FCC Radiation Standard added to IXUS Software

Various standards are being used globally for evaluating compliance for human exposure to radio-frequency electromagnetic fields.  In the United States, the Federal Communications Commission (FCC) has adopted and used recognised safety guidelines since 1985.  The FCC guidelines were derived from recommendations of the National Council on Radiation Protection and Measurements (NCRP) and the Institute of Electrical and Electronics Engineers (IEEE).  The exposure limits used by the FCC are expressed in terms of electric and magnetic field strength and power density for transmitters operating at frequencies from 300kHz to 100GHz.

The actual values used in IXUS software when selecting the FCC standard have been published by the FCC and can be found in either of two informational bulletins on the FCC Web site at OET Bulletin 56 or OET Bulletin 65.

These FCC guidelines were set up in consultation with, and from research supported by various federal health and safety agencies such as the US Environmental Protection Agency (EPA) US Food and Drug Administration (FDA), Occupational Safety and Health Administration (OSHA) and National Institute for Occupational Safety and Health (NIOSH).  Countries in Europe, Africa and Asia have adopted exposure guidelines developed by the International Commission on Non-Ionizing Radiation Protection (ICNIRP).  The ICNIRP safety limits are generally similar to those of the NCRP and IEEE, with a few exceptions.

The NCRP, IEEE and ICNIRP exposure guidelines identify similar threshold levels at which harmful biological effects may occur.  The level of exposure recommended by ICNIRP is somewhat different in the lower and upper frequency ranges and for localised exposure.  In addition, the NCRP, IEEE and ICNIRP guidelines for maximum permissible exposure are different for different transmitting frequencies.

The World Health Organisation (WHO) EMF Project is working towards providing a framework for harmonisation of these different international of RF safety standards.  IXUS Software now allows the user to select the required exposure levels from a selection of different internationally accepted standards.

Source: FCC

Uncertainty model added to IXUS in accordance with IEC 62232 requirements

Two-sided-CI

IXUS now has a built-in, user customisable uncertainty model.  The newly published IEC 62232 Standard requires an uncertainty model for the ray tracing assessment method used in IXUS Modeller software.

Users can choose to include or exclude feed system loss and scattering and reflection uncertainties in the model and have the option to run simulations at the following confidence intervals:

  • Upper two-sided 95%
  • Upper two-sided 80%
  • Best estimate
  • Lower two-sided 80%
  • Lower two-sided 95%

An upper 2-sided 95% confidence interval means that there is a 97.5% certainty that the simulated fields are conservative over the actual fields.  This will typically be used by operators who want to ensure that the calculations they do with IXUS and the resulting control boundaries around antennas are conservative.  A lower 2-sided 95% confidence interval means that there is a 97.5% certainty that the simulated fields are lower than the actual fields.  This might be used by regulators who investigate RF compliance at sites and who want to be confident about non-compliance findings.  ‘Best estimate’ refers to the statistically most likely value.  This is where the simulated value is most likely to equal the actual field value.

In the past performing a compliance assessment that included uncertainty estimations was a laborious process.  This feature simplifies the process and reduces the effort required.  See the attached example for more information on base station compliance assessments and uncertainty.

Full uncertainty analyses were performed for the ray tracing assessment method, as required by the IEC 62232 standard.  A 95% Confidence Interval (CI) is used in the results and related control boundaries presented, ensuring conservative results for 97.5% of all cases.

IEC 62232 – EMSS IXUS – Ray Tracing Case Study.pdf