Phased-Array Radar Talk Jorge Salazar

PHASED ARRAY RADAR SYSTEMS
FOR WEATHER OBSERVATION

National Center For Atmosphere Research (NCAR)
EOL Seminar
Presented by
Jorge L. Salazar-Cerreno
University of Massachusetts, Amherst, MA, USA
R
e-mail: jlsalaza@engin.umass.edu
casa Engineering Research Center for
Collaborative Adaptive Sensing
of the Atmosphere
April 23, 2011

1

Collaborative Adaptive Sensing of the Atmosphere

Outline
• Introduction
• Overview of phased-array antenna for weather radars
• Phased-array antenna requirements for weather radars
• Phased-array antenna design considerations for
weather radar
• CASA phased array radar

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4.
Introduction
Overview of phased-array antenna for weather radars
Phased-array antenna requirements for weather radars
Phased-array antenna design considerations for weather radar
5. CASA phased-array radar

Introduction
• 1905: Phased array transmission was
originally developed in 1905 by Nobel
Laureate Karl Ferdinand Braun who
demonstrated enhanced transmission of
radio waves in one direction.
• 1941: At the MIT Rad Lab , Luis Alvarez
invented a new type of phased array
antenna having excellent radiation F-16
characteristics at 48MHz. Later the B1 US fighter uses AN/APQ-164
design was used AN/APQ-7 EAGLE 3 cm passive electronically scanned

radar
• 1960-1980 : A rapid evolution of passive
phased-array antennas for detection of
ballistic missile attacks. The most
famous radars are the SPY-1 developed
during the 1970’s and the AN/APQ-164
Patriot AN/MPQ-53/65
fitted in the B1B and similar ones in the Radar Set is a passive
Lockheed Martin, The
Soviet MIG-31. AN/TPS-77 is an L-Band,
electronically
phased array

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Introduction

Introduction (cont)
• >1980: Enabling technology Gallium Arsenic
Microwave Monolithic Integrated Circuit
(GaAs MMIC) permitted the integration of low
cost-phases shifters and power amplifiers
permitting the mass production of AESAS
(Active Electronic Phased-array antennas).

• 2006: NSSL is collaborating with the federal
agencies to explore Ways to transition from
maintaining a number of single-function radar
systems, used for aircraft surveillance and
AESA to field will be the
weather observations, to a single Northrop-Grumman
multimission, phased array radar network AN/APG-77 radar
(MPAR)

• Today, several efforts to incorporate SiGe, Si
RF CMOS in the panel Array . A 128 T/R
channel, Low Power Density Panel Array has
been designed at X-Band that integrates the
A 128 T/R channel, Low
following components and circuits. MPAR Power Density Panel Array
has been designed at X-Band

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Introduction

Phased-array weather research projects
CIRPAS-MWR-05XP

(Mobile Weather Radar, 2005, X-Band,
Phased-array) (Center for Interdisciplinary
Remotely-Piloted Aircraft Studies)

• Designed for military application in 1980 Courtesy: Chad Baldi
NPS and ProSensing Inc

• X-band Freq-Phase-Mechanically,
• Single polarization (H)
• Scanning time : ~42 sec
• Scan volume: for 360: azim. x 40: elev.
• Cost: ~10 million

Goshen County Wyoming tornado that was intercepted
Analysis of Performance Characteristics of the Naval Postgraduate School
MWR-05XP Mobile Weather Radar By: Jeffrey B. Knorr , December 2005 during VORTEX 2 (June 5th 2010)

casa
Engineering Research Center for
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Introduction

Phased-Array weather research projects
NWRT-PAR (phase-phase)
(National Weather Radar Testbed-PAR) 19 August 2007
- Phase-phase, S-band, V-polarization.
- Scanning time (~26 sec for 90: azim. x 40 : elev.)
- Only single polarization and BW=1MHZ
-Cost: ~ $27 millions and single polarization

Agile-Beam Phased Array Radar Weather Observations PAR (VCP 12 BMX)
By: D.S Zrink, J.K Kimpel, D.E Forsyth, A.Shapiro, G. Crain, AMS, 60 sector
November 2007 0.5 oversampling in azimuth
Images ~ 43 s

WSR-88D (VCP 12 )
Images ~ 4.1 min

SPY-1 NWRT
From: Rapid Sampling of Severe Storms with the National Weather Radar
Testbed Phased Array Radar, OU Seminar Series, October 2007, Pam

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Introduction

Multi Function Phased Array Antenna (MPAR)
Progress

Current challenges:
• Ultra-low cost array (~ $50k / m2) and Low
cost in operations and maintenance
• Dual polarization (Xpol better than -40dB)
Modest HPA power (8W peak) base on ATSR polarization mode
LRU Low cost (<$20k ea) • Cooling subsystem and antenna calibration
Panel: 78 LRU (~$1.5M)
Douglas Carlson, Jeffrey Herd, Sean Duffy, mark Weber, Glenn Brigham, Michael Rachlin, Daniel Curcio, Cheryl Liss, Chris Weigand,. "Low cost
Phased Array Radar: The Multifunction Phased Array radar (MPAR) for Air Traffic Control and Weather Surveillance". M/A-COM Technology
Solutions Inc. Lowell, MA.

