coefficient |
| B. | High attenuation coefficient |
| C. | High VSWR |
| D. | Low VSWR |
| Answer» E. | |
| 126. |
A square waveguide carries TE11 mode whose axial magnetic field is given by: |
| A. | 5 GHz |
| B. | 7 5 GHz |
| C. | 6 5 GHz |
| D. | 8 GHz |
| Answer» C. 6 5 GHz | |
| 127. |
Fig. shows five thin slots on the walls of a rectangular waveguide carrying TE10 mode. Which of these are radiating (R) and which are non-radiating (NR)? |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» E. | |
| 128. |
The scattering matrix of magic-tee, shown in fig. is: |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» E. | |
| 129. |
With 100 mW input power, the power measured at port 4 is 0 1 mW and 10 mW when port is terminated in a matched load and a short respectively. The directivity of the coupler shown in Fig. |
| A. | 50 dB |
| B. | 40 dB |
| C. | 30 dB |
| D. | 20 dB |
| Answer» D. 20 dB | |
| 130. |
A TE10 rectangular waveguide is to be designed for operation over 25-35 GHz and the band centre is 1 5 times the cut-off frequency. What should be the dimension of the broad side? |
| A. | 15 mm |
| B. | 10 mm |
| C. | 9 mm |
| D. | 7 5 mm |
| Answer» C. 9 mm | |
| 131. |
A waveguide section in a microwave circuit will act as a: |
| A. | Low-pass filter |
| B. | Band-pass filter |
| C. | High-pass filter |
| D. | Band-reject filter |
| Answer» D. Band-reject filter | |
| 132. |
A 75 ohm transmission line is first short terminated and the minima locations are noted. When the short is replaced by a resistive load R |
| A. | 25 ohms |
| B. | 50 ohms |
| C. | 1/2 |
| D. | 1/4 |
| Answer» C. 1/2 | |
| 133. |
On a resistively terminated high frequency loss-less transmission line fed by a 500 MHz source, the VSWR is found to be equal to 2 and the first voltage minimum is measured at 30 cm from the load end. What is the value of the normalised load resistance? |
| A. | 3 |
| B. | 2 |
| C. | 1/2 |
| D. | 1/4 |
| Answer» D. 1/4 | |
| 134. |
When 10 mW power is incident at port 1 of the directional coupler shown in Fig. the power meter at port 4 reads 10 W. When the same power is incident at port 2, the meter reads 10 nW. What are the coupling loss and directivity? |
| A. | 40 dB; 20 dB |
| B. | 30 dB; 40 dB |
| C. | 30 dB; 30 dB |
| D. | 20 dB; 30 dB |
| Answer» D. 20 dB; 30 dB | |
| 135. |
Strapping is used in cavity magnetrons to: |
| A. | Prevent mode jumping |
| B. | Ensure bunching |
| C. | Improve bandwidth |
| D. | Prevent cathode back heating |
| Answer» B. Ensure bunching | |
| 136. |
Klystron operates on the principle of: |
| A. | Amplitude modulation |
| B. | Frequency modulation |
| C. | Pulse modulation |
| D. | Velocity modulation |
| Answer» B. Frequency modulation | |
| 137. |
In mode operation of magnetron, the spokes due to phase focusing effect rotate at an angular velocity corresponding to: |
| A. | One pole/cycle |
| B. | Two poles/cycle |
| C. | Four poles/cycle |
| D. | Six poles/cycle |
| Answer» C. Four poles/cycle | |
| 138. |
The secondary cavity in a two cavity klystron is called the: |
| A. | Buncher cavity |
| B. | Catcher cavity |
| C. | Velocity modulation cavity |
| D. | None of these |
| Answer» C. Velocity modulation cavity | |
| 139. |
Which of the following microwave tube amplifier uses an axial magnetic field and radial electric field? |
| A. | Coaxial magnetron |
| B. | CFA |
| C. | Travelling wave magnetron |
| D. | Reflex klystron |
| Answer» C. Travelling wave magnetron | |
| 140. |
(A) The TW tube which is a wideband microwave amplifier of the helix is used as a slow wave structure of the device. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true but R is not a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are true but R is not a correct explanation of A | |
| 141. |
(A) In some applications, the TM01 mode in circular waveguide is preferred to the TE01 mode or TE11 mode. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true but R is not a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are true but R is not a correct explanation of A | |
| 142. |
(A) The variables choosen for the equivalent circuit of a 2 port network in the microwave range of frequencies are travelling waves rather than total voltage and total currents. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true but R is not a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are true but R is not a correct explanation of A | |
| 143. |
In a travelling-wave tube, the phase velocity of the axial component of the rf field on the slow-wave structure is kept: |
| A. | Equal to the velocity of the electrons |
| B. | Slightly less than the velocity of electrons |
| C. | Slightly more than the velocity of electrons |
| D. | Equal to the velocity of light in free space |
| Answer» C. Slightly more than the velocity of electrons | |
| 144. |
Consider the following statements regarding a cavity wavemeter in a reaction type of circuit as shown in Fig. |
| A. | 1 alone is correct |
| B. | 2 alone is correct |
| C. | 1 and 3 are correct |
| D. | 2 and 4 are correct |
| Answer» E. | |
| 145. |
At microwave frequencies, the size of the antenna becomes: |
| A. | Very large |
| B. | Large |
| C. | Small |
| D. | Very small |
| Answer» E. | |
| 146. |
A slot line is etched on the ground plane of a microstrip. Coupling between the slot line and the microstrip, on the two sides of the same substrate, takes place through which one of the following mechanisms? |
| A. | The coupling is magnetic and is maximum when they are at right angles |
| B. | The coupling is electric and is maximum when they are parallel |
| C. | The coupling is magnetic and is minimum when they are at right angles |
| D. | The coupling is electric and is minimum when they are at right angles |
| Answer» C. The coupling is magnetic and is minimum when they are at right angles | |
| 147. |
The transit time (in cycles) for the electrons in the repeller space of a reflex klystron oscillator for sustaining oscillations is [n is any integer including zero]: |
| A. | 2 (n 1) |
| B. | 2n 1 |
| C. | n + 1/2 |
| D. | n + 3/4 |
| Answer» E. | |
| 148. |
Consider the following statements associated with microstrip patch antennas: |
| A. | 1, 2 and 3 |
| B. | 1 and 2 |
| C. | 2 and 3 |
| D. | 1 and 3 |
| Answer» C. 2 and 3 | |
| 149. |
Which of the following statements about parabolic reflector systems are correct? |
| A. | 1, 2 and 3 |
| B. | 1, 3 and 4 |
| C. | 1, 2 and 4 |
| D. | 2, 3 and 4 |
| Answer» D. 2, 3 and 4 | |
| 150. |
The slow-wave structure of TWT is provided with an attenuator. Which one of the following is the function of such an attenuator? |
| A. | It prevents the RF power from reaching the output of the device when the beam is switched on |
| B. | It prevents oscillations in the device |
| C. | It reduces the noise level of the device |
| D. | It is used to broadband the device |
| Answer» C. It reduces the noise level of the device | |