Physics / mechanism
Millimeter-wave spans 24–100 GHz (wavelengths 3–12 mm), sitting between microwave and sub-THz. Propagation is governed by free-space path loss scaling with f², plus oxygen absorption peaks near 60 GHz (~15 dB/km) and rain fade. Useful upside: high bandwidth (multi-GHz channels vs. tens of MHz at sub-6 GHz), tight beamforming due to short wavelength, and dense spatial reuse. State-of-the-art phased arrays integrate 64–256 antenna elements with beam-steering latency <1 µs. Key parameters: EIRP (typically 40–55 dBm for 5G NR FR2), NF (~5–8 dB at 28 GHz in SiGe/GaN front-ends), and link budget limited to ~100–200 m in NLOS urban environments.
Competitive landscape
Competing approaches: sub-6 GHz 5G (better coverage, lower capacity), Wi-Fi 6E/7 at 6 GHz (unlicensed, shorter range), and sub-THz/D-band (100–300 GHz, emerging for backhaul). Key tension is coverage-vs-capacity. GaN-on-SiC dominates defence/backhaul power applications; SiGe BiCMOS leads cost-sensitive 5G CPE. RFFE consolidation is pressing chipmakers toward integrated transceiver+antenna modules.
Companies using
Connected ideas
Sources
Frontier (open questions)
- To be added.