I think you are getting ahead of yourself hear. A couple of people have pinted out, but Ill state the obvious
Prototype your vibration detector and see if it works. Just power it off a big battery. prototype your detection software and test. can it be built into a small enough processor and can it consume small amounts of power. If it consumes a lot of power then you have to figure out how to reduce that or whether a larger battery is required. Can you transmit the data? is it small packets (suitable for Lora) or is it more. Then can you transmit the data over RF? what frequency/aerial to use. Transmission of RF through ground is generally difficult.
Small steps

Yes. This seems like the most logical way forward.

 

Yes, it would require rethinking the method of deployment. I would be reduced to fewer, higher profile nodes that used much larger batteries and possibly solar charging. You would be able to cover relatively large areas with newer nodes. I assume, too, that vehicles would have to be involved and the currently available modules from Hi-Link during the 24GHz FMCW include ones that can discriminate multiple vehicles, their speeds and direction.

By providing two layers—an outer one looking for vehicles headed in your direction and a inner one that looks for people approaching entry points I would expect much better outcomes with more information about the actual threat.

Thank you for taking the time out and sharing your valuable suggestion. I am working with a team and this method is more of a POC. If it doesn't work your suggestion would be valuable to find an alternate.

 

It may also be that such a system is already available from a security technology supplier. They do have a lot of amazing equipment for sale.

 

It may also be that such a system is already available from a security technology supplier. They do have a lot of amazing equipment for sale.

There are buried cable using electrical or fiberoptic perimeter security systems. I expect they are very expensive.

Of course, they do not use wireless communication.

 

None of the systems that i saw in a catalog quite a few years ago were wired.
The present concern with wireless systems is that they are simple to disable merely by using a transmitter to desensitize the receiver. Totally illegal but rather simple to achieve. Given the very low power levels of the sensor transmitters and the required sensitivity of the system receiver, just a few watts of steady carrier can totally saturate the receive system rendering it unable to communicate with the sensors.