Loading...
RF Report (BLD-2022-0042)APPLE INC. AT&T Site No. CCL04410 10335 North Tantau Avenue Sprint Site Nos. SF96xc031/SF96xc033 Cupertino, California T-Mobile Site No. SF14981A Wireless Base Stations Verizon Site No. 431599 F8UE Page 1 of 5 ©2021 Statement of Hammett & Edison, Inc., Consulting Engineers The firm of Hammett & Edison, Inc., Consulting Engineers, has been retained on behalf of Apple Inc., to evaluate the base stations for personal wireless telecommunications carriers AT&T Mobility, Sprint, T-Mobile, and Verizon Wireless (Site Nos. CCL04410, SF96xc031/SF96xc033, SF14981A, and 431599 “Highway 280 Tantau,” respectively) located on the Apple office building (TA09) at 10335 North Tantau Avenue in Cupertino, California, for compliance with appropriate guidelines limiting human exposure to radio frequency (“RF”) electromagnetic fields. Executive Summary AT&T proposes to replace some of its directional panel antennas above the four-story office building located at 10335 North Tantau Avenue in Cupertino. The proposed operation will, together with the existing base stations at the site, comply with the FCC guidelines limiting public exposure to RF energy; certain mitigation measures are recommended to comply with FCC occupational guidelines. Prevailing Exposure Standard The U.S. Congress requires that the Federal Communications Commission (“FCC”) evaluate its actions for possible significant impact on the environment. A summary of the FCC’s exposure limits is shown in Figure 1. These limits apply for continuous exposures and are intended to provide a prudent margin of safety for all persons, regardless of age, gender, size, or health. The most restrictive limit for exposures of unlimited duration at several wireless service bands are as follows: Transmit “Uncontrolled” Occupational Limit Wireless Service Band Frequency Public Limit (5 times Public) Microwave (point-to-point) 1–80 GHz 1.0 mW/cm2 5.0 mW/cm2 Millimeter-wave 24–47 1.0 5.0 Part 15 (WiFi & other unlicensed) 2–6 1.0 5.0 C-Band 3,700 MHz 1.0 5.0 CBRS (Citizens Broadband Radio) 3,550 1.0 5.0 BRS (Broadband Radio) 2,490 1.0 5.0 WCS (Wireless Communication) 2,305 1.0 5.0 AWS (Advanced Wireless) 2,110 1.0 5.0 PCS (Personal Communication) 1,930 1.0 5.0 Cellular 869 0.58 2.9 SMR (Specialized Mobile Radio) 854 0.57 2.85 700 MHz 716 0.48 2.4 600 MHz 617 0.41 2.05 [most restrictive frequency range] 30–300 0.20 1.0 APPLE INC. AT&T Site No. CCL04410 10335 North Tantau Avenue Sprint Site Nos. SF96xc031/SF96xc033 Cupertino, California T-Mobile Site No. SF14981A Wireless Base Stations Verizon Site No. 431599 F8UE Page 2 of 5 ©2021 General Facility Requirements Base stations typically consist of two distinct parts: the electronic transceivers (also called “radios” or “channels”) that are connected to the traditional wired telephone lines, and the passive antennas that send the wireless signals created by the radios out to be received by individual subscriber units. The transceivers are often located at ground level and are connected to the antennas by coaxial cables. Because of the short wavelength of the frequencies assigned by the FCC for wireless services, the antennas require line-of-sight paths for their signals to propagate well and so are installed at some height above ground. The antennas are designed to concentrate their energy toward the horizon, with very little energy wasted toward the sky or the ground. This means that it is generally not possible for exposure conditions to approach the maximum permissible exposure limits without being physically very near the antennas. Computer Modeling Method The FCC provides direction for determining compliance in its Office of Engineering and Technology Bulletin No. 65, “Evaluating Compliance with FCC-Specified Guidelines for Human Exposure to Radio Frequency Radiation,” dated August 1997. Figure 2 describes the calculation methodologies, reflecting the facts that a directional antenna’s radiation pattern is not fully formed at locations very close by (the “near-field” effect) and that at greater distances the power level from an energy source decreases with the square of the distance from it (the “inverse square law”). This methodology is an industry standard for evaluating RF exposure conditions and has been demonstrated through numerous field tests to be a conservative prediction of