Andrew Wallace MEng (Hons) AMIEE

1
Andrew Wallace MEng (Hons) AMIEE Regional Sales
Specialist
2
(No Transcript)
3
Electromagnetic Spectrum
10km 100m 1m 1cm 100mm 1mm 100A 1A
100km 1 km 100m 10cm 1mm 10mm 0.1mm 10A
ELF VLF LF MF HF VHF UHF SHF
EHF
UV
X-rays
Milli- meter
Microwave
Infrared
3 x 102
3 x 1017
3 x 1015
3 x 1013
3 x 1011
3 x 109
3 x 107
3 x 105
3 x 106
3 x 1010
3 x 108
3 x 1012
3 x 1014
3 x 1016
3 x 104
3 x 1018
4
Microwave Systems
5
Transmission Lines
6
Coaxial Conductors
Outer Conductor
Half Wavelength
Inner Conductor
Er
a
Electric Field
Magnetic Field
b
Impedance Z 138 log10 b ÖEr a
7
Stripline Conductors
Dielectric material
Copper / gold strip
Metallic ground strip
Ground Plane
8
Microstrip Conductors
Ground Plane
Copper / gold strip
Dielectric material
Metallic ground strip
Ground Plane
9
Wave Propagation
10
Waveguide Types
11
Why 50W Connectors
1.4
Attenuation is
lowest at
77W
1.2
50W standard
Normalized
Values
1
0.8
Power handling
capacity peaks
at 30W
0.6
1
20
30
40
50
60
70
100
Characteristic Impedance (W)
12
Coaxial Connectors
13
Connector Standards
GPC 14 14 mm 50 DC to 8.5 GHz IEEE 287
75 DC to 2 GHz IEC 457 Type N 7 mm 50 DC
to 18 GHz Mil-C-39012 75 DC to 2 GHz BS
9210 BNC/TNC 7 mm 50 DC to 4 GHz Mil-C-39012
75 DC to 2 GHz BS 9210 Precifix AA 7
mm 50 DC to 18 GHz IEEE 287 IEC 457 GPC
7 7 mm 50 DC to 18 GHz IEEE 287 IEC
457 SMA 4 mm 50 DC to 26 GHz Mil-C-39012
BS 9210 GPC 3.5 3.5 mm 50 DC to 34
GHz Type K 2.92 mm 50 DC to 46 GHz
14
Connector Types
15
Connector Handling
16
Terminations
17
Attenuators
18
Limiters
Pout Watt
Pin Watt
19
Filters
20
Directional Couplers
C
Coupled
Input
Through
A
B
21
Directional Couplers
22
Bridges Autotesters
Source
Vdetector Const Const G
23
Autotester
24
(No Transcript)
25
Power Splitter
Output
50W
Input
50W
Output
26
Wilkinson Resistive Power Dividers
Output A
Input
100W
Loss 3dB
Output B
16.66 W
Output A
Input
16.66W
Loss 6dB
Output B
16.66W
27
Circulators Isolators
A
B
Low loss A to B B to C C to A
High loss A to C C to B B to A
C
28
PIN Devices
W
P
I
N
W Width Of Layer I
29
The YIG Oscillator
30
YIG Frequency
31
Travelling Wave Tubes (TWT)
Focusing Magnet
Cathode
Collector
Microwave Signal
Electron Flow
Focusing Magnet
R.F. O/P
Axial Velocity Of Electron Microwave
Signal _at_ Velocity
32
Antennas
33
Antennas
34
Tea Time
35
(No Transcript)
36
2-Port Scalar Analysis
VINC
VTRANS
DUT
VREF
37
Scalar Measurement Coefficients

• What quantities can be measured by a Scalar
  Network Analyzer?
• Insertion Loss/Gain
• Return Loss, VSWR (Reflection Coefficient)
• Relationship between reflection expressions
• t magnitude of transmission coefficient
• r magnitude of reflection coefficient
  (Biggest 1 , Smallest 0)
• VSWR 1 r Return Loss -20 log10(r) dB
• 1 - r
• r G t T