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Introduction

Phased-array radar weather requirements
• Inertial free beam steering
• Dual-polarized radars
• High scanning performance
• Flexible scan strategy
• Efficient use of the radiated energy
• Low profile and low weight radars
• Modular architecture
• High reliability and maintainability
• Low cost and low life-cycle cost
• Capability to work in network

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4.
Introduction

What kind of phased-array antenna
architecture we can use?

Quasi optical phased-array
Frequency-scan array antennas reflector

Phased-array antennas

Digital beam forming
Lens antennas/Rotman Lens

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Introduction

Phased-array antenna types
Frequency scanning arrays
Advantages:
• Series feed arrays are frequency-sensitive
• Simple architecture, simple design
• Low cost, low profile, low weight.
• Implemented using MS patch antennas
Disadvantages:
• Limited scanning range ( <30 deg) CIRPAS-MWR-05XP

• Lead to bandwidth restrictions
(10deg/200MHz)
• 1D scanning
• Single polarization ( H or V)
• Use common power source
• Low efficiency (ferrite phase shifters)
Examples:
• IWRAP, MWR-05XP

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4.
Introduction

Phased-array antenna types
Phased-array antenna
Advantages:
• Improve noise behavior since the TR modules
contain itself low noise amplifiers
• Permit ultra low sidelobe levels (<-30dB)
• Improves the efficiency since power is
distributed across thousand of elements.
• Higher levels of reliability , permitting a
failure up to 10% of the elements, without
affect the antenna performance.
• Dual-polarized and 2D-scanning up to 45deg. 0.3-3GHz Vivaldi EASA Canadian SKA Technology
Research
• Low profile, low weight.
Disadvantages:
• Cost (>$1M/m2 at X-band)
• Polarization isolation
• Examples:
• SKA, MPAR, CASA Phased-array S-band MPAR AESA X-band CASA M-AESA

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4.
Introduction

Design considerations for phased-array
antennas in weather radars
• Scanning performance
• Gain loss vs. scan angle
• Beam broadening beam effect vs. scan angle
• Antenna mismatch vs. scan angle
• Polarization distortion vs. scan angle
• TR module architecture and technology
• Reliability and graceful degradation
• Production cost and life cycle cost

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Introduction

Scanning performance:
Gain loss vs. beam position
Measured Active Element Pattern Port H/V stick 10
0

-5
10HH

Active Element Pattern in dB
-10 10HV
10VH
-15 10VV

Composition of the array pattern M=32, d=0.5, Uniform distribution

Active Element Pattern and Reflection Coefficient (mag)
Gain scan loss vs. scan angle 1 0 -20

-25

• Element pattern roll -off 0.9 -2
-30
-4
0.8 AF s
• Reflection coefficient -6
-35
AF Element
AF
0.7 -40 Element TotalElement
-80 -60 -40 -20
Total Theta in deg
0
Total 40
20
c
60 80

4d x d y N x N y
-8 E-Patterns

Pattern dB
0.6
Gθ, φ   [1  Γθ, φ  ]cosθ
2
-10
λ2 0.5 1
ACR CASE4:0.54,with Backplane

-12
0.9
E-Patternc
0.4
cos 1.2

Active Reflection Coefficient (Magnitude)
• -14 0.8
The mutual coupling in elements 0.3 0.7
E-plane( =0)
H-plane( =90)
-16
can affect the scanning 0.6
0.2 -18
performance of the array 0.5

0.1 -20 0.4

-80
0.3 -60 -40 -20 0 20 40 60 80
0 Theta (deg)
0 10
0.2
20 30 40 50 60 70 80
0.1 Scan: 30 deg,ScanLoss: 0dB,Δθ33:0 º º º
Scan: deg, Loss: -3dB, Δθ :3.16
Loss: -0.63dB, Δθ3:1.31
Scan: 600 deg, angle (deg)
0
0 10 20 30 40 50 60 70 80 90
theta (deg)
13