exposure levels. Site and Facility Description Based upon information provided by Apple, including architectural drawings by Hammel, Green and Abrahamson, Inc., dated “10/XX/17,” AT&T Mobility, Sprint, T-Mobile, and Verizon Wireless had installed base stations behind the existing view screen wall above the roof of the four-story office building located at 10335 North Tantau Avenue in Cupertino. The antennas are mounted at an effective height of about 64 feet above ground, 11½ feet above the roof. The following information has been provided by the individual carriers: APPLE INC. AT&T Site No. CCL04410 10335 North Tantau Avenue Sprint Site Nos. SF96xc031/SF96xc033 Cupertino, California T-Mobile Site No. SF14981A Wireless Base Stations Verizon Site No. 431599 F8UE Page 3 of 5 ©2021 AT&T (Proposed Upgrade) • Construction drawings by J5 Infrastructure Partners, dated June 1, 2021 • Two CommScope Model NNH4-45A-R6 and two Quintel Model QS4658-7 in identical pairs (one of each), three Ericsson Model AIR6449, and three CommScope Model NNH4-65A-R6, employing up to 19° downtilt • Two pairs oriented toward 40°T and 225°T, two antennas toward 10°T and 200°T, and one group of four toward 300°T • Maximum effective radiated power 95,470 watts: 80,000 watts* for C-Band, 2,610 watts for WCS, 3,910 watts for AWS, 2,540 watts for PCS, 2,120 watts for cellular, and 4,290 watts for 700 MHz Sprint (Upgrade Proposed in 2019) • Zoning drawings by Fullerton Engineering Design, dated August 28, 2019 • Four RFS Model APXVFRR12X-C and four Samsung Model 64T64R M-MIMO antennas, employing up to 2° downtilt • Oriented in identical pairs toward 0°T, 110ºT, 260°T, and 300°T • Maximum effective radiated power 5,460 watts: 2,810 watts at BRS, 2,170 watts at PCS, 480 watts at SMR T-Mobile (Upgrade Proposed in 2019) • Zoning drawings by Borges Architectural Group, dated December 7, 2018 • Three Ericsson Model AIR32-KRD901146, three RFS Model APXVF13-C-A20, and three Ericsson Model AIR5121 antennas, employing up to 2° downtilt • Oriented in identical groups of three toward 30°T, 160°T, and 280°T • Maximum effective radiated power 10,343 watts: 243 watts at 28 GHz, 4,400 watts at AWS, 4,400 watts at PCS, 1,300 watts at 700 MHz Verizon (Existing) • Zoning drawings by Streamline Engineering and Design, Inc., dated September 28, 2017 • Twelve Amphenol Model HEX454CW0000G antennas, employing no downtilt • Oriented in groups of three toward 0°T, 90°T, 180°T, and 270°T • Maximum effective radiated power 18,640 watts: 9,640 watts at AWS, 4,320 watts at PCS, 2,600 watts at cellular, 2,080 watts at 700 MHz * This is the maximum effective radiated power. The manufacturer reports that the antenna transmits 75% of the time in this band; this factor is incorporated into the calculations. APPLE INC. AT&T Site No. CCL04410 10335 North Tantau Avenue Sprint Site Nos. SF96xc031/SF96xc033 Cupertino, California T-Mobile Site No. SF14981A Wireless Base Stations Verizon Site No. 431599 F8UE Page 4 of 5 ©2021 Study Results For a person anywhere at ground, the maximum RF exposure level due to the proposed AT&T operation by itself is calculated to be 0.33 mW/cm2, which is 39% of the applicable public exposure limit. The maximum calculated cumulative level at ground, for the simultaneous operation of all four carriers, is 40% of the public exposure limit. The maximum calculated cumulative level at the second- floor elevation of any nearby residence† is 2.1% of the public exposure limit. It should be noted that these results include several “worst-case” assumptions and therefore are expected to overstate actual power density levels. Levels on the roof of the building may exceed the applicable public exposure limit, as shown in Figure 3. Recommended Mitigation Measures Due to their mounting locations and height, requiring passage through a locked door to reach the roof, the antennas would not be accessible to unauthorized persons, and so no measures are necessary to comply with the FCC public exposure guidelines. To prevent occupational exposures in excess of the FCC guidelines, it is recommended that appropriate RF safety training, to include review of personal monitor use and lockout/tagout procedures, be provided to all authorized personnel who have access to the structure, including employees and contractors of the wireless carriers and of the property