Transcript 90-GHz Radiometer - Ingegneria Elettronica

“SAPIENZA, UNIVERSITÀ DI ROMA”
FACULTY OF INFORMATION ENGINEERING, COMPUTER SCIENCE AND STATISTICS
Master Degree in Electronic Engineering
MICROWAVE SATELLITE TELECOMMUNICATIONS:
CHARACTERIZATION OF THE ALPHASAT RECEIVING
SYSTEM AND 90-GHz RADIOMETER
Graduant
Pasquale Salemme
Supervisor
Prof. Frank S. Marzano
Assistant Supervisors
Elio Restuccia
(ISCTI)
Fernando Consalvi (FUB)
Rome, 11 October 2011
• Introduction
Summary
• Receiving station architecture
Receiving station diagram block
• Laboratory Measurements
Conical Horn Antenna
Low Noise Amplifier Block
First Conversion Block
Second Conversion Block
Satellite Beacon Receiver SBR
Total receiver noise figure
• Link Budget for the Rome site
Numerical-statistical and Hardware analysis
• 90-GHz Radiometer
Diagram block
RF Characterization
• Conclusions
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the AlphaSat receiving system and 90-GHz Radiometer“
Introduction
• The current need for an increasingly wider bandwidth in satellite radio
communications pushes to exploit higher frequency ranges
• Higher frequency propagation suffers much more atmospheric components
effects that reduce drastically connection availability in unfavourable weather
conditions
• In order to analyze and quantify degradation of transmission channel performance
at Ka-band (20 GHz) and Q-band (40 GHz), European Space Agency
scheduled, in 2012, to launch AlphaSat satellite for conducting radio
propagation studies by a “Technology demonstrator Payload”, denominated
TDP5
• Microwave Laboratory of Communications and Information Technology Institute
(ISCTI, Economic Development Ministry - Communications Department - Rome)
is developing a Q-band receiving station in Rome, designed in collaboration
with Electronic and Telecommunications Engineering Department (DIET) of Rome
University “Sapienza” and Ugo Bordoni Foundation (FUB)
• Components recovered inside an unused receiving station, dedicated to previous
propagation experiments, have been used with a great advantage from
economic point of view
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the Alphasat receiving system and 90-GHz Radiometer“
Receiving station architecture
LNA blockstation
and first
conversion
Receiver
diagram
block
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the AlphaSat receiving system and 90-GHz Radiometer“
Receiving station architecture
Second conversion and IF2 amplifier block
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the Alphasat receiving system and 90-GHz Radiometer“
Laboratory Measurements
Conical Horn Antenna
• Receiver has a conical horn antenna, with operating bandwidth from 40,5 to
42,5 GHz, slightly higher than required but still suitable for the design, as
confirmed by results
• Antenna has been equipped with a rectangular waveguide feeder that
discriminates linear polarization of received e.m. field
Conical horn antenna
hasperformed
been placed
an azimuth
turntable
plane,
•• Measurements
have been
in anon
indoor
environment,
intended
for
provided
with
degrees
scale,
in
order
to
appreciate
up
to
10/60
of
a
microwave e. m. field measurements, provided with anechoic panels disposed
degree
values
(± carriages,
11 degrees
of 10/60
a
on
ceiling,measurements
antenna back wall
and three
freeintosteps
be placed
withinofthe
degree) havein been
and results
normalized
to maximum
environment,
order interpolated
to optimize measure
eliminating
most undesired
e. m.
received power
echoes
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the Alphasat receiving system and 90-GHz Radiometer“
Laboratory Measurements
Maximum antenna gain measurement
“Comparison method with a calibrated antenna”
The method consists in comparing under test antenna with a calibrated antenna
• Measurement distance was about 4 m, lower than foreseen for the far-field
zone (2D2/ = ~16 m)
ut dBi
ant ref dBi
R dB
• Small correction has been done according to current methodology [R. C. Hansen]
•
G
G
 P
PR efficiency:
 PRant ref dBmA  PRant
Maximum aperture
dB
 ut dBm
 1
2
a 
e
Ag

 4
GLIN 
 Ag
 0,6
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the AlphaSat receiving system and 90-GHz Radiometer“
Laboratory Measurements
Cross-polar
antenna
radiation
patterns
Co-polar antenna
radiation
patterns
(±11
2 degrees in steps of 10/60 of a degree)
(±
<- Azimuth co-polar radiation pattern
Azimuth co-polar and cross-polar
radiation patterns
Zenith co-polar and cross-polar
radiation patterns
This antenna minimizes received
power level variations, due to
satellite apparent movement (2 dB
for about ± 1 degree).