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Introduction

Beam broadening vs. scan beam position
Broadside

Aele ( )  Aele (o ) cos( )
ø

3  3o B f / cos( )
Antenna

0.95

0.78

1.34

1.1

-25dB -40dB

Phased Array Antenna Handbook Second Edition, Robert J.
Mailloux 14

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Introduction

Phased array radar performance for a single node
Azimuth resolution (Azr) Azimuth Resolution Vs.Range
54x46 Phased Array Antenna H:0.05km
Azr-max: 1km, Azr-med: 0.7km
Mechanically Steered km
Azimuth Resolution Vs.Range
C(6x60º)
Azr-max: 1.1km, Azr-med: 0.74km
km

Azr R, ,    R sin(3 )
Mechanically Steered km C(6x60º) km
-30 -30
-30
-20 2.5
2.5 -20
-20 2.5
2.5
60o
60o

Range in km

Range in km
Range in km
Range in km
-10 22 -10
-10 22
R: Maximum radar range 0
360oo
360 1.5 00 1.5
1.5 1.5
3  3o B f / cos  Ø : Scan angle
10 11 10
10 11
Ø3: 3dB Beamwidth
20 0.5 20
20 0.5
0.5
Bf: Broadening factor 1.2 for Taylor -25dB 0.5
30 30
30
-20
-20 00 2020 -20
-20 00 20
20
Range in km in km
Range Range in km
Range in km
Az(worst): 11.0 km
Az(worst): km Az(worst): 1.21.1 km (10%)
Az(worst): km (20%)
Az(med): 0.7 km
H=50m
H=3.2km Az(med): 0.74 km (6%)
Az(med): 0.83 km (4%)
Az(med): 0.8 km
Azimuth Resolution Vs.Range Azimuth Resolution Vs.Range
Elevation coverage at maximum scanning range 12 deg (± 6 deg ) 60x46 Phased Array Antenna H:0.05km
B(4x90º)
B(4x90º) km
km
A(3x120º)
A(3x120º) km
km
-30
-30 -30
-30
Hight Single node
-20
-20 2.5
2.5 -20
-20 2.5
2.5
90o
90o
Range in km

Range in km
Range in km

Range in km
-10
-10 22 -10
-10 120o 22
120o
Cone of silence 00 1.5
1.5 00 1.5
1.5
3 km
6% 6% 10
10 11 10
10 11
2km
1.38km 12º
0.5km 20
20 0.5
0.5 20
20 0.5
0.5
N2 30
30 30
30
R=30 km R=30 km
-20
-20 00 20
20 -20
-20 00 20
20
Range in km
Range in km Range in km
Range in km
R=6.25 km Az(worst): 1.4 km (40%)
Az(worst): 1.4 km (40%) Az(worst): 2 km (100%)
Az(worst): 2.0 km (100%)
0.8 km (14%)
Az(med): 0.88 km (10%) Az(med): 0.94 km (18%)
Az(med): 0.84 (20%)

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Introduction

Minimum Radar sensitivity (Zmin)
Minimum Radar Sensitivity (Ze) Radar Parameters

CPmin R 2 L2 SNR
Z min  Parameter Symb Units Value
Pt G 23 3 K w
2
Frequency f GHz 9.41
Wavelength λ m 0.032
Peak transmitter power Pt W 432
E-Plane beamwidth (at broadside) θ3 deg 1.83
H-Plane beamwidth (at broadside) ø3 deg 1.83
31 km
E-Plane scan range Δθ deg 12
6.25 km H-Plane scan range Δø deg 60-90-120
Signal to noise ratio SNR dB 0
0.625 km Noise figure NF dB 4.5
Gain (at broadside) G dB 39
Maximun radar range R km 31
Range resolution ΔR m 25
Bandwidth BW MHz 6
Pulse repetition frequency PRF kHz 3.399
Radar Pulse Scheme System loss L dB 2
Pulse width т us 4.16-41.67
4.16us 41.67us 4.16us 41.67us Pulse compression gain PCG dB 14-24
Minimum detectable signal P min dBm -103.6
Duty cycle D % 18
Dielectric constant of water K - 0.93
Radar constant C 2.5x1016
Time (us)
41.67us 207 us

References: [6] 16

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Introduction

Minimum Radar sensitivity (Zmin)
Minimum Radar Sensitivity (Ze) Minimun Sensitivity Vs.Range
Minimun Sensitivity Vs.Range Radar Parameters Minimun Sensitivity Vs.Range
54x46 Phased Array Antenna
54x46 Phased Array Antenna 54x46 Phased Array Antenna
Tx Pow er: 603mW/elem 432W/secPmin: -104 SNR: 0dB NF:4.5dB
Tx Pow er: 603mW/elem 432W/secPmin: -104 SNR: 0dB NF:4.5dB Tx Pow er: 603mW/elem 432W/secPmin: -104 SNR: 0dB NF:4.5dB
t1: 4.17us BW1: 6MHz PRF1: 3.399KHz dBm PCG1:25mag

