ECE124 – FINALS

1. He founded the wave theory of light in 1878 that

was the basis for computation of Fresnel zone

radius. (CHRISTIAN HUYGENS)

2. The region of the frequency spectrum from

approximately 300 MHz to 300 GHz is/are called

__________. (MICROWAVE REGION)

3. When the terrain is a large body of water, the

appropriate k-factor to use to account for

refractivity of the atmosphere is. (5/12)

4. Frequency in GHz at slant range of 100 km that

yields approximately 146.4 dB line-of-sight path

loss. (5)

5. Usually measured in clockwise direction from true

North, when orienting ground station antennas.

(AZIMUTH)

6. Service area LOS radius in km for a receiver with a

sensitivity of minus 90 dBm, a 100mW transmitter

and isotropic antennas at 755 MHz. (TEN)

7. If the equivalent earth radius factor k deteriorates

and the East station antenna is lower than the West

station antenna, the point of reflection will shift to

what direction of the compass? (WEST)

8. With a 2nd Fresnel zone radius of 46 meters midway

of 100km link, what is the frequency in GHz? (7.07)

9. For a space diversity system in terrestrial LOS links,

the electrical length of the waveguide of the higher

antenna is _______ that of the waveguide of the

lower antenna. (EQUAL TO)

10. For terrestrial LOS, the parabolic antenna gain over

isotropic is _______ the frequency. (DIRECTLY

PROPORTIONAL TO THE SQUARE OF)

11. System reliability for two links with hop reliabilities

of 90.00% and 80.00% respectively. (70%)

12. Earth bulge in meters, midpoint of an 88km hop

when the path is over a large body of water. (362)

13. Fill in the blank to make the statement TRUE.

Replacing the transceivers of an existing LOS link

with one of ______ frequencies, without changing

the antenna heights keeps the link unobstructed or

“line-of-sight”. (HIGHER)

14. Find the signal-to-noise ratio of an amplifier with a

noise figure of six (6) dB and an input SNR of 40 dB.

(25.12)

15. A key *di ko mabasa* with MSS than with FSS.

(DOPPLER EFFECT)

16. Given a one loop full duplex LOZ microwave system

in a space diversity arrangement, how many

receivers are all in use? (TWO)

17. Possible number of antenna heights for a station

when the first Fresnel exactly clears the highest

obstruction. (MANY)

18. If equivalent earth radius factor is greater than

1.33333, and both antennas are of same heights

from same level, the elevation angles are both:

(POSITIVE)

19. Accessibility is a criterion when selecting repeater

station sites, cite another factor that should be

considered. (NEARNESS TO AIRPORTS)

20. For frequency diversity system, improvement is

directly proportional to the ____. Which letter

choice is wrong? (DISTANCE)

21. What is the gain in dBd of a 10 ft diameter parabolic

antenna operating at 2 GHz? (34.37)

22. Cut-off frequency in GHz for a signal propagating at

TE01 mode (as shown) in a rectangular waveguide

with a base or width of 4cm and height of 5cm.

(2.968)

23. Resonant frequency in GHz of the dominant mode

for a 7.07cm x 5cm x 8cm rectangular cavity

resonator. (3.273928984)

24. A gradual waveguide E-bend must be greater than:

(1.5 x HEIGHT)

25. When power is incident at port number 1, this is the

formula to compute for the forward attenuation of

a symmetrical directional coupler. (10log(P1P4))

26. To remove an unwanted wave mode inside a

waveguide very thin conducting line are placed

where the mode’s electric field is ______.

(HIGHEST)

27. A tuning post inside a rectangular waveguide has

this impedance at resonance. (ZERO)

28. In an ideal duplexer or gyrator the isolation is:

(INFINITE)

29. Ferrite devices are useful in microwave applications

because they possess what properties? (MAGNETIC

PROPERTIES AND HIGH RESISTIVITY)

30. How many degrees do the signal shifts when

coupled from port 2 to the E-arm of a hybrid tee

waveguide junction? (-90°)

31. Which of the following is NOT a small LEO satellite?

(IRIDIUM)

32. Which was the earliest used and technologically

simple satellite communication access protocol?

(ALOHA)

33. Type of microwave tube use in common

amplification or pre-HPA coupling. (Travelling Wave

Tube)

34. What was the first national GEO VSAT launched in

August 1997 using a Long March 3B rocket? (Aguila

II)

35. Multiple repeaters in communication satellites are

known by the name: (TRANSPONDERS)

36. Which is NOT a satellite orbit? (TITAN)

37. In the current satellite frequency assignments, how

many bands are there for the uplink frequencies?

(SIX)

38. Which do NOT belong in the series of satellite

launch vehicles? (SPACE SHUTTLE) all the others

are single use only, rockets

39. How much bandwidth is required to send 132 voice-

grade channels by FDM on an international satellite

system? (10 MHz)

40. G/T (dB) = GR(dB) – 10log(Ta-Teq) represents:

(FIGURE OF MERIT)

41. What is Motorola Iridium? (LEO series with 66

satellites)

42. Which mobile communication system has 48

satellites (and 4 spares) at LEO and uses CDMA?

(GLOBALSTAR)

43. Which of the following is a primary advantage of

LEO for two communications? (POWER TO ACCESS)

44. Which satellite orbit does NOT belong? (IRIDIUM)

45. Approximate time in hours it takes Tundra orbit to

circle the earth. (24)

46. Geosynchronous and geostationary earth orbits

must be: (OF CIRCULAR ORBIT)

47. Which orbit does NOT belong in the group?

(TUNDRA, the others are circular orbits)

48. Approximate time in hours for a satellite in

synchronous orbit to circle the earth. (24)

49. Which does NOT have an Aguilla II (Ku band) ground

station, as of 2008? (Seoul, Korea)

50. These “words” can be rearranged to form

sentences. Which one of these sentences is FALSE?

(permittivity of the space is ‘4π x 107’ F/m)