38
Return Loss - Some Typical Values
Return loss
VSWR
Short / Open circuit
0dB
1
Matched load
1
Theory
dB
0
1.02
Practice
40dB
0.01
1.1 - 1.5
Matched antenna (Broadband)
14 - 26dB
0.05 - 0.2
1.5
Typical component
14dB
0.2
lt1.1
Adapter (Co-ax)
gt26dB
lt0.05
1.1 - 1.5
Waveguide / Co-ax transition
14 - 26dB
0.05 - 0.2
1.04 - 1.1
Waveguide flange
26 - 34dB
0.02 - 0.05
39
Scalar Analyzer Block Diagram
Display
Detector
Ramp Generator
Source
40
Frequency Response
Basic System - Single Detector
41
Simple Return Loss Measurement
DUT
RF OUT
Coupled
Detector
port
42
Return Loss and Insertion Loss
Basic system - Autotester and Detector
43
Sources Of Error
A
B
C
A
C
B
Adapter
RF
DUT
Wanted Reflected Signal
Wanted Reference Signal
Load Match
Adapter
Wanted Transmitted Signal
Source Match
Test Port Match
Directivity
44
Transmission Errors - Frequency Response
Detector Frequency Response
Frequency Response Of Cables
45
Transmission Errors - Source Load Match
Calibration
Detector
lo
DUT
rs
rd
r1
r2
Transmission Uncertainty (worst case) u (rs
rd) (rs r1 lo ) (rd r2 lo) (rs r1
r2 rd lo) or in dB 20 log10 (1 u)
46
Reflection Errors - Frequency Response
Autotester test port frequency response
Autotester
47
Reflection Errors - Directivity Source Match
Where ra Actual Reflection Coefficient
rm Measured Reflection Coefficient rs
Test Port Match D Directivity
rs D
48
Use Of Adapters
49
Waveguide Return Loss - single coupler
Single coupler solution
50
Waveguide Return loss - dual coupler
Dual couplers measure incident and reflected power
51
Antenna Return Loss
P
X
P
X
Interference
P
X
P
INC
P
REF
52
AC Detection
P
X
P
REF
P
X
Interference
P
X
P
REF
X
P
INC
53
Frequency and Time Domain
Frequency Domain
Measure Power Spectrum Insertion
loss Return loss Group delay Defines if
the system is working
Time Domain
Identifies the position of the fault
54
Installation and Maintenance
Loose Connection
Damaged Cable
55
Installation and Maintenance
Control Room
Fault
Waveguides
Transmitter
/receiver
56
Real Pulse TDR
Sampling Oscilloscope
Step-function Generator
DUT
Sampling Gate
57
STDR Using a Scalar Analyzer
Scalar Analyzer
Detector
Vo 2
Vo 4
exp (j2pbL)
Fault at distance L reflection coefficient G
Vo
Swept Frequency Source
Divider
LOAD
L
58
Frequency Domain To Time Domain Conversion
F(f) is the complex reflection coefficient in
the frequency domain
Frequency
0
F(t)
-dB
F(t) is the reflection coefficient in the time
domain for an impulse excitation
1
f(t)
0
Time
59
Advantages of Synthetic TDR

• Higher RESOLUTION
• Capable of eliminating effects of DISPERSION
• Excitation BANDWIDTH known exactly
• Full oscillator OUTPUT POWER for all spectral
  components
• Free choice of start and stop frequencies for
  BANDPASS measurements

60
Fault Location Range
Range (ns) Number of Frequency Points 4 x
Bandwidth If the bandwidth is in units of GHz
then the range is in nanoseconds. Convert to
distance by multiplying by 3 x 108 x Vr
61
Fault Location Resolution
Maximum available resolution is given
by Resolution 1.21
Bandwidth This is the time difference
between two discontinuities which are just
separable Resolution is NOT point spacing.
62
Fault Location In Coax
63
Fault Location In Waveguides
Detector
3-Resistor Power Divider
Waveguide Calibration Load
Coax to Waveguide Adapter
64
Dispersion
In dispersive transmission lines wavelength
is not inversely proportional to frequency. Thus
the
period of the observed ripples will vary
Frequency
Fourier Transform
Time
This leads to impulse spreading
65
Non-Linear Sweep
Coax Line Single Fault Linear Sweep
0
Frequency
Waveguide Single Fault Non-Linear Sweep
0
Frequency
66
Lunch
67
(No Transcript)
68
Signal Analysis
Amplitude
Frequency
Time
Amplitude
Amplitude
Time
Frequency
Frequency domain

