Not too many years ago, the amateur bands in the microwave portion of the spectrum, such as 2.4 and 5.7 GHz, were considered the upper limits of ham experimentation, and only the techiest of the techies operated there. Today, those bands or bands adjacent to them are used by your smartphone and your WiFi router, and hams are making contacts at 47 GHz and above. The next frontier is the so-called millimeter-wave bands, and the FCC is considering proposals to allow unlicensed and/or experimental operations on frequencies above 95 GHz.
The ARRL filed comments on the proposal, generally supporting the idea but asking that two millimeter-wave bands in which amateur radio currently has a primary allocation be protected from unlicensed or experimental use. It notes that such use could considerably raise the noise floor on the 134-136 and 248-250 GHz bands, where it says a relatively quiet noise floor is essential for amateur radio experimentation. The League also pointed out that these bands are shared with the Radio Astronomy Service, which has a secondary allocation and also needs a quiet noise floor. The proceeding is ET Docket 18-21.