![](media/image1.png){width="0.95in" height="0.9048611111111111in"}

![](media/image2.png){width="1.0909722222222222in"
height="1.0354166666666667in"}

> ![](media/image3.wmf){width="0.4083333333333333in"
> height="0.7243055555555555in"}
> ![](media/image4.wmf){width="0.30833333333333335in"
> height="1.1805555555555556in"}

![](media/image5.wmf){width="0.7006944444444444in"
height="0.8173611111111111in"}

**SUPPLEMENT C**

**Edition 01-01**

***to***

**OET BULLETIN 65**

**Edition 97-01**

**June 2001**

***IMPORTANT NOTE***

**This version of Supplement C supercedes the 97-01 edition and is
issued in connection with the FCC\'s OET Bulletin 65, Version 97-01. The
information in this supplement provides additional guidance for use by
applicants for FCC equipment authorization in evaluating mobile and
portable devices for compliance with the FCC\'s guidelines for human
exposure to radiofrequency (RF) electromagnetic fields. Users of this
supplement should also consult Bulletin 65 for complete information on
FCC policies, guidelines and compliance-related issues concerning human
exposure to RF fields. OET Bulletin 65 can be viewed and downloaded from
the FCC\'s Office of Engineering and Technology\'s World Wide Web
Internet Site: http://www.fcc.gov/oet/.**

The SAR measurement procedures described in "***[DRAFT]{.underline}*
Recommended Practice for Determining the Spatial-Peak Specific
Absorption Rate (SAR) in the Human Body due to Wireless Communications
Devices: Experimental Techniques**," under Project Number P1528 of the
Standards Coordinating Committee 34, Subcommittee 2, of the Institute of
Electrical and Electronics Engineers (IEEE SCC-34 / SC-2) have been
considered in this edition of Supplement C.

Contributions from the following FCC staff members are also
acknowledged: **Bruce Franca, Robert Cleveland and Kenneth Nichols**

introduction [3](#__RefHeading___Toc517850373)

section 1: fcc rules for rf compliance of mobile and portable devices
[5](#__RefHeading___Toc517850374)

Mobile Devices [5](#mobile-devices)

Portable Devices [6](#portable-devices)

Exposure Categories [6](#exposure-categories)

occupational / controlled exposure
[6](#occupational-controlled-exposure)

general population / uncontrolled exposure
[6](#general-population-uncontrolled-exposure)

section 2: guidelines for evaluating mobile and portable devices
[8](#__RefHeading___Toc517850380)

Determination of Device and Exposure Categories
[8](#determination-of-device-and-exposure-categories)

MPE Evaluation of Mobile Devices [9](#mpe-evaluation-of-mobile-devices)

SAR Evaluation of Portable or Mobile Devices
[10](#sar-evaluation-of-portable-or-mobile-devices)

sar evaluation Techniques [10](#sar-evaluation-techniques)

handset and other transmitter Test Positions
[11](#handset-and-other-transmitter-test-positions)

Tissue Models [12](#tissue-models)

SAR Measurement System Descriptions and Requirements
[13](#sar-measurement-system-descriptions-and-requirements)

Device Test Conditions [14](#device-test-conditions)

SAR Measurement Procedures [14](#sar-measurement-procedures)

SAR Computation Guidelines and Descriptions
[15](#sar-computation-guidelines-and-descriptions)

Measurement and Computational Uncertainties
[17](#measurement-and-computational-uncertainties)

section 3: rf exposure compliance for spread spectrum transmitters
[18](#__RefHeading___Toc517850392)

Methods to Ensure Compliance for Spread Spectrum Transmitters
[19](#methods-to-ensure-compliance-for-spread-spectrum-transmitters)

REFERENCES [23](#__RefHeading___Toc517850394)

appendix A: fcc exposure criteria [27](#__RefHeading___Toc517850395)

FCC Limits for Maximum Permissible Exposure (MPE)
[28](#fcc-limits-for-maximum-permissible-exposure-mpe)

FCC Limits for Specific Absorption Rate (SAR)
[29](#fcc-limits-for-specific-absorption-rate-sar)

APPENDIX B: information FOR documenting SAR compliance
[30](#__RefHeading___Toc517850398)

I: Information on test device and exposure categories
[31](#i-information-on-test-device-and-exposure-categories)

II: Specific Information for SAR Measurements
[32](#__RefHeading___Toc517850400)

III: Specific Information for SAR Computations
[34](#iii-specific-information-for-sar-computations)

APPENDIX C: TISSUE DIELECTRIC Parameters
[36](#__RefHeading___Toc517850402)

Tissue Dielectric Parameters for Head and Body Phantoms
[37](#tissue-dielectric-parameters-for-head-and-body-phantoms)

Typical Composition of Ingredients for Liquid Tissue Phantoms
[38](#typical-composition-of-ingredients-for-liquid-tissue-phantoms)

APPENDIX D: SAR MEASUREMENT PROCEDURES
[39](#__RefHeading___Toc517850405)

Phantom Considerations [39](#phantom-considerations)

recommended Characteristics of Head and Body Phantoms
[40](#recommended-characteristics-of-head-and-body-phantoms)

recommended device test positions for typical Wireless Handset
[41](#recommended-device-test-positions-for-typical-wireless-handset)

devices operating next to a person's ear
[41](#devices-operating-next-to-a-persons-ear)

Recommended test positions for body-worn and other similar
configurations
[43](#recommended-test-positions-for-body-worn-and-other-configurations)

documentation [45](#documentation)

Tissue Dielectric Property Requirements
[45](#tissue-dielectric-property-requirements)

Electric Field Probe Characteristics and Calibration
[46](#electric-field-probe-characteristics-and-calibration)

System Verification [46](#system-verification)

Test Site Ambient Conditions [48](#test-site-ambient-conditions)

Test Device Operating Conditions [49](#test-device-operating-conditions)

Output Power [49](#output-power)

Battery Options [50](#battery-options)

Device operating capabilities [50](#device-operating-capabilities)

Device Operating Modes [50](#device-operating-modes)

Source-Based Time Averaging [51](#source-based-time-averaging)

Recommended SAR Measurement Procedures
[51](#recommended-sar-measurement-procedures)

Procedures to search for peak sar locations
[52](#procedures-to-search-for-peak-sar-locations)

procedures for determining One-gram Averaged SAR
[53](#procedures-for-determining-one-gram-averaged-sar)

Measurement Uncertainties [54](#measurement-uncertainties)

Types of Measurement Uncertainties
[54](#types-of-measurement-uncertainties)

Determining Total System Measurement Uncertainty
[55](#determining-total-system-measurement-uncertainty)

Documenting the measurement uncertainty of sar evaluations
[56](#documenting-the-measurement-uncertainty-of-sar-evaluations)

Documenting the measurement uncertainty for sar system verification
[57](#documenting-the-measurement-uncertainty-for-sar-system-verification)

In August, 1996, the Commission adopted a *Report and Order* in ET
Docket 93-62 amending its rules for evaluating the environmental effects
of radiofrequency (RF) electromagnetic fields. Specifically, the
Commission adopted new guidelines and procedures for evaluating human
exposure to RF emissions from FCC-regulated transmitters and
facilities.[^1] As a part of this proceeding, new limits were adopted
for human exposure to RF emissions from certain mobile and portable
devices. Two subsequent FCC Orders were issued to refine and clarify the
decisions adopted in the original *Report and Order*.[^2] A revised
version of OET Bulletin 65, \"Evaluating Compliance with FCC Guidelines
for Human Exposure to Radiofrequency Electromagnetic Fields\" was also
issued.[^3] One of the areas discussed in Bulletin 65 is compliance with
the limits adopted by the Commission for safe exposure to RF emissions
due to mobile and portable devices such as non-fixed wireless
transmitters and hand-held cellular telephones. The first edition of
Supplement C (97-01) was released in 1997. The purpose of this revised
supplement is to provide parties filing applications for equipment
authorization with guidance on complying with the latest requirements
using up-to-date test procedures. ***This supplement is not intended,
however, to establish mandatory procedures, and other methods and
procedures may be acceptable if based on sound engineering practice.***

The FCC guidelines differentiate between portable and mobile devices
according to their proximity to exposed persons. For portable devices
(47 CFR §2.1093), RF evaluation must be based on specific absorption
rate (SAR) limits. Human exposure to RF emissions from mobile devices
(47 CFR §2.1091) can be evaluated with respect to Maximum Permissible
Exposure (MPE) limits for field strength or power density or with
respect to SAR limits, whichever is most appropriate. Industry groups
and other organizations have been working to develop standardized
product test procedures to evaluate RF exposure compliance with SAR
limits.[^4] The appropriate procedures may be considered in future
revisions of this supplement.

FCC rules require applicants for equipment authorization of certain
portable and mobile devices to include an affirmative statement of
compliance attesting that the devices comply with FCC limits for RF
exposure. The rules also require that technical information be provided
upon request for supporting compliance. The information described in
Appendix B may provide applicants with additional guidance on the type
of documentation that would normally be included in test reports for
demonstrating compliance.

Further information concerning this supplement may be obtained by
contacting the Laboratory Division of FCC\'s Office of Engineering and
Technology at (301) 362-3000 or Kwok Chan at (301) 362-3055. Information
on topics discussed in the OET Bulletin 65 or other supplements can be
obtained from the FCC\'s RF safety group at (202) 418-2464 or e-mail to:
rfsafety@fcc.gov.

As stated in the FCC rules, mobile and portable transmitting devices
that operate in the Cellular Radiotelephone Service, the Personal
Communications Services (PCS), the Satellite Communications Services,
the General Wireless Communications Service, the Wireless Communications
Service, the Maritime Services (ship earth stations only) and
Specialized Mobile Radio Service authorized, respectively, under Part 22
(Subpart H), Part 24, Part 25, Part 26, Part 27, Part 80, and Part 90 of
the FCC rules are subject to routine environmental evaluation for RF
exposure prior to equipment authorization or use. Portable devices
operating in the Wireless Medical Telemetry Service (WMTS) and the
Medical Implant Communications Service (MICS), authorized under Subparts
H and I of Part 95 are subject to routine environmental evaluation for
RF exposure prior to equipment authorization or use. Unlicensed PCS,
U-NII and millimeter wave devices authorized under Part 15 of FCC rules
are also subject to routine environmental evaluation for RF exposure
prior to equipment authorization or use. All other mobile and portable
devices are categorically excluded from routine environmental evaluation
for RF exposure.[^5]

## Mobile Devices

The FCC rules for evaluating mobile devices for RF compliance are found
in 47 CFR §2.1091. For purposes of RF exposure evaluation, a mobile
device is defined as a transmitting device designed to be used in other
than fixed locations and to be generally used in such a way that a
separation distance of at least 20 centimeters is normally maintained
between the transmitter\'s radiating structures and the body of the user
or nearby persons. In this context, the term \"fixed location\" means
that the device, including its antenna, is physically secured at a
permanent location and is not able to be easily moved to another
location. Examples of mobile devices, as defined above, would include
cellular and PCS mobile telephones, other radio devices that use
vehicle-mounted antennas and certain other transportable transmitting
devices. Transmitters designed to be used by consumers or workers that
can be easily re-located, such as a wireless modem operating in a laptop
computer, are considered mobile devices if they meet the 20 centimeter
separation requirement. These devices are normally evaluated for
exposure potential with the MPE limits given in Appendix A. Mobile
devices may also be evaluated with respect to the SAR limits given in
Appendix A for RF exposure compliance, but in such cases it is usually
simpler and more cost-effective to evaluate compliance with respect to
MPE limits based on field strength or power density.

## Portable Devices

The FCC rules for evaluating portable devices for RF exposure compliance
are contained in 47 CFR §2.1093. For purposes of RF exposure evaluation,
a portable device is defined as a transmitting device designed to be
used with any part of its radiating structure in direct contact with the
user's body or within 20 centimeters of the body of a user or bystanders
under normal operating conditions. This category of devices would
include hand-held cellular and PCS telephones that incorporate the
radiating antenna into the hand-piece and wireless transmitters that are
carried next to the body. Portable devices are evaluated with respect to
SAR limits for RF exposure.[^6] The applicable SAR limit for portable
transmitters used by consumers is 1.6 watts/kg, which is averaged over
any one gram of tissue defined as a tissue volume in the shape of a
cube.

## Exposure Categories

With respect to field strength, power density and SAR requirements, both
the 1992 ANSI/IEEE standard and the NCRP exposure criteria (See
References \[1\] and \[30\]), upon which the FCC guidelines are based,
recommend limits with respect to both occupational/controlled and
general population/uncontrolled exposures. The compliance requirements
for each category are based on a person\'s awareness and ability to
exercise control over his or her exposure.

### occupational / controlled exposure

In general, occupational/controlled exposure limits are applicable to
situations in which persons are exposed as a consequence of their
employment, who have been made fully aware of the potential for exposure
and can exercise control over their exposure. This exposure category is
also applicable when the exposure is of a transient nature due to
incidental passage through a location where the exposure levels may be
higher than the general population/uncontrolled limits, but the exposed
person is fully aware of the potential for exposure and can exercise
control over his or her exposure by leaving the area or by some other
appropriate means. Awareness of the potential for RF exposure in a
workplace or similar environment can be provided through specific
training as part of a RF safety program. If appropriate, warning signs
and labels can also be used to establish such awareness by providing
prominent information on the risk of potential exposure and instructions
on methods to minimize such exposure risks.

### general population / uncontrolled exposure

The general population/uncontrolled exposure limits are applicable to
situations in which the general public may be exposed or in which
persons who are exposed as a consequence of their employment may not be
made fully aware of the potential for exposure or cannot exercise
control over their exposure. Members of the general public would come
under this category when exposure is not employment-related; for
example, in the case of a wireless transmitter that exposes persons in
its vicinity. Warning labels placed on low-power consumer devices such
as cellular telephones are not considered sufficient to allow the device
to be considered under the occupational/controlled category, and the
general population/uncontrolled exposure limits apply to these devices.

FCC rules require routine environmental evaluation of RF exposure for
certain mobile and portable devices described in 47 CFR §§2.1091 and
2.1093. Applications to the FCC for equipment authorization of these
transmitters must include an affirmative statement indicating that, to
the best knowledge of the applicant, the device complies with the
FCC-adopted limits for RF exposure. In most cases, it will also be
necessary for the applicant to provide certain information to document
the test procedures used to evaluate compliance. The rules also require
applicants to provide technical data to substantiate compliance when it
is requested.[^7]

Mobile devices identified in 47 CFR §2.1091 that operate at 1.5 GHz or
below with an effective radiated power (ERP) of 1.5 watts or more, or
those that operate at frequencies above 1.5 GHz with an ERP of 3.0 watts
or more are required to perform routine environmental evaluation for RF
exposure prior to equipment authorization or use; otherwise, they are
categorically excluded. Mobile devices may be evaluated with respect to
field strength, power density or SAR limits, as appropriate.
Occasionally, if it is determined that the operation of a categorically
excluded mobile device has the potential of exceeding MPE limit because
of its design or operating conditions, it may be necessary for the
applicant to provide additional information to substantiate compliance
and to determine if an RF evaluation is needed. When RF compliance of a
categorically excluded device cannot be determined with the additional
information, an RF evaluation may be requested as provided for in 47 CFR
§1.1307 (c) and (d).

Certain portable devices identified in 47 CFR §2.1093 are required to
perform routine environmental evaluation for RF exposure prior to
equipment authorization or use. Such portable devices may be evaluated
with respect to SAR limits using either measurement or computer modeling
methods. Because of the lack of standardized test protocols, the FCC has
been requesting technical information to support the evaluation
procedures used to determine compliance while standardized SAR test
procedures are being developed by industry groups and other
organizations. The information in Appendix B identifies the type of
technical descriptions that would normally be appropriate for
demonstrating compliance. Appendix D describes SAR measurement
procedures for handsets and similar transmitters.

## Determination of Device and Exposure Categories

Before routine RF evaluation can proceed, it must be determined whether
a device should be considered under the \"mobile\" or \"portable\"
category, and whether exposure would occur under the
occupational/controlled or general population/uncontrolled conditions.
These decisions will generally determine whether a device should be
evaluated with respect to field strength, power density or SAR limits,
and which set of exposure conditions and limits should be used to
demonstrate compliance.

For certain devices, such as wireless modem modules and other
transmitters that are designed to be integrated into other products or
designed to operate in multiple configurations, RF exposure evaluation
for both mobile and portable conditions may be necessary. When portable
configurations are applicable, RF compliance must be determined with
respect to SAR limits. In situations where a transmitter is in close
proximity to the operator but nearby persons are normally further away
from the device, occupational/controlled exposure limits may be applied
if the exposure is work-related.[^8] Under such conditions, the operator
must be aware of the exposure conditions and can exercise control to
limit the exposure duration and/or conditions to satisfy compliance.
Nearby persons are usually exposed to a weaker field. Since they have no
knowledge of their exposure conditions, the more restrictive general
population/uncontrolled exposure limits must be applied.