Antenna tracking hasn’t been
Zenith co-polar radiation pattern ->
implemented.
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the AlphaSat receiving system and 90-GHz Radiometer“
Laboratory Measurements
Low Noise Amplifier Block
Under
Test (DUT)
consists
of:
DUT gain has been evaluated with a Device
network
analyzer,
measuring
scattering
parameter s21 module in the 32-47- GHz
frequency
range.
working
an isolator
(placed
nextAtto the
antenna)
frequency (39,402 GHz) DUT gain is about
17,3
dB.(which eliminates possible
- an RF
filter
undesired signals, in particular image
frequency ones at 32,590 GHz)
- an LNA
- its output isolator
First Conversion Image Frequency
Isolator - RF filter frequency response forward and reverse
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the AlphaSat receiving system and 90-GHz Radiometer“
Laboratory Measurements
Block LNA Noise Figure
“Y” method
• Using a noise source having two working conditions (powered and not), two
noise powers at two different noise equivalent temperatures are available
• ENR (Excess Noise Ratio) is the characteristic parameter of noise source
previously calibrated by the manufacturer as a function of frequency
ENRLIN 
• “Y” ratio is defined as:
Y
Th  Tc
Tc
Non
Noff
where Non and Noff are noise powers relative to the two-state noise source
• Noise source has been driven by a noise figure meter that automatically
performs measurement steps and returns DUT noise figure value
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the AlphaSat receiving system and 90-GHz Radiometer“
Laboratory Measurements
Block LNA Noise Figure
The measurement takes place in two steps:
LNA operating frequency (39,402 GHz) is higher than the maximum
calibration step: noise source has been connected directly to mixer input.
noise
figure ENR
meter(11,19
working
(2,047
GHz),setmeasurement
Noise source
dB atfrequency
39,402 GHz)
has been
in noise figure
dB
system
needs
a down
converter,
meter and
then
calibration
process constituted
activated by a mixer and a generator
as LO. Whole measurement system noise is taken into account by
measurement step: DUT has been connected between noise source and
calibration
step.
measuring system
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the AlphaSat receiving system and 90-GHz Radiometer“
Laboratory Measurements
First Conversion Block
• It has been assembled using a waveguide mixer and a local oscillator
operating at 35,996 GHz. LNA output signal (39,402 GHz) therefore has
been shifted to IF1 (3,406 GHz). The block also includes isolators
connected to the three mixer ports
• Block conversion loss has been measured by a power meter with a power
sensor:
• DUT output frequency is higher than noise figure meter input range
and so the second IF converter block, present in the receiving chain
(described afterwards), has been used in measurement system, converting
IF1 3,406 GHz in IF2 70 MHz
• Measurement is in single sideband (SSB) because contribution due to
image frequency has been attenuated strongly by the RF filter
• Its attenuation (0,5 dB) can be taken into account
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the AlphaSat receiving system and 90-GHz Radiometer“
Laboratory Measurements
Second Conversion Block
• Second converter looks like a single unit and
translates IF1 3,406 GHz to 70 MHz using its
own
inside
local
oscillator
(3,336
GHz)
(-> 10 MHz caesium-beam primary frequency
standard avaible in ISCTI)
• Conversion gain IF1-IF2 test bench is very
simple and uses a RF generator and a spectrum
analyzer
Frequency
10 to 130
MHz and GHz
startingfrequency
67 to 73 MHz signal in IF1
• Measurement has
beenResponse
done starting
injecting
a 3,406
input
portmeasurement
and the input-output
difference
hastobeen
measured
•converter
For noise
figure
the scheme
is similar
the previous
The IF1-IF2 conversion
gain is about 32 dB.