• Time Domain
• Oscilloscope

Spectrum Analyzer
69
Oscilloscope Display
Time
1/ Fm

• Amplitude

modulation
70
Spectrum Analyzer Display
Carrier
Upper
sideband
Lower
sideband
Modulation
frequency F
m

• Carrier
• frequency

F
c
F
F F
F - F
c
m
c
m
c
71
Spectrum Analyzer Block Diagram
Detector
Log
Mixer
Amp
IF
IF Amplifier
Filters
Input Attenuator
Video
Filters
Voltage
Ramp
controlled
generator
oscillator
Display
72
Microwave Spectrum Analyzer
Harmonic Mixer and Tracking Preselector
RF Input
IF
output
X2
X3
X4
X1
Local
oscillator
73
Preselected
Fundamental
2nd Harmonic
3rd Harmonic
74
Microwave Spectrum Analyzer

• Harmonic
• Mode

Input
To 479.3
4.5 - 9.2 GHz
MHz IF
'Fundamental'
Mode
4.5 GHz
4.96 GHz
4.48 GHz
75
Harmonic Distortion
Amplitude
Frequency
3Fc
Fc
2Fc
76
A practical example illustrates the method
Harmonic Number Carrier Voltage
Ratio 2 -30dB 1/32 3 -38dB 1/79 4 -45dB 1/1
78 Total harmonic distortion 100 1 / (32)2
1 / (79) 2 1 / (178) 2 3.42
77
Spurious Signals
Amplitude
Non harmonically related spurious
Frequency
3Fc
Fc
2Fc
78
Amplitude Modulation
Determined by modulation depth
Carrier FrequencyFc
Modulation
frequency Fm
modulation
sideband amp
x100
2x
carrier amp
(on linear scale)
F F
Fc
F - F
m
C

m
C

79
AM Spectrum With Modulation Distortion

• Distortion components

F F
F -2F
c
m
c
m
80
Receiver Mode
AM DEMODULATION

25
20
15
10
5
0
5
10
15
20
25
Zero span Res bw 30kHz

• Ref 2.010914MHz

200us /div
81
Modulation Asymmetry

• Amplitude

difference
Mixed AM and FM causes asymmetrical sidebands
82
Frequency Modulation Spectrum Analyzer Display

• Modulation frequency frequency of sideband
  spacing

Modulation Index
Frequency deviation
Modulation frequency
F
c
83
FM-Bessel Zero
Fc
84
FM Demodulation

• FM 1.0kHz mod.freq.. 3kHz
  deviation

1kHz
/div
Ref 150.000000MHz FM demod Res bw
10kHz
500 ms/div
85
Intermodulation Measurement

• Device

Spectrum Analyzer
Signal Combiner
86
2 Tone Intermodulation Analysis
F
F
2
1
2F - F
2F - F
1
2
1
2

• 3F - 2F

3F - 2F
2
1
2
1
87
Effect Of Input Level On Signal To Noise
20
30
Signal-to-
40
10kHz
noise
Bandwidth
ratio (dB)
50
60
70
1 kHz
80
Bandwidth
90
100
110
-90
-70
-50
-30
-10
0
Input mixer level (dBm)
88
Effect of Input Level On Distortion
20
3rd order
30
Intermodulation
products
40

• Distortion
• free

50
dynamic
60
range
2nd harmonic
70
(dB)
80
90
100
110
-90
-70
-50
-30
-10
0
10
30
Input mixer level (dBm)
89
Optimum Dynamic Range
20
10kHz
3rd order
Bandwidth
30
intermod.
40
50
60
2nd harmonic
70
1kHz
Bandwidth
80
90
100
110

