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DASY4
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A precision RF Dosimetric Assessment System (DASY4) supplied by Schmidt
& Partner Engineering (SPEAG) of Zurich, Switzerland, is used to
perform precise SAR measurements. The “state-of-the-art” DASY4
system was upgraded from the DASY3 in February 2003. Experience
gained from the years of SAR testing and research, and our close links
with the world leaders in SAR research and measurement through a technical
support agreement ensures that our clients have access to the most
authoritative technical support in the world.
The DASY4 Professional also provides precise measurements to 6 GHz in free
space as well as inside tissue simulating liquids for bio-electromagnetic
research purposes. The flexible data evaluation and visualization
capabilities allow electromagnetic design and performance evaluations in
other applications including SAR optimization, EMI, EMC, PCB, wireless
communications, biomedical applications and industrial RF machines.
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Description of the SAR Measurement System
Probe Positioning System
DASY4 system is based on a high precision 6-axis robot (with a working
range greater that 1.1m), which positions the SAR measurement probes with
a positional repeatability of better than ±0.02 mm. The DASY4 fully
complies with the OET65 C (01-01),
IEEE 1528 and EN50361 SAR measurement
requirements. Unlike some other SAR test systems, the DASY4
measurement uncertainty is guaranteed to be better than the requisite 30%.
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E-Field Probe Type and Performance
The SAR measurements are conducted with the SPEAG dosimetric probes
ET3DV6 (30 MHz - 3 GHz) and ES3DV3 (5.1 GHz - 5.8 GHz)
designed in the classical triangular configuration and optimised for
dosimetric evaluation. The probes are suitable for measurements
close to material discontinuity at the surface of the phantom.
Validation dipoles cover the range 300 MHz to 5.8 GHz. Our
probes are calibrated at the following frequencies, and found to be
have an accuracy better than ±0.25 dB:
- ET3DV6
- 150 MHz
- 350 MHz (Body)
- 450 MHz (Head and Body)
- 835 MHz (Head)
- 900 MHz (Head and Body)
- 1800 MHz (Head and Body)
- 1900 MHz (Head)
- 2450 MHz (Head and Body)
- ES3DV3
- 5200 MHz (Body)
- 5800 MHz (Body)
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Data Acquisition Electronics
Fully duplicated probes and Data Acquisition Electronics (DAE) means
that there is no down time during the probe calibration cycles. The
DAE3 consists of a highly sensitive electrometer-grade preamplifier with
auto-zeroing, a channel and gain switching multiplexer, a fast 16 bit
AD-converter, and a command decoder and control logic unit. The
input impedance of the DAE3 box is 200 MW
the inputs are symmetrical and floating. Common mode rejection is
above 80dB. Transmission to the PC-card is accomplished through an
optical downlink for data and status information as well as an optical
uplink for commands and the clock.
The mechanical probe-mounting device includes two different sensor systems
for frontal and sideways probe contacts. They are used for
mechanical surface detection and probe collision detection.
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