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the AlphaSat receiving system and 90-GHz Radiometer“
Laboratory Measurements
Second Conversion Block – 2nd Image Frequency Rejection
• RF filter, which attenuates first conversion image (32,590 GHz) more than 60 dB,
cannot eliminate second conversion image (3,266 GHz) corresponding to RF
input (39,262 GHz) due to its large bandwidth (about 3 GHz)
• However, thanks to second converter input filter, there is a satisfactory
second conversion image rejection, approximately 48 dB
PIF2 level measurement at 70 MHz
with input at 39,402 GHz (left)
and at 39,262 GHz (right)
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the AlphaSat receiving system and 90-GHz Radiometer“
Laboratory Measurements
Satellite Beacon Receiver SBR
Locked and unlocked states
• Second conversion output, after an amplification stage at IF2, has been
connected to the Satellite Beacon Receiver (SBR)
• SBR is a double frequency conversion receiver which provides an output
voltage Vdc , whose amplitude is related to the input level signal
• SBR automatically looks for and locks an input signal whose frequency is
within its bandwidth research (70 MHz ± 200 kHz)
• It is possible to select search time (one minute minimum, eight minutes
maximum) in a limited frequency range around the last position. After this period,
SBR will scan entire band (± 200 kHz)
• Output voltage Vdc is the receiving station output information to be
recorded by data logger-computer group
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the AlphaSat receiving system and 90-GHz Radiometer“
Laboratory Measurements
Total receiver noise figure
• The various receiving system components have been assembled and then total
noise figure has been measured, using methodology described above, from RF
39,402 GHz input to IF2 70 MHz down converter output
• LNA block noise figure (4,46 dB) essentially determines the total RF-IF2
noise figure value
• Measure can be compared to the theoretical result, using cascade
components noise figure formula:
F2  1 F3  1
Fn  1
Ftot  F 1 

 ... 
 4,67 dB
G1
G 1G 2
G 1 G 2 ..G n 1
• Theoretical value is 0,36 dB lower than one measured at test bench, difference
presumably due to measurement uncertainties composition
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the AlphaSat receiving system and 90-GHz Radiometer“
Link Budget for the Rome site
Numerical-statistical analysis
Satellite-receiver link budget at Q band will be described in terms of: total
additional attenuation (according to ITU-R recommendation), received power,
antenna temperature, system noise temperature, G/T and C/N ratios, all as
function of the probability p that value has been exceeded or not, depending by
considered parameter.
AlphaSat TDP5 characteristics
Working frequency f =39,402 GHz
Maximum gain antenna GPL = 26,7 dBi
Antenna aperture diameter DPL = 0,6 m
Half power beam width Θ3dB = 9 °
Transmitted power PPL = 2,7 dBW
Receiving station characteristics (Roma – ISCTI):
Lat 41° 49’ 53,18’’ N
Long 12° 27’ 58,56’’ E
Antenna aperture diameter DR = 0,245 m
Half power beam width Θ3dB = 2,17 °
Opening efficiency ηa = 0,6
Maximum gain antenna GR = 37,9 dBi
Receiver noise figure NFR = 5,03 dB
Receiver noise temperature TR = 633,41 K
Waveguide losses Lfr = 0,1 dB
Antenna depointing losses Lr=1 dB
Receiver physical temperature T0 = 290 K
Ground noise collected by receiver antenna Tgr = 30 K
Atmospheric mean radiating temperature Tm = 280 K
at 0,1% time
PLL bandwidth B = 100 Hz (20 dBHz)
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the AlphaSat receiving system and 90-GHz Radiometer“
Link Budget for the Rome site
Numerical-statistical analysis
PR (p)  P PL GPL  GR  Lfs  AT (p)
Received Power [dBm]:
where:
AT(p) is total additional attenuation in dB
Lfs is free space attenuation in dB -> Lfs  20log  4 d /  
Prob
[%]
AT
[dB]
PR
[dBm]
Tant
[K]
Tsys
[K]
G/T
[dB/K]
C/N0
[dBHz]
C/N
[dB]
0,05
32,9
-151,0
309,8
942,9
7,0
16,7
-3,3
0,1
24,7
-142,9
309,1
942,0
7,0
24,9
4,9
0,5
11,4
-129,6
289,8
923,2
7,1
38,2
18,2
10
2,0
-120,2
136,9
773,7
7,9
48,3
28,3
50
0,9
-119,0
85,6
723,6
8,2
49,8
29,8
90
0,6
-118,8
68,0
706,5
8,3
50,2
30,2
(  AT ( p )/10)
Tant  Tc 10
(  L fs /10)
Tsys  Tant 10
(  AT ( p )/10)
 Tm(1  10
(  L fr /10)
 T0 (1  10
 0,1% annual time
(~ 9 hours)
)  Tgr
)  TR
(G /T )dB /K  GR  Lfr  Lr  10log(Tsys )
(C / N0 )dBHz  PR _ ISO  G /T  10log(kB )
(C / N )dB  C / N0  B
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the AlphaSat receiving system and 90-GHz Radiometer“
Link Budget for the Rome site
Numerical-statistical analysis
Total additional attenuation and rain contribution [dB]
Expected C/N and C/N0 ratios [dB and dBHz]
Isotropic antenna received and effective powers [dBW]
Expected G/T ratio [dB/K]
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the AlphaSat receiving system and 90-GHz Radiometer“
Link Budget for the Rome site
Hardware analysis- C/N values measurements of RF-IF2 receiver chain