• -70

-90
-50
-30
-10
0
10
30
Input mixer level (dBm)
90
Nomograph To Determine IM Products
25
30
2nd Order
3rd Order

• 20

20
0
0
15
10
5
10
10
0
10
20
5
-10
15
30
0
-20
20
40
-5
-30
25
50
-10
-40
30
60
-20
-50
35
70
-30
-60
40
80
-40
-70
45
90
Intercept
Signal
Intermodulation
point (dBm)
level (dBm)
products dB down
91
Intermodulation Intercept Point
30
Intercept point
20
10
Output
level
0
Fundamental
(dBm)
-10
-20
-30
-40
3rd order
products
-50

• -60

-70
-60
-50
-40
-30
-20
-10
0
Input level (dBm)
92
Square Wave
Spectrum Analyzer
1 / t

• F

F Pulse repetition frequency (PRF)1/T
t Pulse width
Oscilloscope
T1/F
t
93
Pulsed RF
Spectrum Analyzer
P.R.F
1/T
f1/t

• Oscilloscope

t
T
94
Pulsed RF
1
2
Wider pulse than 1 -

• High PRF - Low line density

Narrower lobes
PRF and Line density same
3
4
PRF and line density -
PRF lower than 1 -
same as 3
Higher line density
Wider pulse-Narrow lobes
Pulse width and lobes same
95
Pulse Modulation
Envelope display, or
pulse mode
B.W.lt0.3xP.R.F.
B.W.gt1.7xP.R.F
1. Pulse spacing independent
1. Line spacing constant
in frequency
of frequency span
2. Displayed amplitude
2. Displayed amplitude
independent of
changes with resolution
resolution bandwidth
bandwidth
3. Pulse spacing changes
3. Line spacing independent
of sweep time
with sweep time
96
Zero Span
Amplitude

• Time

Frequency Reference Frequency
Bandwidth Resolution Bandwidth
Displays change in amplitude with time
1. Amplitude demodulation
2. RF rise and fall times
3. Pulse ringing, overshoot and droop
97
Understanding Spectrum Analyzer Controls
Detector
Log
Mixer
Amp
IF Amplifier
IF Filters
Input
Attenuator
Video
Filters
Voltage
controlled
oscillator
Display
98
Resolution Bandwidth

• Wide

resolution
bandwidth
Narrow resolution
Narrow
Narrow bandwidth reveals fine details
bandwidth
99
Resolution Bandwidth

• Wide Filter

100Hz Span
100
Noise Floor
100kHz
-90 dBm
10kHz
-100 dBm
1kHz

• -110dBm

-120dBm
100Hz
-130dBm
10Hz
Noise floor drops as the resolution bandwidth is
reduced
101
Sweep Speed

• Sweep speed too fast

Correct Sweep Speed
102
To display
Video Bandwidth
Output
Input
RF
Input
Detector
Resolution

• Video

filters
bandwidth
Local
oscillator
Need slower sweep to achieve
noise smoothing
103
Sideband Noise

• Local oscillator noise

104
Typical Sideband Noise
10Hz
100Hz
1kHz
10kHz
100kHz
1MHz
3Hz
-30
Resolution

• -40

bandwidths
-50
-60
-70
-80
-90
-100
-110
-120
-130
-140
10Hz
100Hz
1kHz
10kHz
100kHz
10MHz
1MHz
Noise
Frequency offset from carrier
dBc/1Hz
105
Residual FM
High quality

• Poor quality

106
To increase sensitivity
RF Attenuator
Input
Input
Resolution
IF Amplifier
Attenuator
filters
Local oscillator
Increase IF amplifier gain - But noise will
increase

• Reduce input Attenuator - But may introduce
  Intermodulation

107
Residual Responses
Amplitude
Frequency
108
Andrew Wallace MEng (Hons) AMIEE Regional Sales
Specialist
109
Tea Time