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Right answer is (C) Greater

To elaborate: A surface is considered ROUGH if its minimum to maximum protuberance is greater than the critical height calculated using Rayleigh CRITERION. It is considered SMOOTH if protuberance is LESS than critical height.

The correct answer is (d) Snell’s LAW

Easy explanation: Snell’s law is also known as Snell–Descartes law or the law of refraction. It gives a formula to describe the relationship between the ANGLES of incidence and refraction, when referring to light or other waves passing through a boundary between two different isotropic MEDIA, such as WATER, glass, or AIR.

Right option is (b) Bistatic radar equation

To explain I WOULD say: For urban mobile radio systems, models BASED on bistatic radar equation is used to COMPUTE the RECEIVED power due to scattering in the far field. This equation DESCRIBES the propagation of wave in free space which impinges on a scattering object and then reradiated in the direction of receiver.

Correct choice is (b) Rate at which path LOSS INCREASES with distance

The explanation is: The average large scale path loss for an arbitrary T-R separation is expressed as a function of distance by USING a path loss EXPONENT, n. It INDICATES the rate at which the path loss increases with distance.

The correct option is (a) Fading MODEL

The explanation is: Small scale propagation model is also called fading model. Fading model characterize the RAPID fluctuations of the RECEIVED signal strength over very SHORT distance of a few wavelengths or short time duration. The propagation models are used to estimate the performance of wireless CHANNELS.

The correct ANSWER is (a) Operating frequency

The EXPLANATION is: The terms permittivity and CONDUCTIVITY are insensitive to operating frequency when the material is a good conductor. In the case of conductors, it is evident that electric FIELD INSIDE a conductor is zero. That is because free charges reside only on the surface of conductor and not inside.

Correct choice is (b) Diffraction loss

The EXPLANATION is: The reflection coefficient is a function of the MATERIAL properties, and generally depends UPON the wave polarization, angle of incidence and frequency of propagating waves. It is a parameter that DESCRIBES how much of an electromagnetic wave is reflected by an impedance discontinuity in the TRANSMISSION medium.

Right CHOICE is (d) Fresnel reflection COEFFICIENT

To explain I would say: The ELECTRIC field intensity of the reflected and transmitted waves may be related to the incident waves in the medium of origin through the Fresnel reflection coefficient. It is EQUAL to the ratio of the AMPLITUDE of the reflected wave to the incident wave, with each expressed as phasors.

Correct ANSWER is (b) 1 km to 100 km

To explain: OKUMURA’s model is applicable for distances of 1 km to 100 km. It can be used for base STATION antenna heights ranging from 30 m to 1000 m. Okumura DEVELOPED a set of curves GIVING the median attenuation relative to free space in an urban area.

Right choice is (c) Isotropic antenna

For explanation: Isotropic antenna radiates the POWER with unit gain uniformly in all directions. It is an ideal antenna. From PRACTICAL point of view, there is no ACTUAL isotropic antenna. But, an isotropic antenna is often USED as a REFERENCE antenna for the antenna gain.

The correct choice is (d) Sectoring

Easiest explanation: The mechanisms behind electromagnetic wave propagation are DIVERSE. They can be GREATLY attributed to reflection, diffraction and scattering. Due to multiple reflections from various objects, the electromagnetic WAVES travel along different PATHS of varying lengths.

The CORRECT option is (a) True

The explanation: DURKIN’s model is very attractive because it can read in a digital elevation map and perform a site SPECIFIC propagation computation on the elevation data. It can produce a signal strength contour that is reported to be good within a few DB.

Correct answer is (b) LOGARITHMICALLY

The best I can EXPLAIN: Both theoretical and measurement based propagation models indicate that AVERAGE received signal power decreases logarithmically with DISTANCE. It is VALID for both outdoor and indoor channels.

The CORRECT option is (b) False

The explanation is: The plane of incidence is defined as the plane containing the incident, REFLECTED and transmitted waves. The incident LIGHT is polarized with its electric field PERPENDICULAR to the plane containing the incident, reflected, and refracted rays.

