Analysis of Power Density Levels

Analysis of Power Density LevelsCHAPTER FOUR3.5 EXPERIMENTAL creationFigure 4.1 Setup during measurement In this research work, the choice of instrument operation and parameters were established by quality assurance procedures. The following measurement parameters were investigated. These were commentary attenuation, signal detection methods, resolution methods and measurement hold methods. The result of the quality assurance procedures are shown at the appendix. The study to measure and analyze power minginess levels was carried out with a total of 200 sites across the ten regions of Ghana as shown on table 4.1 below. The selection of the site for measurement was based on proportional sampling using mobile cell site population as well as the 2010 population census data. The measurement taken a location was always closer to a cell site than any other sources. The design of the measurement procedures was based on the Electronic Communication military mission (ECC) (ECC, 2007) p rotocol. A calibrated USA Anritsu Spectrum Master MS2720T with a serial number 1338067 and a frequency range of 9 KHz to 43 GHz was attached to a calibrated hand-held Transformational Security (TS) Log-periodic approach TS-6021 with a serial number 00302 and a range of 750 MHz to 3 GHz by an Anritsu RF cable with a serial number 39317A. A magnetic Global Position System (GPS) connected to the Spectrum Master takes the location coordinate during measurement as shown in figure 4.1 aboveTable 4.1 The distribution of 2010 population and sample sites (15 analogue terrestrial stationsRegion of GhanaPopulation(2010 census)Number of FM (June, 2015)Number of cell siteNumber of measurement siteSampling DateGreater AccraAshantiEasternCentralWesternVoltaBrong AhafoNorthern upper berth EastUpper West4,019,3884,783,8122,638,4942,194,6352,3672472,120,6592,3179292,4905411,035671690,4474543322546275024129404123778328321189594832713238238684014142010141244September,2014July,2014June,2015July,2015Se ptember,2015August,2014November,2014October,2014October, 2014October, 2014.The sampling towns and location were pre-determined as plotted on the map in figure 4.2. These locations were mostly regional capitals and some surrounding towns and villages.Figure 4.2 GPS location showing places where radiofrequency measurements were made indicated by the tower symbols on the mapThe measurement at a spot involve taking measurement at three different heights 1.0, 1.5 and 1.7 m above the ground. This is illustrated by the ECC raster below in the figure 4.3 below.Figure 4.3 Revised ECC recommendation (02)04 proposed rasterMeasurements with the antenna was taken in two perpendicular plane at each height, with the axis of the antenna directed toward the reference cell site. A set of mutually perpendicular polarization measurements leads to the estimation of the maximum theatre arriving from a specific direction disregarding of its polarization. The measured field strength in dBV/m from the spe ctrum data was corrected and converted to linear value using equation 4.1 and to V/m using equation 4.2. Figure 4.4 below shows a typical spectrum master measurement in the vertical plane that was taken at a town named Ahodwo in the Ashanti Region of Ghana.Figure 4.4 A typical spectrum master measurement taken at Ahodwo, a location in the Ashanti Region.Where is the corrected electric automobile field strength for cable and antenna loses taking polarization into consideration. was the antenna loss correction factor which is the ratio of the incident electric field to the true electric field. is the measured electric field intensity without correction for cable and antenna and is the cable correction factor.The spacial average when dealing with the electric field strength for each specific frequency lying within the frequency range of interest, the maximum expected spatial average (RMS) across m selected spatial points was given byWhere Emax, i is the maximum expected RMS field strength component at the spatial point i.The combined standard uncertainty u of the maximum expected field strength value calculated at the point i was estimated by taking into account the partial uncertainties of each components with a sensitivity coefficient is given byHenceU ( 4.4To be able to assess the level of compliance with the standard set by the international commission for non-ionizing radiation protection(ICNIRP) and in a multiple frequency environment, the calculated spatial averaged electric field strength from the results of equation (4.3) for each operating frequency was processed into power niggardliness assuming a far field measurement and using the relation belowThe uncertainty for each frequency was propagated to the power density estimated byWhere was the assumed free space impedance (377.). The compliance was calculated by summing the ration of the calculated power density value to that of the reference level as given below.Where represent the various so urces being considered, is the calculated power density from equation (4.7) and is the corresponding ICNIRP public reference power density values.