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RF and transmission line concepts: DCF77, skin effect, matching
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Questions in this quiz (118)
1DCF77 transmits on
- A77.5 Hz
- B77.5 kHz
- C77.5 MHz
- D77.5 GHz
2The data rate of DCF77 is
- A1 bit/s
- B10 bit/s
- C50 bit/s
- D1kbit/s
3What are the impacts of parastic elements?
- ANo change
- BHigh-pass filters are morphing into low-pass filters
- CHighpass filters are morphing into all-pass filters
- DLow-pass filters are showing a high-pass region
4What do you get using XY operation of the oscilloscope and suitable signals?
- AConstructive interference
- BDestructive interference
- CLissajous figures
- DSuperposition
5What happens to the permittivity with increasing (normalized) transmission line width w/h?
- AIt remains constant
- BIt increases
- CIt decreases
- DThe relation is not monotonous
6What advantage do multi-stage matching networks have?
- AMore elements
- BMechanically more robust
- CMore wideband
- DMore expensive
7What is the difference between the video filter and the reolution filter in a spectrum analyzer?
- ANo difference
- BThe video filter is prior to the detector
- CThe video filter is after to the detector
- DA video filter is not part of the spectrum analyzer
8What advantanage do geometrical tapered transmission lines transformers have?
- ASpace-economic design
- BNarrowband matching
- CWideband matching
- DIncreased withstand voltage
9Which diode is best suited for an antenna switch?
- ASchottky diode
- BVaractor diode
- CZener diode
- DPin diode
10By which factor is the troughput of Slotted ALOHA higher than ALOHA?
- A1
- B2
- C10
- D100
11What is the propagation speed over a 50-Ohm PCB microstrip line on FR-4(c0 = 3 * 10^8 m/s)
- Ac0/16
- Bc0/4
- Cc0/2
- Dc0
12An important pioneer of the wireless area is
- AMarroni
- BMascaroni
- CMeloni
- DMarconi
13Why is receiving harder than transmitting?
- AA number of parameters need be synchronized.
- BMore power is needed.
- CThe antenna must be larger.
- DIt is more blessed to give than to receive.
14What impact do parasitics have in RF design?
- AHigh pass filters may morph into low pass filters.
- BThey eat up other components.
- CLow pass filters may morph into high pass filters.
- DHigh pass filters may morph into all pass filters.
15Eddy Currents are ...
- Acircling currents.
- Bcurrents in the skin of a conductor.
- Ccurrents radial to a conductor.
- Dhighest at DC.
16What effect does the skin effect describe?
- ACurrent flows predominantly in the outer part of a conductor.
- BCurrent flows predominantly in the inner part of a conductor.
- CRadial currents are generated.
- DThe conductor is being peeled.
17What is the skin depth of a copper high-power cable?
- A1 mm
- B1 cm
- C1 dm
- DIt depends on the current level.
18In which country there is an island like a "resistor"?
- AGreece.
- BTurkey.
- CCroatia.
- DMalta.
19How many elements does the equivalent circuit of a lossy transmission line segment contain?
- A2
- B3
- C4
- D8
20How many elements does the equivalent circuit of a lossless transmission line segment contain?
- A2
- B3
- C4
- D8
21What is the wave impedance?
- ACharacteristic impedance of a transmission line.
- BReactance of a transmission line.
- CSusceptance of a transmission line.
- DImaginary part of the load impedance.
22Who came up with the telegraph equations?
- AOliver Heaviside
- BGuillelmo Marconi
- CHeinrich Hertz
- DJames Maxwell
23Why is 50 Ohm as a cable impedance popular?
- AIt is close to the optimum for maximum efficiency of power transfer.
- BDue to the center value of the Smith chart.
- CFixed nature constant, can't be changed.
- DResults in the longest life time of a cable.
24Which of the following facts is true?
- Agamma is always independent of L' and C'.
- Bgamma is always independent of R' and G'.
- Cv inside the transmission line is depending on L' and C'.
