Antenna

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       Home Pathloss 4.0 Pathloss 5.0 Download Telco Tools Refference Movie pathloss 5.0 sent email to me : pathloss.anwar@gmail.com GSM (chapter 2 : Antennas) Selasa, 24 November 2009 di 20.26 | GSM CHAPTER 2 ANTENNAS Chat to me (Do Not Email To This account) Blog Archive ANTENNA PARAMETERS  GAIN Since an antenna is passive, the only way to obtain gain in any direction is to increase the directivity by concentrating the radiation in the wanted direction. For a loss free antenna the
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     Home     Pathloss 4.0     Pathloss 5.0    Download    Telco Tools     Refference     Movie  pathloss 5.0  GSM (chapter 2 : Antennas) Selasa, 24 November 2009 di 20.26 |  GSM   CHAPTER 2   ANTENNAS   ANTENNA PARAMETERS   GAIN   Since an antenna is passive, the only way to obtaingain in any direction is to increase the directivity byconcentrating the radiation in the wanted direction.For a loss free antenna the directivity can be givenwith the same number as the gain if the latter is givenwith respect to an isotropic antenna. Hence, in thischapter the distinction between gain and directivity isnot always strictly maintained. The directivity can beincreased by reflectors or by stacking dipoles on thesame vertical line. The latter method can be usedbecause a number of coherent radiation sourcesinterfere constructively (in directions where theyradiate in phase) and destructively (in directions where they are in “anti phase” and more or l esscancel each other out). Each doubling of the numberof dipole elements (corresponding to a doubling in sent email to me :pathloss.anwar@gmail.comChat to me (Do Not EmailTo This account)Blog Archive    ► 2010  (6) o   ► Januari  (6)    WCDMA BasicTutorial      WCDMA Link Budget      MicDecoder      The Application of Land Use and LandCover      White Paper : UMTS900      Traffic Engineering      ▼ 2009  (29) o   ► Desember  (1)    White Paper   o   ▼ November  (16)    SmallVille 9    length) increases the gain in the main direction by 3dB. Figure 1 shows some different antenna arrays.The gain is different in different directions. However,when the antenna gain is quoted it is usually givenfor the direction of maximum radiation.   Figure 1 Antenna Arrays   Since the concentration of radiation is inverselyproportional to the solid angle of the beam, the gaincan be estimated if the beamwidths are known:   G = 10 x log 31000/(V3 x H3)   G = Antenna gain relative isotropic antenna (dBi)   V3 = Vertical beamwidth relative -3 dB points(degree centigrades)    H3 = Horizontal beamwidth relative -3 dB points(degree centigrades)   BEAMWIDTH      Heroes 4      GSM (chapter 2 :Antennas)      GSM (chapter 1)      Draw Smith ChartUsing excell      Link Planning Tools(excell worksheet)      SRTM Indonesia danPhilipina      Pathloss 4.0(Equipment Files)      Pathloss 4.0(InterferenceModule)      PATHLOSS 4.0(MICROWAVEREPEATERS)      Pathloss 4.0(Diffraction Module)      Pathloss 4.0      PATHLOSS 5.0:CHAPTER 4 (ImportSite List From cs...      PATHLOSS 5.0:CHAPTER 3 (ARFConfiguration)      PATHLOSS 5.0:CHAPTER 2 (GISConfiguration)      PATHLOSS 5.0:CHAPTER 1(Installation)   o   ► Oktober  (2)    NEIGHBOURANALYSIS (part 1)      H+A+C+K the phonewith one SISX   o   ► September  (1)    Pathloss 5.0   o   ► Maret  (1)    Pathloss 5.0 RevissionHistory......   o   ► Februari  (4)  Vertical Beamwidth   Since the concentration of radiation is proportional to L/l, the vertical beamwidth decreases as the gainincreases. The vertical beamwidth can be estimated if the length of the antenna is known:   V3 = 15300/(F x l)   V3 = Vertical beamwidth relative - 3 dB points(degrees centigrades)   F  = Frequency (MHz)   l = Antenna length (meter)   ANTENNA DOWN TILTING   The vertical beam of an antenna is normally directedtowards the horizon, assuming the antenna iscorrectly mounted. Lowering the beam below the horizon is known as “down tilt” (Figure 2). Consequently, if the beam is directed above the horizon, “up tilt” is a chieved. Below is a descriptionof the methods used to achieve down tilt and adiscussion on how down tilt can improve theperformance of a system. Up tilt will not bediscussed further.   Figure 2 Antenna Down Tilt (Basic Geometry)   ELECTRICAL TILT   Electrical down tilt requires an antenna with anumber of vertically stacked dipoles. (Here, the word    Share Some thing inhere      NetworkOptimization      Information aboutPathloss 5.0 Price      EMISSIONDESIGNATORS   o   ► Januari  (4)    Pathloss 5.0      Communication LineOf Sight (LOS)      Propagasi GelombangRadio      Globbal Mapper 10      ► 2008  (6) o   ► Desember  (6)    CDMA dan SpreedSpectrum      MULTIPLEXING      TEMS Investigation      Heroes Season 3      Pathloss 4.0 Tools      Pathloss 4.0   TranslatorFollowerswhos.amung.usSubscribe To Post  “dipole” represents other radiating elements as well.) The individual dipoles can be oriented vertically, which is the most common orientation in cellularsystems. They can also be oriented horizontally or ata slant (±45°) position. If all dipoles are fed with thesame phase, the main beam of the vertical patternwill be perpendicular to the mechanical axis of theantenna (towards the horizon). A phase differencebetween the dipoles will result in a beam that deviates from the horizontal. Different tilt angles areavailable, depending on the antenna manufacturer. Typical values are 2° and 6°. An advantage of using electrical tilt is that the antenna is always mounted in a vertical position irrespective of tilt. A disadvantage is that the antennas must be ordered with a certain tilt angle. (Antennas with adjustable electrical tilt are available on the market to avoid the disadvantage of  fixed tilt values. The antennas have a limited gain and are expensive.)   MECHANICAL TILT   Mechanical tilt is achieved by changing themechanical alignment of the antenna. All antennamanufacturers have adjustable brackets designed forthis purpose. It is possible to combine the electricaland mechanical methods.   CELL PLANNING ASPECTS ON DOWN TILT   Down tilt can be used to overcome coverage and/orinterference problems. To be able to discuss down tiltfrom a general point of view, some specialapplications must be excluded, i.e. antennas on extreme hill tops, the “Manhattan syndrome”, etc. In these cases, tilt can always be motivated. As ageneral rule, to reduce co-channel interference, threecriteria must be fulfilled:   1. Short site-to-site distances (small cells)   2. High mounted antennas   3. High gain antennas (narrow vertical beam)   Komentar About Me Pathloss50 Lihat profil lengkapku   Pathloss 5.0  by  Pathloss 4.0 . 
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