Right OPTION is (B) False

To elaborate: The indoor radio channel differs from the TRADITIONAL mobile radio channel. The DISTANCES covered are much SMALLER and variability of the environment is much greater for a much smaller range of T-R separation distances.

The correct choice is (a) Okumura MODEL

The BEST explanation: The HATA model is an empirical formulation of the graphical path loss data provided by Okumura. It is VALID from 150 MHz to 1500 MHz. Hata presented the urban AREA propagation loss as a standard formulation. It supplied correct Equations for application to other situations.

Right option is (c) Stronger

Best explanation: The actual RECEIVED SIGNAL in a mobile radio environment is often stronger than what is PREDICTED by reflection and diffraction model ALONE. This is because when a radio wave incidence upon the rough surface, reflected energy is SPREAD out in all directions.

The CORRECT choice is (c) Fresnel zone

Explanation: The concept of diffraction loss is a FUNCTION of the path difference AROUND an obstruction. It can be explained by Fresnel ZONES. Fresnel zones represent successive regions where secondary waves have a path length from Tx to Rx which are nλ/2 greater than total path length.

The correct choice is (b) Distance between Tx and Rx

To explain: At high frequency, diffraction depends on the geometry of the OBJECT, as well as the amplitude, phase, and POLARIZATION of the incident wave at the POINT of diffraction. It gives RISE to a bending of waves even when line of SIGHT does not exist between transmitter and receiver.

Right OPTION is (a) Surface having SHARP irregularities

Explanation: Diffraction OCCURS when radio path between transmitter and receiver is obstructed by a surface that has sharp irregularities (edges). The secondary WAVES resulting from the obstructing surface are present THROUGHOUT the space and even behind the obstacle.

Correct answer is (b) Both mediums have DIFFERENT ELECTRICAL properties

Best explanation: When a radio wave propagating in one medium IMPINGES upon ANOTHER medium having different electrical properties. The wave is partially reflected and partially transmitted.

The correct choice is (a) Effective isotropic radiated POWER

The BEST I can explain: EIRP stands for Effective Isotropic Radiated Power. It is the amount of power that a theoretical isotropic antenna would emit to produce the peak power density observed in the direction of MAXIMUM antenna gain. EIRP also takes into account the losses in transmission line and CONNECTORS and INCLUDES the gain of the antenna.

Correct option is (b) Fixed and wired

To elaborate: Fixed and wired configuration describes a desktop in an office. The device use fixed networks for PERFORMANCE reasons. Neither WEIGHT nor POWER consumption of the devices allows for mobile USAGE.

Right choice is (d) ADDITIONAL radio energy

Explanation: Objects such as lamp posts and trees TEND to scatter energy in all DIRECTIONS. They provide additional radio energy at a receiver. Scattering may ALSO refer to particle-particle collisions between MOLECULES, atoms, electrons, photons and other particles.

Correct choice is (c) ISOTROPIC antenna

Explanation: Isotropic antenna is an ideal antenna that directs the power UNIFORMLY in all DIRECTIONS. It is a theoretical point source of electromagnetic. It is practically not possible. It is mainly used as a HYPOTHETICAL antenna to MEASURE the gain.

The correct choice is (a) G=(4πAe)/λ^2

Easy explanation: The GAIN of the antenna is PROPORTIONAL to effective APERTURE area. Therefore, antennas with large effective apertures are high gain antennas and have small ANGULAR beam widths. Most of their power is radiated in a narrow beam in one DIRECTION, and little in other directions.

The CORRECT option is (a) Large scale propagation model

The best EXPLANATION: Large scale propagation model are useful in estimating the radio COVERAGE area of a transmitter. They can predict the mean signal strength for an arbitrary transmitter-receiver (T-R) separation distance. They CHARACTERIZE signal strength over large T-R separation distances.