- Dv inside the transmission line is always equal to c.
25What is the propagation speed of a 50-Ohm PCB microstrip line on FR-4?
- Ac/10
- Bc/4
- Cc/3
- Dc/2
26What are the telegraph equations?
- A2 decoupled quadratic differential equations.
- B2 coupled quadratic differential equations.
- C2 decoupled linear differential equations.
- D2 coupled linear differential equations.
27Which of the following statements is true?
- AThe cable impedance is always real-valued.
- BThe cable impedance is always complex-valued.
- CThe real part of the cable impedance is positive.
- DThe real part of the cable impedance is negative.
28What happens if you connect cables of different wave impedances?
- AThe connectors don't fit.
- BPower is being radiated.
- CThere are reflections.
- DThe cables are being destroyed.
29What does the s stand for with respect to the reflection parameters?
- ASurface
- BSource
- CScatter
- DSmith
30Which matrices are being multiplied when twoports are cascaded?
- AZ-matrices
- BY-matrices
- CS-matrices
- DT-matrices
31What return loss signifies a good matching situation?
- A0 dB
- B-3 dB
- C20 dB
- D-20 dB
32What power proportion is reflected when the Return Loss is 10 dB?
- A1%
- B10%
- C50%
- D100%
33What can be said for passive, lossless twoports?
- A|s11|^2+|s22|^2=1
- B|s11|^2+|s12|^2=1
- C|s11|^2+|s21|^2=1
- DNone of the above.
34Which value of the reflection coefficient does the center of the Smith-Chart correspond to?
- A-1
- B0
- C1
- Dj
35How many L-topologies of LC networks do exist?
- A2
- B4
- C8
- D16
36How many L-topologies of LC networks can always be used at least for a given matching situation?
- A1
- B2
- C4
- D8
37A Lambda/4-line transforms the reflection factor in the Smith Chart ...
- Aby a 1/8 turn.
- Bby a 1/4 turn.
- Cby half a turn.
- Dby a full turn.
38Which of the following lengths transforms a high-impedance load to a short-circuit?
- Alambda/2
- B8*lambda/4
- C13*lambda/4
- D13*lambda/2
39A transmission line of electrical length lambda transforms an impedance of (100+j50) Ohm into...
- A(100+j50) Ohm
- B(100-j50) Ohm
- C(25+j50) Ohm
- D(25-j50) Ohm
40What advantage does a multistage matching circuit have (L-topology)?
- Asimple
- Blow price
- Crobust to interference
- Dmore wideband
41What is the difference between a spectrum analyzer and a network analyzer?
- Alower end of the operating frequency
- Bhigher end of the operating frequency
- Ca network analyzer has an output port
- Dthe color of the case
42For which equipment do we have calibration kits consisting of short, load and open?
- Anetwork analyzer
- Bspectrum analyzer
- Cpower meter
- DRF generator
43Which equipment needs several directional couplers to do the measurement?
- Anetwork analyzer
- Bspectrum analyzer
- Cpower meter
- DRF generator
44What does the word "Vector" in Vector Network Analyzer signify?
- Athe measurement is carried out over ten parameter dimensions or more
- Bboth amplitude and phase are being measured
- Cthe measurement are evaluated at hundreds of frequency points
- Dmarketing expression
45Which elements are parts of an SC filter?
- Aresistors
- Binductors
- COpAmps
- Dmixers
46The Q factor of a quartz filter is ...
- Amuch higher than that of an LC filter.
- Bmuch lower than that of an LC filter.
- Cabout the same as that of an LC filter.
- Dnegative.
47The loaded Q is ...
- Aalways higher than the unloaded Q.
- Balways lower than the unloaded Q.
- Cthe same as the unloaded Q.
- D(depends on series or parallel resonance circuit).
48What is the Richards transform?
- AConversion of open into short-circuited transmission lines.
- BConversion of capacitors into transmission lines.
- CConversion of capacitors into inductors.
- DPrewarping of the frequency response.
