Attachment rad1.2meter 180 watt

This document pretains to SES-STA-20020522-00818 for Special Temporal Authority on a Satellite Earth Station filing.

IBFS_SESSTA2002052200818_260723

                                                               ATTACHMENT B
                                                               Page 1 of 5



                      Analysis of Non-Ionizing Radiation
                     for a 1.2 Meter Earth Station System


This report analyzes the non-ionizing radiation levels for a 1.2 meter
earth station system. The analysis and calculations performed in this report
are in compliance with the methods described in the FCC Office of Engineering
and Technology Bulletin, No. 65 first published in 1985 and revised in 1997
in Edition 97-01. The radiation safety limits used in the analysis are in
conformance   with the    FCC R&O 96-326.   Bulletin No. 65    and the    FCC
R&O specifies that there are two separate tiers of exposure limits that are
dependant on the situation in which the exposure takes place and/or the
status of the individuals who are subject to the exposure. The Maximum
Permissible   Exposure (MPE) limits for persons in a General Population/
Uncontrolled environment are shown in Table 1. The        General Population/
Uncontrolled MPE is a function of transmit frequency and is for an exposure
period of thirty minutes or less. The MPE limits for persons in an
Occupational/Controlled environment are shown in Table 2. The Occupational
MPE is a function of transmit frequency and is for an exposure period of six
minutes or less. The purpose of the analysis described in this report is to
determine the power flux density levels of the earth station in the
far-field, near-field, transition region, between the subreflector or feed
and main reflector surface, at the main reflector surface, and between
the antenna edge and the ground and to compare these levels to the
specified MPEs.




  Table 1. Limits for General Population/Uncontrolled Exposure(MPE)

  Frequency Range (MHz)              Power Density (mWatts/cm**2)

        30-300                                   0.2
       300-1500                          Frequency(MHz)*(0.8/1200)
      1500-100,000                               1.0


  Table 2. Limits for Occupational/Controlled Exposure(MPE)

  Frequency Range (MHz)              Power Density (mWatts/cm**2)

        30-300                                   1.0
       300-1500                          Frequency(MHz)*(4.0/1200)
      1500-100,000                               5.0




Table 3 contains the parameters that are used to calculate the various power
densities for the earth stations.


                                                                   ATTACHMENT B
                                                                   Page 2 of 5


Table 3.   Formulas and Parameters Used for Determining Power Flux Densities

     Parameter                Abbreviation       Value               Units
     Antenna Diameter             D              1.2                 meters
     Antenna Surface Area         Sa             II * D**2/4         meters**2
     Feed Flange Diameter         Df              19.0               cm
     Area of Feed Flange          Fa             II * Df**2/4        cm**2
     Frequency                    Frequency      14250               MHz
     Wavelength                   lambda      300/frequency(MHz)     meters
     Transmit Power               P               180.00             Watts
     Antenna Gain                 Ges            43.2                dBi
     Pi                           II             3.1415927           n/a
     Antenna Efficiency           n              0.65                n/a


1.   Far Field Distance Calculation

The distance to the beginning of the far field can be determined from the
following equation:(1)

     Distance to the Far Field Region,(Rf) = 0.60 * D**2 / lambda                 (1)
                                           = 41.0 meters


The maximum main beam power density in the Far Field can be determined
from the following equation:(2)

     On-Axis Power Density in the Far Field,(Wf) = Ges * P / 4 * II * Rf**2 (2)
                                                 = 177.684 Watts/meters**2
                                                 = 17.768 mWatts/cm**2


2.   Near Field Calculation

Power flux density is considered to be at a maximum value throughout the
entire length of the defined Near Field region. The region is contained
within a cylindrical volume having the same diameter as the antenna.
Past the boundary of the Near Field region the power density from the
antenna decreases linearly with      respect to increasing     distance.

The distance to the end of the Near Field can be determined from the
following equation:(3)

     Extent of the Near Field,(Rn) = D**2 / (4 * lambda)                          (3)
                                   = 17.1 meters


The maximum power density in the Near Field can be determined from the
following equation:(4)

     Near Field Power Density,(Wn) = 16.0 * n * P / II * D**2                     (4)
                                   = 414.792 Watts/meters**2
                                   = 41.479 mWatts/cm**2


                                                                  ATTACHMENT B
                                                                  Page 3 of 5

3.   Transition Region Calculations

The Transition region is located between the Near and Far Field regions.
The power density begins to decrease linearly with increasing distance
in the Transition region. While the power density decreases inversely
with distance in the Transition region, the power density decreases
inversely with the square of the distance in the Far Field region. The
maximum power density in the Transition region will not exceed that
calculated for the Near Field region. The power density calculated in
Section 1 is the highest power density the antenna can produce in any of
the regions away from the antenna. The power density at a distance Rt
can be determined from the following equation:(5)

