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Correct OPTION is (b) STRIPLINE

Explanation: Stripline is a conductor SANDWICHED between two ground planes. It is more difficult to make than microstrip; however, it does not RADIATE as microstrip does.

The CORRECT choice is (c) 53.9Ω

Easy explanation: CHARACTERISTIC IMPEDANCE of MICROSTRIP =.

Correct option is (d) Microstrip is ever onequarter or one-half wavelength LONG.

Easy explanation: Microstrip is a FLAT conductor separated by an insulating dielectric from a large conducting ground plane. The microstrip is usually onequarter or one-half wavelength long and is used for transmission in the UHF and microwave REGION.

The correct choice is (d) Series RESONANT circuit

Easy EXPLANATION: If the line ACTS as a series resonant circuit, its impedance is ZERO. If the line is of such a length that it acts as a parallel resonant circuit, its impedance is near infinity. If the line is some intermediate length, it is REACTIVE.

Correct CHOICE is (a) True

The explanation is: To the generator, an open one-quarter wavelength LINE looks LIKE a series resonant circuit and a one-half wavelength line looks like a PARALLEL resonant circuit. This is just the OPPOSITE of a shorted line.

The correct answer is (b) Length is between ONE quarter and one HALF of wavelength

To explain I would say: If the open TRANSMISSION line is less than one-quarter wavelength, the generator sees a CAPACITANCE. If the line is between one-quarter and one-half wavelength, the generator sees an INDUCTANCE. These characteristics repeat for lines that are some multiple of one-quarter or one-half wavelengths.

Correct answer is (a) Length is one quarter WAVELENGTH

Explanation: If the line length is less than one-quarter wavelength at the OPERATING frequency, the shorted line looks like an inductor to the GENERATOR. If the shorted line is between one quarter and one-half wavelength, it looks like a capacitor to the generator.

Right answer is (B) Length of line is one half wave lengths

The best explanation: When the length of the TRANSMISSION line is one half of the wavelength, a standing wave pattern is PRODUCED where the current and voltage at the generator and the end of the transmission line is same. In this case, the line LOOKS LIKE a series resonant circuit to the generator.

The CORRECT answer is (a) 0

The EXPLANATION is: The reflection coefficient of a LINE that is fully terminated in its characteristic impedance is 0. This is because there is no REFLECTED voltage on the line.

The CORRECT CHOICE is (a) The sum of forward and reflected signals

Easiest explanation: In an UNMATCHED line, standing WAVES are formed which is a combination of forward and reflected SIGNAL. The signal actually on a line is simply the algebraic sum of the forward and reflected signals.

The correct OPTION is (d) Constant

Easiest EXPLANATION: If a voltmeter is moved down a matched LINE from the generator to LOAD and the RMS voltage values are plotted, the resulting wavelength versus voltage line will be flat.

The correct CHOICE is (a) MATCHED lines

Easy explanation: Ideally, a transmission line should be terminated in a LOAD that has a resistive impedance equal to the characteristic impedance of the line. This is CALLED a matched line.

Right answer is (C) Some VALUE between 0 and infinity

Explanation: In PRACTICE, however, the load on a transmission line is neither infinite nor 0Ω; rather, it is TYPICALLY some value in between. The load may be RESISTIVE or may have a reactive component.

The correct option is (c) HIGH FREQUENCY high power signal

To elaborate: If the load at the end of a line is an open circuit or a short circuit or has an impedance other than the characteristic impedance of the line, the signal is not fully absorbed by the load. This causes the signal to get reflected back the line and CAUSE a STANDING wave.

Correct ANSWER is (c) Standing waves do not affect signal strength

For explanation I WOULD say: Standing waves are not desirable. Some of the energy is reflected from the end of the line and ACTUALLY moves BACK up the line. This reflection indicates that the power produced by the generator is not totally absorbed by the load. When there is a power loss naturally the strength of the signal goes down.

The correct answer is (C) Delay lines

For explanation I would say: A signal APPLIED at one end of a line appears some time later at the other end of the line. This is called the time delay or TRANSIT time for the line. A transmission line USED specifically for the purpose of achieving delay is called a delay line.

Right OPTION is (B) 2.4 x 10^8 m/s

The explanation is: Velocity of transmission = Velocity FACTOR x Velocity in free SPACE = 0.8 x (3 x 10^8) = 2.4 x 10^8 m/s.

The CORRECT option is (B) 50Ω

To EXPLAIN I would say: The characteristic IMPEDANCE of a CABLE is independent of length. Thus for 1m or 100m the characteristic impedance is 50Ω.

Right option is (b) False

The BEST explanation: When the length of a transmission line is longer than several wavelengths at the signal frequency, the two PARALLEL conductors of the transmission line appear as a COMPLEX impedance. The wires EXHIBIT considerable series inductance whose reactance is significant at high frequencies.

