microwaves in a well hole

Anyone have any experience launching microwaves into rock surrounding a well hole? What type of antenna, did the energy penetrate, what VSWR did you get, etc?

Here are some articles about microwave propagation in underground tunnels, which may help.
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Yeah, thanks. I found some of those types already. What I am interested in is actual propagation thru the rock, especially limestone.

I think it depends on frequency as well. You may check UWB ground penetration radar as keywords in your search.

I have studied a similar problem many years ago.
In ~1970 there was a paper by Japanese authors in IEEE Trans. on Antennas and Propagation, about UHF and microwave transmission experiment in a long highway tunnel in Japan. The general results were such that in a 7-meter "diameter" tunnel (not circular cross section), the best propagation without deep fades was observed above 1 GHz, up to 4 GHz.
I used the motive to test microwave propagation in a gas pipeline; by modeling it with a rusty 2" steel pipe, the best results were obtained at X-band.
I think the best way is to run a test in a particular well; as the "pipe" is not conductive but a lossy dielectric (limestone, etc.), it may not be the best waveguide. In Australian deep mine they used X-band and horns to communicate with a shaft elevator down to several miles.
In my opinion, for a normal well, 2.45 GHz may be good to secure a communication channel.

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And to add: propagation of microwaves through a rock (not through the well) is poor as a wet inhomogeneous rock will fast disperse the signal. In mines, to communicate through rock, long waves are usually good.
Again, only a real test can tell. Modeling makes not much sense.