This is the Multiples Choice Questions Part 10 of the Series in Transmission Fundamentals as one of the Communications Engineering topic. In Preparation for the ECE Board Exam make sure to expose yourself and familiarize in each and every questions compiled here taken from various sources including but not limited to past Board Examination Questions in Electronic System and Technologies, Communications Books, Journals and other Communications References.

### Online Questions and Answers Topic Outline

- MCQs in Transmission System
- MCQs in Transmission Medium
- MCQs in Velocity and Line Wavelength
- MCQs in Characteristics Impedance
- MCQs in Primary Line Constants and Propagation Constants
- MCQs in Standing Waves
- MCQs in Voltage Standing Wave Ratio
- MCQs in Telephone Lines and Cables
- MCQs in Wave Guides
- MCQs in Balanced and Unbalanced Lines
- MCQs in Twisted pair wire, Coaxial Cable
- MCQs in Decibel
- MCQs in Signal and Noise Fundamentals

### MCQs in Transmission Fundamentals Series

Following is the list of multiple choice questions in this brand new series:

**Transmission Fundamentals MCQs**

**MCQs from Number 1 – 50**Answer key:

**PART I**

**MCQs from Number 51 – 100**Answer key:

**PART II**

**MCQs from Number 101 – 150**Answer key:

**PART III**

**MCQs from Number 151 – 200**Answer key:

**PART IV**

**MCQs from Number 201 – 250**Answer key:

**PART V**

**MCQs from Number 251 – 300**Answer key:

**PART VI**

**MCQs from Number 301 – 350**Answer key:

**PART VII**

**MCQs from Number 351 – 400**Answer key:

**PART VIII**

**MCQs from Number 401 – 450**Answer key:

**PART IX**

**MCQs from Number 451 – 500**Answer key:

**PART X**

### Continue Practice Exam Test Questions Part X of the Series

451. Considering a coaxial transmission line, maximum voltage on the line divided by the minimum voltage equals the

- a. Characteristic impedance
- b. ISWR
- c. VSWR
- d. Inductive reactance

452. In a transmission line, if the SWR or maximum current to a minimum current ratio of 2:1, the ratio of the maximum voltage to the minimum voltage is

- a. 1:4
- b. 4:1
- c. 1:2
- d. 2:1

453. Transmission lines are either balanced or unbalanced with respect to

- a. Negative terminal
- b. Input
- c. Ground
- d. Positive terminal

454. The load is properly matched with the transmission line if the standing wave ratio is equal to

- a. 50
- b. 10
- c. 5
- d. 1

455. The radiation resistance of a quarterwave antenna is

- a. 49 ohms
- b. 288 ohms
- c. 72 ohms
- d. 144 ohms

456. A radio transmission line of 500 ohms impedance is to be connected to an antenna having an impedance of 200 ohms. What is the impedance of a quarter wave matching line?

- a. 300
- b. 316
- c. 316.5
- d. 361

457. The VSWR for a line terminated in its Zo is

- a. 0
- b. 1
- c. 1.5
- d. Infinity

458. Which of the following is used to measure SWR?

- a. Multimeter
- b. Reflectometer
- c. Spectrum analyzer
- d. Oscilloscope

459. A 75 – j50 ohm load is connected to a coaxial transmission line of Zo = 75 ohms at 10 GHz. The best method of matching consists in connecting

- a. A short circuited stub at the load
- b. A capacitance at some specific distance from the load
- c. An inductance at the load
- d. A short-circuited stub at some specific distance from the load

460. For a two-wire line, Zo is higher when

- a. The wire size is small with respect to the spacing of the conductors
- b. The spacing is varied in accordance with the frequency
- c. The D:d ratio is smaller
- d. The wire is large with respect to the spacing of the conductors

461. A resultant wave due to the combination of incident and reflected wave

- a. Electromagnetic wave
- b. Sine wave
- c. Standing wave
- d. Current

462. For transmission line load matching over a range of frequencies, it is best to use a

- a. Balun
- b. Broadband directional coupler
- c. Double stub
- d. Single stub

463. If the load impedance matches the characteristic impedance of the line, there are _____ standing waves.

- a. More
- b. Less
- c. No
- d. Ten(10)

464. VSWR stands for

- a. Voltage sending wave ratio
- b. Voltage receiving wave ratio
- c. Very small wave radiation
- d. Voltage standing wave ratio

465. Reflections on a transmission line can occur when

- a. Impedance of the source and load are matched
- b. Impedance of the source and the load are mismatched
- c. Resonance conditions are obtained
- d. Power transfer between source and load is maximum

466. A transmission line with characteristic impedance (Zo) of 300 ohms is terminated in a resistance load (RI). If by measurement, the minimum and maximum voltage through the load are 12 and 20 micro volts, respectively, what is the SWR?

- a. 1.67
- b. 0.6
- c. 6.7
- d. 3.67

467. A measure of the mismatched between line and load impedance is called as

- a. Reflection coefficient
- b. Standing wave ratio
- c. Loss
- d. Standing waves

468. Transmission lines when connected to antenna have

- a. Capacitive load
- b. Resistive load whose resistance is less than characteristic impedance
- c. Resistive load at the resonant frequency
- d. Resistive load whose resistance is greater than the characteristic impedance of the line

469. At matched condition, SWR is equal to

- a. Zero
- b. One
- c. 100
- d. Infinite

470. An HF transmission line has a characteristic impedance of 600 ohms and is terminated by an antenna. The SWR along the line when the antenna impedance is 500 ohms is

- a. 1.2:1
- b. 1:2.1
- c. 2:1
- d. 1:2

471. A characteristic of an infinite transmission line is that

- a. The impedance in equals impedance out
- b. It carries waves at the velocity of light
- c. It can be connected to mismatched loads
- d. The impedance varies with the length of the line

