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HomeMy WebLinkAboutUP23-0004 T-Mobile RF Certification from EngineerVertical Bridge • Site No. US-CA-5437 T-Mobile West LLC • Proposed Base Station No. SC60554A 1491 Lower Honcut Road • Oroville, California E9XE Page 1 of 4 ©2023 Statement of Hammett & Edison, Inc., Consulting Engineers The firm of Hammett & Edison, Inc., Consulting Engineers, has been retained by Vertical Bridge, a wireless telecommunications facilities provider, to evaluate the T-Mobile West LLC base station (Site No. SC60554A) proposed to be located at 1491 Lower Honcut Road near Oroville, California, for compliance with appropriate guidelines limiting human exposure to radio frequency (“RF”) electromagnetic fields. Executive Summary T-Mobile proposes to install directional panel antennas on a tall pole, configured to resemble a pine tree, to be sited at 1491 Lower Honcut Road near Oroville. The proposed operation will comply with the FCC guidelines limiting public exposure to RF energy. 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 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 Vertical Bridge • Site No. US-CA-5437 T-Mobile West LLC • Proposed Base Station No. SC60554A 1491 Lower Honcut Road • Oroville, California E9XE Page 2 of 4 ©2023 General Facility Requirements Base stations typically consist of two distinct parts: the electronic transceivers (also called “radios”) that are connected to the traditional wired telephone lines, and the 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 Vertical Bridge, including drawings by Assurance Development, dated February 21, 2023, T-Mobile proposes to install twelve directional panel antennas – three CommScope Model FFVV-65C-R3-V1, three Ericsson Model AIR6419, and six* antennas for future operation – on a 95-foot steel pole, configured to resemble a pine tree,† to be sited on the west side of a farm parcel to the east of Ahart Road, about 1,400 feet to the north of its intersection with School Street, in unincorporated Butte County, about 8 miles south of Oroville. The CommScope and Ericsson antennas would employ 2° and up to 19° downtilt, respectively, would be mounted at an effective height of about 91 feet above ground, and would be oriented in identical groups of four at about 120° spacing, to provide service in all directions. The maximum effective radiated power in any * It is recommended that the RF exposure conditions be re-evaluated for compliance with FCC limits at such time as these antennas are to be put into service. † Foliage atop the pole puts the overall height at about 100 feet. Vertical Bridge • Site No. US-CA-5437 T-Mobile West LLC • Proposed Base Station No. SC60554A 1491 Lower Honcut Road • Oroville, California E9XE Page 3 of 4 ©2023 direction would be 76,380 watts, representing simultaneous operation at 59,310 watts for BRS,‡ 6,200 watts for AWS, 5,430 watts for PCS, 1,900 watts for 700 MHz, and 3,540 watts for 600 MHz service. Also proposed to be located on the pole, at an effective height of about 86 feet above ground, is a microwave “dish” antenna, for interconnection of this site with others in the T-Mobile network. 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 T-Mobile operation, including the contribution of the microwave dish, is calculated to be 0.020 mW/cm2, which is 2.4% of the applicable public exposure limit. The maximum calculated level at the second-floor elevation of any nearby residence§ is 2.0% 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. No Recommended Mitigation Measures Due to their mounting location and height, the T-Mobile antennas would not be accessible to unauthorized persons, and so no measures are necessary to comply with the FCC public exposure guidelines. It is presumed that T-Mobile 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 T-Mobile West LLC at 1491 Lower Honcut Road near Oroville, 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. ‡ The manufacturer reports that the antenna transmits 75% of the time in this band; this factor is incorporated into the calculations. A statistical factor of 32% is also included, to account for spatial distribution of served users, based on the United Nations International Telecommunication Union ITU-T Series K, Supplement 16, dated May 20, 2019. § Located about 280 feet to the southwest. Vertical Bridge • Site No. US-CA-5437 T-Mobile West LLC • Proposed Base Station No. SC60554A 1491 Lower Honcut Road • Oroville, California E9XE Page 4 of 4 ©2023 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 April 3, 2023