Radiated Measurements

Radiated measurements are test procedures used to evaluate the electromagnetic energy emitted from a device into free space. They are essential for assessing electromagnetic compatibility (EMC), radio performance, and regulatory compliance.

Application Areas

Radiated testing is relevant for devices with:

• Integrated antennas

• No accessible RF connectors

• EMI-critical designs (e.g., high-speed digital circuits)

It is commonly used in:

• EMC compliance testing

• Antenna performance validation

• CE, FCC, ISED, and MIC conformity assessments

Common Measurement Parameters

• Radiated emissions (typically 9 kHz to 6 GHz or higher), measured in dBµV/m or dBm

• Harmonics and spurious emissions

• Equivalent Isotropically Radiated Power (EIRP)

• Total Radiated Power (TRP) and Total Isotropic Sensitivity (TIS)

• Antenna radiation patterns

Measurement Setup and Instruments

Typical setups include:

• Antennas: log-periodic, horn, or biconical types depending on the frequency

• Test environments: semi-anechoic chamber (SAC), fully anechoic room (FAR), or open area test site (OATS)

• Measurement instruments: EMI receiver or spectrum analyzer

• Turntable and antenna mast for angular scanning

• Signal conditioning components such as low-noise amplifiers and bandpass filters

Measurements are generally performed at distances of 3 or 10 meters. The device under test (DUT) operates in normal or specific modes to evaluate emissions and performance over the air.

Standards and Regulatory Relevance

Radiated testing is required under many standards:

• CISPR 11 / 22 / 32 – for radiated EMI from industrial, IT, and multimedia equipment

• FCC Part 15.109 / 15.209 – for unintentional and intentional radiators

• ETSI EN 301 489, EN 300 328, EN 303 413 – for RF and EMC testing of wireless products

• 3GPP TS 38.521 – for TRP/TIS testing of 5G user equipment