SAR EVALUATION CONSIDERATIONS FOR WIRELESS HANDSETS
This document describes the SAR evaluation requirements for consumer wireless handsets such as cellphones, including smart phones and cordless phones that operate next to the ear. Recent generation cellphones generally have multiple transmitters that operate simultaneously. These SAR procedures are applicable to both licensed and unlicensed transmitters that are built-in within handsets to support technologies such as WWAN, WLAN, DECT and Bluetooth. In general, the SAR test reduction and exclusion provisions discussed in KDB Publication 447498 D01 should be applied to streamline both standalone and simultaneous transmission SAR measurements and similarly, the published RF exposure KDB procedures must be applied to test the different wireless technologies, such as 3GPP, 3GPP2, WiMax, 802.11, and Bluetooth.1 When simultaneous transmission SAR measurement is required, the test procedures in KDB Publication 865664 D01 must be used. The SAR test considerations for recent generation smart phones supporting simultaneous transmission configurations, power reduction implementations, VoIP transmission, NFC, wireless charging and other operating modes are discussed in this guidance.
2. SAR EVALUATION CONSIDERATIONS
2.1. General Handsets are tested for SAR compliance in head, body-worn accessory and other applicable use configurations according to the procedures described in the following subsections. Some of the other use configurations may include wireless routing/hotspot mode and UMPC mini-tablet related use conditions. For phones with other near body use configurations that cannot be restricted from use through acceptable user disclosure, the general test procedures described in 4.2.2 and 4.2.3 of KDB Publication 447498 D01 should be considered.
2.2. Head exposure conditions Head exposure for voice mode is limited to next to the ear exposure conditions. The SAR measurement procedures in KDB Publication 865664 D01 must be applied for test results to be acceptable, unless further guidance has been provided by the FCC. Head SAR compliance should be tested according to the test positions defined in IEEE Std 1528-2013 using the SAM phantom. For handsets that do not operate with a traditional earpiece, where the ear reference point (ERP) can become undefined or inapplicable, a KDB inquiry describing the audio transmission technology and expected use conditions is required to determine the acceptable SAR test configurations. When data mode operates in next to the ear configurations, either data alone or in conjunction with voice transmissions, SAR evaluation is required for such use conditions.
2.3. Body-worn accessory exposure conditions Body-worn accessory exposure is typically related to voice mode operations when handsets are carried in body-worn accessories. 2 The body-worn accessory procedures in KDB Publication 447498 D01 should be used to test for body-worn accessory SAR compliance, without a headset connected to it. When the same wireless transmission configuration is used for testing body-worn accessory and hotspot mode SAR, respectively, in voice and data mode, SAR results for the most conservative test separation distance configuration may be used to support both SAR conditions. When the reported SAR for a body-worn accessory, measured without a headset connected to the handset, is > 1.2 W/kg, the highest reported SAR configuration for that wireless mode and frequency band should be repeated for the body-worn accessory with a headset attached to the handset.
2.4. Hotspot mode exposure conditions For cellphones that support wireless routing capabilities, the relevant hand and near-body exposure conditions are tested according to the hotspot mode SAR procedures in KDB Publication 941225 D06. A test separation distance of 10 mm is required between the phantom and all surfaces and edges with a transmitting antenna located within 25 mm from that surface or edge.4 When the form factor of a handset is smaller than 9 cm × 5 cm, a test separation distance of 5 mm (instead of 10 mm) is required for testing hotspot mode. When the separation distance required for body-worn accessory testing is greater than or equal to that tested for hotspot mode, using the same wireless mode test configuration for voice and data, such as WCDMA, LTE and Wi-Fi, and for the same surface of the phone, the hotspot mode SAR data may be used to support body-worn accessory SAR compliance for that particular configuration (surface).
2.5. Phablet SAR test considerations The UMPC mini-tablet SAR procedures in KDB Publication 941225 D07 are primarily intended for devices with an overall diagonal dimensions ≤ 20 cm that operate like a tablet and mainly support handheld interactive use next to or near the body of users, with no provision for next to the ear voice mode operations. Early generation mini-tablets are typically designed and optimized for mobile web access and multimedia support; whereas earlier smart phones are primarily intended for voice communication with varying data capabilities. As the use conditions for recent generation UMPC mini-tablets and smart phones are gradually merging; some UMPC mini-tablets are also supporting next to the ear voice mode operations and smart phones are incorporating certain mini-tablet operating characteristics. This new generation of devices has been referred to by industry as “phablets.” For smart phones, with a display diagonal dimension > 15.0 cm or an overall diagonal dimension > 16.0 cm, that can provide similar mobile web access and multimedia support found in mini-tablets or UMPC mini-tablets and support voice calls next to the ear, unless it is confirmed otherwise through KDB inquiries, the following phablet procedures should be applied to evaluate SAR compliance for each applicable wireless modes and frequency band. Devices marketed as phablets, regardless of form factors and operating characteristics must be tested as a phablet to determine SAR compliance.
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