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WorksheetsMicrowave/Satellite Communication
Total questions: 65
Worksheet time: 2hrs 21mins
Microwave resonators are used in
microwave oscillators
microwave narrow band amplifier
microwave frequency metres
all of the above
In microwave system the function of mode filter is
to suppress modes with lower cut off frequencies
b. to suppress modes with higher cut off frequencies
to change mode of wave transmission
both (b) and (c)
c. to change mode of wave transmission
Atomic and molecular resonance is observed in many substances
at microwave frequencies
at low frequencies
at frequencies used in AM broadcast
at both (light blue) and (yellow)
Microwave links are typically 50 km apart
because of atmospheric attenuation
because of output tube power limitation
because of earth's curvature
to ensure that applied dc voltage is not excessive
Satellite communication systems use the frequency band
10 to 20 MHz
50 to 70 MHz
3 to 6 GHz
100 to 120 GHz
The characteristic impedance of a cable is about
300 Ω
50 Ω
5 Ω
2 Ω
For a directional coupler the power is in the ratio of
40 dB
30 dB
20 dB
10 dB
A microwave connector should have high SWR.
True
False
In microwave circuits, a mode transducer is used to
change mode of wave transmission
change direction of wave transmission
change polarization of wave transmission
change mode, direction or polarization wave transmission
Microwaves
get reflected by ionosphere
are absorbed by ionosphere
are neither reflected nor absorbed by ionosphere
are both reflected and absorbed by ionosphere
To study electromagnetic radiations from astronomical objects, radio astronomers use
low frequencies
medium frequencies
microwaves
none of the above
Microwaves are used for
telephony
radio broadcast
TV systems
all of the above
The main advantage of using micro waves for communications is
large bandwidth
small bandwidth
low power
high power
use microwave frequencies to transmit information in a line of sight or space-wave propagation
(a)
The number of feet or meters an obstacle is raised higher in elevation owing to the
curvature
k-factor
earth bulge
fresnel zonme
relative curvature
Determine the EIRP in dBm for a microwave system with the following parameters,
transmitted power = 5 dBm, transmitting and receiving antenna gain = 15 dB each.
25
30
20
35
Calculate the earth bulge in meters at the middle of a 36 km microwave link. Assume typical value for k-factor.
25.4
18
19
20
Calculate the free space loss for a 30-km microwave link operating at 5GHz.
134dB
135dB
136dB
137dB
Calculate the free space loss for a 40-km microwave link operating at 6 GHz.
139 dB
142 dB
140 dB
141 dB
A line-of-sight radio link operating at a frequency of 8.1 GHz has a separation of 30
km between antennas. A natural obstacle is located 12 km from one of the
antennas. What is the radius of the first Fresnel zone at the obstacle?
40.76m
67.9m
16.3m
9.8m
A line-of-sight radio link operating at a frequency of 8.1 GHz has a separation of 30
km between antennas. A natural obstacle is located 12 km from one of the
antennas. By how much must the beam clear the obstacle?
40.76 m
9.8 m
67.9 m
9.8 m
The main benefit of using microwaves is
lower cost equipment
simpler equipment
greater transmission distances
more spectrum space for signals
Coaxial cable is not widely used for long microwave transmission lines because of
its
high loss
high cost
large size
excessive radiation
It is a measure of reliability expressed as the average number of hours between
successive failures
MTBF
MTTR
downtime
outage time
Most radar antennas use
dipole
broadside array
collinear array
horn and parabolic reflector
The best system configuration to overcome multipath fading of microwave system
over the water
space diversity
frequency diversity
polarization diversity
wavelength diversity
A 50-km microwave link is established from Cavite to Quezon with the following
parameters:
frequency of operation: 9.6 GHz
transmit & receive antenna gain: 20 dB each
receiver sensitivity: -90 dBm
other losses: 10 dB
If the power to the transmitting antenna feed line is 3 W, what is the EIRP in dBm?
54.77 dBm
55.88 dBm
56.99 dBm
53.66 dBm
Calculate the radio horizon for a 500-ft transmitting antenna and a receiving antenna of 20-ft.
37.95 mi
110.63 km
37.95 km
110.63 mi
Calculate the free-space loss (in dB) in a microwave communications link that is 45 km apart and operating at 8.5 GHz.
141 dB
42 dB
143 dB
144 dB
Venus is considered to be Earth’s twin as its radius is about 6000 km with an acceleration due to gravity of 8.87 m/s². Assuming that Venus is a sphere, find the orbital velocity of a satellite (in km/hr) 30000 km above Venus.
2980 kph
1070 kph
10720 kph
12070 kph
Maya-3 and Maya-4 are the first Philippine university-built satellites designed and developed by the first batch of scholars under the Space Technology and Applications Mastery, Innovation, and Advancement program. This project is implemented by the University of the Philippines-Diliman in collaboration with the Kyushu Institute of Technology in Japan. In its high level specifications sheet, the mean orbital altitude of the satellites is 400 km and both satellites have elevation angles of 10° and 80°. In what orbit does Maya-3 and Maya-4 belong?
