How are 4G and 5G handset antennas designed?
Cellular device antennas must cover many bands, in 5G NR from 410 MHz to 7.125 GHz in FR1 and 24.25 GHz and above in FR2, with several antennas for MIMO and carrier aggregation, inside metal-framed phones only millimeters thick.[1] Designers use multi-branch PIFAs, monopoles and slot antennas that excite chassis modes, switchable aperture tuning, and separate mmWave phased-array modules.[2]
Why is low band hardest?
At 700 MHz, λ is about 43 cm, so a 15 cm phone is about 0.35λ long and its antenna volume is electrically small. The chassis itself must radiate, bandwidth is limited by the Chu limit, and the hand detunes it strongly; tuning is used to move a narrow resonance across low-band frequencies.[2][3]
How do metal-frame phones work as antennas?
Slots or gaps cut into the metal frame divide it into segments that are fed and tuned as IFA- or loop-like radiators, with the rest of the chassis acting as ground. Gap positions are chosen where hands are least likely to cover them, and multiple feeds share the frame.[2]
What constraints shape handset antennas?
- Total radiated power and sensitivity requirements in free space, head and hand (CTIA, operator specs).[4]
- SAR limits near the head and body.[5]
- Isolation among four or more cellular antennas for 4×4 MIMO.
- Coexistence with Wi-Fi, GNSS, UWB and NFC.
Frequently asked questions
How many antennas does a 5G phone have?
Typically many: several sub-6 GHz cellular antennas plus mmWave modules in mmWave-capable models, and Wi-Fi, GNSS, NFC and UWB.
What is FR2?
The 5G NR mmWave frequency range starting at 24.25 GHz.
Why do phones reduce power near the head?
To meet SAR limits, using proximity sensors and power back-off.
See also
References
Online sources accessed October 21, 2026; printed works cited by edition. See all sources.
- “3GPP TS 38.101-1 and 38.101-2: NR User Equipment radio transmission and reception (FR1 and FR2)”. 3GPP. current release.
- “Modern Small Antennas”. K. Fujimoto and H. Morishita, Cambridge University Press. 2013.
- “Physical Limitations of Omni-Directional Antennas”. L. J. Chu, Journal of Applied Physics, vol. 19, pp. 1163-1175. December 1948.
- “Test Plan for Wireless Device Over-the-Air Performance”. CTIA Certification. current version.
- “47 CFR 2.1093 — Radiofrequency radiation exposure evaluation: portable devices”. U.S. FCC, eCFR. current text.