It is possible to use EMI (electromagnetic induction) methods using several frequencies. Here are two references:

F.X. Simon, J. Thiesson, A. Tabbagh, 2017. Which EM Properties with Multi-frequency Low Induction Number Slingram Apparatus?. DOI 10.3997/2214-4609.201701982. Conference: 23rd European Meeting of Environmental and Engineering Geophysics

Haoping Huang and Douglas C. Fraser 2002. Dielectric permittivity and resistivity mapping using high-frequency, helicopter-borne EM data. GEOPHYSICS, VOL. 67, NO. 3 (MAY-JUNE 2002); P. 727 – 738

Hi Lakshika,

If you don't have the opportunity to come back on the field and try other techniques, some options arestill offered to you. In a first instance, I would recommend to try to determine the velocity of each of your layers, giving access to the relative permittivity (computed from εr=(c/v)^2).

Kind regards,

Cedric

It would be good if you could provide more information why you want to measure the dielectric permittivity of the subsurface using an independent method? As indicated by Cedric, it is in principle possible to determine the subsurface dielectric permittivity from the GPR data if multi-offset measurements available. More information can be found here:

Huisman, J.A., S.S. Hubbard, J.D. Redman and P.A. Annan. 2003. Measuring soil water content with ground penetrating radar: a review. Vadose Zone Journal, 2(4), 476-491.

It would also help if you could indicate why TDR is not an option for you. Is it because of cost constraints, or difficulty of inserting sensor, or limited subsurface access to do in-situ measurements?

Best Regards,

Sander

Thank you for answering my question.

@Johan Alexander - We would like to further ensure our interpretation of geological layers (identified using the GPR system) using a another method. An accurate boundary between geological layers are very important for the next step of our research. Currently, we are facing difficulties obtaining the TDR instrument. Therefor we are searching for an alternative method to measure dielectric constant of the soil. Thank you for your valuable insight regarding my question

You can used GPR and Topp Equation to derive for soil moisture.

Hi,

Knowing dielectric permittivity is equivalent to knowing the radar velocity. Either one is used for time to depth conversion. I recommend to carry out Radar Velocity Survey at the field to have velocity data of subsurface soil.

I agree with the previous comments that it would be most appropriate to perform multi-offset GPR measurements at the site of interest in order to determine the radar wave velocity. This ensure that the same volume of subsurface is being investigated.

If you find reference in situ permittivity measurements essential and TDR is not an option, a relatively cheap way may be to use capacitance probes or water content sensors based on a ring oscillator. Some of the more advanced dielectric soil moisture sensors are factory-calibrated and are able to provide relatively accurate permittivity estimates. More information can be obtained here:

Qu, W., H.R. Bogena, J.A. Huisman and H. Vereecken. 2013. Calibration of a novel low-cost time domain transmission soil water content sensor. Vadose Zone Journal, 12(1), doi:10.2136/vzj2012.0139.

Bogena, H., J.A. Huisman, C. Oberdoerster and H. Vereecken. 2007. Evaluation of a low-cost soil water content sensor for wireless network applications. Journal of Hydrology, 344, 32-42.

I am sure that there are more sensors that can do this. Please do realize that TDR will likely provide more accurate permittivity estimates. In addition, the sampling volume of these in-situ sensors is much smaller, which may lead to interpretation problems.

Hope this helps!

Best,

Sander

i'm agree with recomendation from Cedric Sachet .. My research also related to GPR. Use the equation of εr=(c/v)^2) to get the value of dieletric constant of the soil.