CPmin R 2 L2 SNR
t1: 4.17us BW1: 6MHz PRF1: 3.399KHz dBm PCG1:25mag t1: 4.17us BW1: 6MHz PRF1: 3.399KHz dBm PCG1:25mag
t2: 41.7us BW2: 6MHz PRF2: 3.399KHz dBm PCG2:250mag H:3.2km
t2: 41.7us BW2: 6MHz PRF2: 3.399KHz dBm PCG2:250mag H:0.05km t2: 41.7us BW2: 6MHz PRF2: 3.399KHz dBm PCG2:250mag H:3.2km
Zemax: 5.43dBZ, Ze med: 3.33dBZ

Z min 
Mechanically2.22dBZ
Zemax: 5.23dBZ, Ze med: Steered
Mechanically Steered dBZ
dBZ
Zemax: 6.08dBZ, Ze med: 3.47dBZ
C(6x60º)
6.03dBZ,
C(6x60º) 2.47dBZ
dBZ
-30
-30 -30
Pt G 23 3 K w
2
-20
-20
15
15
10 -20
15
10 10

Range in km
Range in km

Range in km
-10
-10 5 -10
5 5
0
0 0
0 0 0
G ,   r A D(1   ,   ) cos 
2 -5
10
10 -5 10 -5
-10
-10 -10
20
20 20
-15
-15 -15
30
30 30
-20
-20 0
0 20
20 -20 0 20
Range in km
Elevation coverage at maximum scanning range 12 deg (± 6 deg )
Ze(worst): 5.43 dBZ
Ze(worst): 5.23 dBZ
Minimun Sensitivity Vs.Range
H=50m
H=3.2km 6.03
Ze(worst): 6.08 dBZ (Δ: 0.7dB)
Minimun Sensitivity Vs.Range 0.8dB)
Ze(med):Array Antenna dBZ
60x46 Phased 3.33 64x46 Phased Array Antenna
Ze(med): 2.22 dBZ
Tx Pow er: 543mW/elem 432W/secPmin: -104 SNR: 0dB NF:4.5dB TxZe(med): 2.47 dBZ 0dB NF:4.5dB
Pow er: 512mW/elem 432W/secPmin: -104 SNR: (Δ: 0.3dB)
3.47 0.1dB)
Hight Single node t1: 4.17us BW1: 6MHz PRF1: 3.399KHz dBm PCG1:25mag
t1: 4.17us BW1: 6MHz PRF1: 3.399KHz dBm PCG1:25mag
7.18dBZ, 2.81dBZ
Zemax: 7.22dBZ, Ze med: 3.79dBZ Zemax: 9.37dBZ, Ze med: 3.35dBZ
9.42dBZ, 4.32dBZ
B(4x90º)
B(4x90º) dBZ A(3x120º)
A(3x120º) dBZ
No covered Area: -30 -30
~23% 15 15
-20 -20
Cone of silence 10 10

Range in km
Range in km

3 km -10 5 -10 5
2km 6% 6%
1.38km 12º 0 0 0 0
0.5km
10 -5 10 -5
N2
-10 -10
R=30 km R=30 km 20 20
-15 -15
R=6.25 km
30 30
-20 0 20 -20 0 20
Ze(worst): 7.18 dBZ (Δ: 2 dB)
7.22 1.8dB) References: [6]4.1dB)
9.37
Ze(worst): 9.42 dBZ (Δ: 4.0dB)
17
2.81 0.6dB)
Ze(med): 3.79 dBZ (Δ: 0.5dB) 3.35 1.1dB)
Ze(med): 4.32 dBZ (Δ: 1.0dB)

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Introduction

Polarization losses vs. scan beam position
Cross-polarization level vs. Scan angle in azimuth and elevation
Size: 64x46 elements, dx:1.6cm, dy=2.2cm
Co-polar and cross-polar patterns for embedded
Element: Aperture coupled patch antenna patch antenna in array 18x32 elements
Er: 2.17 h=20mil

30.0
0

25.0 Co-polar H
-10

Amplitude of AEP(dB)
Co-polar V
X-polar H
20.0
Broadside
~13dB -20
X-polar V

~20dB
X-pol (dB)

15.0 -30

10.0 X-pol (port-v) at elev=7.5deg -40

X-pol (port-v) at elev= 0deg
5.0 -50
~29dB ~13dB
0.0 -60
-80 -60 -40 -20 0 20 40 60 80
0 30 45 60 Theta(deg)
Scan angle (deg)

Cross-polarization level planar array of 64x46 elements, dx=1.6cm,
dy=2.2cm using HFSS (Finite Array Tool)

18

Phased-Array Radar Talk Jorge Salazar

Phased-Array Radar Talk Jorge Salazar

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