development of active phased array weather radar

© 2012 Toshiba Corporation

Development of Active Phased Array Weather Radar

Masakazu Wada

2© 2011 Toshiba Corporation 2Development of Active Phased Array Weather Radar

Comparison of Dual-Pol and Phased-array Radar

Dual-Pol Radar

（ parabolic antenna ）PAWR

(phased array antenna)

Elevation: Mechanical

Azimuth: MechanicalScanning

Elevation: Electronic

Azimuth: Mechanical

About 20／ 5 to10 minutes

Elevation Number

／ Time Interval

About 100／ 10 to 30 seconds

Zh ， Vh ， Wh ， Zdr ， Kdp ，ρhv

Parameter Zh ， Vh ， Wh

Parabolic radar Phased Array Weather Radar


Concept on Phased-array RadarAbout 2mAbout 2m

Ab

ou

t 2m

Ab

ou

t 2m

＜ Antenna Scan ＞•1 degree of azimuth beam width by slotted antenna mechanically

•1 degree of elevation beam width by Antenna electronically

•Fan beam transmission•Multi-beams receiving by DBF

•3D fast observation with one rotation

＜ Cost Performance ＞•1-dimension Active Phased Array Antenna and DBF （ Digital Beam Forming)

•Maximize the Cost Performance•The same price range as compared to parabolic radar

Overview of AntennaOverview of Antenna Overview of Antenna ScanOverview of Antenna Scan


..…

Block Diagram

Digital Signal Processor•Pulse Compression•Calculate Radar Reflectivity Doppler Velocity Velocity Width

I/Q Data Accumulation(for study)

Tra

nsm

itter

an

d R

ece

iver

(24

line

s)

Re

ceive

r(9

6 lin

es)

……

……

…S

lotte

d W

ave

gu

ide

an

ten

na

(12

8

ele

me

nts)

Rx F

req

ue

ncy C

on

versio

n(1

28

line

s)

Tx Frequency

Conversion

……

……

D/A

Digital Seed

～A

/D a

nd

I/Q(1

28

line

s)

……

……

….

. DB

F

……

……

….

.

DBF output (16 beams)

No DBF output (128 I/Q data)

Use Gallium Nitride

on Tx Amp


Active Phased Array Antenna


2.2m

2.1m


Tx/Rx Unit

Include 8ch Tx/Rx Elements The system uses 3 units 　

Tx/RxCard

Condensercard

FrequencyConversion

Card


Receiving Unit

RxCard

FrequencyConversion

Card

Include 8ch Rx Elements The system uses 13 units 　


Frequency Conversion Card


A/D I/Q Unit

16ch A/D & I/Q The system uses 8 units


DBF Unit

The system uses DBF technique to calculate beam form from 128 I/Q data


Observation Mode

Prepare wide observation mode and fast obsevation mode

Specification

Maximum

Power Up to 430W

Frequency 9320 to 9445MHz, 5MHz step

Beam Width

(after DBF) About 1 degree

Mode Fast

Observation

Wide

Observation

Coverage 20㎞ 60㎞

Scan

Interval 10 seconds 30 seconds

Number of

Hit About 10 About 20

Number of

Elevation About 100 About 100

12© 2011 Toshiba Corporation 12

Phased-array Radar installed in Osaka Univ.

Development of Active Phased Array Weather Radar


Left: Radar Processor

Right: Radar Controller

Active Phased Array Weather Radar installed in Osaka Univ.


Conclusion

• Active Phased-array Weather Radar is able to generate 3D data without any gap in the period of 10 to 30seconds, in order to capture cumulonimbus quickly.

• We have installed Active Phased-array Radar on Osaka urban area and are evaluating it now.

• To protect safety of critically significant infrastructure such as urban area and Airport from disaster, Toshiba propose multiple observation using dual-pol solid-state radar and 1D phased-array radar.

This research is supported by the National Institute of Information and Communications Technology, Japan.


Toshiba’s Presentations in the ExhibitionToshiba’s Presentations in the ExhibitionExhibitor Booth

<No. 5005>

Right in front of main entrance


Measurement ( Anechoic Chamber )

We have one of the largest Chamber in Eastern Japan.


NSI Receiver

-40

-30

-20

-10

0

10

-80 -60 -40 -20 0 20 40 60 80

Am

plitud

e [d

B]

Azimuth [deg]

-40

-30

-20

-10

0

10

-80 -60 -40 -20 0 20 40 60 80

Am

plitu

de [

dB]

Elevation [deg]

Near field dataAmplitude Phase

Azimuth

Elevation

Calculated far field pattern


Antenna Pattern ( Azimuth)

Mechanical Beam Forming by Slot Antenna

Antenna Pattern (Azimuth)

- 50

- 40

- 30

- 20

- 10

0

- 80 - 60 - 40 - 20 0 20 40 60 80

Azimuth [deg]

Am

plitu

de[d

B]

＜ Beam Width ＞1degree or less<Side lobe>-23dB or less


Transmission and Receiving Pattern ( Elevation)

Transmission and Reception (Multi Beam) Pattern

- 50

- 40

- 30

- 20

- 10

0

- 45 - 30 - 15 0 15 30 45

Elevation[deg]

Am

plitu

de[d

B]

TX_8element Rx_EL0deg Rx_EL1deg Rx_EL2deg Rx_EL3deg Rx_EL4degRx_EL5deg Rx_EL- 1deg Rx_EL- 2deg Rx_EL- 3deg Rx_EL- 4deg Rx_EL- 5deg

1 transmission beam and receiving multi beam by DBFElectronic Scan EL 0deg to 90 deg

＜ Beam Width ＞1degree (Rx)<Side lobe>-10dB or less (Tx)-23dB or less (Rx)


Forecast of potential

Developing stage

Developing stage Maturation Decline stage

Decline stage

Strong rainfallStrong rainfall

Forcast at this Forcast at this

Vertical Integrated Liquid (VIL) and by the vertical distribution of precipitation, it is possible to predict the precipitation may fall to the ground

in the near future

Life cycle of Cumulonimbus

21© 2011 Toshiba Corporation 2110/20/2011Development of Active Phased Array Weather Radar

Transmission power can be reduced compared with conventional radar systems on a detection-range basis.

>> Reduction in operating voltage of the transmitter circuits>> Downsizing of the transmitter>> Suppression of the level of interference wave, etc.

Klystron Solid-state Pulse Compression Radar

TransmittedWaveform

Peak power can be minimized

without lowering the average power

time t

Am

plif

ier

Frequency

Del

ay ti

me

Chirp modulation ( Frequency modulation )1) add the frequency modulation on the transmission pulse 2) transmit this linear FM pulse3) put the received signal through the time delay filter 4) collect the divided frequency power in the received pulse

1) 2) 3) 4)

Pulse Compression TechniquePulse Compression Technique

development of active phased array weather radar

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