49What is a Kuroda transform?
- ALinear spectrum becomes a repetitive spectrum.
- BCurrent-voltage-conversion.
- CAdmittance-impedance-conversion.
- DUsing unit elements inductors may be transformed into capacitors.
50What is the output attenuation at one port of a resistive 2-way splitter?
- A0 dB
- B3 dB
- C6 dB
- D12 dB
51The through loss T [dB] of a passive directional coupler is ...
- Aalways 0
- Ba negative value
- Ca positive value
- Dnone of the above
52What can be said about coupling C [dB] vs. through loss T [dB] of a passive directional coupler?
- AC=T
- BC
- CC>T
- Dnone of the above
53A choke balun is another word for ...
- Acurrent balun
- Bvoltage balun
- Ctransformerless balun
- Ddiscrete balun
54What does the word 'Modem' stand for?
- Amodified demolisher
- Bmodular Emulator
- Cmodulator/demodulator
- Dmodified employer
55Which modulation scheme is represented by the top plot?
- ABPSK
- BQPSK
- CQAM
- DFSK
56Which modulation scheme is represented by the plot?
- ABPSK
- BQPSK
- CQAM
- DFSK
57Which modulation scheme is represented by the plot?
- ABPSK
- BQPSK
- CQAM
- DFSK
58Which modulation scheme is represented by the plot?
- ABPSK
- BQPSK
- CQAM
- DFSK
59What is the use of Gray coding?
- AMaximization of the symbol distance within the constellation
- BMinimization of the bit-errors
- CEncryption of the message
- DBlack-and-white colorization of the image information
60How do you get the impulse response of a Raised-Cosine filter?
- AIt is the same as the impulse response of a Root-Raised-Cosine filter.
- BBy taking the square root of the impulse response of a Root-Raised-Cosine filter.
- CBy squaring the impulse response of a Root-Raised-Cosine filter.
- DBy convolving the impulse response of a Root-Raised-Cosine filter with itself.
61How many amplitudes are there in a 16-QAM signal (baseband)?
- A1
- B2
- C3
- D4
62Where is the pulse shaping filter in a GMSK system?
- Abefore the modulator (in the transmitter)
- Bafter the modulator (in the transmitter)
- Cafter the mixer but before the demodulator (in the receiver)
- Dafter the demodulator (in the receiver)
63What modulation index does MSK have?
- A0
- B0.3
- C0.5
- D1
64What advantage does a CPM system have compared with switched oscillators for the generation of FSK?
- Ano phase jumps
- Bfaster changes of the frequency
- Ccheaper
- Dsmaller
65How many amplitudes are there in a GMSK signal?
- A1
- B2
- C3
- D4
66What phase change does an MSK signal produce during one symbol duration?
- A±22.5º
- B±45º
- C±90º
- D±180º
67What does the abbreviation SDMA stand for?
- AScatter-division multiple access
- BSplutter-division multiple access
- CSecret-division multiple access
- DSpace-division multiple access
68What kind of channel access does GSM use?
- ATDMA
- BCDMA
- CSDMA
- DPDMA
69What kind of channel access does UMTS use?
- ATDMA
- BCDMA
- CSDMA
- DPDMA
70How are collisions avoided with the ALOHA protocol?
- Aby 'Listen-before-Talk'
- Bby random delay of the packets
- Cby increased transmission power
- Dby improved receivers
71What drawback do spread-spectrum systems have?
- ANear-far problem
- Bprivacy
- Cfading immunity
- Djamming immunity
72Which system does not use OFDM?
- AADSL
- BUMTS
- CLTE
- DDVB
73How does OFDM turn a linear convolution into a circular convolution?
- Acyclostationarity
- Bcyclic extension
- Crandom cycles
- Dbicycles
74What diode is well suited as an RF switch?
- APIN diode
- BVaractor diode
- CSchottky diode
- DTunnel diode
75What can be said for the quadratic range of a diode detector?
- AThe output voltage is proportional to the input power.