The correct option is (B) N-type connector

To explain I would SAY: The best-performing coaxial connector is the N-type connector, which is USED mainly on large coaxial CABLE at the higher frequencies, both UHF and microwave. N-type connectors are complex and expensive, but do a better job than other connectors in maintaining the electrical characteristics of the cable through the interconnections.

Right answer is (b) F-type connector

To explain I would say: The least expensive coaxial cable connector is the F-type connector, which is widely used for TV sets, VCRs, DVD players, and cable TV. The cable PLUG and its matching CHASSIS jack are shown in FIG. 13-6. The shield of the coaxial cable is crimped to the connector, and the solid wire center conductor of the cable, rather than a separate pin, is used as the CONNECTION. A hex-shaped outer ring is threaded to attach the plug to the mating jack.

The correct option is (d) BNC

Easiest explanation: BNC connectors are WIDELY used on 0.25-in coaxial cables for attaching test INSTRUMENTS, such as oscilloscopes, frequency counters, and spectrum analyzers, to the EQUIPMENT being tested. BNC connectors are ALSO widely used on 0.25-in coaxial cables in LANs and some UHF radios.

The correct choice is (a) PL-259

To elaborate: The PL-259 is also referred to as a UHF connector, can be used up to low UHF values (less than 500 MHZ), although it is more widely used at HF and VHF. It can accommodate both LARGE (up to 0.5-in) and SMALL (0.25-in) coaxial cable.

Correct answer is (b) 0.219ft

To explain I would say: A PAIR of conductors does not act as a transmission line unless it is at LEAST 0.1λ long.

 λ = 984/450 = 2.19 ft

0.1λ = 2.19 X (0.1) = 0.219 ft.

Right option is (b) Banana pin connector

Explanation: The most COMMON TYPES of coaxial CABLE CONNECTORS are the PL-259 or UHF, BNC, F, SMA, and N-type connectors. Banana pin connectors are used in POWER cables.

Correct choice is (c) Simple resistive conductors

The explanation: Cables USED to carry RF energy are not simply resistive conductors but are complex equivalents of INDUCTORS, capacitors, and RESISTORS. If simple resistive conductors are used then undesirable effects such as noise, power loss OCCURS.

Right OPTION is (a) 0.1λ

Best explanation: A pair of CURRENT carrying conductors is not considered to be a transmission line unless it is at LEAST 0.1λlong at the signal FREQUENCY.

Correct CHOICE is (c) Balun

Easy explanation: It is sometimes necessary or desirable to convert from balanced to unbalanced operation or VICE VERSA. This is DONE with a device called a balun, from “balanced-unbalanced.”

Right answer is (c) Common mode REJECTION

To elaborate: When the noise affects the transmission, its effect is on both the wires but SINCE they are 180° out of phase when the signal reaches the RECEIVER the noise gets CANCELLED out. This is called common-mode rejection, and noise reduction can be as great as 60 to 70 dB.

The CORRECT answer is (a) True

The explanation: Balanced-line wires offer significant PROTECTION from noise pickup and crosstalk. Because of the identical POLARITIES of the signals on balanced lines, any external signal induced into the cable (noise) APPEARS on both wires SIMULTANEOUSLY but cancels at the receiver.

The correct option is (B) 180°

Explanation: In a balanced LINE, the same current flows in each WIRE with RESPECT to GROUND, although the direction of current in one wire is 180° out of phase with the current in the other wire.

Right choice is (d) Balanced line

Best EXPLANATION: A balanced line is one in which NEITHER wire is CONNECTED to ground. INSTEAD, the signal on each wire is referenced to ground.

The correct choice is (a) Plastic dielectric

Explanation: The coaxial cable consists of a solid center conductor SURROUNDED by a dielectric material, USUALLY a plastic insulator such as Teflon. Outside the insulation, there is a SECOND conductor MADE of FINE wires.

Correct option is (b) Telephone

The explanation is: Twisted-pair cable USES two insulated solid copper wires covered with insulation and loosely twisted together. This type of cable was first used in telephone wiring and is STILL used for that TODAY. But it is also used for security system wiring of sensors and other equipment.

The correct option is (a) Plastic

The best EXPLANATION: A parallel transmission line is a two-wire balanced line in which INSULATING spacers have been USED to KEEP the wires separated. Such lines are rarely used TODAY. The spacing between the wires is maintained by a continuous plastic insulator.

Correct choice is (c) High power signal

Explanation: The primary REQUIREMENTS of a transmission line are that the line introduces minimum attenuation, less NOISE to the signal and the line did not radiate any of the SIGNALS as RADIO energy. All transmission LINES and connectors are designed with these requirements in mind.