• To compensate partially the deterioration caused by use of an antenna with gain
lower than one recommended by ESA, PLL bandwidth B has been reduced
from 1 kHz to 100 Hz, improving C/N ratio of 10 dB
• An RF generator set at 39,402 GHz, followed by appropriate attenuation,
simulates satellite signal
• Second conversion block output signal at IF2 (70 MHz) has been applied to a signals
analyzer, able to measure C/N ratio (B = 100 Hz)
• MatLab® results are very near to measured C/N values, as shown in the
graph below
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the AlphaSat receiving system and 90-GHz Radiometer“
Link Budget for the Rome site
Hardware analysis - Output voltage vs. received power graph
• Output voltage vs. received power graph has been obtained using the whole
system, including the SBR with PLL bandwidth B equal to 30 Hz, in this case,
to check frequency locking stability
For a stable frequency locking the
lowest power received level PRF is
about -136 dBm, corresponding to
a off-duty probability lower than
0,2%. Frequency locking becomes
unstable with a lower received power
level. Signal loss occurs for power
level lower than -140 dBm
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the AlphaSat receiving system and 90-GHz Radiometer“
90-GHz Radiometer
Diagram Block
• In progress at ISCTI Microwave Laboratory, designed in collaboration with Ugo
Bordoni Foundation (FUB)
• Two reference temperatures radiometer
• Designed to perform, in parallel with the 40-GHz AlphaSat receiver, additional
estimates of attenuation, obtained from brightness temperature
observations of the same propagation atmosphere zone by suitable algorithms
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the AlphaSat receiving system and 90-GHz Radiometer“
90-GHz Radiometer
Diagram Block
• Antenna Orthogonal Mode Transducer OMT (Orthogonal Polarization Selector)
• RF Network Selector: four circulator cascade at switching field inversion
• Hot load: Diode Noise Generator+Isolator – Cold load: termination at room temperature
• Gunn diode local oscillator and mixer conversion
• Quadratic Detector type: Diode Tunnel + Post integrator
• ADC Conversion
• Data acquisition unit (RS-232) and control
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the AlphaSat receiving system and 90-GHz Radiometer“
90-GHz Radiometer
RF Characterization
• Vector Network Analyzer with bandwidth extension from 75 to 110 GHz by
WR10 waveguide
• Magnitude and phase of the four scattering parameters
• Instrument calibration with "gold" calibration kit, useful for high precision
measurements at high frequency
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the AlphaSat receiving system and 90-GHz Radiometer“
90-GHz Radiometer
RF Characterization – RF Network Selector
• Switches controlled by a network control unit that connect periodically gate mixer
with the other four
All measures and graphs of Alphasat TDP5 receiver characterization and of 90-Ghz
s12
 s21
11 
22
radiometer
are shown in attached CD-ROM
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the AlphaSat receiving system and 90-GHz Radiometer“
Conclusions
• The activity devoted to the study and realization of a Q-band (40 GHz) receiving
station for AlphaSat satellite and a 90-GHz Radiometer, located in Rome (Italy),
has been illustrated.
• Components recovered inside an unused receiving station, dedicated to previous
propagation experiments, have been used with a great advantage from economic
point of view.
• On the other hand this has exacted constraints in design choices that led to the
described system configuration.
• Obviously receiver performances, even if they demonstrate proposed solution
validity, can be improved by nowadays available technology, in particular for the
antenna and the low noise amplifier, which largely imply overall system receiver
efficiency.
• Final check will be possible after satellite AlphaSat launch and, after a
reasonable data registration time period, it will be possible to assess
performances described in this presentation.
• Short-term future developments will deal with:
Implementation and boxing of the Q-band receiver outdoor and indoor
sections and of 90-GHz Radiometer
Procurement of motorized dual-feed reflector antenna (TEMIX? Proposal
under evaluation) -> aperture diameter of 120 cm (against current 24 cm)
-> C/N increase of about 14 dB
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the AlphaSat receiving system and 90-GHz Radiometer“
Papers
This work has been presented at COST Action IC0802 “Propagation tools and
data for integrates Telecommunication, Navigation and Earth Observation systems”
(28-30 September 2011, Institute of Atmospheric Physics, Prague, Czech Republic)
and will be submit at EuCAP 2012 “6th European Conference on Antennas and
Propagation” (26-30 March 2012, Congress Centre, Prague)
Pasquale Salemme
“Microwave Satellite Telecommunications: characterization of the AlphaSat receiving system and 90-GHz Radiometer“