The FCC's license and tower records, searchable on a map.

Search by callsign, licensee, FRN, radio service, or frequency, and refine by status, state, county, city, ZIP, grant and expiration date, and buildout. The copy covers commercial and private land mobile, microwave, paging, rural telephone, GMRS, broadcast auxiliary, and coast stations, so the transmitters that share spectrum with your customers' channels are all in one search. Market-based licenses are in it too: CBRS Priority Access Licenses, AWS, 600 and 700 MHz, PCS, and the auctioned 800 and 900 MHz SMR and 900 MHz broadband blocks. Each one is placed by the county or market it covers rather than the licensee's mailing address, with its block and licensed spectrum, so a search for a county finds the PALs licensed there. Leased spectrum is in there too: the FCC records a lease separately from the license it came from, and those records are loaded as well, so a leased transmitter appears alongside licensed ones with the license it leases from named. Coordinate-and-radius search plots on a map, where fixed sites drop as pins and licensed mobile areas of operation draw as their own circles, so you see the whole licensed footprint instead of just the transmitter sites.

Search recent and pending FCC license applications by callsign, applicant, FRN, file number, or location, filtered by radio service, status, purpose, frequency, ZIP, and action date, so you can see what is being filed before it becomes a license.

Hand over an FCC Registration Number and get the whole footprint in one answer: every license, every pending application, every registered tower, and every tower application filed under it, with their licensed sites on a map. Click any licensee name in a search result to get there, and put the whole portfolio on your watch list in one click. Worth more than a name search, because the two disagree. One registration routinely files under several names, so a city turns up separately as its emergency management, public works, and airport, while several different registrations can all call themselves the city. Type the number the way it appears on the paperwork, padded or not. You can also go the other way and find which registration numbers a business files under.

Search the Antenna Structure Registration database by ASR number, owner, FAA study number, or location, with map pins and refine-by city, owner ZIP, status, and height in feet or meters. See who owns a structure, how tall it is, and what is registered near a site, and add any structure to your watch list straight from the results.

Sentinel RF holds the FAA's complete set of active obstruction NOTAMs, thousands of structures at any moment, refreshed every twenty minutes and joined to the ASR record. You do not have to be watching a tower to see its NOTAM: on every map that shows towers, a structure with one is painted its own color, with the NOTAM number, text, and end date in the pin, and the ASR search can list only the towers whose lights are out right now, in any county or radius. Where the FAA left the ASR number off, the structure is matched by its coordinates.

Search filed antenna-structure applications by file number, ASR number, applicant, FAA study number, or location, filtered by status, purpose, and city, so you see what is proposed or in process, not just what is already built.

Every search also runs as a coordinate-and-radius query, plotting licenses or structures on a map. Handy when you are planning a channel, checking for interference, or sizing up a site. On a phone, one tap centers the map on where you are standing.

Flip any map between street, satellite, and terrain base layers. Satellite shows what is really on the ground at a site; terrain shows the ridges a path has to clear. The map remembers which view you work in.

Pick a site and a band segment and get every in-use frequency with the nearest co-channel user pinned on the map, plus how busy the adjacent channels are at your channel step. Quiet candidates stand out before you go to coordination. Certified frequency coordination is still required; this is the homework that makes it smoother.

The regional planning committee's channel allotments for the county at your site, pulled from the public CAPRAD planning database and cross-checked against active licenses in the FCC ULS, so you can see which allotted channels appear unassigned before you start the RPC conversation.

Pick your site and the far end of the path and every channel in the fixed-microwave band plan (Lower and Upper 6, 11, 18, 23 GHz and more) is screened the way a coordinator frames it: each licensed path within the coordination area, both directions, with the real path geometry from the FCC ULS, the 47 CFR 101.115 antenna envelopes, radio-horizon shielding, and the 47 CFR 101.105 interference criteria. Channels come back candidate, review, or in use, with the controlling exposure named and its margin in dB. A screen, not a coordination: the prior coordination notice under 101.103 still follows, and this is the homework that makes it go quickly.

The paging plans a dealer actually meets, screened the way the rules frame them rather than the way one template would. On the Part 22 channels, 152 and 158 MHz, 454 and 459 MHz, and 931 MHz, every channel is classified clear, review, or blocked under the FCC's own contour overlap test, run in both directions against each licensed incumbent, with the controlling one named and its power, height, and both contour radii shown so the verdict is checkable. Where an incumbent turns out to be a rural telephone system the stricter protections for those channels are applied instead. Where the FCC data does not carry an incumbent's power or antenna height, the channel comes back review rather than clear, because a missing number is not evidence of a quiet channel. Licensees who hold a channel across a whole market or the entire country are counted too, even though they have no transmitter site to be near or far from, so a channel someone already owns nationwide never comes back looking open. That case is not rare: in the 929-930 MHz band three companies hold thirteen of the thirty-five exclusive channels nationwide, and those channels are not available anywhere no matter how quiet the air is at your site. That band is reported differently for the same reason: its channels are auctioned or permanently shared and no rule sets a test to measure them against, so the search reports who holds and who is on the air, and says plainly that occupancy is not availability. The 72 and 75 MHz point-to-point channels behind a paging system are listed the same honest way, because the rules state no test for those either.

A TOWAIR-style check for a proposed structure: height and nearby public-use airports and heliports screened against the FAA obstruction criteria, so you know before quoting a tower job whether an FAA filing is likely in the picture. A screening aid, not a determination.

Ask for a callsign, licensee, or frequency right in the flow of a chat question, without leaving what you were doing.