1. Development of Active Phased Array Weather Radar
My name is Masakazu Wada, I’m a chief specialist of Toshiba Corporation.
First of all, I am pleased to have this opportunity.
Today, I would like to talk about Active Phased Array Weather Radar.
Our Phased Array radar is developed based on Solid-State technology.
So, therefore, I would like to show you a short movie introducing solid-state radar and phased array radar, which takes about 3 minutes.
Masakazu Wada

2. Comparison of Dual-Pol and Phased-array Radar
Parabolic radar
Phased Array Weather Radar
Dual-Pol Radar
（parabolic antenna）
PAWR (phased array antenna)
Elevation: Mechanical
Azimuth: Mechanical
Scanning
Elevation: Electronic
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
I’ll show you a comparison of Dual-Pol and Phased-array radar.
Dual-pol radar uses dual polarization data for accurate measurement and it generally adopts a parabolic antenna.
So, the biggest difference is a scanning method.
Dual-pol radar uses mechanical scanning, on the other hand, Phased-array Radar uses electronic scanning for elevation direction.
Dual-pol radar needs several rotations to get the 3D data by changing the elevation angle every time.
It takes 5 to 10 minutes to acquire one 3D data.
For Phased-array Radar, it only takes 10 to 30 seconds to acquire one 3D data, which includes 100 elevation angles in one rotation.
Development of Active Phased Array Weather Radar

3. Concept on Phased-array Radar
About 2m
About 2m
Overview of Antenna
Overview of Antenna Scan
＜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
＜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
The phased array radar is conventionally used for military affairs, and is generally expensive.
In order to develop low cost Phased Array Weather Radar, We adopted to rotate 1dimensional phased array antenna in horizontal direction, instead of adopting 2 Dimensional phased-array.
The Antenna consists from 128 slotted antennas.
These slotted antennas are arranged perpendicularly.
A horizontal beam width of this 2 meter slotted antenna is 1 degree.
For transmitting, we use fan beam, which has wide angle in elevation, by using 24 out of 128 slotted antennas.
For receiving, we use all slotted antenna and make multi beam with 1 degree beam width by DBF, Digital Beam Forming.
We can calculate 16 beams simultaneously.
Development of Active Phased Array Weather Radar

4. Block Diagram ………… ………… …………….. …………….. .. … … ～ DBF output (16 beams)
Receiver (96 lines)
Rx Frequency Conversion (128 lines)
A/D and I/Q (128 lines)
DBF
DBF output (16 beams)
Digital Signal Processor
Pulse Compression
Calculate
Radar Reflectivity
Doppler Velocity Velocity Width
Slotted Waveguide antenna (128 elements)
…………
…………
……………..
……………..
No DBF output (128 I/Q data)
I/Q Data Accumulation
(for study)
Transmitter and Receiver (24 lines) ..
This is a block diagram of our Phased-array radar.
There are two main parts, one is antenna part, and the other is processing part.
In the antenna part, 24 slotted antenna transmit radio wave and all 128 slotted antenna receive back scattering from rain.
After that, Frequency conversion card changes frequency from 9GHz to 60MHz.
And then IF signals of 128 channels is digitized and converted to I/Q data.
Then DBF unit calculate 16 beams simultaneously on the basis of 128 I/Q data.
The interface between antenna part and processing part is digital only by using optical rotary joint.
And processing equipment calculate and display 3D graphical image. … …
Tx Frequency Conversion ～
D/A
Digital Seed
Use Gallium Nitride on Tx Amp
Development of Active Phased Array Weather Radar

5. Active Phased Array Antenna
2.1m
This is the picture of Phased Array Antenna.
128 slot antennas are arranged perpendicularly.
The dimension of antenna is 2.1m by 2.2m.
Transmitting units, receiving units, and a DBF unit are attached at the rear side of Antenna.
2.2m
Active Phased Array Antenna
Development of Active Phased Array Weather Radar

6. Tx/Rx Unit Include 8ch Tx/Rx Elements The system uses 3 units
Condenser
card
Tx/Rx Card
Frequency Conversion Card
This is Transmitting and receiving unit. This unit include 8ch Elements. The system uses 3units.
Include 8ch Tx/Rx Elements The system uses 3 units　
Development of Active Phased Array Weather Radar

7. Receiving Unit Include 8ch Rx Elements The system uses 13 units
Rx Card
Frequency Conversion Card
This picture is Receiving Unit. This unit includes 8ch Receiving Elements. The system uses 13 units.
Include 8ch Rx Elements The system uses 13 units　
Development of Active Phased Array Weather Radar