## MPE Evaluation of Mobile Devices

Human exposure to RF emissions from mobile devices (47 CFR §2.1091) may
be evaluated based on the MPE limits adopted by the FCC for electric and
magnetic field strength and/or power density, as appropriate, since
exposures are assumed to occur at distances of 20 cm or more from
persons.[^9] The 1992 ANSI/IEEE standard (See Reference \[1\]) specifies
a minimum separation distance of 20 cm for performing reliable field
measurements to determine adherence to MPE limits.[^10] If the minimum
separation distance between a transmitter and nearby persons is more
than 20 cm under normal operating conditions, compliance with MPE limits
may be determined at such distance from the transmitter. When
applicable, operation instructions and prominent warning labels may be
used to alert the exposed persons to maintain a specified distance from
the transmitter or to limit their exposure durations and usage
conditions to ensure compliance. If the use of warning labels on a
transmitter is not effective or desirable, the alternative of performing
SAR evaluation with the device at its closest range to persons under
normal operating conditions may be used.

The field strength and power density limits adopted by the FCC are based
on whole-body averaged exposure and the assumption of spatially averaged
RF field levels relate most accurately to estimating whole-body averaged
SAR. This means some local values of exposures exceeding the stated
field strength and power density limits may not necessarily imply
non-compliance if the spatial average of RF fields over the exposed
portions of a person's body does not exceed the limits. Field strength
and power density measurements are typically made in all directions
surrounding the radiating structures of a mobile device in normal
operating configurations, without the influence of nearby persons and
objects. The measurements are spatially averaged over the exposed
portions of an average person's body to determine compliance. In certain
situations such as vehicle-mounted antennas or other antennas located on
metallic surfaces, the exposure should be evaluated with the antenna
mounted on a metallic surface to account for the localized peaks
produced by standing waves due to ground reflections near the antenna.

## SAR Evaluation of Portable or Mobile Devices

Human exposure to RF emissions from portable devices (47 CFR §2.1093),
as defined by the FCC, must be evaluated with respect to the FCC-adopted
limits for SAR. Evaluation of mobile devices, as defined by the FCC, may
also be performed with respect to SAR limits, but in such cases it is
usually simpler and more cost-effective to evaluate compliance with
respect to field strength or power density limits. For certain devices
that are designed to be used in both mobile and portable configurations
similar to those described in 47 CFR §2.1091(d)(4), such as certain
desktop phones and wireless modem modules, compliance for mobile
configurations is also satisfied when the same device is evaluated for
SAR compliance in portable configurations.

Since SAR limits do not apply to devices operating above 6.0 GHz (See
References \[1\] and \[30\]), millimeter wave devices operating under
§15.253 and §15.255 of the FCC rules in portable configurations must be
evaluated with respect to power density limit. At shorter wavelengths
above 6.0 GHz, instead of the usually recommended 20 cm measurement
distance for lower frequencies, reliable power density measurements can
normally be made at 5 cm or more from the transmitter. If a device
normally operates at closer than 5 cm from persons, power densities may
be computed using numerical modeling techniques (e.g., FDTD or finite
element methods) to determine compliance. In certain
occupational/controlled exposure conditions, operating instructions and
warnings labels may be required to limit the exposure duration and
conditions to satisfy compliance.

### sar evaluation Techniques

Portable transmitters used by consumers typically operate over the
output power range of less than 100 mW to several watts, using either
analog or digital modulation techniques. For most handsets, the antenna
radiates within 1-2 cm of the user\'s head or body. Even at low power
levels, relatively high field strengths would be expected near the
antenna. The field strength and field distributions are highly dependent
on the location, orientation and electromagnetic characteristics of
adjacent objects, such as the user's body. The user of a handset is
normally in the reactive near-field region of the antenna where the
electromagnetic field is mostly non-propagating. The energy absorbed by
the user is mainly due to the electric fields induced by magnetic fields
generated from current flowing along the antenna and other radiating
structures of the device. The RF energy is scattered and attenuated as
it propagates through the body tissues. Maximum energy absorption is
usually expected in the more absorptive high water-content tissues near
the surface of the head or body. To account for near-field energy
coupling effects, portable transmitters are evaluated with realistic
head and body models using SAR measurement or computer modeling
techniques (See References \[3\], \[9-10\], \[13-14\], \[18\] and
\[28\]).

SAR compliance for low power transmitters are evaluated with electric
field measurements inside homogeneous tissue models or computer modeling
techniques using anatomically equivalent tissue models (See References
\[3\], \[10\], \[13\] and \[35\]). In either case, SAR is determined
according to this equation:

$$\text{SAR = }\frac{|E|^{2}\sigma}{\rho}\text{ ,}$$

where \|*E*\| is the magnitude of the measured or computed RMS electric
field, σ is the conductivity and ρ is the mass density of the
tissue-equivalent media. SAR is a measure of the rate of energy
absorption per unit mass at a specific location in the tissue media. SAR
may be expressed in units such as watts/kg or milliwatts/gm. Under
certain circumstances, SAR can also be determined from temperature rises
due to RF energy absorption in tissue media according to the equation:

$$\text{SAR = C}\frac{\delta T}{\delta t}\text{ ,}$$

where C is the specific heat of tissue, δT is the temperature rise and
δt is the exposure duration (See References \[2-3\], \[19\] and \[31\]).
However, in order to use temperature techniques, relatively high power
is required to expose the tissue over a very short duration to avoid
thermal diffusion errors. Therefore, temperature methods are typically
not applicable for evaluating low power transmitters for SAR.

### handset and other transmitter Test Positions

Because of near-field coupling effects, small changes in the positioning
of a test device may sometimes lead to unexpected changes in energy
absorption in the tissue medium. To address this matter, the SCC-34/SC-2
has developed specific test positions for testing handsets. These test
positions are described in Appendix D. As explained in the SCC-34/SC-2
SAR measurement document (See Reference \[19\]), handsets should be
tested on the left and right side of a head phantom in a range of test
configurations to obtain a conservative estimate of the exposures
expected by the user population. For handsets with retractable antennas,
SAR should be evaluated with the handset antenna in its fully extended
and fully retracted positions for each test configuration. Most handsets
generally do not perform well with their antennas partially extended. If
such antenna positions can lead to excessive RF current flow on the
chassis, maximum energy absorption in the cheek region may be expected.
Since such conditions do not represent normal usage, operating
instructions and caution statements should be used to inform users to
avoid operating with these antenna positions.

SCC-34/SC-2 has also recommended use of a specific head model for SAR
evaluation (See Reference \[19\]). Although the head model has been
specified by SCC-34/SC-2, it is not yet commercially available. In the
interim until the SCC-34/SC-2 head model becomes available, other head
phantoms may continue to be used to evaluate handsets for SAR compliance
with the device test positions recommended by the SCC-34/SC-2, unless
the handset cannot be positioned properly or the test positions do not
correspond to the normal use positions of the device. In those
instances, applicants for equipment authorization should contact the
Commission's laboratory for alternative test procedures. These test
device positions should also be used with computational modeling methods
to evaluate SAR compliance.

The effect of a hand holding a handset has also been an issue with
respect to obtaining accurate SAR measurements. Test facilities have
been evaluating handsets by placing the device in a non-metallic holder
to position it precisely against the head or body phantom. When handsets
are evaluated without a hand model, more energy is absorbed in the head
phantom that allows a more conservative exposure condition to be
evaluated. Since a standardized hand model is not available, handsets
should be tested in a low-loss dielectric holder to minimize device test
position uncertainty.

For devices that are designed to operate in body-worn operating
configurations, such as shoulder, waist or chest-worn transmitters, SAR
compliance should be evaluated using a flat phantom with the procedures
described in Appendix D.

### Tissue Models

The dielectric properties of the tissue media used for testing the SAR
of a handset are specified in Appendix C. The RF energy absorption
characteristics of body tissues is related to the tissue water content.
High water-content tissues such as muscle and skin can absorb more RF
energy than low water-content tissues such as fat and bone or skull. At
RF and microwave frequencies, tissue properties are characterized by
their permittivity and conductivity at normal body temperatures, about
37°C. The tissue dielectric parameters are temperature sensitive. For
high water content tissues, permittivity may decrease at a rate of about
0.5 %/°C and conductivity may increase at a rate of about 2 %/°C (See
Reference \[8\]). The simulated tissues used in SAR measurements usually
follow similar temperature variations. The dielectric properties of
simulated tissue materials are formulated with the equivalent tissue
properties at 37°C, for room temperature use, to facilitate SAR
evaluation under ambient conditions.

There are several formulations for making high water-content simulated
tissues. An opaque gel consisting of water, salt, polyethylene powder
and a gelling agent called TX-151 has been used for high power
applications using thermographic or temperature methods to measure SAR
(See Reference \[8\]). A liquid mixed from water, sugar, salt and a
compound called HEC for adjusting the liquid viscosity is commonly used
for measuring the SAR of low power transmitters (See Reference \[15\]).
At above 1.2-1.5 GHz, the sugar is usually replaced with glycol or other
chemical agents to achieve the required dielectric parameters specified
in Appendix C. [Note: Glycol may react with certain plastic material,
including the phantom shell and E-field probe housing; therefore, it
should be used with caution.]{.underline}

The liquid tissue medium is transparent, which offers advantages in
setting up and performing measurements. It also simplifies the SAR
measurements by using only one type of homogeneous tissue medium. The
liquid is contained in a shell representing the head or body, typically
molded from fiberglass or other plastic materials with very low RF
absorption. The measured dielectric constant and conductivity of the
tissue medium should be within the tolerance requirements specified for
the target tissue parameters listed in Appendix C (See References
\[11-12\], \[15\] and \[19\]). The tissue dielectric parameters should
usually be measured daily when SAR measurements are performed or more
often if the parameters are expected to deviate due to temperature
changes or conditions of higher evaporation rates. The tissue dielectric
parameters can be usually characterized with several techniques. A
coaxial probe, slotted line or TEM line may be used with a network
analyzer to measure the reflection parameters of the tissue material for
computing the dielectric parameters (See References \[6\], \[16\] and
\[19\]).

## SAR Measurement System Descriptions and Requirements 

An SAR measurement system usually consists of a small diameter isotropic
electric field probe, a multiple axis probe positioning system, a test
device holder, one or more phantom models, the field probe
instrumentation, a computer and other electronic equipment for
controlling the probe and making the measurements (See References
\[26-27\] and \[35\]). Other supporting equipment, such as a network
analyzer, power meters and RF signal generators, are also required to
measure the dielectric parameters of the simulated tissue media and to
verify the measurement accuracy of the SAR system.

Several types of electric field probes have been used for making SAR
measurements. The probes are on the order 25-30 cm long. It is
recommended that the probe tip diameter should be less than 8.0 mm to
achieve an acceptable spatial resolution in the measurement and to
minimize probe boundary-effects errors (See Reference \[19\]). These
probes are constructed with three miniature dipoles, typically about
1.5-2.5 mm long, loaded with a diode sensor at the gap of each dipole
for measuring electric field strength in three orthogonal directions.
The sensors, each consisting of a dipole and a diode detector, are
deposited and bonded on a substrate that offers minimal perturbation to
the incident field. The substrates are usually arranged in an I-beam
(H-beam) or triangular (delta) configurations to allow each detector to
measure the field component parallel to its axis with minimal effects
from the other two sensors. The detected RF signal is carried on high
resistance leads along the length of the probe to minimize RF pickup.
The signal is filtered by the high resistance lines to produce a very
low frequency signal at the probe output. The probe is fastened to the
probe positioner where it is connected to the probe electronics. The
signals are compensated and converted by instrumentation amplifiers and
precision A/D converters and processed by computer software to SAR
values.

The electric field probe and associated instrumentation are usually
calibrated together on most SAR measurement systems (See Reference
\[19\]). At low field strength levels, the sensors in the probe are
designed to operate as true square-law detectors and the output voltage
is proportional to the square of the measured electric field. At higher
field strength levels, the output of the diode detector becomes directly
proportional to electric field and the probe must be properly
compensated. A probe must be calibrated in the type of tissue media
formulated for the test frequencies. Some probes are calibrated in two
stages, in air and then in tissue media, to obtain calibration factors
that can be used to convert the detected signal to SAR. Below 800 MHz,
probes are typically calibrated using thermal (temperature rise)
techniques. At higher frequencies, standard waveguides may be filled
with the required tissue medium to calibrate the probe output voltages
against analytically calculated field values (See References \[17\],
\[19\] and \[31\]). The applicable field probe calibration requirements
are described in the SCC-34/SC-2 SAR measurement procedures (See
Reference \[19\]).

Besides probe calibration, the accuracy of the SAR measurement system
should also be verified using calibrated RF signal source(s) within the
transmitting frequency band(s) of the test device. The SAR measurement
system should usually be verified daily when SAR measurements are
performed. If the measured 1-g SAR values deviate by more than 10% from
the target reference value(s) specified for the RF signal source(s), the
discrepancies must be resolved before continuing with the SAR
measurement. It is recommended that a flat phantom and a half-wave
dipole matched to the tissue medium be used to verify the accuracy of
SAR measurement systems (See Appendix D).

Several head and body models have been used by different test facilities
to evaluate SAR. The measured SAR is dependent on the RF current
distribution and RF energy coupling characteristics established by the
test device and the tissue model. As indicated above, until the
SCC-34/SC-2 head model is commercially available, the FCC will continue
to accept other head models provided the test procedures described in
this document are followed.

## Device Test Conditions 

Most handsets and portable transmitters are battery operated. Devices
must be tested at full power to demonstrate SAR compliance, which may
sometimes drain a fully charged battery in less than half an hour.
Depending on the measurement resolution and the field scanning
procedures used, it may take 10-20 minutes to complete each measurement;
therefore, it is important to start each test with a fully charged
battery. In order to verify whether a device has been tested at full
power, conducted output power measurements should be performed before
and after each SAR measurement to confirm the output power. The use of
external DC power adapters or other signal leads that are not normally
required during normal use should be avoided because they may perturb
the field and change the exposure conditions.

Most handsets have built-in test modes that may be used for basic
performance evaluations. Such test signals offer a consistent means for
testing SAR and are recommended for evaluating SAR. When test modes are
not available or inappropriate for testing a handset, the actual
transmission should be activated through a base station simulator or
similar equipment.

Handsets should be tested at the high, middle and low frequency channels
in each transmission mode. The performance of a handset may vary within
a transmission band due to its design. In some cases where helical or
patch antennas are used, device performance may shift because of
dielectric loading from the user's body. If a device operates with a
duty factor, the maximum duty factor should be used for evaluating SAR.
Handsets operating in CDMA mode should be tested with full vocoder rate
at 100% duty factor because the output power for these devices usually
varies randomly according to RF propagation conditions between the
devices and the base station.

## SAR Measurement Procedures

The detailed procedures for testing handsets are described in Appendix
D.

## SAR Computation Guidelines and Descriptions

The SAR measurement configurations for testing portable transmitters,
such as device positioning, test conditions and tissue model
requirements for the head and body should be used to evaluate SAR with
computational methods. While the SCC-34/SC-2 is developing recommended
computational procedures for SAR evaluation (See Reference \[20\]), the
following describes the procedures that have been typically used by
others to simulate SAR test conditions. Additional guidance on the type
of information that should be included in test reports to demonstrate
SAR compliance using computational modeling techniques is included in
Appendix B of this supplement.

Currently, the finite-difference time-domain (FDTD) algorithm is the
most widely accepted computational method for SAR modeling (See
References \[13\], \[24\], \[32-33\] and \[38-41\]). This method adapts
very well to the tissue models that are usually derived from MRI or CT
scans (See References \[10\], \[13\] and \[37\]), such as those
currently used by many research institutions. The FDTD method offers
great flexibility in modeling the inhomogeneous structures of anatomical
tissues and organs. It has been used in many far-field electromagnetic
applications during the last three decades. With recent advances in
computing technology, it has become possible to apply this method to
near-field applications for evaluating handsets.

In the early development of SAR modeling using FDTD techniques,
computations were performed with rectangular and spherical dielectric
models exposed in the near field of a dipole or a monopole positioned on
a metal box to verify the technique\'s applicability for evaluating
handsets (See References \[7\], \[21-22\], \[25\] and \[36\]).
Currently, different techniques have been developed to model the exact
shape and dimensions of a handset (See References \[40\]), including its
display and keypad, through computer aid design (CAD) data provided by
the handset manufacturer. While this effort is continuing, concern has
been expressed over the validity of most handset models that do not
consider the effects of the inner electronics and complex chassis or
shielding structures of a handset as part of the device model.

Computing resources and memory requirements are often of concern for
most numerical simulations. The memory required for FDTD computations is
directly related to the resolution of the tissue and handset models. The
numerical algorithms used to implement the FDTD method may vary with the
optimization techniques used to improve the modeling accuracy and
computational efficiency. To satisfy the wave propagation requirements
in infinite free space, numerical absorbing boundaries are applied to
truncate the computation domain to simulate reflectionless propagation
through the absorbing boundaries. Several types of absorbing boundary
conditions (ABC) have been developed for FDTD computations, including
Mur, Liao, retarded-time and the perfectly-matched-layers (See
References \[4-5\] and \[29\]). The performance of these ABCs may vary
but their effects on SAR in highly absorptive dielectric media, such as
body tissues, are normally insignificant.