- BThe output voltage is proportional to the input power squared.
- CThe output voltage is proportional to the frequency of the input signal.
- DThe output voltage is proportional to the Fermi level.
76What diode is well suited for a tunable oscillator?
- ASchottky diode
- BZener diode
- CAvalanche diode
- DVaricap
77Where does the Gunn diode derive its name?
- Alooks like a pistol
- Blooks like a gun
- Cglobally distributed undoped double n-layer
- Dafter a physicist
78What does dBc mean?
- Alogarithmic ratio to elementary charge
- Blogarithmic power density compared to circular radiator
- Cdual-band (centered)
- Dlogarithmic power ratio compared to carrier signal
79Which characteristic is the least important for a power amplifier?
- Alinearity
- Blow noise
- Chigh efficiency
- Dthermic capability
80What does the expression conditional stability mean with respect to amplifiers?
- AInstability might occur within a certain temperature range.
- BInstability might occur for a certain power supply voltage.
- CInstability might occur for a certain active load.
- DInstability might occur for a certain passive load.
81What are stability circles?
- ALocations for poles to be found.
- BImpedances on the circles result in stable designs.
- CImpedances within stability circles are forbidden regions.
- DImpedances within the circles result in stable designs.
82What does the noise figure express?
- AFrequency shape of noise.
- BAcoustic phenomenon.
- CSignal gain for high-level signals.
- DDegradation of input SNR to output SNR.
83How many diodes are there in a double-balanced mixer?
- A1
- B2
- C3
- D4
84How do you call an active FET mixer?
- AGilbert Cell
- BDilbert Cell
- CCascode
- DCurrent mirror
85What is the benefit of a double-balanced mixer versus a single-balanced mixer?
- Asmaller conversion loss
- Bsimpler
- Chigher signal levels
- Dhigher port isolations
86What components are there in a passive double-balance mixer besides diodes?
- AFETs
- Bswitches
- Ctransformers
- Dbipolar transistors
87How do you call the effect, when strong interferers are being mixed into the IF because of phase noise?
- Areciprocal mixing
- Bintermodulation
- Cspurious emission
- Dphase discrimination
88The spectral shape of phase noise ...
- Ais always white.
- Bshows strictly f tendency.
- Cshows 1/f^2 tendency.
- Dincreases for higher frequency.
89Which of the following blocks is not part of a PLL?
- Aphase discriminator
- BFM modulator
- CVCO
- Dloop filter
90Which of the following frequencies cannot be produced by an integer-N synthesizer (ref freq = 100kHz)?
- A1000.10 MHz
- B9999.99 MHz
- C1'235.0 MHz
- D400 kHz
91How large is the field part in air for striplines?
- ALarger than for microstrip lines.
- BSmaller than for microstrip lines.
- CEqual to that of for microstrip lines.
- DNo statement can be made.
92What power proportion is reflected when the Return Loss (|?11|) is 20 dB?
- A0.1%
- B1%
- C10%
- D50%
93What happens to the wave impedance of a PCB line with increasing width?
- AIt stays the same.
- BIt is decreasing.
- CIt is increasing.
- DIt gets frequency dependent.
94A quarterwave 50-Ohm transmission line transforms an impedance of (100 + ?50)Ω into ...
- A(20 + ?10)Ω
- B(20 − ?10)Ω
- C(100 + ?50)Ω
- D(100 − ?50)Ω
95What is the main difference between a spectrum analyzer and a network analyzer?
- ALower end of the operating frequency
- BHigher end of the operating frequency
- CA network analyzer has an output port
- DColor of the case
96For which equipment do we have calibration kits consisting of short, load and open?
- ANetwork analyzer
- BSpectrum analyzer
- CPower meter
- DRF generator
97Which equipment needs several directional couplers to do the measurement?
- ANetwork analyzer
- BSpectrum analyzer
- CPower meter
- DRF generator
98What does the word ”Vector” in Vector Network Analyzer signify?
