The fundamental trade-off
millimetre wave (mmWave) 5G and Sub-6GHz 5G represent different points on the spectrum trade-off between range and capacity. Understanding the difference is important for FWA planning, though in the UK context, the practical choice for most deployments is made by your operator rather than by you.
Sub-6GHz 5G
Sub-6GHz covers all 5G spectrum below 6 GHz – in practice, the 700 MHz, 3.5 GHz and 2.1 GHz bands in the UK. The 3.5 GHz n78 band is the primary 5G workhorse band, used by all UK operators for most urban and suburban coverage. It delivers a practical combination of range (several hundred metres to 1-2 km in built environments) and capacity (peak speeds of 400-800 Mbps per user under ideal conditions).
700 MHz 5G extends coverage geography significantly. EE uses this band for rural 5G coverage under the Shared Rural Network programme. The trade-off is lower capacity per unit of spectrum compared to 3.5 GHz, which means lower peak speeds – but better building penetration and range.
mmWave 5G
mmWave at 26 GHz carries enormous amounts of spectrum – Ofcom awarded 200 MHz blocks in the 26 GHz band – which enables multi-gigabit speeds. The cost is extremely limited range. At 26 GHz, signal is absorbed by rain, blocked by most building materials, and cannot propagate around corners. Useful range from a mmWave base station is typically 100-300 metres in line-of-sight conditions.
In the UK, mmWave deployments are sparse. Vodafone and Three hold mmWave spectrum. Deployments are focused on specific venues (stadiums, transport hubs) and dense urban streets where line-of-sight CPE is feasible and the throughput capacity justifies the infrastructure cost.
What this means for UK FWA
For the vast majority of UK FWA deployments in 2025 and 2026, the relevant technology is Sub-6GHz 5G on n78, sometimes supplemented by 700 MHz for rural reach. mmWave is not a practical consideration for most home or SME FWA installations.
If you are in a dense urban location within line of sight of a mmWave deployment – close to a major transport hub or in a central business district – a mmWave-capable CPE could deliver gigabit speeds. But the hardware needs to explicitly support the n258 (26 GHz) band, and coverage maps need to confirm deployment at your specific location. This is a niche use case.