Soil moisture level sensing using Frequency domain reflectometry

TI has two devices that might help, the FDC1004 and FDC2214. The FDC1004 has a shield feature which helps to prevent unwanted interference from nearby sources, such as a human hand. That might not be relevant for your application. The FDC2214 is generally more sensitive, so I suggest looking into that device first.

The devices I mentioned have instructions in the datasheet and app notes about how to set them up. The FDC1004 a more traditional charge-based capacitance measurement. The FDC2214 drives the external LC tank (part of which is variable based on your external sensor) and outputs the change in capacitance.

The actual sensor design has to be done by you, but these devices can drive the sensor and provide the capacitance result in a digital format.

Shibin,

Can you start a new thread with this request so that it can be directed to the correct team? The FDC devices I mentioned above only work up to 10MHz, so two orders of magnitude less than what you are looking for.