A sinusoidal waveform is typically used as the excitation source at the
antenna feed-point of a handset to perform the computations. The signal
is allowed to propagate and interact with the objects modeled in the
computational domain by means of numerical iterations. The FDTD
algorithm iterates the field propagation in both space and time until
the field conditions in the computational domain reach sinusoidal steady
state. The total field at selected tissue locations can be computed to
determine the SAR. In order to maintain numerical stability for the
computational algorithms, the Courant condition that provides the
minimum relationship for selecting the time and spatial resolutions used
in the computation must be satisfied (See References \[24\] and
\[38-39\]). The iteration speed and expected computational errors are
related to the parameters used for meeting the Courant condition.

One of the advantages of using computational modeling is its ability to
model the complex heterogeneous structures of anatomical tissues and to
simulate the field scattering that occurs within the tissues. The
handset and the head or other tissue structures are digitized according
to the permittivity and conductivity of the respective material and
dielectric media. In order to compute SAR accurately, the appropriate
tissue dielectric properties must be used in the computation. The list
of tissue dielectric parameters compiled by Dr. Camelia Gabriel
constitutes the most widely accepted database for this information (See
Reference \[12\]). The dielectric parameters of selected tissues have
been derived from this database and made available for viewing and
downloading at the FCC\'s Office of Engineering and Technology\'s World
Wide Web Internet Site: <http://www.fcc.gov/oet/>.

Generally, the basic FDTD algorithms and associated special techniques
are validated with benchmark models when the computational techniques
are developed. Once the computational accuracy is established,
validations are only required when changes are made to certain
algorithms. The similar benchmark validation procedures are also used to
verify the validity of head and body models constructed for the
computations. The use of benchmark validations to confirm computational
and modeling accuracy can be viewed as the equivalent of equipment
calibration in SAR measurements. Since validation techniques generally
vary among different test sites, it may be necessary to include the
technical information on benchmark validation procedures to substantiate
compliance.

Special FDTD techniques have been concurrently developed by various
researchers to provide more accurate and efficient methods for modeling
handsets and antennas (See References \[23\], \[32\] and \[34\]). It has
been recently shown that the exact dimensions of an antenna and its
location on the handset must be precisely modeled in order to obtain
accurate results (See Reference \[40\]). Since the inner electronics of
a handset are typically not modeled, appropriate means should be used to
verify the validity of a handset model for compliance testing.

Currently there are no standard procedures for selecting the electric
field components surrounding an FDTD cell or at a grid point to
determine the total electric field at a tissue location. The total field
is typically computed from the averages of 3-12 field components that
are located at a grid point or surrounding a cell in the tissue model
and have introduced SAR variations in the computations. These variations
are usually dependent on the local field gradients. There is also no
standard method for computing the one-gram averaged SAR and various
methods have been used. At a tissue interface or along an irregular
surface of the phantom, the local field values are computed from field
components in different tissue types. To accurately compute the one-gram
SAR in the shape of a one-gram cube involving different tissues can be
difficult. Until computational procedures are available from SCC-34/SC-2
(See Reference \[20\]), the procedures used to compute the one-gram SAR
should be described in the test report to support compliance.

The sinusoidal or pulsed signal used to excite the antenna of a handset
is typically of arbitrary amplitude. The computed SAR values must be
normalized to the measured output power of the actual device. It is
recommended that the final SAR be normalized to the maximum conducted
output power measured by the manufacturer. When technical data is
requested, the information described in Appendix B may be used to
determine the type of supporting information for demonstrating
compliance.

## Measurement and Computational Uncertainties

Although measurement and computational techniques are being improved,
standardized procedures have not yet been established. Therefore, the
margin of error for typical measurement and computational systems is
directly related to the latest technical developments for SAR
evaluation. Systems that use unreliable techniques or those that do not
produce repeatable results should not be used to test devices for FCC
compliance.

Measurement uncertainties are the results of errors related to system
instrumentation, field probe response and calibration, tissue dielectric
properties and tissue parameter characterization. Uncertainties due to
measurement procedures include test device placement, probe positioning,
the algorithms used to interpolate, extrapolate and analyze the
measurement data to determine the one-gram averaged SAR. A list of the
SAR measurement uncertainty components described in the SCC-34/SC-2 SAR
document is included Appendix D.

For numerical methods, computational uncertainties are usually the
results of errors due to numerical algorithm implementation, benchmark
validation, methods used to compute SAR from the field components and
procedures used to determine the one-gram averaged SAR. Uncertainties in
the test device and tissue models are due to modeling techniques, tissue
model implementation, assignment of tissue dielectric parameters and the
modeling resolution. Information on such uncertainties is relevant to
SAR evaluation and may be requested in order to support compliance with
SAR exposure limits (See Reference \[20\]).

For spread spectrum transmitters operating under 47 CFR §15.247, it is
specified in 47 CFR §15.247(b)(4) that these devices must operate in a
manner that ensures the public is not exposed to RF energy levels in
excess of the Commission\'s guidelines.[^11] These devices are
categorically excluded from routine environmental evaluation because
they generally operate at relatively low power levels where there is a
high likelihood of compliance with the RF exposure standards. For some
low power devices, it may be necessary to ensure compliance with the RF
exposure limits by using a combination of simple procedures such as
installation and operating instructions, warning instructions and/or
warning labels on the device to ensure that the device will not expose
nearby persons above the applicable MPE limits[^12]. In most cases, the
\"worst case\" distance at which an MPE limit is met for mobile devices
can be estimated according to the power density produced by an isotropic
source with radiated output power equivalent to that transmitted by the
device as discussed in OET Bulletin 65.[^13]

If a transmitter is designed to operate next to the body of its user or
at close proximity to persons, a RF evaluation may be requested
according to 47 CFR §1.1307(c) and (d). These types of evaluations are
typically limited to transmitters that are intended to operate in very
close proximity to the body, using 0.5 watt of output power or more with
a high signal transmitting duty factor, and which do not incorporate
obvious effective means for users to meet RF exposure compliance.[^14]
When RF evaluation is requested, the procedures described in this
supplement for evaluating mobile and portable devices with respect to
MPE or SAR limits may be used.

For purposes of determining RF exposure, the transmission protocols used
by certain spread spectrum transmitters may qualify the device for
source-based time averaging. The applicable duty factor may be
determined according to the RF output power \"on\" and \"off\" time
durations, either as a signal with a repeatable duty cycle or by
establishing a worst case duty factor using power off durations
identified by the transmission protocol. Duty factors related to device
usage, frequency hopping or other similar transmission conditions are
normally not acceptable as source-based, time averaging factors for RF
evaluations.

For transmitters that use external or remote antennas for indoor or
outdoor operations, appropriate installation procedures should be
provided to the installer to ensure the antenna is installed to provide
the specified distance from nearby persons to satisfy compliance. For
other transmitters which do not normally operate next to persons, such
as a wireless LAN transmitter located on a desktop, certain operating
and usage instructions may be included in the operator\'s manual to
caution users to maintain a specified distance from the transmitter to
ensure compliance. In some of the above situations where a low power
device is designed to operate near the body of the user, the use of a
warning label on the transmitter to caution users to limit their
exposure duration and/or maintain certain specific usage conditions can
also be acceptable for demonstrating compliance.[^15]

As is explained in the FCC\'s *Report and Order* in ET Docket 96-8 (FCC
97-114, Section 9), these are steps that can be taken by the responsible
parties to ensure that these devices are operated in accordance with the
RF guidelines for human exposure adopted by the Commission. The methods
used to ensure compliance must be effective, and the installation,
operation and warning instructions or warning labels should explain
their purpose and provide appropriate means for satisfying
compliance.[^16] The appropriate equations for estimating power
densities produced by typical antennas, including high gain aperture
antennas, are described in OET Bulletin 65. It should be emphasized that
categorical exclusion from routine environmental evaluation must not be
interpreted as an exemption from compliance with the RF exposure
requirements in §15.247(b)(4).

## Methods to Ensure Compliance for Spread Spectrum Transmitters

The examples shown in the Table 1 are not intended to establish
mandatory procedures for RF exposure compliance for spread spectrum
transmitters. Other methods and procedures may be acceptable based on
device output power, operating configurations and exposure conditions.
The range of power levels and distances used are approximate values
representative of typical operating conditions for most spread spectrum
transmitters operating at 915 or 2450 MHz. For certain fixed and mobile
transmitters that are not designed to be carried next to the body of a
user during normal operation, the use of appropriate operating and
warning instructions in the operator\'s manual or warning labels on the
device may offer effective means to prevent users and nearby persons
from exposure at a specified distance from the device where RF exposure
limits could be exceeded.[^17]

**Table 1. Applicable Methods to Ensure Compliance for Spread Spectrum
Transmitters.**

+----------------------+----------+-----------------------------------+
| **[Transmitter or    | **[Ou    | **[Applicable Methods to Ensure   |
| Device               | tput]{.u | Compliance]{.underline}**[^20]    |
| Type                 | nderline |                                   |
| ]{.underline}**[^18] | }**[^19] |                                   |
+----------------------+----------+-----------------------------------+
| Cordless phone       | ≤ 0.3 W  | If the device or its antenna      |
| handsets and most    | at 915   | operates at less than 2.5 cm from |
| other transmitters   | MHz      | a person's body (excluding hands, |
| using monopole or    |          | wrists, feet and ankles), the     |
| dipole type antennas | or       | potential for exceeding SAR limit |
| as an integral part  |          | is dependent on the operating     |
| of the device.       | ≤ 0.2 W  | configurations and exposure       |
|                      | at 2450  | conditions of the device.         |
|                      | MHz      | Operating and warning             |
|                      |          | instructions in the operator\'s   |
|                      |          | manual may be used to ensure      |
|                      |          | compliance. If such instructions  |
|                      |          | are ineffective for ensuring      |
|                      |          | compliance, especially when the   |
|                      |          | output is greater than 50-100 mW, |
|                      |          | it may be necessary to            |
|                      |          | demonstrate compliance with       |
|                      |          | respect to SAR limit.             |
+----------------------+----------+-----------------------------------+
| Cordless phone       | \> 0.3 W | Generally at above 300 mW (200 mW |
| handsets and other   | at       | at 2450 MHz), the potential for   |
| transmitters that    |          | exceeding SAR limit is dependent  |
| are carried next to  | 915 MHz  | on the antenna design and device  |
| the body of the user |          | operating conditions.             |
| or operate at        | or       |                                   |
| distances closer     |          | Warning instructions and warning  |
| than approximately 5 | \> 0.2 W | labels may be used to limit the   |
| cm to the body of    | at 2450  | exposure durations and/or         |
| users or nearby      | MHz      | conditions to ensure compliance.  |
| persons.             |          | However, if manufacturers believe |
|                      |          | that such warning instructions    |
|                      |          | and labels will not be effective  |
|                      |          | in keeping persons at the         |
|                      |          | specified distances necessary to  |
|                      |          | ensure compliance, especially     |
|                      |          | when the output is greater than   |
|                      |          | 400-500 mW, it may be necessary   |
|                      |          | to demonstrate compliance with    |
|                      |          | respect to SAR limit.[^21]        |
+----------------------+----------+-----------------------------------+
| Transmitters using   | \> 0.3 W | Operating and warning             |
| monopole or dipole   | at       | instructions in the operator\'s   |
| type antennas as an  |          | manual indicating the minimum     |
| integral part of the | 915 MHz  | separation distance between the   |
| device, normally     |          | antenna and nearby persons in     |
| operating at closer  | or       | order to avoid extended periods   |
| than 20 cm to users  |          | of exposure at closer than this   |
| or nearby persons    | \> 0.2 W | distance to ensure SAR            |
| but more than        | at 2450  | compliance.                       |
| approximately 5 cm   | MHz      |                                   |
| away from such       |          | When operating and warning        |
| persons.             |          | instructions are ineffective, the |
|                      |          | use of warning labels on the      |
|                      |          | transmitting element may also be  |
|                      |          | necessary to caution nearby       |
|                      |          | persons to limit their exposure   |
|                      |          | duration and/or conditions to     |
|                      |          | ensure compliance.                |
|                      |          |                                   |
|                      |          | If warning labels are not         |
|                      |          | desirable, SAR evaluations, even  |
|                      |          | though they may not be required,  |
|                      |          | may be used to demonstrate        |
|                      |          | compliance to obviate the need    |
|                      |          | for any warning label that might  |
|                      |          | otherwise be necessary.           |
+----------------------+----------+-----------------------------------+
| Transmitters using   | \> 2.5 W | Professional installation:        |
| external antennas,   | at 915   | provide installers with           |
| including Omni,      | MHz      | instructions indicating the       |
| patch, logarithmic,  |          | separation distance between the   |
| parabolic reflector  | ≤ 2.5 W  | transmitter/antenna and nearby    |
| and dish type        | at 915   | persons to ensure RF exposure     |
| antennas. For        | MHz      | compliance, and to inform         |
| outdoor operations,  |          | installers to ensure compliance   |
| antennas generally   | or       | through proper installation.      |
| mounted at remote    |          |                                   |
| locations such as    | ≤ 4 W at | Professional installation is      |
| the top or side of   | 2450 MHz | preferred for these types of      |
| most buildings where |          | operations. However, end-user     |
| the antennas are at  |          | installation may require certain  |
| least 20 cm away     |          | additional information to allow   |
| from nearby persons. |          | persons who do not have           |
|                      |          | professional skills to properly   |
|                      |          | install the antennas to ensure    |
|                      |          | compliance.                       |
|                      |          |                                   |
|                      |          | Transmitters operating at 2.5 W   |
|                      |          | EIRP (1.5 W ERP) or less at 915   |
|                      |          | MHz, or at 4 W EIRP (2.4 W ERP)   |
|                      |          | or less at 2450 MHz, generally    |
|                      |          | are not expected to exceed MPE    |
|                      |          | limits when nearby persons are 20 |
|                      |          | cm or more from most antennas;    |
|                      |          | special instructions and warnings |
|                      |          | are normally not necessary to     |
|                      |          | ensure compliance.                |
+----------------------+----------+-----------------------------------+
| Transmitters using   | \> 2.5 W | If the MPE distance is greater    |
| indoor antennas that | at 915   | than that required for normal     |
| operate at 20 cm or  | MHz      | operation of the device,          |
| more from nearby     |          | operating instructions, warning   |
| persons.             | ≤ 2.5 W  | instructions and/or warning       |
|                      | at 915   | labels may be used to ensure      |
|                      | MHz      | compliance by indicating the      |
|                      |          | minimal separation distance to    |
|                      | or       | comply with MPE limits.           |
|                      |          |                                   |
|                      | ≤ 4 W at | If the antennas are               |
|                      | 2450 MHz | professionally installed to       |
|                      |          | ensure compliance, warning        |
|                      |          | instructions and warning labels   |
|                      |          | are not necessary.                |
|                      |          |                                   |
|                      |          | Transmitters operating at 2.5 W   |
|                      |          | EIRP (1.5 W ERP) or less at 915   |
|                      |          | MHz, or at 4 W EIRP (2.4 W ERP)   |
|                      |          | or less at 2450 MHz, generally    |
|                      |          | are not expected to exceed MPE    |
|                      |          | limits when nearby persons are 20 |
|                      |          | cm or more from most antennas.    |
|                      |          | Therefore, special instructions   |
|                      |          | and warnings are normally not     |
|                      |          | necessary to ensure compliance.   |
+----------------------+----------+-----------------------------------+
| Transmitters using   | \> 4.0 W | If MPE limit may be exceeded in   |
| high gain antennas   |          | the main beam of the antenna,     |
| for indoor or        | at 2450  | installation procedures, warning  |
| outdoor operations.  | MHz      | instructions and/or warning       |
|                      |          | labels as described above may be  |
|                      |          | used to ensure compliance by      |
|                      |          | providing professional installers |
|                      |          | and end-users with instructions   |
|                      |          | to point the main beam of the     |
|                      |          | antenna at locations not occupied |
|                      |          | by persons and to warn others to  |
|                      |          | maintain a specified distance     |
|                      |          | from the antenna.                 |
+----------------------+----------+-----------------------------------+

\[1\] American National Standards Institute (ANSI), \"Safety Levels with
Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3
kHz to 300 GHz,\" ANSI/IEEE C95.1‑1992 (previously issued as IEEE
C95.1-1991). Copyright 1992 by the Institute of Electrical and
Electronics Engineers, Inc. (IEEE), New York, N.Y. 10017. For copies
contact the IEEE: 1-800-678-4333 or 1-908-981-1393.

\[2\] American National Standards Institute (ANSI), \"Recommended
Practice for the Measurement of Potentially Hazardous Electromagnetic
Fields - RF and Microwave". ANSI/IEEE C95.3-1992. Copyright 1992, The
Institute of Electrical and Electronics Engineers, Inc. (IEEE), New
York, NY 10017. For copies contact the IEEE: 1-800-678-4333 or
1-908-981-1393. A new edition is expected for release in 2001.

\[3\] Balzano, Q., O. Garay, and T. Manning, \"Electromagnetic energy
exposure of simulated users of portable cellular telephones", IEEE
Transactions on Vehicular Technology, Vol. 44 (3), pp. 390-403, 1995.

\[4\] Berenger, J., \"A Perfectly Matched Layer for the Absorption of
Electromagnetic Waves", Journal of Computational Physics, 114, pp.
185-200, 1994.