472. A quarter wave transmission line shorted at the end:

- a. Has the characteristics of parallel tuned circuit
- b. Has the characteristics of a series tuned circuit
- c. Has a minimum current at the end
- d. Reflects a low impedance to the supply

473. The outer conductor of a coaxial transmission line is usually grounded at the:

- a. Input and output
- b. Output only
- c. Input only
- d. Point of infinite resistance

474. A certain feedline has a high SWR. It can be caused by:

- a. An impedance mismatched
- b. Use of non-resonant line
- c. Matching the load to the line
- d. Excessive transmitter output

475. If the input impedance of an antenna is 300 ohms and it is fed with a 600 ohm balanced transmission line, the SWR on the line is

- a. 4
- b. 3
- c. 2
- d. 0.5

476. A radio transmission line of 300 ohms impedance to be connected to an antenna having an input impedance of 150 ohms. The impedance if a quarter wave matching line is ___ ohms

- a. 212
- b. 450
- c. 600
- d. 150

477. The ratio of the reflected voltage to the incident voltage on the transmission line is termed as

- a. Reflection coefficient
- b. Standing wave ratio
- c. Loss
- d. Standing waves

478. Indicate the three types of transmission line energy losses

- a. Radiation, I2R and dielectric Heating
- b. Conductor heating, dielectric heating and radiation resistance
- c. I2R, RL and temperature
- d. Dielectric separation insulation breakdown and radiation

479. Termination means

- a. Load connected to the output end of a transmission line
- b. Result of disconnecting a line from a transmitter
- c. Looking back impedance of a line with no load
- d. Result of cutting both ends of a conductor

480. When transmission line uses ground return, it is called a/n _____ line.

- a. Ungrounded
- b. Unbalanced
- c. Grounded
- d. Balanced

481. Permeability is the measure of superiority of a material over a vacuum as a path of magnetic lines of force. The permeability of free space is equal to _____ henry/meter

- a. 1.257 x 10-6
- b. 1.527 x 10-6
- c. 7.251 x 10-6
- d. 5.217×10-6

482. The most commonly used transmission line is a

- a. Two-wire balanced line
- b. Single line
- c. Three-wire line
- d. Coax

483. The characteristic impedance of a transmission line does not depend upon its

- a. Length
- b. Conductor diameter
- c. Conductor spacing
- d. Thickness of armor

484. What is the impedance of a balance 4-wire with a diameter of 0.25cm and spaced 2.5 cm apart using an insulator with a dielectric constant of 2.56?

- a. 100 ohms
- b. 65 ohms
- c. 75 ohms
- d. 50 ohms

485. It is required to match a 73-ohm antenna to a 600 ohm polyethylene coaxial feeder line, with a velocity factor of 0.66 by means of a quarter wave matching a transformer. At a frequency of 150 MHz, the impedance of the matching section is____ ohms.

- a. 209.28
- b. 310.5
- c. 150.28
- d. 450.82

486. If the terminating impedance is exactly equal to the characteristic impedance of the transmission line, the return loss is____

- a. Zero
- b. Infinity
- c. One
- d. Negative

487. The characteristic impedance of a transmission line is the impedance measured at the ____ when its length is infinite.

- a. Shorted end of the line
- b. Midsection
- c. Input
- d. Output

488. The characteristic impedance of a transmission line is 70 ohms and has a load of 35 ohms. The SWR and reflection coefficient are _____ and _____ respectively

- a. 2 and 0.333
- b. 1 and 0.666
- c. 2 and 0.666
- d. 1 and 0.333

489. It is required to match a 200 ohm load to a 300 ohm transmission line to reduce the SWR and attain resonance. A quarter wave transformer used, directly connected to the load has a Zo of ____ ohms.

- a. 245
- b. 425
- c. 524
- d. 254

490. What quarter wave transformer will match a 100 ohm-line to an antenna whose value is 175 ohms?

- a. 150 ohms
- b. 137.5 ohms
- c. 132.29 ohms
- d. 16.58 ohms

491. The mismatch between antenna and transmission line impedance cannot be corrected by

- a. Using an LC network
- b. Adjusting antenna length
- c. Using a balun
- d. Adjusting the length of the transmission line

492. A pattern of voltage and current variation along a transmission line not terminated in its characteristic impedance is called

- a. An electric field
- b. Radio waves
- c. Standing waves
- d. Magnetic field

493. The most desirable value of SWR on a transmission line is

- a. 0
- b. 1
- c. 2
- d. Infinity

494. In transmission lines, the most desirable reflection coefficient is

- a. Zero
- b. 0.5
- c. 1
- d. Infinity

495. At very high frequencies, transmission lines are used as _____.

- a. Tuned circuits
- b. Antennas
- c. Insulators
- d. Resistors

496. What is the reflection coefficient of a 100 ohm characteristic impedance line and a 300 ohm load?

- a. 0.25
- b. 0.3
- c. 0.5
- d. 0.75

497. The minimum voltage along a transmission line is 260 volts, while the maximum is 390 volts. The SWR is

- a. 0.67
- b. 1.0
- c. 1.2
- d. 1.5

498. A single conductor running from the transmitter to the antenna

- a. RG-8/U
- b. Single line wire
- c. Twin-lead
- d. Microstrip

499. What characteristic impedance is needed to match a 50-ohm line to a 300 ohm-load?

- a. 221 ohms
- b. 122 ohms
- c. 212 ohms
- d. 112 ohms

500. Indicate the false statement. The SWR on a transmission line is infinity; the line is terminated in

- a. Short circuit
- b. A complex impedance
- c. An open circuit
- d. A pure reactance