As a ham I have a bit of knowledge about radios and RF energy and can say without a doubt that the frequency to which you're referring is extremely common and would require extraordinary wattage to do you any real harm, especially since 2.5GHz (12cm WL) can be interfered with by the walls of your home, rain, trees, etc. As the frequency increases the more interference solid objects can offer. Also, you would have to be exposed to this RF energy with a power density of 5mW/cm^2 for 6 minutes before your neighbor would be in violation of FCC regulations. Additionally, even if the frequency that you describe is indeed being used by your neighbor and transmitted using a directional antenna, creating a tighter beam than a unidirectional antenna, your neighbor may, be a licensed radio operator (like me) and would be permitted to be using these frequencies and you would not be able to prevent it provided you are not being exposed to energy greater than the maximum permissible exposure (MPE) dictated by the FCC.
Infrasound has proven to be an interesting field of research and is certainly yielding some interesting results pertaining to health and more. That said, for me to believe that you are being subjected to sound at the frequencies and dbs that would be required, but only you, is quite a stretch.
Now, I want to bring in my friend Occam. He says that the simplest explanation is probably the right one. Here I'd say you definitely are running afoul of Occam's Razor. Why would your neighbor mount such an protracted, extensive and expensive campaign against you? The other, simpler explanation is that you may be wildly paranoid and may need some professional psychiatric help. Or a Faraday cage. You decide.
Legally, however, you can certainly make a complaint to the police but expect it to go nowhere. You can try a civil suit but, again, be prepared to spend a lot of money for it to go nowhere.