owner. It is recommended that boundary lines be marked on the roof with blue and yellow paint to identify areas within which exposure levels are calculated to exceed the public and occupational FCC limits, respectively, as shown in Figure 3. No work in the yellow-shaded areas, or directly in front of the antennas themselves such as might occur during certain maintenance activities above the roof, should be allowed while the pertinent antennas are in operation, unless other measures can be demonstrated to ensure that occupational protection requirements are met. It is recommended that explanatory signs‡ be posted at the roof access door, at the antennas, at the two doorways leading outside the view screen, at the boundary stripes, and on the view screen wall in front of the antennas, readily visible from any angle of approach to persons who might need to work within that distance. † Located at least 480 feet away, based on photographs from Google Maps. ‡ Signs should comply with OET-65 color, symbol, and content recommendations. Contact information should be provided (e.g., a telephone number) to arrange for access to restricted areas. The selection of language(s) is not an engineering matter, and guidance from the landlord, local zoning or health authority, or appropriate professionals may be required. APPLE INC. AT&T Site No. CCL04410 10335 North Tantau Avenue Sprint Site Nos. SF96xc031/SF96xc033 Cupertino, California T-Mobile Site No. SF14981A Wireless Base Stations Verizon Site No. 431599 F8UE Page 5 of 5 ©2021 Conclusion Based on the information and analysis above, it is the undersigned’s professional opinion that the proposed operation of the base stations at 10335 North Tantau Avenue in Cupertino, California, will comply with the prevailing standards for limiting public exposure to radio frequency energy and, therefore, will not for this reason cause a significant impact on the environment. The highest calculated level in publicly accessible areas is much less than the prevailing standards allow for exposures of unlimited duration. This finding is consistent with measurements of actual exposure conditions taken at other operating base stations. Training authorized personnel and posting explanatory signs are recommended to establish compliance with occupational exposure limits. Authorship The undersigned author of this statement is a qualified Professional Engineer, holding California Registration Nos. E-13026 and M-20676, which expire on June 30, 2023. This work has been carried out under his direction, and all statements are true and correct of his own knowledge except, where noted, when data has been supplied by others, which data he believes to be correct. William F. Hammett, P.E. 707/996-5200 July 20, 2021 FCC Radio Frequency Protection Guide FCC Guidelines Figure 1 1000 100 10 1 0.1 0.1 1 10 100 103 104 105 Occupational Exposure Public Exposure PCS CellFM Po w e r De n s i t y (m W / c m 2) The U.S. Congress required (1996 Telecom Act) the Federal Communications Commission (“FCC”) to adopt a nationwide human exposure standard to ensure that its licensees do not, cumulatively, have a significant impact on the environment. The FCC adopted the limits from Report No. 86, “Biological Effects and Exposure Criteria for Radiofrequency Electromagnetic Fields,” published in 1986 by the Congressionally chartered National Council on Radiation Protection and Measurements (“NCRP”). Separate limits apply for occupational and public exposure conditions, with the latter limits generally five times more restrictive. The more recent standard, developed by the Institute of Electrical and Electronics Engineers and approved as American National Standard ANSI/IEEE C95.1-2006, “Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz,” includes similar limits. These limits apply for continuous exposures from all sources and are intended to provide a prudent margin of safety for all persons, regardless of age, gender, size, or health. As shown in the table and chart below, separate limits apply for occupational and public exposure conditions, with the latter limits (in italics and/or dashed) up to five times more restrictive: Frequency Electromagnetic Fields (f is frequency of emission in MHz) Applicable Range (MHz) Electric Field Strength (V/m) Magnetic Field Strength (A/m) Equivalent Far-Field Power