© 2020 Virginia Diodes, Inc.
—All Rights Reserved
7 October 2020
To correct for the loss of the WR10 1-inch section and a waveguide taper, the WR10 1-inch section and various tapers were
measured using calibrated VNA frequency extension modules for multiple frequency bands, from 90 GHz to 1.1 THz. Contact VDI
for information on power measurements above 1.1 THz.
Waveguide Band
Loss of PM5 Sensor Head
including 1”
WR10SWG (dB)
Loss of Waveguide
Taper (dB)
WR10
0.17
N/A
WR8.0
0.17
0.13
WR6.5
0.18
0.16
WR5.1
0.19
0.18
WR4.3
0.19
0.28
WR3.4
0.19
0.32
WR2.8
0.20
0.35
WR2.2
0.20
0.40
WR1.9
0.25
0.50
WR1.5
0.30
0.65
WR1.2
0.35
0.85
WR1.0
0.40
1.05
WR0.65
0.60
1.50
WR0.51
0.70
N/A
Current and Future Measurement Standards
There are no generally accepted standards for power measurements around 100 GHz and above. The purpose of
“Appendix Two” is to describe the methods that
VDI uses to measure power levels from VDI sources. In this way VDI hopes to keep its customers fully informed of its measurement techniques and foster a
greater discussion of the best methods to perform such measurements. Possible methods to compare power measurements made by different research
laboratories are also important topics, but they have not been considered here. VDI will update this document from time to time to reflect improved measurement
techniques and equipment upgrades.
Figure 7:
Data for taper and PM5B sensor
head loss for various frequency
bands are shown. The loss
through the PM5B Sensor Head
includes loss through the 1”
WR10SWG and internal
waveguide losses. Internal
waveguide loss is approximated
to be the same as the loss
through the 1” WR10SWG.
Based on the measurements, the
scaling factor for a given
waveguide taper can be
approximated to a constant
value. The dotted black lines
indicate significant absorption
regions through air (assuming
50% humidity).
Appendix
Two
VDI Power Correction Factors
0.00
0.50
1.00
1.50
2.00
2.50
3.00
0
100
200
300
400
500
600
700
800
900
1000
1100
Lo
ss
(
d
B
)
Frequency (GHz)
Loss Through Waveguide Taper and PM5 Sensor Head (including 1" WR10SWG)
PM5 Sensor Head (including WR10SWG)
Taper Loss (Measured)
Total Loss (Measured)
PM5 Sensor Head Scaling Factor (including WR10SWG)
Taper Loss (Scaling Factor)
Total Loss (Scaling Factor)
Absorption Line
Figure 8:
This table lists VDI correction factors for various waveguide bands.
