5G Spectrum Sharing Forces Military Radar Systems Off Their Legacy Bands

The FCC's ongoing reallocation of mid-band spectrum (3.1-3.55 GHz) for commercial 5G services directly conflicts with military radar and communications systems that have operated in these bands for decades. The AN/SPN-43 aircraft marshaling radar used on Navy carriers, multiple Air Force airborne early warning radars, and Army ground-based air defense radars all operate in the 3.1-3.55 GHz range. The DoD has been directed to vacate or share these frequencies to make room for 5G auction winners who paid $81 billion for C-band spectrum. The immediate problem is that these radar systems cannot simply be retuned to different frequencies. Their transmitters, receivers, antennas, and signal processing are physically designed for specific bands. Moving a radar to a new frequency requires redesigning the hardware, which for military systems means a new acquisition program with 5-10 year timelines and billions in costs. Meanwhile, the commercial 5G buildout is happening now, creating interference zones around military installations and operating areas. The downstream impact is that Navy carriers approaching ports with active 5G networks experience interference that degrades their precision approach radars, forcing pilots to use less accurate landing systems in poor weather. Air Force ranges co-located near growing cities find their radar testing increasingly constrained. The Army's Patriot and THAAD radar systems, which operate in nearby bands, face potential interference as 5G buildouts expand near military bases. This persists because spectrum is governed by two separate authorities with conflicting mandates. The FCC maximizes commercial spectrum value and the revenue from auctions. The NTIA advocates for federal spectrum needs but lacks veto power over FCC auctions. When the C-band auction generated $81 billion, the economic pressure to reallocate military spectrum became politically irresistible. DoD was offered relocation funds but the money is insufficient to redesign and replace entire radar families within the commercial buildout timeline. The structural issue is that spectrum in the mid-band is finite and the commercial demand for 5G bandwidth is enormous. Military systems were allocated these bands in an era when commercial wireless demand was negligible. Now that mid-band spectrum is worth thousands of dollars per MHz-POP, the economic incentive to push military systems out overwhelms the national security argument for keeping them. There is no institutional framework for valuing military spectrum usage in economic terms that can compete with commercial auction prices.