HomeMy WebLinkAboutCUP 01-24; Marja Acres PCS Facility; Conditional Use Permit (CUP) (6)' ! • :. I c
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Del Mar, CA 92014
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RADIO FREQUENCY POWER DENSITY EMISSIONS REPORT
For
Sprinf.). · ~wllhNEXTa
Site: CA-6439-B, Tamarack
Located at:
4901 El Camino Real
Carlsbad, CA 92008
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2/23/2006
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The special provisions contained herein have been prepared by or under the direction of the
following Registered Engineer.
DarangTech
1049 Camino Del Mar. Bldg. 2 .& Del Mar. CA. 92014 .& 888.988.0099 .& WW111.dtecbcom.com
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INTRODUCTION
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Dtech Communications, LLC has been retained by Sprint to determine whether their
communication facility comply with Federal Communications Commission (FCC) Radio
Frequency (RF) Safety Guidelines. This report provides a cumulative assessment, where
possible, of RF power density levels in percentages of the FCC's Maximum Permissible
Exposure (MPE) Limits and recommended compliance actions when applicable.
BACKGROUND
The engineering staff at Dtech does not establish the guidelines used to insure safety
exposure levels emitted from Radio Frequency (RF) Electromagnetic Fields associated with
SMR, Cellular, PCS, radio and television equipment. Dtech uses the guidelines and standard
adopted by the Federal Communications Commission in 1996 and further amended in
August 1997 by a Second Memorandum Opinion and Order. The guidelines established
Maximum Permissible Exposure (MPE) Limits well below a level the majority of the
scientific community believes may pose a heath risk. The FCC uses these MPE Limits to
regulate RF exposure levels on all wireless communication facilities. The FCC's guidelines
are described in detail in OET (Office of Engineering & Technology) Bulletin No. 65
"Evaluating Compliance with FCC Guidelines for Human Exposure to Radiofrequency
Electromagnetic Radiation". Table 1 below summarizes the current MPE safety limits.
Table 1: FCC Maximum Permission Exposure (MPE) Umits_(from OET-65)
Frequency General Occupational/ Controlled
(Mhz) Public/Uncontrolled MPE
MPE (mW/cm2)
(mW/cm2)
30-300 .2 1.0
300-1500 Frequency (Mhz)/1500 Frequency (Mhz)/300
_(0.2 -1.0) (1.0-S.Ol
1500-100,000 1.0 5.0
General population/uncontrolled limits apply in situations in which the general public
may be exposed or in which persons who are exposed as a consequence of their
employment, and may not be fully aware of the potential for exposure or cannot exercise
control over their exposure. Therefore, members of the general public always fall under
this category when exposure in not employment-related.
Occupational/controlledlimits apply in situations in which persons are exposed as a
consequence of their employment, and those persons have been made fully aware of the
potential for exposure and can exercise control over their exposure.
Occupational/ controlled limits also apply where exposure is of a transient nature as a
result of incidental passage through a location where exposure levels may be above
1049 Camino Del Mar. Bldg. 2 A Del Mar. CA 92014 A 888.988.0099 A IIJIIJW.dtechcom.com
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general population/uncontrolled limits, as long as the exposed person has been made
fully aware of the potential for exposure and can exercise control over his or here
exposure by leaving the area or by some other appropriate means.
It is important to understand that the FCC guidelines specify exposure limits not emission
limits. Therefore, in order for a transmitting facility or operation to be out of compliance
with the FCC's RF guidelines an area or areas where levels exceed the MPE limits must, first
of all, be in some way accessible to the public or to workers. When accessibility to an area
where excessive levels is appropriately restricted, the facility or operation can certify that it
complies with the FCC requirements.
SITE DESCRIPTION
The subject site is located at 4901 El Camino Real, Carlsbad, CA 92008. Sprint's site
consists of an equipment shelter located on the ground and 3 sectors (faces), A, Band C,
each containing 4 directional panel antenna designed to radiate RF (Radio Frequency) energy
into the horizon. The antennae are mounted on a monopalm located on an adjacent hilltop
and connected to the equipment (radios) via coaxial cables.