- AThe measurement is carried out over ten parameter dimensions or more.
- BBoth amplitude and phase are being measured.
- CThe measurement are evaluated at hundreds of frequency points.
- DMarketing expression
99What is the use of Gray coding?
- AMinimization of BER.
- Baximization of average symbol power.
- CEncryption of the message.
- DBlack-and-white colorization of the image information.
100How do you get the impulse response of a Raised-Cosine filter?
- ABy squaring the impulse response of a Root-Raised-Cosine filter.
- BBy convolving the impulse response of a Root-Raised-Cosine filter with itself.
- CBy taking the square root of the impulse response of a Root-Raised-Cosine filter.
- DIt is the same as the impulse response of a Root-Raised-Cosine filter.
101Where is the pulse shaping filter in a GMSK system?
- Abefore the modulator (in the transmitter)
- Bafter the modulator (in the transmitter)
- Cafter the mixer (in the transmitter)
- Dafter the demodulator (in the transmitter)
102What can be said for the quadratic range of an RF diode detector?
- AThe output voltage is proportional to the input power.
- BThe output voltage is proportional to the input power squared.
- CThe output voltage is proportional to the frequency of the input signal.
- DThe output voltage is proportional to the Fermi level squared.
103What diode is best suited for building a tunable oscillator?
- AVaractor diode
- BTunnel diode
- CSchottky diode
- DPIN diode
104The maximal transducer gain of an amplifier ...
- A... is smaller than or equal to |?21|.
- B... is larger than or equal to |?21|.
- C... is smaller than or equal to |?11|.
- D... can be made negative.
105Ideally, |?11| of an amplifier should be ...
- A0
- B-1
- C1
- D∞
106The cable losses of the RG-58 in the lab are mainly due to . . .
- Aage of the cables
- Bskin effect & dielectric losses
- Cblack cable coating
107What does the sweep time in the automatic setting depend upon inside a VNA or the SA?
- Avideo bandwidth & resolution bandwidth
- Bbeam intensity
- Ccarrier frequency
108What happens to the wave impedance with increasing (normalized) transmission line width ?/ℎ?
- AIt remains constant.
- BIt increases.
- CIt decreases.
- DThe relation is not monotonic.
109Coaxial cables are . . .
- Asymmetric systems
- Bbalanced systems
- Cunbalanced systems
- Ddifferential systems
110Which of the following access schemes are deployed within GSM?
- ATDMA & FDMA
- BCDMA & PDMA
111What advantage do single-stage matching networks have?
- AMore elements.
- BMechanically more robust.
- CMore wideband.
- DEase of building.
112The VSWR along a transmission line . . .
- Amay get complex valued.
- Bis always a number ≥ 1.
- Cmay be a negative number.
- Dis 0.5 in its best case (ideal).
113Which of the following elements do you find in baluns?
- Acoil transformers
- Bcoils
- Ccapacitors
- Dtransmission lines
- Eall of them
114Which diode is best suited for a fast RF detector?
- ASchottky diode.
- BVaractor diode.
- CZener diode.
- DPIN diode.
115A image filter suppresses ...
- A... the signal of interest
- B... the IF signal
- C... bands that may fall onto the IF
- D... the LO signal
116What happens with respect to the HD3 if a linear, passive element with ? = 10 dB is appended to a receiver chain?
- AOIP3 ... of the total chain decreases
- BOIP3 ... of the total chain increases
- CIIP3 ... of the total chain decreases
- DIIP3 ... of the total chain increases
117What happens with respect to the NF if a linear, passive element with ? = 10 dB is appended to a receiver chain?
- ANF drops to 0 dB
- BNF decreases
- CNF remains constant
- DNF increases
118What happens with respect to the NF if the bandwidth of a filter in a receiver chain is reduced?
- ANF drops to 0 dB
- BNF decreases
- CNF remains constant
- DNF increases
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- Quiz on Untitled, created by Cedric Renda on 29/08/2020.
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- Cedric Renda
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