\[5\] Berntsen, S. and S. Hornsleth, \"Retarded Time Absorbing Boundary
Conditions", IEEE Transactions on Antenna and Propagation, 42(8), pp.
1059-1064, August 1994.

\[6\] Burdette, E., F. Cain and J. Seals, \"In vivo Probe Measurement
Technique for Determining Dielectric Properties at VHF Through Microwave
Frequencies", IEEE Transactions on Microwave Theory and Techniques,
8(4), pp. 414-427, April 1980.

\[7\] Chatterjee, I., M. Hagmann, and O. Gandhi, "Electromagnetic
absorption in a multi-layered slab model of tissue under near- field
exposure conditions," Bioelectromagnetics, vol. 1, pp. 379-388, 1980.

\[8\] Chou, C., G. Chen, A. Guy and K. Luk, \"Formulas for Preparing
Phantom Muscle Tissue at Various Radiofrequencies", Bioelectromagnetics,
5, pp. 435-441, 1984.

\[9\] Cleveland, R. and T. Athey, "Specific absorption rate (SAR) in
models of the human head exposed to hand-held UHF portable radios,"
Bioelectromagnetics, vol. 10, pp. 173-186, 1989.

\[10\] Dimbylow, P., and S. Mann, \"SAR Calculations in an Anatomically
Realistic Model of the Head for Mobile Communication Transceivers at 900
MHz and 1.8 GHz", Phys. Med. Biol., 39(12), pp. 1537-1553, 1994.

\[11\] Drossos, A., V. Santomaa, and N. Kuster, "The dependence of
electromagnetic energy absorption upon human head tissue composition in
the frequency range of 300-3000 MHz," IEEE Transactions on Microwave
Theory and Techniques, vol. 48, no. 11, pp. 1988-1995, Nov. 2000.

\[12\] Gabriel, C., \"Compilation of the Dielectric Properties of Body
Tissues at RF and Microwave Frequencies", Brooks Air Force Technical
Report AL/OE-TR-1996-0037, 1996.

\[13\] Gandhi, O., G. Lazzi and C. Furse, \"EM Absorption in the Human
Head and Neck for Mobile Telephones at 835 and 1900 MHz,\" IEEE Trans.
on Microwave Theory and Techniques, 44 (10), pp. 1884-1897, October
1996.

\[14\] Guy A. and C. Chou, "Specific absorption rates of energy in man
models exposed to cellular UHF mobile-antenna fields," IEEE Transactions
on Microwave Theory and Techniques, vol. 34, no. 6, pp. 671-680, June
1986.

\[15\] Hartsgrove, G., A. Kraszewski and a. Surowiec, \"Simulated
Biological Materials for Electromagnetic Radiation Absorption Studies",
Bioelectromagnetics, 8, pp. 29-36, 1987.

\[16\] Hewlett-Packard Company, \"Basics of Measuring the Dielectric
Properties of Materials", Application Note 1217-1. For copies contact
Hewlett-Packard at 1-800-452-4844.

\[17\] Hill, D., \"A Waveguide Technique for the Calibration of
Miniature Implantable Electric Field Probes for Use in Microwave
Bioeffects Studies", IEEE Transactions on Microwave Theory and
Techniques, pp. 92-99, Jan 1982.

\[18\] Hombach, V., K. Meier, M. Burkhardt, E. Kuhn, and N. Kuster, "The
dependence of EM energy absorption upon human head modeling at 900 MHz,"
IEEE Transactions on Microwave Theory and Techniques, vol. 44, no. 10,
pp. 1855-1863, Oct. 1996.

\[19\] IEEE Standards Coordinating Committee 34 on Product Performance
Standards Relative to the Safe Use of Electromagnetic Energy,
"***[Draft]{.underline}*** Recommended Practice for Determining the
Spatial-Peak Specific Absorption Rate (SAR) in the Human Body Due to
Wireless Communications Devices: Experimental Techniques," P1528, 2001.

\[20\] IEEE Standards Coordinating Committee 34 on Product Performance
Standards Relative to the Safe Use of Electromagnetic Energy,
"***[Draf]{.underline}t*** Recommended Practice for Determining the
Spatial-Peak Specific Absorption Rate (SAR) in the Human Body Due to
Wireless Communications Devices: Computational Techniques," P1529,
preliminary draft, 1999.

\[21\] Iskander, M., P. Barber, C. Durney, and H. Massoudi, "Irradiation
of prolate spheroidal models of humans in the near-field of a short
electric dipole," IEEE Transactions on Microwave Theory and Techniques,
vol. 28, no. 7, pp. 801-807, July 1980.

\[22\] King, R., "Electromagnetic field generated in model of human head
by simplified telephone transceiver", Radio Science, vol. 30, no. 1, pp.
267-281, Jan. 1995.

\[23\] Karimullah, K., K. Chen, and D. Nyquist, "Electromagnetic
coupling between a thin-wire antenna and a neighboring biological body:
Theory and experiment," IEEE Transactions on Microwave Theory and
Techniques, vol. 28, no. 11, pp. 1218-1225, Nov. 1980.

\[24\] Kunz, K. and R. Luebbers, \"The finite Difference time Domain
Method for Electromagnetics", CRC Press, 1993.

\[25\] Kuster, N. and Q. Balzano, "Energy absorption mechanism by
biological bodies in the near field of dipole antennas above 300 MHz",
IEEE Transactions on Vehicular Technology, vol. 41, no. 1, pp. 17-23,
Feb. 1992.

\[26\] Kuster, N., R. Kastle, and T. Schmid, \"Dosimetric Evaluation of
Handheld Mobile Communications Equipment with Known Precision", IEICE
Transactions, E80-A(5), pp. 1-8, May 1997.

\[27\] Meier, K., M. Burkhardt, T. Schmid and N. Kuster, \"Broadband
Calibration of E-field Probes in Lossy Media,\" IEEE Transactions on
Microwave Theory and Techniques, 44(10), pp. 1954-1962, October 1996.

\[28\] Meier, K., V. Hombach, R. Kastle, R. Y-S. Tay, and N. Kuster,
"The dependence of electromagnetic energy absorption upon human-head
modeling at 1800 MHz," IEEE Transactions on Microwave Theory and
Techniques, vol. 45, no. 11, pp. 2058-2062, Nov. 1997.

\[29\] Mur, G., \"Absorbing Boundary Conditions for the
Finite-Difference Approximation of the time-Domain electromagnetic Field
Equations", IEEE Transactions on Electromagnetic Compatibility, 23(4),
pp. 377-382, November 1981.

\[30\] National Council on Radiation Protection and Measurements (NCRP),
\"Biological Effects and Exposure Criteria for Radiofrequency
Electromagnetic Fields", NCRP Report No. 86, 1986. Copyright NCRP,
Bethesda, MD, 20814, USA. For copies contact NCRP Publications:
1-800-229-2652.

\[31\] National Council on Radiation Protection and Measurements (NCRP),
\"A Practical Guide to the Determination of Human Exposure to
Radiofrequency Fields", NCRP Report No. 119, 1993. Copyright NCRP,
Bethesda, MD 20814. For copies contact: NCRP Publications at:
1-800-229-2652.

\[32\] Nyquist, D., K. Chen, and B. Guru, "Coupling between small
thin-wire antennas and a biological body," IEEE Transactions on Antennas
and Propagation, vol. 25, no. 6, pp. 863-866, Nov. 1977.

\[33\] Okoniewski, M. and M. Stuchly, \"A Study of the Handset Antenna
and Human Body Interaction", IEEE Transactions on Microwave Theory and
Techniques, 4(10), pp. 1855-1864, October 1996.

\[34\] Okoniewski, M., E. Okoniewski and M. Stuchly, \"Three-Dimensional
Subgridding Algorithm for FDTD", IEEE Transactions on Antenna and
Propagation, 45(3), pp. 422-429, March 1997.

\[35\] Schmid, T., O. Egger and N. Kuster, \"Automated E-Field Scanning
System for Dosimetric Assessments", IEEE Trans. Microwave Theory and
Techniques, 44(1): 105-113, January 1996.

\[36\] Schoenborn, F., M. Burkhardt, and N. Kuster, "Differences in
energy absorption between heads of adults and children in the near field
of sources", Health Physics, vol. 74, no. 2, pp. 160-168, 1998.

\[37\] Stuchly, M., A. Kraszewski, S. Stuchly, G. Hartsgrove, and R.
Spiegel, "RF energy deposition in a heterogeneous model of man:
Near-field exposures," IEEE Transactions on Biomedical Engineering, vol.
34, no. 12, pp. 944-949, Dec. 1987.

\[38\] Taflove, A., \"Computational Electrodynamics - The
Finite-Difference Time-Domain Method", Artech House, 1995.

\[39\] Taflove, A. \"Review of the Formulation and Applications of the
Finite-Difference Time-Domain Method for Numerical Modeling of
Electromagnetic Wave Interactions with Arbitrary Structures", Wave
Motion, 10, pp. 547-582, 1988.

\[40\] Tinniswood, A., C. Furse and O. Gandhi, "Computations of SAR
Distributions for Two Anatomically Based Models of the Human Head Using
CAD files of Commercial Telephones and the Parallelized FDTD Code," IEEE
Transactions on Antennas and Propagation. Vol. 6, No. 6, June, 1998.

\[41\] Yee, K., \"Numerical Solution of Initial Boundary Value Problems
Involving Maxwell\'s Equations in Isotropic Media," IEEE Transactions on
Antenna and propagation, 14(3), pp. 302-307, May 1966.

\[42\] "Military Handbook, Anthropometry of US Military Personnel",
DOD‑HDBK 743A February 1991.

***Note***: For further information and details on these limits see OET
Bulletin 65, §§1.1307, 1.1310, 2.1091 and 2.1093 of FCC rules.

## FCC Limits for Maximum Permissible Exposure (MPE)

\(A\) Limits for Occupational/Controlled Exposure

Frequency Electric Field Magnetic Field Power Density Averaging Time

Range Strength (E) Strength (H) (S) \|E\|^2^, \|H\|^2^ or S

(MHz) (V/m) (A/m) (mW/cm^2^) (minutes)

0.3-3.0 614 1.63 (100)\* 6

3.0-30 1842/f 4.89/f (900/f^2^)\* 6

30-300 61.4 0.163 1.0 6

300-1500 \-- \-- f/300 6

1500-100,000 \-- \-- 5 6

\(B\) Limits for General Population/Uncontrolled Exposure

Frequency Electric Field Magnetic Field Power Density Averaging Time

Range Strength (E) Strength (H) (S) \|E\|^2^, \|H\|^2^ or S

(MHz) (V/m) (A/m) (mW/cm^2^) (minutes)

0.3-1.34 614 1.63 (100)\* 30

1.34-30 824/f 2.19/f (180/f^2^)\* 30

30-300 27.5 0.073 0.2 30

300-1500 \-- \-- f/1500 30

1500-100,000 \-- \-- 1.0 30

f = frequency in MHz \*Plane-wave equivalent power density

NOTE 1: See Section 1 for discussion of exposure categories.

NOTE 2: The averaging time for General Population/Uncontrolled exposure
to fixed transmitters is not applicable for mobile and portable
transmitters. See 47 CFR §§2.1091 and 2.1093 on source-based
time-averaging requirements for mobile and portable transmitters.

## FCC Limits for Specific Absorption Rate (SAR) 

**(A) Limits for Occupational/Controlled Exposure (W/kg)**

  -------------------- --------------------- -----------------------------
  Whole-Body           Partial-Body          Hands, Wrists, Feet and
                                             Ankles

  0.4                  8.0                   20.0
  -------------------- --------------------- -----------------------------

**(B) Limits for General Population/Uncontrolled Exposure (W/kg)**

  -------------------- --------------------- -----------------------------
  Whole-Body           Partial-Body          Hands, Wrists, Feet and
                                             Ankles

  0.08                 1.6                   4.0
  -------------------- --------------------- -----------------------------

NOTE 1: See Section 1 for discussion of exposure categories.

NOTE 2: ***Whole-Body SAR*** is averaged over the entire body,
***partial-body SAR*** is averaged over any 1 gram of tissue defined as
a tissue volume in the shape of a cube. ***SAR for hands, wrists, feet
and ankles*** is averaged over any 10 grams of tissue defined as a
tissue volume in the shape of a cube.

NOTE 3: At frequencies above 6.0 GHz, SAR limits are not applicable and
MPE limits for power density should be applied at 5 cm or more from the
transmitting device.

Note 4: The time averaging criteria for field strength and power density
do not apply to general population SAR limit of 47 CFR §2.1093.

The information described in this Appendix should be included in test
reports submitted for equipment authorization that requires SAR
evaluation. The information is generally necessary to evaluate test
results and to determine RF exposure compliance.

I: Information on Test Device and Exposure Categories

II: Specific Information for SAR Measurements

III: Specific Information for SAR Computations

## I: Information on test device and exposure categories

**1) General information**

a.  FCC ID -- each RF exposure test report must include the FCC ID of
    the device evaluated.

b.  an affirmative statement of compliance with FCC RF exposure (see 47
    CFR §2.909)

c.  device category-- identify if the SAR evaluation is for a mobile or
    portable transmitter

d.  RF exposure environment -- state the applicable exposure condition
    for the transmitter operating environment, Occupational/Controlled
    or General Population/Uncontrolled

**2) Device operating configurations and test conditions**

a.  whether the test device is a production unit or an *identical*
    prototype (see 47 CFR §2.908)

b.  a brief description of the test device operating configurations,
    including

    i.  operating modes and operating frequency range(s)

    ii. maximum device rating for each operating mode and frequency
        range

    iii. operating tolerances

    iv. antenna type and operating positions

    v.  applicable body-worn configurations

    vi. battery options that could affect the SAR results

c.  procedures used to establish the test signals

d.  applicable source-based time-averaging duty factor and the duty
    factor used in the tests

e.  maximum output power measured before and after each SAR test

[]{#__RefHeading___Toc517850400 .anchor}II: Specific Information for SAR
Measurements

1)  **Measurement system and site description**

    a.  a brief description of the SAR measurement system

    b.  a brief description of the test setup

2)  **Electric field probe calibration**

    a.  a description of the probe, its dimensions and sensor offset
        etc.

    b.  a description of the probe measurement errors

    c.  most recent calibration date

3)  **SAR measurement system verification**

    a.  A brief description of the RF radiating source used to verify
        the SAR system performance within the operating frequency range
        of the test device (see Appendix D)

    b.  a list of the tissue dielectric parameters, ambient and tissue
        temperatures, output power, peak and one-gram averaged SAR for
        the measured and expected target test configurations

    c.  a list of the error components contributing to the total
        measurement uncertainty

4)  **Phantom description**

    a.  a description of the head and body phantoms used in the tests,
        including shell thickness and other tolerances

5)  **Tissue dielectric property**

    a.  the composition of ingredients for the tissue material used in
        the SAR tests

    b.  the tissue dielectric parameters measured at the middle of each
        operating frequency range of the test device

    c.  the temperature range and operating conditions of the tissue
        material during each SAR measurement

6)  **Device positioning**

    a.  a description of the dielectric holder or similar mechanisms
        used to position the test device in the specific test
        configurations

    b.  a description of the positioning procedures used to evaluate the
        highest exposure expected under normal operating configurations

    c.  sketches and illustrations showing the device positions, with
        respect to the phantom; including separation distances and
        angles, as appropriate

    d.  a description of the antenna operating positions, extended,
        retracted or stowed etc. and the configurations tested in the
        SAR evaluation

7)  **Peak SAR locations**

    a.  a description of the coarse resolution, surface or area scan
        procedures used to search for all possible peak SAR locations
        within the phantom

    b.  a description of the interpolation procedures applied to the
        measured points to identify the peak SAR locations at a finer
        spatial resolution

    c.  description, illustration and SAR distribution plots showing the
        peak SAR locations with respect to the phantom and the test
        device

    d.  identifying the peak SAR locations used to evaluate the highest
        one-gram averaged SAR

8)  **One-gram averaged SAR**

    a.  a description of the fine resolution, volume or zoom scan
        procedures used to determine the highest one-gram averaged SAR
        in the shape of a cube

    b.  a description of the extrapolation procedures used to estimate
        the SAR value of points close to the phantom surface that are
        not measurable

    c.  a description of the interpolation procedures applied to the
        measured and extrapolated points to obtain SAR values at a finer
        spatial resolution within the zoom scan volume

    d.  a description of the integration procedures applied to the
        interpolated SAR values within the zoom scan volume to determine
        the highest 1 or 10-gram SAR in the shape of a cube

9)  **Total measurement uncertainty**

    a.  a tabulated list of the error components and uncertainty values
        contributing to the total measurement uncertainty (see Appendix
        D)

    b.  reporting the combined standard uncertainty and expanded
        uncertainty (for k≥2) of each measurement

    c.  if compliance cannot be ensured after taking measurement
        uncertainty into account, an explanation of the procedures that
        have been used to reduce the measurement uncertainty and
        applicable means that can be used to ensure compliance

10) **Test results for determining SAR compliance**

    a.  if the channels tested for each configuration (left, right,
        cheek, tilt/ear, extended, retracted etc.) have similar SAR
        distributions, a plot of the highest SAR for each test
        configuration should be sufficient; otherwise additional plots
        should be included to document the differences

    b.  all of the measured SAR values should be documented in a
        tabulated format with respect to the test configurations

