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RF Report.pdfVerizon Wireless • Proposed Base Station (Site Name “Vallco COW Temp”) 19333 Vallco Parkway • Cupertino, California Q7RV Page 1 of 3 Statement of Hammett & Edison, Inc., Consulting Engineers The firm of Hammett & Edison, Inc., Consulting Engineers, has been retained on behalf of Verizon Wireless, a personal wireless telecommunications carrier, to evaluate the base station (Site Name “Vallco COW Temp”) proposed to be located at 19333 Vallco Parkway in Cupertino, California, for compliance with appropriate guidelines limiting human exposure to radio frequency (“RF”) electromagnetic fields. Executive Summary Verizon proposes to install directional panel antennas on a tall steel pole to be sited at 19333 Vallco Parkway in Cupertino. The proposed operation will comply with the FCC guidelines limiting public exposure to RF energy. Prevailing Exposure Standards 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 FCC limit for exposures of unlimited duration to radio frequency energy for several personal wireless services are as follows: Wireless Service Frequency Band Occupational Limit Public Limit Microwave (Point-to-Point) 5–80 GHz 5.00 mW/cm2 1.00 mW/cm2 WiFi (and unlicensed uses) 2–6 5.00 1.00 BRS (Broadband Radio) 2,600 MHz 5.00 1.00 WCS (Wireless Communication) 2,300 5.00 1.00 AWS (Advanced Wireless) 2,100 5.00 1.00 PCS (Personal Communication) 1,950 5.00 1.00 Cellular 870 2.90 0.58 SMR (Specialized Mobile Radio) 855 2.85 0.57 700 MHz 700 2.40 0.48 [most restrictive frequency range] 30–300 1.00 0.20 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. A small antenna for reception of GPS signals is also required, mounted with a clear view of the sky. Verizon Wireless • Proposed Base Station (Site Name “Vallco COW Temp”) 19333 Vallco Parkway • Cupertino, California Q7RV Page 2 of 3 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”). The conservative nature of this method for evaluating exposure conditions has been verified by numerous field tests. Site and Facility Description Based upon information provided by Verizon, it is proposed to install three Andrew Model SBNH- 1D6565B directional panel antennas on top of a 55-foot mast on a trailer to be parked at the north end of the parking lot behind the Apple building located at 19333 Vallco Parkway in Cupertino, near the bend in Perimeter Road, on the southwest side of Interstate 280. The antennas would employ up to 4° downtilt, would be mounted at an effective height of about 55 feet above ground, and would be oriented at about 120° spacing, to provide service in all directions. The maximum effective radiated power in any direction would be 13,100 watts, representing simultaneous operation at 5,220 watts for AWS, 5,750 watts for PCS, and 2,130 watts for 700 MHz service; no operation on cellular frequencies is presently proposed from this site. There are reported no other wireless telecommunications base stations at the site or nearby. Study Results For a person anywhere at ground, the maximum RF exposure level due to the proposed Verizon operation is calculated to be 0.028 mW/cm2, which is 2.9% of the applicable public exposure limit. The maximum calculated level at the second-floor elevation of any nearby building* is 3.3% 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 from the proposed operation. There are no residential buildings located within 1,000 feet radius of the site. * The Vallco Shopping Center located at 10123 North Wolfe Road, about 400 feet to the southwest. Verizon Wireless • Proposed Base Station (Site Name “Vallco COW Temp”) 19333 Vallco Parkway • Cupertino, California Q7RV Page 3 of 3 No Recommended Mitigation Measures Due to their mounting location and height, the Verizon antennas would not be accessible to unauthorized persons, and so no mitigation measures are necessary to comply with the FCC public exposure guidelines. It is presumed that Verizon will, as an FCC licensee, take adequate steps to ensure that its employees or contractors receive appropriate training and comply with FCC occupational exposure guidelines whenever work is required near the antennas themselves. Conclusion Based on the information and analysis above, it is the undersigned’s professional opinion that operation of the base station proposed by Verizon Wireless at 19333 Vallco Parkway 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. 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, 2017. 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 September 29, 2016 FCC Radio Frequency Protection Guide FCC Guidelines Figure 1 Frequency (MHz) 1000 100 10 1 0.1 0.1 1 10 100 103 104 105 Occupational Exposure Public Exposure PCS CellFM PowerDensity(mW/cm2)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 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, and higher levels also are allowed for exposures to small areas, such that the spatially averaged levels do not exceed the limits. However, neither of these allowances is incorporated in the conservative calculation formulas in the FCC Office of Engineering and Technology Bulletin No. 65 (August 1997) for projecting field levels. Hammett & Edison has built those formulas into a proprietary program that calculates, at each location on an arbitrary rectangular grid, the total expected power density from any number of individual radio sources. The program allows for the description of buildings and uneven terrain, if required to obtain more accurate projections. 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 BW 0.1 Pnet D 2 h , in mW /cm 2, and for an aperture antenna, maximum power density Smax = 0.1  16    Pnet   h 2 , in mW /cm 2, where BW = half-power beamwidth of the antenna, in degrees, and Pnet = net power input to the antenna, in watts, D= distance from antenna, in meters, h= aperture height of the antenna, in meters, and = 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 D2 , in mW /cm 2, where ERP = total ERP (all polarizations), in kilowatts, RFF = relative field factor at the direction to the actual point of calculation, and D= distance from the center of radiation to the 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 has been built into a proprietary program that calculates, at each location on an arbitrary rectangular grid, the total expected power density from any number of individual radiation sources. The program also allows for the description of uneven terrain in the vicinity, to obtain more accurate projections.