non-penetrating sensing

[Gordon Starr <gcstarr@facstaff.wisc.edu>]

Roger,
        Another possibility for a non penetrating sensor is a surface contacting
waveguide.  We have constructed and tested a few of these for use in conjunction
with TDR and Network Analyzers.  The system and probe perform adequately
for some purposes, but only measure moisture to a few centimeters below the
surface. This small range makes the probe sensitive to surface roughness
(generally
not such a problem in sand).  The electronic noise factor caused by surface
roughness
can mean big problems with TDR, (not so much with synthesized TDR and Network
Analyzer).
        Our best data came from making surface measurements in the wheel
track of
an all terrain vehicle.  This study has not been published yet, However look for
an article coming soon and if you are interested, please feel free to
contact us.

Regards


************************************************
*   Gordon Starr, Research Associate           *
*   University of Wisconsin, Madison             *
*   College of Agriculture                                  *
*   Soil Science Department                            * 
*   1525 Observatory Drive                               *
*   Madison, WI 53716                                       *
*   608-262-0415                                                *
*   gcstarr@facstaff.wisc.edu                           *
*                                                                             *
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