## III: Specific Information for SAR Computations

1)  **Computational resources**

    a.  a summary of the computational resource required to perform the
        SAR computations for the test transmitter and phantom
        configurations

    b.  a summary of the computational requirements with respect to
        modeling and computing parameters for determining the highest
        exposure expected for normal device operation, such as minimal
        computational requirements and those used in the computation

2)  **FDTD algorithm implementation and validation**

    a.  a summary of the basic algorithm implementation applicable to
        the particular SAR evaluation, including absorbing boundary
        conditions, source excitation methods, certain standard
        algorithms for handling thin metallic wires, sheets or
        dielectric materials etc.

    b.  descriptions of the procedures used to validate the basic
        computing algorithms described in a) and analysis of the
        computing accuracy based on these algorithms for the particular
        SAR evaluation

3)  **Computational parameters**

    a.  a tabulated list of computational parameters such as cell size,
        domain size, time step size, tissue and device model separation
        from the absorbing boundaries and other essential parameters
        relating to the computational setup requirements for the SAR
        evaluation

    b.  a description of the procedures used to handle computation
        efficiency and modeling accuracy for the phantom and the test
        device

4)  **Phantom model implementation and validation**

    a.  identify the source of the phantom model, its original
        resolution and the procedures used to code and assign tissue
        dielectric parameters for the SAR evaluation

    b.  verify the phantom model is appropriate for determining the
        highest exposure expected for normal device operation

    c.  describe procedures used to verify that the particular phantom
        model has been correctly constructed for making SAR
        computations, such as comparing computed and measured SAR
        results of a dipole source

5)  **Tissue dielectric parameters**

    a.  a description of the types of tissues used in the phantom models
        and the sources of tissue dielectric parameters used in the
        computations

    b.  verify that the tissue types and dielectric parameters used in
        the SAR computation are appropriate for determining the highest
        exposure expected for normal device operation

    c.  a tabulated list of the dielectric parameters used in the device
        and phantom models

6)  **Transmitter model implementation and validation**

    a.  a description of the essential features that must be modeled
        correctly for the particular test device model to be valid

    b.  descriptions and illustrations showing the correspondence
        between the modeled test device and the actual device, with
        respect to shape, size, dimensions and near-field radiating
        characteristics

    c.  verify that the test device model is equivalent to the actual
        device for predicting the SAR distributions for satisfying 47
        CFR §§2.907 and 2.908 of Commission Rules

    d.  verify the SAR distribution at the high, middle and low
        channels, similar to those considered in SAR measurements for
        determining the highest SAR

7)  **Test device positioning**

    a.  a description of the device test positions (left, right, cheek,
        tilt/ear, extended and retracted etc.) used in the SAR
        computations

    b.  illustrations showing the separation distances between the test
        device and the phantom for the tested configurations, similar to
        the reporting procedures used in SAR measurements

8)  **Steady state termination procedures**

    a.  a description of the criteria and procedures used to determine
        that sinusoidal steady state conditions have been reached
        throughout the computational domain for terminating the
        computations

    b.  reporting the number of time steps or sinusoidal cycles executed
        to reach steady state

    c.  a description of the expected error margin provided by the
        termination procedures

9)  **Computing peak SAR from field components**

    a.  a description of the procedures used to compute the sinusoidal
        steady total electric field with selected field components at
        each tissue location

    b.  a description of the expected error margin provided by the
        algorithms used to compute the SAR at each tissue location
        according to the selected field components and tissue dielectric
        parameters

10) **One-gram averaged SAR procedures**

    a.  a description of the procedures used to search for the highest
        one-gram averaged SAR, including the procedures for handling
        inhomogeneous tissues within the one-gram cube

    b.  specify the weight and dimensions of the one-gram cube of tissue

    c.  a description of the expected error margin provided by the
        algorithms used in computing the one-gram SAR

11) **Total computational uncertainty --** a description of the expected
    error and computational uncertainty for the test device and tissue
    models, test configurations and numerical algorithms etc.

12) **Test results for determining SAR compliance**

    a.  illustrations showing the SAR distribution of dominant peak
        locations produced by the test transmitter, with respect to the
        phantom and the test device, similar to those reported in SAR
        measurements

    b.  a description of how the maximum device output rating is
        determined and used to normalized the SAR values for each test
        configuration

    c.  a description of the procedures used to compute source-based
        time-averaged SAR

The head and body tissue parameters given in this Appendix should be
used to test transmitters operating in the cellular, PCS, U-NII, spread
spectrum (47 CFR §15.247) and other frequencies bands (See References
\[8\], \[12\] and \[15\]). When a transmission band overlaps with one of
the target frequencies specified in this Appendix, the tissue dielectric
parameters of the tissue medium at the middle of a device transmission
band should be within 5% of the parameters specified at that target
frequency. At other frequencies, the dielectric parameters should be
linearly interpolated between the closest pair of target frequencies
specified in this Appendix to determine the applicable dielectric
parameters corresponding to the middle of a device transmission band. It
has been reported that a 5% tolerance in tissue parameters may not be
easily achieved at certain frequencies. Under such circumstances, 10%
tolerance may be used until more precise tissue recipes are available.

To maintain consistency in using SAR measurement and computational
methods to determine compliance, the homogeneous phantom models used in
SAR measurements are also recommended for use in SAR computations. When
inhomogeneous models are used to compute SAR, the tissue dielectric
parameters based on the 4-Cole-Cole equation, as described by Dr.
Camelia Gabriel \[12\], may be used. Selected tissue parameters are
available for viewing and downloading at the FCC\'s Office of
Engineering and Technology\'s World Wide Web Internet Site:
http://www.fcc.gov/oet/.[^22]

## Tissue Dielectric Parameters for Head and Body Phantoms

The head tissue dielectric parameters recommended by the IEEE
SCC-34/SC-2 in P1528 have been incorporated in the following table.
These head parameters are derived from planar layer models simulating
the highest expected SAR for the dielectric properties and tissue
thickness variations in a human head (See Reference \[11\]). Other head
and body tissue parameters that have not been specified in P1528 are
derived from the tissue dielectric parameters computed from the
4-Cole-Cole equations described in Reference \[12\] and extrapolated
according to the head parameters specified in P1528.

  -------------------- ------------ ----------- ------------ ------------
  Target Frequency     Head                     Body         

  (MHz)                ε~r~         σ (S/m)     ε~r~         σ (S/m)

  150                  52.3         0.76        61.9         0.80

  300                  45.3         0.87        58.2         0.92

  450                  43.5         0.87        56.7         0.94

  835                  41.5         0.90        55.2         0.97

  900                  41.5         0.97        55.0         1.05

  915                  41.5         0.98        55.0         1.06

  1450                 40.5         1.20        54.0         1.30

  1610                 40.3         1.29        53.8         1.40

  1800 -- 2000         40.0         1.40        53.3         1.52

  2450                 39.2         1.80        52.7         1.95

  3000                 38.5         2.40        52.0         2.73

  5800                 35.3         5.27        48.2         6.00
  -------------------- ------------ ----------- ------------ ------------

(ε~r~ = relative permittivity, σ = conductivity and ρ = 1000 kg/m^3^)

The following tissue formulations are provided for reference only as
some of the parameters have not been thoroughly verified. The
composition of ingredients may be modified accordingly to achieve the
desired target tissue parameters required for routine SAR evaluation.

## Typical Composition of Ingredients for Liquid Tissue Phantoms

<table style="width:100%;">
<colgroup>
<col style="width: 20%" />
<col style="width: 8%" />
<col style="width: 8%" />
<col style="width: 8%" />
<col style="width: 8%" />
<col style="width: 8%" />
<col style="width: 8%" />
<col style="width: 8%" />
<col style="width: 8%" />
<col style="width: 8%" />
<col style="width: 8%" />
</colgroup>
<tbody>
<tr class="odd">
<td rowspan="2"><p><strong>Ingredients</strong></p>
<p>(% by weight)</p></td>
<td colspan="10"><strong>Frequency (MHz)</strong></td>
</tr>
<tr class="even">
<td colspan="2">450</td>
<td colspan="2">835</td>
<td colspan="2">915</td>
<td colspan="2">1900</td>
<td colspan="2">2450</td>
</tr>
<tr class="odd">
<td>Tissue Type</td>
<td>Head</td>
<td>Body</td>
<td>Head</td>
<td>Body</td>
<td>Head</td>
<td>Body</td>
<td>Head</td>
<td>Body</td>
<td>Head</td>
<td>Body</td>
</tr>
<tr class="even">
<td>Water</td>
<td>38.56</td>
<td>51.16</td>
<td>41.45</td>
<td>52.4</td>
<td>41.05</td>
<td>56.0</td>
<td>54.9</td>
<td>40.4</td>
<td>62.7</td>
<td>73.2</td>
</tr>
<tr class="odd">
<td>Salt (NaCl)</td>
<td>3.95</td>
<td>1.49</td>
<td>1.45</td>
<td>1.4</td>
<td>1.35</td>
<td>0.76</td>
<td>0.18</td>
<td>0.5</td>
<td>0.5</td>
<td>0.04</td>
</tr>
<tr class="even">
<td>Sugar</td>
<td>56.32</td>
<td>46.78</td>
<td>56.0</td>
<td>45.0</td>
<td>56.5</td>
<td>41.76</td>
<td>0.0</td>
<td>58.0</td>
<td>0.0</td>
<td>0.0</td>
</tr>
<tr class="odd">
<td>HEC</td>
<td>0.98</td>
<td>0.52</td>
<td>1.0</td>
<td>1.0</td>
<td>1.0</td>
<td>1.21</td>
<td>0.0</td>
<td>1.0</td>
<td>0.0</td>
<td>0.0</td>
</tr>
<tr class="even">
<td>Bactericide</td>
<td>0.19</td>
<td>0.05</td>
<td>0.1</td>
<td>0.1</td>
<td>0.1</td>
<td>0.27</td>
<td>0.0</td>
<td>0.1</td>
<td>0.0</td>
<td>0.0</td>
</tr>
<tr class="odd">
<td>Triton X-100</td>
<td>0.0</td>
<td>0.0</td>
<td>0.0</td>
<td>0.0</td>
<td>0.0</td>
<td>0.0</td>
<td>0.0</td>
<td>0.0</td>
<td>36.8</td>
<td>0.0</td>
</tr>
<tr class="even">
<td>DGBE</td>
<td>0.0</td>
<td>0.0</td>
<td>0.0</td>
<td>0.0</td>
<td>0.0</td>
<td>0.0</td>
<td>44.92</td>
<td>0.0</td>
<td>0.0</td>
<td>26.7</td>
</tr>
<tr class="odd">
<td>Dielectric Constant</td>
<td>43.42</td>
<td>58.0</td>
<td>42.54</td>
<td>56.1</td>
<td>42.0</td>
<td>56.8</td>
<td>39.9</td>
<td>54.0</td>
<td>39.8</td>
<td>52.5</td>
</tr>
<tr class="even">
<td>Conductivity (S/m)</td>
<td>0.85</td>
<td>0.83</td>
<td>0.91</td>
<td>0.95</td>
<td>1.0</td>
<td>1.07</td>
<td>1.42</td>
<td>1.45</td>
<td>1.88</td>
<td>1.78</td>
</tr>
</tbody>
</table>

Salt: 99^+^% Pure Sodium Chloride Sugar: 98^+^% Pure Sucrose

Water: De-ionized, 16 MΩ^+^ resistivity HEC: Hydroxyethyl Cellulose

DGBE: 99^+^% Di(ethylene glycol) butyl ether,
\[2-(2-butoxyethoxy)ethanol\]

Triton X-100 (ultra pure): Polyethylene glycol mono \[4-(1,1, 3,
3-tetramethylbutyl)phenyl\]ether

**Tissue Recipe as reported by Hartsgrove et. al. in "Simulated
Biological Materials for Electromagnetic Radiation absorption Studies,"
Bioelectromagnetics 8:29-36 (1987)**

  ------------------------------- ------------------- -------------------
  **Ingredients (% by weight)**   **Head/Brain**      **Body/Muscle**

  Water                           40.4                52.5

  Salt (NaCl)                     2.5                 1.4

  Sugar                           56.0                45.0

  HEC                             1.0                 1.0

  Bactericide                     0.1                 0.1

  Dielectric constant @ 900 MHz   41.2                54.7

  Conductivity @ 900 MHz (S/m)    1.22                1.38
  ------------------------------- ------------------- -------------------

The SAR measurement procedures described in this Appendix are primarily
intended for testing wireless handsets and similar transmitters that
operate next to a person's head. The test configurations for evaluating
body-worn SAR compliance are also described. The procedures in this
Appendix should be used in conjunction with the general information
provided in Section 2.

SAR is evaluated using simulated tissue medium contained in a realistic
human shaped phantom shell that allows a small diameter, miniature
electric field probe to measure the electric field within the tissue
regions exposed to the transmitter configured in normal operating
positions. Since the RF energy absorption characteristics of human
tissues are frequency dependent, the dielectric properties of simulated
tissue media used for SAR evaluations must match the target tissue
properties specified at the operating frequency range of the device (See
Appendix C).

## Phantom Considerations

Handsets that are held on the side of a person\'s head next to the ear
have been tested using two general types of realistic-shaped head
phantoms: with and without a simulated external ear attached to the head
model. A simulated ear with a thickness of approximately 2-3 mm,
consisting of low-loss dielectric material has been used to model a
person\'s ear compressed by the earpiece of a wireless handset on some
head models. Others have used a 2-4 mm thick, circular shaped, low-loss
dielectric spacer to simulate the ear separation distance.

The IEEE SCC-34/SC-2 has established criteria for developing a
standardized head model to test handsets for SAR compliance. This head
model has been derived from selected head dimensions of male, U.S. Army
personnel (See Reference \[42\]). The committee has specified the
phantom shell to be constructed of low-loss dielectric material with
dielectric constant less than 5.0 and loss tangent not exceeding 0.05.
The thickness of the phantom shell should be 2.0 mm with less than ± 0.2
mm variations in shape and thickness for regions where SAR is to be
measured and ± 0.5 mm for other regions. A 4.0 mm thick low-loss
dielectric spacer is used to simulate the ear separation distance on
this head model.

A reference plane has been defined by three points consisting of a point
on each ear spacer and the tip of the mouth to minimize test device
positioning errors. The points on each ear spacer are known as the ear
reference points; each is located at 1.5 cm above the ear canal location
in the reference plane. During SAR measurements, the centerline on the
front of a handset is aligned to this predefined reference plane and the
earpiece is positioned at the level of the ear reference point. The ear
spacer is tapered abruptly to zero thickness below the ear reference
point, along a line perpendicular to the reference plane. By using a
standardized head model with specific ear simulation requirements,
device positioning errors are reduced and lower SAR measurement
uncertainty is expected (See Reference \[19\]).

The construction of a liquid phantom must allow unrestricted electric
field probe access to search for all possible peak SAR locations
produced by a portable transmitter under test. The tissue material
within the phantom shell measured from the ear reference point should be
at least 15 cm deep. In most situations, split head models are used to
test transmitters on the left and right side of the head. A separate
flat phantom should be used to test exposures in body-worn
configurations and other body regions that are relatively flat, such as
the chest and abdomen.

Note: . When the SCC-34/SC-2 head phantom becomes commercially
available, the Commission will issue a Public Notice establishing a
transition period of 3-6 months to allow interested parties to acquire
this head phantom. After the transition period, the SCC-34/SC-2 head
phantom should be used for SAR testing. Until that time, other head
phantoms may be used with the procedures in this Appendix. These
procedures must be used for applications evaluated by Telecommunications
Certification Bodies (TCBs).

### recommended Characteristics of Head and Body Phantoms

The following information provides additional guidance on head and body
models that are considered acceptable for routine evaluation of most
wireless handsets and similar portable transmitters. The SCC-34/SC-2
head conforms to the relevant portions of these criteria:

-   The shape, dimensions and complexity of a human shaped head phantom
    should be appropriate for evaluating the near-field exposure
    conditions expected by the users of a transmitter device under
    normal operating conditions.

-   The head phantom should include a portion of the neck, preferably
    extending to the base of the neck. Shoulders are not necessary.

-   

-   For existing head phantoms, before the SCC-34/SC-2 phantom is
    available, a lossless spacer that provides 6.0 mm or less separation
    from any point on the outer surface of the ear spacer to the tissue
    medium should be used. A 4.0 ± 0.2 mm thick low-loss dielectric
    spacer similar to that recommended for the SCC-34/SC-2 head phantom
    is recommended.

-   Body-worn operating configurations should be tested using a flat
    phantom. The length and width of the phantom should be at least
    twice the corresponding dimensions of the test device, including its
    antenna. The body dielectric parameters specified in Appendix C
    should be used to demonstrate body-worn SAR compliance.

-   The head and body phantom shell should be made of low-loss
    dielectric material with dielectric constant and loss tangent less
    than 5.0 and 0.05 respectively. The shell thickness for all regions
    coupled to the test device and its antenna should be within 2.0 ±
    0.2 mm. The phantom should be filled with the required head or body
    equivalent tissue medium to a depth of 15.0 ± 0.5 cm.

