How do hands and bodies affect antennas?
The human body is a lossy, high-permittivity dielectric at RF, so a hand gripping a phone or a wearable on the wrist both detunes the antenna and absorbs part of its radiation. Measured total efficiency of handset antennas commonly drops by several dB in hand and head positions compared with free space, which is why operators and CTIA test plans specify head and hand phantom configurations.[1][2]
Why does the body absorb RF?
Tissues have high relative permittivity (tens) and significant conductivity at UHF and microwave frequencies, so currents induced in the body dissipate energy. The same mechanism is quantified for safety as specific absorption rate (SAR).[3]
How are hand effects mitigated?
- Place antennas where hands rarely cover them (top and bottom edges of phones).
- Use multiple antennas with switching or MIMO, so at least one remains clear.
- Use impedance or aperture tuning driven by sensing of the use case.
- Prefer magnetic (loop) near fields for body-worn devices where appropriate.[2]
How are body effects tested?
Standardized phantoms filled with tissue-simulating liquids or solids model the head (SAM phantom) and hand; CTIA OTA test plans define free-space, head, hand and head-plus-hand positions for TRP and TIS.[1][3]
Frequently asked questions
How much does a hand reduce efficiency?
Often several dB, varying strongly with grip and frequency.
Does the body affect wearables more?
Yes; very close spacing to tissue increases both detuning and absorption.
What is a SAM phantom?
The Specific Anthropomorphic Mannequin head model used in SAR and OTA testing.
See also
References
Online sources accessed October 21, 2026; printed works cited by edition. See all sources.
- “Test Plan for Wireless Device Over-the-Air Performance”. CTIA Certification. current version.
- “Modern Small Antennas”. K. Fujimoto and H. Morishita, Cambridge University Press. 2013.
- “IEC/IEEE 62209-1528: Measurement procedure for the assessment of specific absorption rate of human exposure to radio frequency fields from hand-held and body-mounted wireless communication devices”. IEC/IEEE. 2020.