LEO
MEO
GEO
TEO
For the 10° elevation angle, calculate the satellite range of Maya-3 from an Earth station. (Assume the radius of the Earth to be 6370 km). d(km)=(R+h)2−R2cos2(β)−Rsinβ
1349 km
1394 km
1493 km
1439 km
For the 10° elevation angle, calculate the Free Space Loss of Maya-3 from an Earth station if the operating frequency is 437.375 MHz
137.30 dB
147.86 dB
148.42 dB
138.70 dB
A 48-km microwave link is established from Baguio to Dagupan with the following parameters:
frequency of operation: 11 GHz
transmit & receive antenna gain: 20 dB each
receiver sensitivity: -90 dBm
other losses: 6 dB
If the power to the transmitting antenna feed line is 2 W, what is the EIRP in dBm?
50 dBm
51 dBm
52 dBm
53 dBm
A 48-km microwave link is established from Baguio to Dagupan with the following parameters:
frequency of operation: 11 GHz
transmit & receive antenna gain: 20 dB each
receiver sensitivity: -90 dBm
other losses: 6 dB
What is the Free-Space Loss for the 48-km microwave link?
140.89 dB
143.89 dB
146.89 dB
149.86 dB
A 48-km microwave link is established from Baguio to Dagupan with the following parameters:
frequency of operation: 11 GHz
transmit & receive antenna gain: 20 dB each
receiver sensitivity: -90 dBm
other losses: 6 dB
the power to the transmitting antenna feed line is 2 W
Calculate RSL in dBm.
-78.99 dBm
-79.88 dBm
-77.77 dBm
-76.66 dBm
A 48-km microwave link is established from Baguio to Dagupan with the following parameters:
frequency of operation: 11 GHz
transmit & receive antenna gain: 20 dB each
receiver sensitivity: -90 dBm
other losses: 6 dB
If an obstacle is situated 10 km from one of the antennas, by how much must the beam clear the obstacle?
17.6 m
13 m
8.8 m
9.9 m
A 48-km microwave link is established from Baguio to Dagupan with the following parameters:
frequency of operation: 11 GHz
transmit & receive antenna gain: 20 dB each
receiver sensitivity: -90 dB
What is the Earth bulge at the obstacle for obstacle is situated 10 km from one of the antennas?
22.35 m
11.17 m
16.45 m
19.80 m
Two types of Micro Stations
(a)
These are points in the system where the baseband signals either originate or terminate
(a)
These are points where the baseband signals maybe reconfigured or simply repeated or amplified
(a)
two types of microwave repeaters
(a)
this microwave repeater re-radiates microwave energy without additional electronic power
(a)
this microwave repeater acts as a receiver and transmitter
(a)
It is the number of feet or meters an obstacle is raised higher in elevation owing to the curvature
(a)
the ratio of fictitious earth's radius to the actual radius of the earth
(a)
this formula is use for re=ro/1-0.04665e^(0.005577Ns)
(a)
sub-standard, standard,super-standard and infinity condition are
(a)
a wavefront has expanding properties as it travels through space
(a)
It is defined as the power radiated by an antenna in its favored direction and taking the gain
(a)
It is a loss incured by an electromagnetic waves as it propagates in a a straight line
(a)
the rf signal level impinging on the far end receive antenna as if it were an isotropic antenna
(a)
it is simply the level of signal at the receiving end of the transmission
(a)
it is simply the ratio of the receive signal level and the noise power
(a)
it is the attenuation allowance so that anticipated fading will still keep the signal above specified minimum RF output
(a)
it suggest that there is more than one transmission path or method of transmission available between a transmitter and receiver
(a)
It is simply modulating two different RF carrier frequencies with the same IF intelligence, then transmitting both RF signals to a given destination.
space diversity
frequency diversity
hybrid diversity
quad diversity
The output of the transmitter is fed to two or
more antennas that are physically separated
by an appreciable number of wavelengths.
space diversity
frequency diversity
polarization diversity
quad diversity
A single RF carrier is propagated with two
different electromagnetic polarization either
vertical or horizontal.
Polarization Diversity
Frequency Diversity
Space Diversity
Quad Diversity
Consists of standard frequency-diversity with
antennas vertically separated as in space
diversity
space diversity
quad diversity
hybrid diversity
frequency diversity
it combines frequency, space, polarization and receiver diversity into one system
quad diversity
frequency diversity
receiver diversity
hybrid diversity
A physical object that orbits or revolves
around another physical body
(a)
two types of satellite
(a)
A microwave repeater in the sky, placed in an
orbit around the Earth and carries onboard
transmitting and receiving equipment
(a)
Electronic communication system employing
artificial satellites that act as a radio relay
stations in outer space.
(a)