### recommended device test positions for typical Wireless Handset 

Specific test positions have been prescribed by the SCC-34/SC-2 for
testing handsets using the standardized head model recommended by this
committee. For routine SAR evaluation, these test positions, as descibed
below, should be used for testing handsets and similar portable
transmitters that operate on the side of a person's head, next to the
ear. Flat phantom models should be used to test handsets and
push-to-talk (PTT) devices that can be held in front of the user's face
or transmit in body-worn operating configurations using belt-clips,
holsters or similar accessories. The test device should be placed in a
holder or positioner made of low-loss dielectric material with
dielectric constant and loss tangent less than 5.0 and 0.05
respectively. If the device holder is suspected to perturb the fields
from the test device, which may affect device performance or introduce
unacceptable SAR measurement errors, such as handsets with internal
antennas, the error must be assessed and accounted for in the total
measurement uncertainty. Device holder perturbation may be verified by
testing the device on a flat phantom in each frequency band and antenna
position with and without using the holder.

#### devices operating next to a person's ear 

This category includes most wireless handsets with fixed, retractable or
internal antennas located toward the top half of the device, with or
without a foldout, sliding or similar keypad cover. The handset should
have its earpiece located within the upper ¼ of the device, either along
the centerline or off-centered, as perceived by its users. This type of
handset should be positioned in a normal operating position with the
"test device reference point" located along the "vertical centerline" on
the front of the device aligned to the "ear reference point" (See
Reference \[19\]). The "[test device reference point]{.underline}"
should be located at the same level as the center of the earpiece
region. The "[vertical centerline]{.underline}" should bisect the front
surface of the handset at its top and bottom edges. A "[ear reference
point]{.underline}" is located on the outer surface of the head phantom
on each ear spacer. It is located 1.5 cm above the center of the ear
canal entrance in the "[phantom reference plane]{.underline}" defined by
the three lines joining the center of each "ear reference point" (left
and right) and the tip of the mouth (See Reference \[19\]).[^23]

A handset should be initially positioned with the earpiece region
pressed against the ear spacer of a head phantom. For the SCC-34/SC-2
head phantom, the device should be positioned parallel to the "N-F" line
defined along the base of the ear spacer that contains the "ear
reference point". For interim head phantoms, the device should be
positioned parallel to the cheek for maximum RF energy coupling. The
"test device reference point" is aligned to the "ear reference point" on
the head phantom and the "vertical centerline" is aligned to the
"phantom reference plane". This is called the "[initial ear
position]{.underline}". While maintaining these three alignments, the
body of the handset is gradually adjusted to each of the following
positions for evaluating SAR:

1)  "Cheek/Touch Position" -- the device is brought toward the mouth of
    the head phantom by pivoting against the "ear reference point" or
    along the "N-F" line for the SCC-34/SC-2 head phantom. This test
    position is established:

    i.  When any point on the display, keypad or mouthpiece portions of
        the handset is in contact with the phantom.

    ii. (or) When any portion of a foldout, sliding or similar keypad
        cover opened to its intended self-adjusting normal use position
        is in contact with the cheek or mouth of the phantom.

        For existing head phantoms -- when the handset loses contact
        with the phantom at the pivotingpoint, rotation should continue
        until the device touches the cheek of the phantom or breaks its
        last contact from the ear spacer.

2)  "Ear/Tilt Position" -- With the handset aligned in the "Cheek/Touch
    Position":

    i.  If the earpiece of the handset is not in full contact with the
        phantom's ear spacer (in the "Cheek/Touch position") and the
        peak SAR location for the "Cheek/Touch" position is located at
        the ear spacer region or corresponds to the earpiece region of
        the handset, the device should be returned to the "initial ear
        position" by rotating it away from the mouth until the earpiece
        is in full contact with the ear spacer.

    ii. (otherwise) The handset should be moved (translated) away from
        the cheek perpendicular to the line passes through both "ear
        reference points" (note: one of these ear reference points may
        not physically exist on a split head model) for approximate
        2-3 cm. While it is in this position, the device handset is
        tilted away from the mouth with respect to the "test device
        reference point" until the inside angle between the vertical
        centerline on the front surface of the phone and the horizontal
        line passing through the ear reference point isby 15 80°. After
        the tilt, it is then moved (translated) back toward the head
        perpendicular to the line passes through both "ear reference
        points" until the device touches the phantom or the ear spacer.
        If the antenna touches the head first, the positioning process
        should be repeated with a tilt angle less than 15 80° so that
        the device and its antenna would touch the phantom
        simultaneously. This test position may require a device holder
        or positioner to achieve the translation and tilting with
        acceptable positioning repeatability.

If a device is also designed to transmit with its keypad cover closed
for operating in the head position, such positions should also be
considered in the SAR evaluation. The device should be tested on the
left and right side of the head phantom in the "Cheek/Touch" and
"Ear/Tilt" positions. When applicable, each configuration should be
tested with the antenna in its fully extended and fully retracted
positions. These test configurations should be tested at the high,
middle and low frequency channels of each operating mode; for example,
AMPS, CDMA, and TDMA. If the SAR measured at the middle channel for each
test configuration (left, right, Cheek/Touch, Tile/Ear, extended and
retracted) is at least 2.0 dB lower than the SAR limit, testing at the
high and low channels is optional for such test configuration(s). If the
transmission band of the test device is less than 10 MHz, testing at the
high and low frequency channels is optional. A complete set of tests for
a handset operating with a retractable antenna has 24 configurations for
each operating mode, as shown in the following table.

**^Recommended\ handset\ and\ head\ phantom\ test\ positions\ for\ FCC\ compliance\ evaluation^**

+-------------+-----------+---------+----------+----------+----------+
| **Phantom   | **Device  | **      | **SAR    |          |          |
| Confi       | Test      | Antenna | (W/kg)** |          |          |
| gurations** | Po        | Pos     |          |          |          |
|             | sitions** | ition** | **Device |          |          |
|             |           |         | Test     |          |          |
|             |           |         | channel, |          |          |
|             |           |         | F        |          |          |
|             |           |         | requency |          |          |
|             |           |         | &        |          |          |
|             |           |         | Output** |          |          |
+-------------+-----------+---------+----------+----------+----------+
|             |           |         | **       | **       | **       |
|             |           |         | Channel: | Channel: | Channel: |
|             |           |         | \_\_\_** | \_\_\_** | \_\_\_** |
|             |           |         |          |          |          |
|             |           |         | **\_\_\_ | **\_\_\_ | **\_\_\_ |
|             |           |         | MHz**    | MHz**    | MHz**    |
|             |           |         |          |          |          |
|             |           |         | **\_\_\_ | **\_\_\_ | **\_\_\_ |
|             |           |         | mW**     | mW**     | mW**     |
+-------------+-----------+---------+----------+----------+----------+
| **Left Side | **Cheek / | e       |          |          |          |
| of**        | Touch**   | xtended |          |          |          |
|             |           |         |          |          |          |
| **Head**    |           |         |          |          |          |
+-------------+-----------+---------+----------+----------+----------+
|             |           | re      |          |          |          |
|             |           | tracted |          |          |          |
+-------------+-----------+---------+----------+----------+----------+
|             | **Ear /   | e       |          |          |          |
|             | Tilt**    | xtended |          |          |          |
+-------------+-----------+---------+----------+----------+----------+
|             |           | re      |          |          |          |
|             |           | tracted |          |          |          |
+-------------+-----------+---------+----------+----------+----------+
| **Right     | **Cheek / | e       |          |          |          |
| Side of     | Touch**   | xtended |          |          |          |
| Head**      |           |         |          |          |          |
+-------------+-----------+---------+----------+----------+----------+
|             |           | re      |          |          |          |
|             |           | tracted |          |          |          |
+-------------+-----------+---------+----------+----------+----------+
|             | **Ear /   | e       |          |          |          |
|             | Tilt**    | xtended |          |          |          |
+-------------+-----------+---------+----------+----------+----------+
|             |           | re      |          |          |          |
|             |           | tracted |          |          |          |
+-------------+-----------+---------+----------+----------+----------+

#### Recommended test positions for body-worn and other configurations

Body-worn operating configurations should be tested with the belt-clips
and holsters attached to the device and positioned against a flat
phantom in normal use configurations. Devices with a headset output
should be tested with a headset connected to the device. The body
dielectric parameters specified in Appendix C should be used. Both the
physical spacing to the body of the user as dictated by the accessory
and the materials used in an accessory affect the SAR produced by the
transmitting device. For purpose of determining test requirements,
accessories may be divided into two categories: those that do not
contain metallic components and those that do.

When multiple accessories that do not contain metallic components are
supplied with the device, the device may be tested with only the
accessory that dictates the closest spacing to the body. When multiple
accessories that contain metallic components are supplied with the
device, the device must be tested with each accessory that contains a
unique metallic component. If multiple accessories share an identical
metallic component (e.g., the same metallic belt-clip used with
different holsters with no other metallic components), only the
accessory that dictates the closest spacing to the body must be tested.

Body-worn accessories may not always be supplied or available as options
for some devices that are intended to be authorized for body-worn use. A
separation distance of 1.5 cm between the back of the device and a flat
phantom is recommended for testing body-worn SAR compliance under such
circumstances. Other separation distances may be used, but they should
not exceed 2.5 cm. In these cases, the device may use body-worn
accessories that provide a separation distance greater than that tested
for the device provided however that the accessory contains no metallic
components..

In order for users to be aware of the body-worn operating requirements
for meeting RF exposure compliance, operating instructions and caution
statements should be included in the manual. The information should
allow users to make informed decisions on the type of body-worn
accessories and operating configurations that are appropriate for the
device. The following are *examples* of typical statements that provide
end-users with the necessary information about body-worn accessories:

1\. For a product that has the potential to be used in a body worn
configuration and has been tested and certified with a specific
accessory device(s):

"For body worn operation, this phone has been tested and meets the FCC
RF exposure guidelines when used with the (*manufacturer name*)
accessories supplied or designated for this product. Use of other
accessories may not ensure compliance with FCC RF exposure guidelines. "

2\. For a product that has the potential to be used in a body worn
configuration and has not been certified with a specific accessory
device(s):

"For body worn operation, this phone has been tested and meets FCC RF
exposure guidelines when used with an accessory that contains no metal
and that positions the handset a minimum of (specified distance) from
the body. Use of other accessories may not ensure compliance with FCC RF
exposure guidelines."

3\. For a product that has the potential to be used in a body worn
configuration with future manufacturer designed accessories:

"For body worn operation, this phone has been tested and meets the FCC
RF exposure guidelines when used with a (*manufacturer name*) accessory
designated for this product or when used with an accessory that contains
no metal and that positions the handset a minimum of (specified
distance) from the body."

Transmitters that are designed to operate in front of a person's face,
in push-to-talk configurations, should be tested for SAR compliance with
the front of the device positioned at 2.5 cm from a flat phantom.
Frontal face-phantoms are typically not recommended because of the
potential of higher E-field probe boundary-effects errors in the
non-smooth regions of these face phantoms, such as the nose, lips and
eyes etc. For devices that are carried next to the body, such as
shoulder, waist or chest-worn transmitters, SAR compliance should be
tested with the accessories, including headsets and microphones,
attached to the device and positioned against a flat phantom in normal
use configurations.

### documentation

Device test positions should be documented graphically and identify the
separation distances and tilt angles used during the SAR evaluation.
This will allow, if necessary, the test to be repeated accurately with
the device positioned as specified in the test report. A close-up
photo(s) of the actual test device positioned against the phantom during
the SAR measurement should also be included in the test report to
document the test setup.

## Tissue Dielectric Property Requirements

The tissue media should be checked at the beginning of a series of SAR
measurements to determine if the dielectric parameters are within the
tolerances of the specified target values. The dielectric parameters
should be verified daily and more often as required by the ambient
conditions. For example, when the liquid temperature deviates by more
than 2°C from that recorded for the measured dielectric parameters and
under conditions of extremely low humidity or high evaporation rates.
The tissue parameters should be measured with the coaxial probe, slotted
line or TEM line techniques described in the SCC-34/SC-2 SAR measurement
document (See Reference \[19\]).

The tissue dielectric parameters specified in Appendix C should be used
as the target values for testing (See References \[11-12\] and \[19\]).
These parameters are generally accepted as equivalent to the
corresponding tissue properties at 37°C, for use in single-tissue
homogeneous phantom models. Examples of the typical composition of
ingredients used to achieve these parameters under normal ambient
conditions are also included in Appendix C. The use of other
compositions and formulations to arrive at the same tissue parameters
may also be acceptable. SAR measurements should be performed under
normal ambient conditions, suitable for the test equipment, typically
within 20-26° C and 30-70% humidity. The temperature of the tissue
medium during the SAR measurement should be within ± 2.0°C of the
temperature at which the dielectric parameters are measured. The
relative permittivity and conductivity of the tissue material should be
within 5% of the values given in Appendix C, 10% when precise tissue
recipes are not available at certain frequencies. Transmitters operating
at other frequencies should be tested using tissue parameters based on
the linearly interpolated values shown in Appendix C, corresponding to
the mid-band frequency of each operating mode. The instrumentation error
associated with the measured tissue parameters should be accounted for
in the overall SAR measurement uncertainty.

## Electric Field Probe Characteristics and Calibration

The E-field probes used for SAR measurements should have a dynamic range
of 0.01-100 W/kg to cover the range of signal levels and modulation
characteristics used by most mobile and portable wireless devices. The
field probes used in SAR measurements are typically calibrated to
measure single frequency fields. The probe output follows the square-law
response of its detectors at low field strength levels. As the field
strength level increases, special circuitry or compensation software are
used to achieve a linear response. When measuring pulsed signals with
low duty factors or high peak-to-average ratios, the probe must be
calibrated with correction factors to accurately measure SAR with
respect to the average power. If the signal level exceeds the square-law
response of the diode detectors in an E-field probe, the output can
become sensitive to the signal modulation and the error is usually
dependent on the form of modulation. A probe must be properly calibrated
to measure the SAR corresponding to the average energy absorption
produced by a modulated signal. A probe linearity of ± 0.25 dB should be
ensured at the device test frequencies during routine SAR evaluation.

The variation in sensitivity among the sensors in a field probe must be
correctly compensated for during probe calibration. It is highly
desirable for a probe to have a uniform response to all incident fields,
independent of field polarization and direction of propagation. However,
the isotropic response of a probe is often non-ideal due to construction
tolerances, asymmetry in sensor location, differences in detector
sensitivity among the channels, differences in line impedance and
feedback from the feed lines. It is extremely important that these
undesirable characteristics are carefully evaluated during probe
calibrations by rotating the probe along its axis and orienting the
probe and its sensors to different field polarizations and directions of
propagation. The axial and hemispherical isotropy errors of a probe
should be within ± 0.25 and ± 0.5 dB, respectively, at the device test
frequencies during routine SAR measurement.

A field probe must be calibrated in tissue media with the target
dielectric parameters specified in Appendix C, corresponding to the
operating frequency ranges of the test device. The responses of a field
probe are dependent on signal frequency, modulation characteristics,
power level, field polarization, field gradients and the direction of
field propagation. Other factors such as RF noise, static and ELF
fields, temperature, humidity and the proximity of media boundaries from
the probe tip can also affect the calibration of a field probe. At less
than 800 MHz, probes are calibrated using thermal techniques. At above
800 MHz, an appropriate waveguide filled with the required tissue medium
may be used to calibrate the output voltages of a probe against
analytically calculated field values (See References \[17\], \[19\] and
\[27\]).

## System Verification

Routine record keeping procedures should be established for tracking the
calibration and performance of SAR measurement systems. When SAR
measurements are performed, the entire measurement system should be
checked daily within the device transmitting frequency ranges to verify
system accuracy. A flat phantom irradiated by a half-wavelength dipole
is typically used to verify the measurement accuracy of a system. The
measurement system should also be evaluated periodically with and
without the built-in compensation and correction factors to verify the
measurement sensitivity and to identify system components that could be
out of tolerance. When a radiating source is not available at the
operating frequency range of the test device to verify system accuracy,
a source operating within 100 MHz of the mid-band channel of each
operating mode may be used. The measured one-gram SAR should be within
10% of the expected target values specified for the specific phantom and
RF source used in the system verification measurement.

The following describes the recommended test configuration for verifying
SAR measurement systems using a flat phantom and a dipole radiating
source to determine if the system meets its performance (Note: systems
may be verified at 300 MHz until standard dipoles at below 300 MHz are
available):

1.  A balanced half-wave (λ/2) dipole should be used as the radiating
    source. The dipole should be matched to the source impedance of the
    signal generator. The specific flat phantom should be filled with
    the required tissue medium at its intended operating frequency. The
    current distribution along the two arms of the half-wave dipole
    should be matched to within 5% of each other. The thickness of the
    dipole must not exceed the separation distance between the outer
    surfaces of the dipole and the phantom shell by 20%. The
    construction of the dipole should provide extremely stable operating
    characteristics at its intended operating frequency to produce
    repeatable SAR distributions in the specific flat phantom. The
    recommended dipole specifications described in the latest
    SCC-34/SC-2 draft on SAR measurement procedures should be used (See
    Reference \[19\]).

2.  Before the dipole can be used to verify the performance of SAR
    measurement systems, its radiating characteristics must be fully
    characterized at the intended operating frequency.

