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Bryx_EST > Transmission Media and Antenna Systems w/4K1 > Flashcards

Transmission Media and Antenna Systems w/4K1 Flashcards

1
Q

Characteristic Impedance of a coax line

A

(138/√Er)⦁log(D/d)
D=Outer Conductor diameter
d=inner conductor diameter
Er=Dielectric constant

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2
Q

Dielectric Constant of Polyethylene

A

2.27

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3
Q

Line Impedance of a parallel-strip line spaced 1cm apart with length 50cm

A

Zo=377(w/l)
=377(1cm/50cm)
=7.54 Ω

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4
Q

Average power rating of RG 58/Cu

A

50W

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5
Q

Coax used for high temperature

A

RG-211A

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6
Q

Converting between dBm, dBrnC, TLP(transmission level point) and dBrnCO

A

dBrnC=dBm+90

TLP(dB)=dBrnC-dBrnCO

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7
Q

You are measuring noise in a voice channel at a -4 dB test point level, the meter reads -73dBm, convert the reading into dBrnCO

A

dBrnC=dBm+90
dBrnC=-73dBm+90
dBrnC=17 dBrnC

TLP=dBrnC-dBrnCO
-4dB=17 dBrnC - dBrnCO
dBrnCO=21 dBrnCO

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8
Q

Impedance inversion can be obtained by

A

a quarter wave line

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9
Q

The dielectric constants of materials commonly used in transmission lines range from about

A

1.2 to 2.8

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10
Q

Typically, the velocity factor (Vf) of the materials used in transmission lines range from

A

0.6-0.9

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11
Q

For an air dielectric two wire line, the minimum characteristic impedance value is____

A 
Zo=(276/√ϵr)⦁log(2D/d)
for minimum char. impedance, D=d 
therefore, 
Zo=(276/√1)⦁log(2)
Zo=83Ω
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12
Q

Reflection coefficient formula

A

t=(Zl-Zo)/(Zl+Zo)
Zl=Load impedance
Zo=Characteristic impedance

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13
Q

Typical characteristic impedance of RG-8A/u

A

50Ω

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14
Q

Characteristic impedance of a quarter-wave transformer

A

Zo=(276/√ϵr)⦁log(2D/d)

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15
Q

Standard tariff for flat rate telephone service beyond normal flatrate in that area

A

WATS (WIDE AREA TELEPHONE SERVICE )

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16
Q

Frequency that’s out -of-band signaling between toll central office (Bell system standard)

A

3700 Hz

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17
Q

If SWR is infinite, what is the type of load?

A

SWR=Vmax/Vmin
SWR=Zo/Zl
SWR can only be infinite if Zl approx. 0. If Zl is approx. 0, then the load is purely reactive

18
Q

Maximum digit of an international telephone number (CCITT REC.E161)

A

12 digits

19
Q

One Erlang is equal to___?

A

36 CCS (Centum Call Second)
1CCS=100 call-seconds
if 1 Erlang is 1 call hour or 1 call-3600 seconds,
simply divide it by 100 to get the equivalent in Centum Cal-Second

20
Q

Standard Telephone Bandwidth

A

300-3400 Hz

21
Q

Component in telephone set which primary function is for compensation of local loop length

A

Varistor

22
Q

Receiver used for conventional telephone handset

A

Electromagnetic

23
Q

Minimum quality circuit available using PTN (packet-based transport networks ()

A

Basic Voice grade

24
Q

Direct Distance Dialing (DDD) network is called

A

Dial-up network

25
Q

What special service circuit is connecting two private branch exchange (PBX)

A

Tie Trunk

26
Q

Power loss in a telephone hybrid

A

-3dB

27
Q

The first Strowger step-by-step switch was first used in _____

A

1897

28
Q

What is the CCITT recommendation for a preparation of loss plan, a variable loss plans and a fixed loss plan?

A

G.122

29
Q

Resistivity constant of copper?

A

1.7x10^-Ω-m

30
Q

What kind of cell is appropriate for load management, fast moving mobiles and low-usage areas

A

Umbrella cells

31
Q

Standard base stations are being replaced by what?

A

adaptive array

32
Q

What is the basis of the first generation wireless loop?

A

Analog Cellular telephony

33
Q

When a calling party hears a “busy” tone on his telephone, then the call is____

A

completed

34
Q

Short circuited stubs are preferred to open-circuited stubs because the latter are____

A

liable to radiate

35
Q

What is the ratio of the reflected voltage to the incident voltage?

A

coefficient of reflection

36
Q

It is used to determine antenna impedance

A

Quarter-wave matching

37
Q

Typical coax cable impedance?

A

50-75Ω

38
Q

Waveguide becomes compulsory to use above what frequencies?

A

Above 3GHz

39
Q

Nominal voice channel bandwidth

A

4kHz

40
Q

Echo suppressors are used on all system when the round trip propagation time exceeds ____

A

50ms

41
Q

Impedance of a quarter wave matching line

A

Zo’=√(Zo⦁Zl)

42
Q

The apparent speed of propagation along a waveguide based on the distance between wavefronts along the walls of the guide is called

A

phase velocity

Bryx_EST (5 decks)

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