1. The actual received signal is ______ than what is predicted by reflection and diffraction model.
a) Weaker
b) Equal
c) Stronger
d) Very weak
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
2. Scattered energy in all directions provides _________ at a receiver.
a) Channels
b) Loss of signal
c) No energy
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
3. Surface roughness are often tested using __________
a) Rayleigh criterion
b) Lawson criterion
c) Barkhausen stability criterion
d) Nyquist criterion
Explanation: Rough surface is often tested using a Rayleigh criterion. It defines the critical height of surface protuberances for a given angle of incidence. The Rayleigh criterion is the criterion for the minimum resolvable detail. The imaging process is said to be diffraction-limited when the first diffraction minimum of the image of one source point coincides with the maximum of another
4. A surface is considered rough if protuberance is ________ than critical height.
a) Equal
b) Less
c) Greater
d) No relation
Explanation: 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.
5. RCS of scattering object is defined as the ratio of _______
a) Power density of signal scattered to power density of radio wave incident
b) Power density of radio wave incident to power density of signal scattered
c) Power density of incident waves to power density of reflected wave
d) Power density of reflected wave to power density of incident waves
Explanation: The radar cross section of a scattering object is defined as the ratio of the power density of the signal scattered in the direction of the receiver to the power density of the radio wave incident upon the scattering object. It has unit of square meters
6. Which equation is used to calculate the received power due to scattering for urban mobile radio system?
a) Laplace equation
b) Bistatic radar equation
c) Poisson’s equation
d) Maxwell equation
Explanation: 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
7. In ionosphere propagation, waves arriving at the receiving antenna using the phenomenon of _______
a) Scattering
b) Refraction
c) Diffraction
d) Radiation
Explanation: Scattering is a general physical process where some forms of radiation, such as light, sound, or moving particles, are forced to deviate from a straight trajectory by one or more paths. It is due to localized non-uniformities in the medium through which they pass.
8. Power density is basically termed as ________ power per unit area.
a) Reflected
b) Refracted
c) Radiated
d) Diffracted
Explanation: Power density is the amount of power (time rate of energy transfer) per unit volume. It is also termed as radiated power per unit area. In energy transformers including batteries, fuel cells, motors, etc., power density refers to a volume. It is then also called volume power density.
9. Which of the following is not an outdoor propagation model?
a) Longley-Rice model
b) Ericson Multiple Breakpoint Model
c) Hata model
d) Okumura model
Explanation: Ericson multiple breakpoint model is an indoor propagation model. Longley-Rice, Hata and Okumura model are outdoor propagation models. Most of these models are based on a systematic interpretation of measurement data obtained in the service area.
10.Longley –Rice model is applicable to _________
a) Point to point communication
b) All to all communication
c) Point to multipoint communication
d) Multipoint microwave distribution sstem
Explanation: The Longley-Rice model is applicable to point-to-point communication systems in the frequency range from 40 MHz to 100 GHz. They are applicable for different kinds of terrain. Terrain profile may vary from a simple curved Earth profile to a highly mountainous profile.