     Transition region Power Density,(Tt) = Wn * Rn / Rt                         (5)
                                          = 41.479 mWatts/cm**2


4.   Region between the Feed Assembly and the Antenna Reflector

Transmissions from the feed assembly are directed toward the antenna
reflector surface, and are confined within a conical shape defined by the
type of feed assembly. The most common feed assemblies are waveguide
flanges, horns or subreflectors. The energy between the feed assembly and
reflector surface can be calculated by determining the power density at
the feed assembly surface. This can be determined from the following
equation:(6)

     Power Density at Feed Flange,(Wf) = 4 * P / Fa                              (6)
                                       = 2539.425 mWatts/cm**2


5.   Main Reflector Region

The power density in the main reflector is determined in the same manner
as the power density at the feed assembly. The area is now the area of
the reflector aperture   and can be determined from      the   following
equation:(7)

     Power Density at the Reflector Surface,(Ws) = 4 * P / Sa              (7)
                                                 = 636.620 Watts/meters**2
                                                 = 63.662 mWatts/cm**2


6.   Region between Reflector and the Ground

Assuming uniform illumination of the reflector surface, the power density
between the antenna and the ground can be determined from the following
equation:(8)

     Power Density between Reflector and the Ground,(Wg) = P / Sa          (8)
                                                     = 159.155 Watts/meters**2
                                                     = 15.915 mWatts/cm**2


                                                                   ATTACHMENT B
                                                                   Page 4 of 5


Table 4. Summary of Expected Radiation levels for Uncontrolled Environment

                               Calculated Maximum Radiation
                                    Power Density Level
   Region                             (mWatts/cm**2)        Hazard Assessment


1. Far Field (Rf)   = 41.0 meters          17.768              Potential Hazard

2. Near Field (Rn) = 17.1 meters           41.479              Potential Hazard

3. Transition Region
   Rn < Rt < Rf, (Rt)                      41.479              Potential Hazard

4. Between Feed Assembly                   2539.425            Potential Hazard
   and Antenna Reflector

5. Main Reflector                          63.662              Potential Hazard

6. Between Reflector                       15.915              Potential Hazard
   and Ground




Table 5. Summary of Expected Radiation levels for Controlled Environment

                               Calculated Maximum Radiation
                                    Power Density Level
   Region                             (mWatts/cm**2)        Hazard Assessment


1. Far Field (Rf)   = 41.0 meters          17.768              Potential Hazard

2. Near Field (Rn) = 17.1 meters           41.479              Potential Hazard

3. Transition Region
   Rn < Rt < Rf, (Rt)                      41.479              Potential Hazard

4. Between Feed Assembly                   2539.425            Potential Hazard
   and Antenna Reflector

5. Main Reflector                          63.662              Potential Hazard

6. Between Reflector                       15.915              Potential Hazard
   and Ground




It is the     applicant's responsibility     to     ensure that the public and
operational   personnel are not exposed      to     harmful levels of radiation.


                                                                  ATTACHMENT B
                                                                  Page 5 of 5




7.0 Conclusions

Based on this analysis, harmful areas of radiation will exist in areas around
the antenna and in the path of the antenna toward the satellite to which it is
transmitting. It is concluded, however, that the ANSI/FCC Maximum Permissible
Exposure (MPE) limits of 1 mW/cm2 for Uncontrolled areas and 5 mW/cm2 for
Controlled areas would not be exceeded in areas normally occupied by the
public-at-large or by the earth station’s operating personnel. The applicant
proposes to maintain compliance with the MPE limits by one or more of the
following methods:


Means of Compliance Uncontrolled Areas

The antenna will be located in a roped off area. The general public will not
have access to areas within ½ diameter from the edge of the antenna.   Because
at one diameter removed from the main beam of the antenna or ½ diameter removed
from the edge of the antenna, RF levels are lower by a factor of 100 or 20 dB,
none of the areas exceeding the MPE levels will be accessible by the general
public.

Radiation hazard signs will be posted while this earth station is in operation
to warn individuals of the potential for hazardous radiation. The applicant
will ensure that no people or buildings or other obstacles will be in the areas
that exceed the MPE levels. Earth station personnel will be trained to ensure
that the transmission path is clear at all times that the antenna is in
operation.


Means of Compliance Controlled Areas


The earth station’s operational personnel will not have access to the areas that
exceed the MPE levels while the earth station is in operation.

The transmitters will be turned off during antenna maintenance.



Document Created: 2002-05-23 10:57:58
Document Modified: 2002-05-23 10:57:58

© 2024 FCC.report
This site is not affiliated with or endorsed by the FCC