3.  The phantom shell (or box) should be constructed of low-loss
    dielectric material with dielectric constant less than 5 and loss
    tangent less than 0.05. The material thickness on the side that
    couples to the dipole (the bottom) must not be thicker than 6.5 mm
    for use at below 1.0 GHz and 5.0 mm at other frequencies. The
    variations in shell thickness along regions coupled to the dipole
    must be less than ± 0.2 mm. The material for the other sides must
    not be thicker than 10 mm.

4.  The phantom should be at least ¾ wavelength long, in the direction
    parallel to the dipole and ½ wavelength wide, in the direction
    perpendicular to the dipole. Smaller phantom dimensions may be
    acceptable if it can be demonstrated that the measured one-gram SAR
    is within ± 1% of that produced by a phantom with the required
    phantom dimensions. The phantom should hold of 15 ± 0.5 cm of the
    required tissue medium.

5.  The SAR system should be verified using this flat phantom setup,
    preferably, at the mid-band frequency of a test device, but not more
    than 100 MHz from this frequency.

6.  The dielectric parameters of the tissue medium used to verify the
    SAR system should be within 5% of those used to obtain the reference
    data (target SAR values) and should also satisfy the requirements
    specified in Appendix C.

7.  A uniform separation distance of 15.0 mm ± 0.2 mm should be
    maintained between the dipole axis and the inside surface of the
    phantom shell (tissue medium surface) at the dipole feed-point
    location. At above 1.0 GHz, a separation distance of 10.0 mm ± 0.2
    mm should be used. A precision low-loss dielectric spacer and
    holding apparatus should be used to maintain dipole positioning
    repeatability.

8.  Each end of the dipole should not deviate by more than 2° from the
    dipole axis with respect to the dipole feed-point. The sagging of
    the phantom, due to the weight of the tissue medium, at its closest
    location to the dipole feed-point should be within 1° from the
    straight line joining the two points on the phantom that are closest
    to the ends of the dipole, with respect to each of these points on
    the phantom.

9.  The measured one-gram SAR at the surface of the phantom above the
    dipole feed-point should be within 10% of the target reference
    value. The SAR distribution must be identical to the reference data.

10. Since the dielectric properties of the phantom shell and its
    thickness along regions coupled to the dipole may affect the dipole
    impedance and the measured SAR values, the target SAR values may
    only be applicable for the specific combination of dipole and flat
    phantom configuration. The following table contains a summary of the
    acceptable range of dipole and phantom separation distances for the
    dipole dimensions described in P1528.

    **[Dipole Thickness, Flat Phantom Sagging and Separation Distance
    Requirements]{.underline}**

<table>
<colgroup>
<col style="width: 11%" />
<col style="width: 8%" />
<col style="width: 8%" />
<col style="width: 11%" />
<col style="width: 11%" />
<col style="width: 11%" />
<col style="width: 12%" />
<col style="width: 7%" />
<col style="width: 6%" />
<col style="width: 11%" />
</colgroup>
<tbody>
<tr class="odd">
<td><p>Frequency</p>
<p>(MHz)</p></td>
<td>Dipole Length</td>
<td><p>Half of</p>
<p>Dipole</p>
<p>Length</p></td>
<td><p>2 °</p>
<p>Dipole</p>
<p>Deviation</p></td>
<td><p>1 °</p>
<p>Phantom</p>
<p>Sagging</p></td>
<td><p>Maximum</p>
<p>Shell</p>
<p>Thickness</p></td>
<td><p>Dipole</p>
<p>to Tissue</p>
<p>Separation</p></td>
<td><p>Max.</p>
<p>Dipole</p>
<p>Dia.</p></td>
<td><p>Min.</p>
<p>Air</p>
<p>Gap</p></td>
<td><p>0.5% of</p>
<p>0.6 λ</p>
<p>(Sagging)</p></td>
</tr>
<tr class="even">
<td>300</td>
<td>420.0</td>
<td>210.0</td>
<td>7.3</td>
<td>3.67</td>
<td>6.5</td>
<td>15.0</td>
<td>6.4</td>
<td>5.3</td>
<td>3.00</td>
</tr>
<tr class="odd">
<td>450</td>
<td>288.0</td>
<td>144.0</td>
<td>5.0</td>
<td>2.51</td>
<td>6.5</td>
<td>15.0</td>
<td>6.4</td>
<td>5.3</td>
<td>2.00</td>
</tr>
<tr class="even">
<td>835</td>
<td>161.0</td>
<td>80.5</td>
<td>2.8</td>
<td>1.41</td>
<td>6.5</td>
<td>15.0</td>
<td>6.4</td>
<td>5.3</td>
<td>1.08</td>
</tr>
<tr class="odd">
<td>900</td>
<td>149.0</td>
<td>74.5</td>
<td>2.6</td>
<td>1.30</td>
<td>6.5</td>
<td>15.0</td>
<td>6.4</td>
<td>5.3</td>
<td>1.00</td>
</tr>
<tr class="even">
<td>1450</td>
<td>89.1</td>
<td>44.6</td>
<td>1.6</td>
<td>0.78</td>
<td>5.0</td>
<td>10.0</td>
<td>3.8</td>
<td>3.1</td>
<td>0.62</td>
</tr>
<tr class="odd">
<td>1800</td>
<td>72.0</td>
<td>36.0</td>
<td>1.3</td>
<td>0.63</td>
<td>5.0</td>
<td>10.0</td>
<td>3.8</td>
<td>3.1</td>
<td>0.50</td>
</tr>
<tr class="even">
<td>1900</td>
<td>68.0</td>
<td>34.0</td>
<td>1.2</td>
<td>0.59</td>
<td>5.0</td>
<td>10.0</td>
<td>3.8</td>
<td>3.1</td>
<td>0.47</td>
</tr>
<tr class="odd">
<td>2000</td>
<td>64.5</td>
<td>32.3</td>
<td>1.1</td>
<td>0.56</td>
<td>5.0</td>
<td>10.0</td>
<td>3.8</td>
<td>3.1</td>
<td>0.45</td>
</tr>
<tr class="even">
<td>2450</td>
<td>51.8</td>
<td>25.9</td>
<td>0.9</td>
<td>0.45</td>
<td>5.0</td>
<td>10.0</td>
<td>3.8</td>
<td>3.1</td>
<td>0.37</td>
</tr>
<tr class="odd">
<td>3000</td>
<td>41.5</td>
<td>20.8</td>
<td>0.7</td>
<td>0.36</td>
<td>5.0</td>
<td>10.0</td>
<td>3.8</td>
<td>3.1</td>
<td>0.30</td>
</tr>
</tbody>
</table>

(all dimensions in mm)

## Test Site Ambient Conditions

The RF interference characteristics and ambient conditions at a test
facility should be fully characterized to determine their influences on
the SAR measurement. RF noise may enter the measurement equipment either
by conduction through cables or through radiated fields. These unwanted
signals may be rectified by metal-to-metal junctions and semiconductor
devices resulting in DC offsets or low frequency signals that cannot be
separated from the desired signal detected by the electric field probe.
Other conditions such as ground loops and cable conditions that can
change the loading conditions of the instrumentation, resulting in noise
or oscillation, should also be evaluated regularly. These conditions
should be checked daily before SAR measurements are performed. The
impact of RF interference on SAR measurements may be verified by
performing a SAR measurement with the test device powered off. During
compliance measurements, the RF environment should be closely monitored
to ensure measurement accuracy. The ambient conditions at a test site,
such as the temperature and humidity, may affect the operating stability
of the measurement equipment and tissue dielectric parameters. These
conditions should also be closely monitored during each SAR measurement
to ensure measurement accuracy.

## Test Device Operating Conditions

Most handsets and portable transmitters are battery operated. The
devices should operate with a fully charged battery for each SAR test.
The performance and operating tolerances of a test device should be
fully characterized to ensure that it is identical to the production
units for meeting compliance. The output power of the test sample should
not be set using test software or test mode sequences to artificially
higher or lower output levels than those pre-programmed for production
units. Transmitters should be tested at the maximum output level for
normal operation within the intended wireless networks, to avoid
undesirable performance issues that could lead to SAR changes. The
measured SAR values may be scaled to cover certain output tolerances
expected among production units during normal use provided the scaled
values are within 5% of the measured values. Unless an external DC power
adapter or other signal leads are required for the normal operation of a
device, such as connecting a headset to the device for body-worn use,
they should not be used in the SAR tests.

### Output Power

In order to determine if device output has been stable during a SAR
measurement, conducted power should be measured before and after each
SAR test to verify if the output changes are within the tolerance
specified for the device. Conducted output power can be measured at a
service output port available on most handsets or with an antenna
adapter. It is also recommended that the SAR should be checked at a
reference location, such as above the ear reference point of the head
phantom, immediately before and after each SAR measurement to verify
device output and SAR drifts.

### Battery Options

Most wireless handsets and portable transmitters may operate with
several battery options, such as internally built-in batteries, standard
battery packs, a slim pack to save space or a long lasting pack for
extended use without frequent recharging. These batteries often have
different cell configurations and physical dimensions. In some
situations, the battery design may cause some device performance and SAR
variations. If the radiated output power of a handset varies with its
battery options, the corresponding SAR may also change. An increase in
radiated output power could mean higher energy absorption in tissues.
However, a reduction in radiated power due to mismatch or increased RF
current on the device housing could also lead to higher SAR. For devices
that operate linearly, the measured SAR is expected to be proportional
to output power. When changes in radiated output are used to estimate
whether there is sufficient SAR margin to ensure compliance for all the
battery options, the output changes should be linearly proportional to
the measured SAR.

### Device operating capabilities

For certain devices that are designed to operate with a substantially
low operating duty factor where constant peak output power is neither
supported by the hardware nor its battery, SAR compliance should be
evaluated at the highest operating duty factor expected during normal
use. If a device or its battery is not designed to maintain a constant
average output power, SAR should be evaluated with respect to the
highest exposure expected based on battery capacity. The measured SAR
should typically correspond to the average output power measured before
and after the SAR measurement. Testing a device beyond its intended
maximum capability and/or capacity may sometimes lead to unpredictable
performance conditions that could produce unacceptable test results.
These types of test configurations should not be used.

### Device Operating Modes

If a portable transmitter has built-in test modes that can be used to
evaluate the highest exposure during normal use, SAR should be tested
with these test modes. An unmodulated carrier is usually used in AMPS
mode test sequences. For TDMA mode, the test mode signal is usually
modulated by the time-division duty factor. Testing TDMA devices with an
unmodulated CW signal and adjusting the SAR with a duty factor is not
recommended. The test mode signal for CDMA, direct-sequence transmitters
should correspond to the full vocoder rate and maximum occupied
bandwidth of the device. Frequency hopping spread spectrum devices
should be tested at fixed frequencies corresponding to the high, middle
and low frequency channels to avoid field probe sampling time
incompatibility issues. For devices that operate with a transmission
band less than 10 MHz, testing at the middle channel is generally
sufficient; otherwise, SAR should be tested at the high, middle and low
channels.

For devices that operate in multiple modes within the same frequency
band, all modes with a maximum source-based time-averaged output within
1.0 dB of the mode with the highest output should be tested to
demonstrate compliance. For example, testing SAR in AMPS mode is
sufficient for both AMPS and TDMA modes if the time-averaged peak output
power for TDMA mode is at least 1.0 dB lower than the AMPS mode. For
devices that operate with complex modulations, SAR should be tested with
the transmission characteristics corresponding to the highest exposure
during normal use. When test mode signals are not available or
inappropriate for testing such device, the test signal should be
activated through a base-station simulator or equivalent test equipment.
The signal power from a base-station simulator must not produce any
measurable SAR within the measurement regions of the phantom. The
downlink signals at the location of the test device should be about
20-30 dB lower than the uplink signal produced by the test device to
avoid measurement errors.

### Source-Based Time Averaging

Duty factors related to device usage, software programming or
asynchronous operations that are not inherent to or defined by the
transmission protocols of the wireless network providing services to the
transmitter generally do not satisfy source-based time averaging
requirements. However, for certain devices that are hardware limited by
design and are restricted to operate with a maximum RF duty factor,
source-based time averaging (See 47 CFR §2.1093) may be considered. When
source-based time averaging is required to demonstrate compliance, the
device must be tested for SAR compliance with the source-based
time-averaging factor included in the test signal. Devices operating
with built-in duty factors should not be tested with CW equivalent
signals to avoid over-stressed operating conditions, which could lead to
unpredictable device performance and produce unacceptable test results.
The time averaging criteria used for the Occupational/Controlled
exposure environment are not source-based and must not be applied to
devices operating in the General Population/Uncontrolled exposure
environment (See 47 CFR §§2.1091(d)(1)-(2) and §2.1093(d)(4)-(5)).

## Recommended SAR Measurement Procedures

The SAR measurement protocol and test procedures should be documented.
The calibration traceability of field probes and other supporting
equipment should be attached to the SAR reports when such information is
requested. In each SAR report, the rationale for evaluating a device
with the specific test configurations to demonstrate compliance should
be clearly documented. The device operating conditions, such as output
power stability (drifts), performance variations (tolerances) or other
physical, mechanical and electrical variations, which could introduce
unacceptable changes in SAR results must be carefully characterized and
considered in the SAR evaluation to determine compliance. The test
sample used in a SAR evaluation must be substantially identical (see 47
CFR §2.908) to production units to ensure the test results are
acceptable for demonstrating compliance.

For measurements using homogeneous phantoms, the peak SAR locations are
usually located at or near the surface of the phantom. The measurement
system must search for these peaks and determine the highest SAR
averaged over any one gram of tissue medium in the shape of a cube
through additional measurements at one or more of these peak locations.
Since the field probe is calibrated at the geometric center of its
sensor elements, where the measurement point is defined. The highest SAR
typically occurring near the surface of a homogeneous phantom cannot be
measured by an electric field probe with its sensors located 2-4 mm
behind the probe tip. These SAR values must be computed by extrapolating
the closest measured points to the surface of the phantom for
determining the highest one-gram averaged SAR.

The spatial resolution of a field probe is related to a small volume
surrounding the sensors within the probe. The size of this measurement
volume is probe dependent. The measured field values are reduced at
maximum field location and enhanced at minimum field locations according
to this averaging volume. To minimize this type of measurement error,
probes with a tip diameter larger than 8.0 mm should not be used (See
Reference \[19\]). In steep gradient or non-uniform fields, higher
isotropy error may be expected because the sensors are displaced at the
probe tip and from the probe axis. At boundaries of dielectric
interfaces, the tip of a probe must be immersed at least 2-3 probe
diameters beyond the sensors to measure SAR correctly within the tissue
medium. This boundary effect happens at both the air-to-tissue and
tissue-to-phantom-surface interface. To minimize such measurement
errors, it is also necessary to avoid making measurements with the probe
tip in direct contact with the phantom surface. For most probes, a
separation of at least half a probe diameter should be maintained
between the probe tip and the phantom surface to avoid requiring complex
compensation procedures to further reduce probe boundary-effects errors.

### Procedures to search for peak sar locations

There are no established procedures on how to search for the peak SAR
locations and measure the one-gram averaged SAR in the shape of a cube.
Different extrapolation, interpolation and integration algorithms have
been used in existing measurement systems to determine the highest
one-gram SAR to show compliance. The following procedures should be used
to ensure the test results are acceptable.

To search for the peak SAR locations produced by a test device in a head
or body phantom, the electric field probe should be scanned along the
inside surface of the phantom filled with the required tissue medium. A
coarse resolution scan, also know as area scan, is used to determine the
approximate peak locations near the surface of the phantom, typically in
an area larger than that projected by the transmitter and its antenna.
The measurement should be performed at a fixed distance of 8.0 mm or
less from the inside surface of the phantom, with less than ± 1.0 mm
variation. Laterally, the measurement points should provide a spatial
resolution that is sufficient for the interpolation algorithms used by
the SAR measurement system to identify the peak SAR locations to within
± 5.0 mm. This typically requires an area scan resolution of 1-2 cm. The
SAR distribution may be plotted to verify the peak SAR locations with
respect to the near-field exposure characteristics of the transmitter.
All peaks within 2.0 dB (58.5%) of the highest peak identified by the
interpolated data should be evaluated with a fine resolution volume scan
to determine the highest one-gram averaged SAR (See Reference \[19\]). A
SAR plot of the surface scan region with a sketch or picture of the test
device superimposed on the contours should be used to identify the peak
SAR locations.

If a peak SAR location is near the edge of a scan region, within 5.0 mm
for one-gram SAR and 10.8 mm for 10-gram SAR (half the linear dimensions
of the cube), the area scan should be repeated with an expanded scanning
region. When SAR is measured along the side wall of a phantom or on
curved surfaces where the probe axis is not perpendicular to the phantom
surface, probe isotropy and probe boundary-effects errors must be
carefully considered for making accurate measurements. For some
measurement systems, the E-field probe may have been calibrated or
compensated to measure SAR with the probe axis oriented within ± 30°
from that normal to the phantom surface. If this is not the case, either
the phantom or the field probe should be re-oriented to reduce the
measurement error.