8. Frequency Conversion Card
This is Frequency Conversion card in Tx / Rx units. This unit will change frequency from 9GHz to 60MHz.
Development of Active Phased Array Weather Radar

9. 16ch A/D & I/Q The system uses 8 units
A/D I/Q Unit
This picture shows Analog to digital converter and I/Q signal converter unit. This unit includes 16ch A/D & I/Q. The system uses 8 units.
16ch A/D & I/Q 　The system uses 8 units
Development of Active Phased Array Weather Radar

10. The system uses DBF technique to calculate beam form from 128 I/Q data
DBF Unit
This picture shows DBF unit. This system uses DBF technique to calculate beam form from 128 I/Q data.
The system uses DBF technique to calculate beam form from 128 I/Q data
Development of Active Phased Array Weather Radar

11. Prepare wide observation mode and fast obsevation mode
This table shows general specifications of Phased-array radar.
There are two modes for observation.
One is “Fast observation mode”, which observes a short distance in 10 seconds, and the other is “Wide observation mode”, which observes about 60km distance in 30 seconds.
Prepare wide observation mode and fast obsevation mode
Development of Active Phased Array Weather Radar

12. Phased-array Radar installed in Osaka Univ.
Active Phased Array Antenna
The picture shown in right is the Phased Array installed in Osaka University.
Left: Radar Processor
Right: Radar Controller
Active Phased Array Weather Radar installed in Osaka Univ.
Development of Active Phased Array Weather Radar

13. 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.
Now, conclusion
This research is supported by the National Institute of Information and Communications Technology, Japan.
Development of Active Phased Array Weather Radar

14. Toshiba’s Presentations in the Exhibition
Exhibitor Booth
<No. 5005>
Right in front of main entrance
If you haven’t visited Toshiba booth yet, why don’t you come and visit us.
Thank you for your attention.

15. Development of Active Phased Array Weather Radar

16. Measurement ( Anechoic Chamber )
This picture shows the antenna pattern measurement in electric darkroom. We have one of the largest darkroom in the East Japan.
Anechoic chamber
We have one of the largest Chamber in Eastern Japan.
Development of Active Phased Array Weather Radar

17. Calculated far field pattern
NSI Receiver
Amplitude
Phase
Near field data
Azimuth
Measurement results such as near-field distributions and far-field patterns are obtained by the NSI 2000 software on the host PC from the I and Q data.
Elevation
Calculated far field pattern
Development of Active Phased Array Weather Radar

18. Antenna Pattern ( Azimuth)
＜Beam Width＞ 1degree or less
<Side lobe>
-23dB or less
This is an antenna pattern of azimuth for transmitting and receiving. Beam width is 1 degree or less. Side lobe level is -23dB or less. Antenna pattern for azimuth is mechanically formed by slotted antenna.
Mechanical Beam Forming by Slot Antenna
Development of Active Phased Array Weather Radar

19. Transmission and Receiving Pattern ( Elevation)
＜Beam Width＞ 1degree (Rx)
<Side lobe>
-10dB or less (Tx)
-23dB or less (Rx)
This is an antenna pattern of elevation for transmitting and receiving. Transmitting electric wave is fan beam. In this drawing, the fan beam width is 10 degree with eight transmitting elements. Side lobe level is -10dB or less. For the receiving, 10 multi-beam of 1 degree beam width are formed by DBF. Elevation angle is electronically scanned. The tilt angle of this Antenna is 30 degrees.
By carrying out electronic scanning from -30 degree to +60 degree, all the ascending vertical angles from 0 to 90 degree can be observed at high-speed and high-density.
1 transmission beam and receiving multi beam by DBF
Electronic Scan EL 0deg to 90 deg
Development of Active Phased Array Weather Radar

20. Life cycle of Cumulonimbus
Forecast of potential
Maturation
Developing stage
Decline stage
Forcast at this
Strong rainfall
Life cycle of Cumulonimbus
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

21. Pulse Compression Technique
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.
Peak power can be minimized
without lowering the average power
Klystron
Solid-state Pulse
Compression Radar
Transmitted
Waveform
Chirp modulation ( Frequency modulation )
1) add the frequency modulation on the transmission pulse ) transmit this linear FM pulse 3) put the received signal through the time delay filter ) collect the divided frequency power in the received pulse
1) ) ) )
time t
Amplifier
Frequency
Delay time
Development of Active Phased Array Weather Radar
10/20/2011