Internet over radio is not a new idea and is actually used by many every day. Most commonly a transceiver's mic input is used to connect a computer between a transmitter/receiver and the transmitting antenna. Amateur radio operators have made these interfacing devices semi-popular in the past few years as digital modes of communication such as psk31 and MFSK16 became more popular on high frequency bands. The vast majority of these techniques incorporate the use of the PC sound card to code and decode audio tones both sent from the transceiver (or PC itself) and received from the antenna. Most all of these digital modes work with standard ASCII characters and use open source software to operate. It is not difficult to transmit data securely to another know point over the air with these ideas in mind. If desired, the software itself can be implemented as a keyboard, as proper design and placement can provide a simplistic means of data input. As long as a least 2 computers have the ability to communicate with each other
in this fashion, there is nothing at all stopping them passing data (that includes entire files, though slow, and strings) to the transmitter.
Frequency shifting, PL tones, offsets, differential up/down links and other methods can be used in conjunction with private transmission types to insure broadcasted data remains in constant motion. As long as a computer or transceiver (preferably both) on both ends is programmed for identical spectrum scanning, both stations can follow each other while consistently moving across frequency bands.
The most successful transmissions I have been associated with have taken place at or above 10ghz. Microwave frequencies provide the best environment to pass RF digital transmissions in. Unfortunately microwave frequencies also reduce broadcasting distance drastically when compared to HF frequencies and may also be a health danger if one is consistently exposed to the antenna's effective radiated field.
That's a broad scratch on the surface but I hope it gives a better general idea of the mechanics behind your question.
I had a lot of fun with this interface. I would consider it the most customizable on the market to this day. The thought behind it is well worth the read for anyone truely interested in this subject matter.
Transmitter: icom 756 pro III
Antenna: I suggest custom building (though Force 12 is a great company)
Towers: US tower ... freestanding CRANK-UP