Exposures levels everywhere on the ground, up to the monopalm tower must comply with
FCC's most restrictive Uncontrolled/General Public MPE (Maximum Permissible
Exposure) Limits. Aside from the monopalm itself, there are no additional areas that would
be considered as "Occupational/Controlled". Verizon and Cingular are also located at the
subject site at the time of this report. Their antennae are mounted on separate, adjacent
monopalms of similar heights. Their detail site specifications are unavailable; however, for
purposes of a cumulative study, conservative estimates can be derived from the drawings for
the computer simulation. (See table 3 below and attached drawings for further detail)
Table 3: Site Confij!,uration used for calculations
Per Sector (Max) Sprint-SMR Verizon Cingular-Cingular-
Celluar PCS
Max ERP per channel (Watts) 36 250 100 200
Total channels per sector 12 4 10 10
Max Composite ERP per sector 432 1000 1000 2000
(Watts)_
Min Antenna Radiation Center 30 30 30 30
Height Above Ground (feet)
Frequency SMR/Cellular Cellular (824 -Cellular PCS (1850-
(806-866Mhz) 896Mhz) (824-1990Mhz)
896Mhz}
Antenna Make/Model EMS Wireless EMS Wireless Powerwave Powerwave
FV65-12-00 RR65-12-00 7750 7750
1049 Camino Del Mar. Bldg. 2 A Del Mar. CA 92014 A 888.988.0099 A www.dtechcom.com
Max Antenna Down tilts
lectrical/Mechanical
CALCULATION METHOD
0 0 0 0
Dtech uses the FCC's guidelines for predicting emission levels as described in OET (Office
of Engineering & Technology) Bulletin No. 65 "Evaluating Compliance with FCC
Guidelines for Human Exposure to Radiofrequency Electromagnetic Radiation". Please
refer to appendix A for the brief electromagnetic theory behind our calculations. As a
conservative measure, the cumulative MPE (Maximum Permissible Exposure) analysis is
performed under worse case conditions: (a) both near field and far field models are used; (b)
all transmitters transmit at maximum power and maximum number of channels available; (c)
all transmitters transmit simultaneously; (d) calculation points are performed at bore sight or
in the antenna's main beam; (e) line-of-sight is assumed (no signal attenuations due to
obstructions); (f) for multiple carriers, each carrier's exposure is combined to obtain the
cumulative MPE at the facility. Actual powers are typically well below the worse case
conditions depending on the number of channels occupied at any given time. In addition,
each carrier has different antenna azimuths therefore worse case condition for each carrier
occurs at different points in space. To simply sum up all the worse case conditions, as in this
analysis, is unrealistic in the real world. However, it does give a good conservative picture of
the upper limit.
1049 Camino De/Mar, Bldg. 2 .& De/Mar. C4 92014 .& 888.988.0099 .& JPWw.dtechcom.rom
RESULTS
Cumulative calculations are made at human height above grade at continuous distances from
the tower in a level plane and the results will be compared to the most restrictive
Uncontrolled/General Public MPE (Maximum Permissible Exposure) Limit. Figure 1
below shows the results.
Fig ure 1· Expected emission levels compared to FCC's Gen eral Public/Uncontrolled MPE Limit
calculated at human height above ground leveL
Calculated Levels on Ground
4.00 ,.-------------------------, --~------~ 3.50 -t-----:---=-~----:---r-'--,...------.,---1 --Sprint-SMR
3.00 -t------,----,~--=--+-+-'--~-----..-----i --Verizon
2.50 i------:-----=----l--t---;P--'~---ill-~k--'---1 C ingular-CelluJar
-CinguJar-PCS 2.00 i-----~~-'----1--t--t-+--fllt--~.------i -Cumulative 1.50 +-----:::---'--"------1-
1.00 t---'-::'-::::::::-.:.....:.-:-::-:-::-,---l---r" ........ r-t-~~r-+-t--y;J'-N=-~~--1
0.50 i--------T-::1~=\'W~-·~IIt-;:j'"':lct.,....;;:::-=-.::~_,.,~
0.00 ~. ;;;;;;;;:;;;:;;::;;:~:;;:;:;~~~Yc~~~,._[£::~~;:t
10 100 1000
Horizontal Distance From Antenna (feet)
Figure1 show that the calculated maximum exposure level resulting from Sprint's site is
1.22% of the FCC's most restrictive General Public MPE (Maximum Permissible Exposure)
Limit on the ground in any direction. The combined, maximum exposure level for all
carriers is calculated to be 3.52%. It should be pointed out again that these results reflect
worse-case conditions and should be considered as the upper limit. Measured levels under
normal operating conditions are typically much less.
1049 Camino Del Mar. Bldg. 2 A Del Mar. CA 92014 A 888.988.0099 A 1/IWJJI.dtedxom.com
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RECOMMENDATION(S)
Since the antennae are mounted on a tall tower and therefore not accessible by the general
public, no compliance action is required. It is presumed that Sprint's employees and
contractors are aware of the transmitting antennae and will take appropriate precautions
when working near them.