### procedures for determining One-gram Averaged SAR

The fine resolution volume scan region, also known as the zoom scan
region, should be centered at the peak SAR locations determined by the
extrapolated data from the area scan measurements. The number of
measurement points required in a zoom scan to provide an accurate
one-gram averaged SAR is dependent on the field gradients at the peak
SAR location. In smooth gradients, the one-gram averaged SAR can be
correctly predicted with only a few measurement points. When steep field
gradients exist, many measurement points evenly distributed within the
one-gram volume of the tissue medium may be required to correctly
predict the volume averaged SAR. The zoom scan region should extend in
each direction for at least 1.5 times the linear dimensions of a 1- or
10-gram cube of tissue from each peak. The zoom scan spatial resolution
should allow the interpolation algorithms used by the SAR measurement
system to compute SAR values on a 2 mm grid with less than 5% error,
which typically requires a zoom scan resolution of 5-8 mm (See Reference
\[19\]).

The peak field values near the surface of a homogeneous phantom are
usually not measurable because the sensors in a field probe are located
at 2-4 mm behind the tip of the probe and the measurement point is
defined at the geometric center of the sensors where the calibration is
defined. These SAR values must be computed by extrapolating the closest
measured points to the surface of the phantom to determine the highest
one-gram averaged SAR. The extrapolation algorithm must compensate for
the field attenuation based on a series of measurement points along a
straight line, extending from the phantom surface through the peak SAR
location, in the zoom scan region. The first two measurement points
should be inside the one-gram averaging volume. Both points should be
less than 1.0 cm from the phantom and liquid surface. The last
measurement point should be outside the one-gram averaging volume,
typically within the zoom scan region. The SAR value for the last
measurement point should be less than 25% of the value measured for
first point closest to the phantom surface. The separation distance
between adjacent measurement points should be less than 5.0 mm. The
extrapolation coefficients should be determined with an appropriate
curve-fitting algorithm, such as a 4^th^ order polynomial least-square
fit. The same set of coefficients should be used to extrapolate the SAR
values that cannot be measured within the zoom scan region (See
Reference \[19\]). The extrapolated SAR values should have the same
spatial resolution as the zoom scan measurements.

The interpolated and extrapolated SAR values from the zoom scan
measurement are integrated in the shape of a 1- or 10-gram cube, for
example, with a trapezoidal algorithm, to determine the highest volume
averaged SAR in the zoom scan region. SAR compliance is determined
according to the highest 1- or 10-gram SAR measured for all the zoom
scans performed for each area scan. The error associated with the
extrapolation, interpolation and integration algorithms used in the area
and zoom scans should be analyzed and included in the total measurement
uncertainty.

## Measurement Uncertainties

Measurement uncertainties are calculated using the tolerances of the
instrumentation used in the measurement, the measurement setup
variability, and the technique used to perform the SAR evaluation. The
overall uncertainty is calculated in part by identifying uncertainties
in the instrumentation chain used in performing each of the procedures
in the evaluation. Methods for evaluating and expressing measurement
uncertainties can be found in the NIST Technical Note 1297
(TN1297)[^24], entitled "Guidelines for Evaluating and Expressing the
Uncertainty of NIST Measurement Results". Another source of reference is
the NIS 81 document, entitled "The Treatment of Uncertainty in EMC
Measurements,"[^25] published by the National Physical Laboratory of the
United Kingdom.

### Types of Measurement Uncertainties

In general, the components of uncertainty may be categorized according
to the method used to evaluate them. The evaluation of uncertainty by
the statistical analysis of series of observations is termed a "Type A"
evaluation of uncertainty. The evaluation of uncertainty by means other
than the statistical analysis of series of observations is termed a
"Type B" evaluation of uncertainty. Each component of uncertainty,
however evaluated, is represented by an estimated standard deviation
termed "standard uncertainty", which equals the positive square root of
the estimated variance. Details of Type A and Type B uncertainties are
explained in NIST - TN1297Error: Reference source not found.

The "combined standard uncertainty" of the measurement result represents
the estimated standard deviation of the result. It is obtained by
combining the individual standard uncertainties of both "Type A" and
"Type B" evaluations using the usual root-sum-squares method of
combining standard deviations by taking the positive square root of the
estimated variances.

"Expanded uncertainty" is a measure of uncertainty that defines an
interval about the measurement result within which the measured value is
confidently believed to lie. It is obtained by multiplying the combined
standard uncertainty by a "coverage factor". Typically, the coverage
factor ranges from two to three. For a normal distribution, if the
combined standard uncertainty is a reliable estimate of the standard
deviation, a coverage factor of two defines an interval having a level
of confidence of approximately 95%. A coverage factor of three defines
an interval having a level of confidence greater than 99%.

A detail report of uncertainty should consist of a complete list of the
components specifying for each the method used to obtain its numerical
value. The uncertainty in the result of a measurement generally consists
of multiple components which may be grouped into either "Type A" or
"Type B" uncertainties. There is not always a simple correspondence
between the classification of categories "Type A" or "Type B" evaluation
of uncertainty and the previously used classification of random and
systematic uncertainties in earlier standards. The term "systematic
uncertainty" can be misleading and should be avoided.

### Determining Total System Measurement Uncertainty 

SAR measurement uncertainties are the results of errors due to system
instrumentation, field probe response and calibration, and the
dielectric parameters of the tissue medium. Uncertainties due to
measurement procedures include test device placement, probe positioning
procedures, the extrapolation, interpolation and integration algorithms
used to determine the one-gram averaged SAR. The error components
associated with the total SAR measurement uncertainty for evaluating
portable transmitters can be grouped into four main categories -
assessment, source, device positioning and phantom uncertainties.
Assessment uncertainty is related to the instrumentation and procedures
used to assess the spatial peak SAR value in a given SAR distribution
for a given setup. Source uncertainty is related to the test and
operating parameters of the test device used in an evaluation that
produced the SAR distribution. Device positioning uncertainty is related
to the changes in SAR due to variations in device test position. Phantom
uncertainty describes the variation of a phantom model with respect to
the desired model and tissue dielectric parameters defined in the
measurement protocol, such as those recommended by SCC-34/SC-2.

The total SAR measurement uncertainty stated in a SAR report quantifies
the quality and accuracy of the measurements with respect to the
uncertainty of the instrumentation and measurement techniques used for
the evaluation. A summary of the uncertainty analysis, including the
uncertainty components considered for the SAR measurement should be
described in the test report to support compliance. A statement of
compliance indicating the maximum measured one-gram averaged SAR with
the corresponding expanded measurement uncertainty for each operating
mode and operating configuration tested for the device should be
included in the SAR report. Expanded uncertainty should be determined
for a confidence interval of 95% or higher, which corresponds to a
"coverage factor" of two or more.

The measurement uncertainty components that should be considered in a
typical SAR evaluation, similar to those recommended by the SCC-34/SC-2,
are described below. The SAR equipment manufacturer may have evaluated
some of these uncertainty components according to specific measurement
conditions, however, additional analyses may be required for the
uncertainty components that are dependent on the operating conditions
and test configurations of an individual test device. When pre-grant and
post-grant samples are tested by the FCC, the Commission will give the
applicant or grantee the benefit of the uncertainty for its measurements
to establish compliance. A device will not be failed when it is measured
above the limit by less than the uncertainty of the Commission's
measurement. For this reason, applicants are encouraged to avoid using
any equipment or test procedures with large measurement uncertainties to
evaluate SAR compliance. In general, the following uncertainty
components should be addressed to estimate the total SAR measurement
uncertainty (See Reference \[19\]):

#### Documenting the measurement uncertainty of sar evaluations

A.  Assessment Error (measurement system)

    I.  Probe Calibration Error

        1.  Axial Isotropy Error

        2.  Hemispherical Isotropy Error

        3.  Spatial Resolution Tolerance

        4.  Boundary-effects Error

        5.  Linearity Error

        6.  Sensitivity Error

        7.  Response Time Error

        8.  Integration Time Error

    II. Readout Electronics Error

    III. Errors from RF Ambient Conditions

    IV. Probe Positioner Calibration Error (absolute)

    V.  Probe Positioning Error with respect to the Phantom Shell

    VI. Errors from the Extrapolation, Interpolation and Integration
        Algorithms

B.  RF Source Error (test device)

    I.  Test Sample Output Power Drift Error

    II. SAR Variation due to Performance Tolerance of the Test Sample

    III. SAR Variation due to Tolerance of Production Units

C.  Test Device Positioning Error

    I.  Test Sample Positioning Error

    II. Device Holder or Positioner Tolerance

D.  Phantom and Setup Errors (See Reference \[19\])

    I.  Phantom Production Tolerance (shape and thickness)

    II. Target Liquid Conductivity Tolerance

    III. Measured Liquid Conductivity Error

    IV. Target Liquid Permittivity Tolerance

    V.  Measured Liquid Permittivity Error

#### Documenting the measurement uncertainty for sar system verification

A.  Assessment Error (measurement system)

    I.  Probe Calibration Error

        1.  Axial Isotropy Error

        2.  Hemispherical Isotropy Error (when applicable)

        3.  Spatial Resolution Tolerance

        4.  Boundary-effects Error

        5.  Linearity Error

        6.  Sensitivity Error

        7.  Response Time Error

        8.  Integration Time Error

    II. Readout Electronics Error

    III. Errors from RF Ambient Conditions

    IV. Probe Positioner Calibration Error (absolute)

    V.  Probe Positioning Error with respect to the Phantom Shell

    VI. Errors from the Extrapolation, Interpolation and Integration
        Algorithms

B.  RF Source Error (typically a half-wave dipole)

    I.  Input Power Measurement Error

    II. Output Power Drift Error

C.  RF Source Positioning Error

    I.  Separation Distance Error from the Source to the Tissue Medium

    II. RF Source (dipole) Holder or Positioner Tolerance

D.  Phantom and Setup Error (See Reference \[19\])

    I.  Phantom Construction Tolerance (shape, dimensions and thickness)

    II. Target Liquid Conductivity Tolerance

    III. Measured Liquid Conductivity Error

    IV. Target Liquid Permittivity Tolerance

    V.  Measured Liquid Permittivity Error

[^1]: ^?^ See *Report and Order,* in ET Docket 93-62, FCC 96-326, 11 FCC
    Rcd. 15123 (1996). The Commission\'s environmental rules for RF
    exposure are described in 47 CFR §1.1307(b).

[^2]: ^?^ See *First Memorandum Opinion and Order*, ET Docket 93-62, FCC
    96-489, 11 FCC Rcd. 17512 (1997). See also *Second Memorandum
    Opinion and Order and Notice of Proposed Rule Making*, ET Docket
    93-62, FCC 97-303, 12 FCC Rcd. 13494 (1997).

[^3]: ^?^ OET Bulletin 65*,* Edition 97-01, released August 25, 1997.
    This document can be downloaded from the FCC\'s World Wide Web
    Internet site: http://www.fcc.gov/oet/.

[^4]: ^?^ Standards Coordinating Committee 34, Subcommittee 2, of the
    Institute of Electrical and Electronics Engineers, Inc. (IEEE
    SCC-34/SC-2) has been developing recommended procedures for
    evaluating portable devices for compliance with SAR limits using
    experimental or numerical methods. Additional information is
    available at the IEEE Standards Association Internet Web Site:
    http://standards.ieee.org/ and the SCC-34/SC-2 Web Site:
    http://grouper.ieee.org/groups/scc34/sc2/.

[^5]: ^?^ See 47 CFR §§ 1.1307(b)(1), 2.1091 and 2.1093 for details.

[^6]: ^?^ Both the ANSI/IEEE and NCRP exposure criteria are based on a
    determination that potentially harmful biological effects can occur
    at a SAR level of 4.0 W/kg as averaged over the whole-body.
    Appropriate safety factors were then added to arrive at limits for
    both whole-body exposure (0.4 W/kg for \"controlled\" or
    \"occupational\" exposure and 0.08 W/kg for \"uncontrolled\" or
    \"general population\" exposure, respectively) and for partial-body
    exposure (localized SAR), such as might occur in the head of the
    user of a hand-held cellular telephone.

[^7]: ^?^ See 47 CFR §2.1091 and §2.1093.

[^8]: ^?^ An example would be certain transmitters used at checkout
    stands.

[^9]: ^?^ The FCC adopted limits for field strength and power density
    that are generally based on Sections 17.4.1 and 17.4.2, and the
    time-averaging provisions recommended in Sections 17.4.1.1 and
    17.4.3, of \"Biological Effects and Exposure Criteria for
    Radiofrequency Electromagnetic Fields,\" NCRP Report No. 86 (1986),
    National Council on Radiation Protection and Measurements (NCRP).
    With the exception of the limits on exposure to power density above
    1500 MHz and the limits for exposure to lower frequency magnetic
    fields, these MPE limits are also generally based on the guidelines
    contained in the RF safety standard developed by the Institute of
    Electrical and Electronic Engineers, Inc. (IEEE) and adopted by the
    American National Standards Institute (ANSI). See Section 4.1 of
    ANSI/IEEE C95.1-1992, \"Safety Levels with Respect to Human Exposure
    to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz\".

[^10]: ^?^ Although ANSI/IEEE does not explicitly state when SAR
    measurements are preferable to MPE measurements, we believe that the
    20 cm distance is appropriate based on Sec. 4.3(3) of ANSI/IEEE
    C95.1-1992.

[^11]: ^?^ See *Report and Order*, in ET Docket 96-8, FCC 97-114,
    Amendment of Parts 2 and 15 of Commission\'s Rules Regarding Spread
    Spectrum Transmitter.

[^12]: ^?^ Warning instructions and labels also include certain caution
    statements that are needed to ensure compliance. Warnings are
    typically used in situations where there could be imminent danger,
    such as exposing to the main beam of a high gain antenna operating
    at substantially high output power. Caution statements and labels
    are more appropriate for informing the users of most Spread Spectrum
    devices to follow specific installation and operating requirements
    to ensure compliance for all exposed persons.

[^13]: ^?^ Power density estimates based on simplified sources are
    different than the computational methods used in routine SAR
    evaluation where the test device and/or tissue models are
    constructed numerically to simulate the exposure conditions and to
    calculate power density or SAR.

[^14]: ^?^ Both conducted and radiated output power should be considered
    in near-field exposure conditions. The output indicated in the above
    (500 mW) is appropriate when the device and its antenna are both
    operating at more than 2.5 -- 3.0 cm from a person's body, such as
    certain hand-held terminals. If a device, its antenna or other
    radiating structures are operating at closer than 2.5 cm from a
    person's body or in contact with the body, SAR evaluation may be
    necessary when the output is more than 50 -- 100 mW, depending on
    the device operating configurations and exposure conditions.

[^15]: ^?^ This does not include devices that are designed to operate in
    contact with a person's body, such as cordless phones and certain
    body-worn transmitters.

[^16]: ^?^ See footnote Error: Reference source not found.

[^17]: ^?^ See footnote Error: Reference source not found.

[^18]: ^?^ The applicable methods for ensuring compliance are divided
    into transmitter groups according to their output power levels. The
    operating configurations and exposure conditions of a transmitter
    and its antenna(s) must be clearly defined in order for the above
    procedures to be applicable.

[^19]: ^?^ The output power levels indicated in the above table are EIRP
    for fixed and mobile operations defined in 47 CFR §§1.1307 and
    2.1091. For portable operating configurations, as defined in 47 CFR
    §2.1093, both conducted and radiated (EIRP) output power should be
    considered for near-field exposure conditions. EIRP is the product
    of the maximum output power available at the antenna terminal of the
    transmitter and the antenna gain. When applicable, a source-based
    time-averaging duty factor may be considered for determining
    compliance.

[^20]: ^?^ When a transmitter transmits simultaneously at multiple
    frequencies or operates in conjunction with other transmitters or
    antennas, all transmitters, antennas and operating frequencies must
    be considered to determine RF exposure compliance. When a
    fixed-mounted antenna is co-located with other antennas, the
    requirements of 47 CFR §1.1307(b)(3) are applicable.

[^21]: ^?^ This output level is applicable when the device and its
    antenna are both operating more than 2.5 -- 3.0 cm from a person's
    body; excluding hands, wrists, feet and ankles.

[^22]: ^?^ The tissue dielectric properties provided in this Appendix
    and at the FCC Web Site are based on the 4-Cole-Cole model described
    by C. Gabriel, \"Compilation of the Dielectric Properties of Body
    Tissues at RF and Microwave Frequencies,\" Brooks Air Force
    Technical Report AL/OE-TR-1996-0037.

[^23]: ^?^ The terms "[test device reference point]{.underline}",
    "[vertical centerline]{.underline}", "[ear reference
    point]{.underline}", "[phantom reference plane]{.underline}" and
    "[initial ear position]{.underline}" in this section are specific
    references used to align a test device to the head phantom.

[^24]: ^?^ NIST Technical Note 1297 can be downloaded from the Internet
    site
    [http://physics.nist.gov/Pubs/guidelines/TN1297/tn1297s.pdf]{.underline}.
    It can also be order by contacting NIST Calibration Program,
    Building 820, Room 232, Gaithersburg, MD 20899-0001 or by telephone
    at (301)-975-2002.

[^25]: ^?^ NIS 81 can be ordered by contacting United Kingdom
    Accreditation Services (UKAS), 21-47 High Street. Feltham, Middlesex
    TW13 4UN; Tel: +44(0)20 8917 8556, Fax: +44(0)20 8917 8500/8499.