Operating Frequency

Operating Frequency

NFC operates exclusively at 13.56 MHz, a frequency in the High Frequency (HF) band of the radio spectrum designated as an ISM (Industrial, Scientific, Medical) frequency available for license-free use worldwide. This single operating frequencyoperating frequency13.56 MHz ISM band frequency used by all NFC communicationsView full → is shared by all NFC protocols — NFC-A, NFC-B, NFC-F, and NFC-V — and by both ISO 14443 and ISO 15693 standards.

Why 13.56 MHz

The choice of 13.56 MHz for NFC and HF RFID reflects several engineering trade-offs:

• Global availability: The 13.56 MHz ISM band is allocated worldwide without requiring a radio license. This is critical for an international standard — a tag manufactured in Asia must work with a reader sold in Europe and a phone designed in the US.
• Wavelength and near-field behavior: At 13.56 MHz, the wavelength is approximately 22 meters. NFC's operating range of 0-10 cm is well within the near-field region (lambda/2pi is approximately 3.5 m), meaning communication occurs through magnetic inductive coupling rather than propagating radio waves. This is why NFC works reliably through materials and is not affected by multipath interference.
• Balanced penetration: 13.56 MHz penetrates water, human tissue, and non-metallic packaging materials reasonably well, making it suitable for wearables, medical devices, and consumer product tags.
• Adequate data rates: The frequency supports data rates from 1.66 kbps (NFC-V) to 848 kbps (ISO 14443ISO 14443Standard for contactless smart cards at 13.56 MHz (Types A and B)View full →-4), sufficient for most NFC payload sizes (URLs, vCards, small data records, payment tokens).

Frequency Precision and Tolerances

NFC systems must maintain the carrier frequency within tight tolerances to ensure reliable inductive coupling. The ISO 14443 standard specifies a frequency tolerance of +/- 7 kHz (approximately +/- 0.05%). Reader oscillator circuits use crystal-controlled references to maintain this precision. Tags do not generate their own frequency — they respond at whatever frequency the reader provides.

Regulatory Framework

Although 13.56 MHz is ISM and license-free, NFC systems must comply with regional emission limits on RF field strength:

These limits ensure NFC devices do not interfere with other ISM band users while still providing sufficient field strength to power passive tags at the intended operating distance.