Density (mW/cm2) 0.3 – 1.34 614 614 1.63 1.63 100 100 1.34 – 3.0 614 823.8/ f 1.63 2.19/ f 100 180/ f2 3.0 – 30 1842/ f 823.8/ f 4.89/ f 2.19/ f 900/ f2 180/ f2 30 – 300 61.4 27.5 0.163 0.0729 1.0 0.2 300 – 1,500 3.54 f 1.59 f f /106 f /238 f/300 f/1500 1,500 – 100,000 137 61.4 0.364 0.163 5.0 1.0 Frequency (MHz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© RFR.CALC™ Calculation Methodology Assessment by Calculation of Compliance with FCC Exposure Guidelines Methodology Figure 2 © The U.S. Congress required (1996 Telecom Act) the Federal Communications Commission (“FCC”) to adopt a nationwide human exposure standard to ensure that its licensees do not, cumulatively, have a significant impact on the environment. The maximum permissible exposure limits adopted by the FCC (see Figure 1) apply for continuous exposures from all sources and are intended to provide a prudent margin of safety for all persons, regardless of age, gender, size, or health. Higher levels are allowed for short periods of time, such that total exposure levels averaged over six or thirty minutes, for occupational or public settings, respectively, do not exceed the limits. Near Field. Prediction methods have been developed for the near field zone of panel (directional) and whip (omnidirectional) antennas, typical at wireless telecommunications base stations, as well as dish (aperture) antennas, typically used for microwave links. The antenna patterns are not fully formed in the near field at these antennas, and the FCC Office of Engineering and Technology Bulletin No. 65 (August 1997) gives suitable formulas for calculating power density within such zones. For a panel or whip antenna, power density S = 180  θ BW × 0.1 × Pnet π×D×h , in mW/cm2, and for an aperture antenna, maximum power density Smax = 0.1 × 16 × η × Pnet π × h 2 , in mW/cm2, where qBW = half-power beamwidth of antenna, in degrees, Pnet = net power input to antenna, in watts, D = distance from antenna, in meters, h = aperture height of antenna, in meters, and h = aperture efficiency (unitless, typically 0.5-0.8). The factor of 0.1 in the numerators converts to the desired units of power density. Far Field. OET-65 gives this formula for calculating power density in the far field of an individual RF source: power density S = 2.56 × 1.64 × 100 × RFF 2 × ERP 4 × π × D2 , in mW/cm2, where ERP = total ERP (all polarizations), in kilowatts, RFF = three-dimensional relative field factor toward point of calculation, and D = distance from antenna effective height to point of calculation, in meters. The factor of 2.56 accounts for the increase in power density due to ground reflection, assuming a reflection coefficient of 1.6 (1.6 x 1.6 = 2.56). The factor of 1.64 is the gain of a half-wave dipole relative to an isotropic radiator. The factor of 100 in the numerator converts to the desired units of power density. This formula is used in a computer program capable of calculating, at thousands of locations on an arbitrary grid, the total expected power density from any number of individual radio frequency sources. The program also allows for the inclusion of uneven terrain in the vicinity, as well as any number of nearby buildingsRIYDU\LQJKHLJKWV, to obtain more accurate projections. APPLE INC. 10335 North Tantau Avenue Cupertino, California Wireless Base Stations F8UE Figure 3 Recommended Mitigation Measures AT&T Site No. CCL04410 Sprint Site Nos. SF96xc031/SF96xc033 T-Mobile Site No. SF14981A Verizon Site No. 431599 Calculated RF Exposure Levels on Roof 2021c FEET FEET 50 0 50 100 Calculations performed according to OET Bulletin No. 65, August 1997. Colors shown represent percent of applicable FCC public limit. [blank] <100%>100%>500%>5000% Notes: See text. Base drawing from Fullerton Engineering Design, dated October 18, 2017. Calculations performed according to OET Bulletin 65, August 1997. Shaded color Boundary marking Sign type Legend:Exceeds Occupational - Yellow CAUTION N/A blank Less Than Public - Green INFORMATION Exceeds 10x Occupational - Orange WARNING Exceeds Public - Blue NOTICE • Mark boundaries as shown (roof access door locked) • Post explanatory signs (including Y signs in front of antennas) • Provide training No r t h outer roof access door AT&T antennas Sprint antennas T-Mobile antennas Verizon antennas outer roof access door view screen wall