CONCLUSION
Based on the results and recommendation(s) above, it is the undersigned's professional
opinion that Sprint's site will be in full compliance with the FCC's Radio Frequency Safety
Guidelines. The worse-case emission levels on the ground are calculated to be well below
the FCC's safety limits.
1049 Camino Del Mar, Bldg. 2 .& Del Mar. CA 92014 .& 888.988.0099 .& www.dtechcom.com
Appendix A:
Electromagnetic Emissions Theory
Discussed below is an abbreviated explanation of the theory behind Dtech Communications'
electromagnetic studies. This explanation is for individuals with no background in
Electromagnetic Theory and may seem oversimplified by individuals with some exposure to
RF propagation theory.
The power density surrounding an antenna varies as a function of location, distance and
orientation. The fields around an antenna may be divided into two principal regions: (a)
near-field (Cylindrical) and (b) far-field (Spherical). The boundary between the two is
defined as R=2D2jt.., where Dis the maximum physical dimension of the antenna and A is
the wavelength. It is necessary to predict both the near and far field power density of an
antenna array. The predicted result is averaged over the human body with the assumption
that the human body is 2 meters tall.
The Far Field (Spherical) Model
As described by the FCC, a prediction for power density in the far field of a single radiating
point antenna can be derived from the following general equation:
Where:
Eq. 1
S is the power density
P is the power input into the antenna
Gi is the gain of the antenna relative to an isotropic radiator
r is the distance from the antenna
Equation 1 can be modified to consider the following: First, since the power radiated is not
a point source, the Effective Radiated Power (ERP) is used. Second, the FCC calculates the
power based upon a half wave dipole (2.15 dB gain correction factor). Third, multiple
channels are combined and transmits them through one antenna. Therefore, the total
composite ERP is used. Fourth, a 2.56 multiplication factor is added to help compensate for
reflected waves. Lastly, antennas have both horizontal and vertical components. When the
antenna is mounted on a structure, distortion will occur. Therefore, the deep nulls in the
antenna pattern are removed for calculations to more closely model the actual pattern from
the antenna at a cell site. In other words, only the vertical component is factored into the
calculations. (Ignoring the horizontal component will give a worst-case calculation).
The modified formula is:
1049 Camino DelMar. Bldg. 2 A DelMar. CA 92014 A 888.988.0099 A www.dtechcom.mm
' . (
S = ERP * 102 * 1.64 *A* 2.56 Wlcm2
4*n*r2
Eq. 2
where:
S is the Power Density (WI cm2)
ERP is the composite Effective Radiated Power in Watts (W)
A is the antenna pattern attenuation ratio relative to the main lobe gain
r is the horizontal distance to the antenna
The Near Field (ylindrical) Model
The near field power density prediction may be modeled by treating the vertical collinear
antenna as an array of N elements spaced one wavelength apart. The contribution from
each element is summed vectorially and divided by area of a unit sphere to obtain the power
density.
The general formula is
S(S,q>) = EIRP(S,q>) I (4n r2) Eq. 3
Where:
EIRP(S,q>) is the effective isotropic radiated power at a particular azimuth 8
and elevation q>, is found by extrapolating the published horizontal and
vertical gain patterns of the antenna to form a three-dimensional antenna
gain pattern
r is the distance from the antenna
With the adjustments noted in the above far field model, the modified formula is as follows:
S=
where:
ERP * 102_Wicm2
4 * 1t * r * D * Hl360
S is the Power Density (WI cm2)
Eq.4
ERP is the composite Effective Radiated Power in Watts (W)
Dis the vertical antenna aperture
H is the 3dB horizontal beam width of the antenna pattern
r is the horizontal distance to the antenna
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Appendix B:
References
[1 J Guidelines for Evaluating the Environmental Effects of Radio frequenry Radiation, Second
Memorandum Opinion and Order, ET Docket 93-62, adopted August 25, 1997.
[2] Guidelines for Evaluating the Environmental Effects of Radio frequenry Radiation, Report and
Order, ET Docket 93-62, FCC 96-326, adopted August 1, 1996. Federal Register
41006 (1996).
(3] Guidelines for Evaluating the Environmental Effects of Radio frequenry Radiation, Notice of
Porposed Rulemaking, ET Docket 93-62, 8 FCC Red 2849 (1993).
[4] The Telecommunication Act of 1996,47 U.S.C. Section 332 (c)(7)(B)(iv).
(5] www.fcc.gov /Bureaus /Engineering Technology/Documents /bulletins I oet65/
www.fcc.gov I oet/rfsafety
Attachment(s):
• Site drawings
1049 Camino Del Mar, Bldg. 2 A. Del Mar, CA 92014 .&. 888.988.0099 .&. 1/J//JW.dtechcom.rom