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Oddajniki mobilne telefonije (bazne postaje in mobilni telefoni) delujejo na frekvenčnem območju od 300 MHz do 3 GHz (valovne dolžine od 10 cm do nekje enega m) v tem frekvenčnem pasu so zajeti vsi mobilni sistemi kot so NMT 420MHz, GSM 900MHz, GSM 1800MHz in UMTS. Osnovni deli vsakega mobilnega sistema so mobilni telefon, bazna postaja, nadzornik baznih postaj in centrala mobilnega sistema. K mobilnem telefonu in bazni postaji spada tudi ena ali več anten, ki oddaj elektromagnetno valovanje v prostor (sevajo) in iz njega sprejemajo. Edina vira visokofrekvenčnega neionizirnega elektromagnetnega sevanja je mobilni telefon in bazna postaja. Zato obstajajo uredbe in standardi, ki določajo mejne vrednosti za velikosti elektromagnetnih polj. Večina predpisov po državah temelji na priporočilih mednarodne komisije za zaščito pred neionizirnim sevanjem (ICNIRP). Namen diplomske naloge je izmeriti elektromagnetno poljsko jakost pri različnih mobilnih telefonih različnih vrednosti SAR blizu antenskega stolpa. Merimo s širokopasovnim merilnim instrumentom PMM 8053 rezultat takšne meritve je zgolj ena izmerjena vrednost, ki predstavlja največjo vrednost EMS v določenem merilnem frekvenčnem območju Transmitters of mobile telephony (base stations and mobile phones) function on the frequency area from 300 MHz to 3 GHz (wave length from 10 cm to about one meter). All mobile systems like NMT 420 MHz, GSM 900 MHz, GSM 1800 MHz and UMTS are covered in this frequency area. Basic parts of every mobile system are mobile phones, base station, base stations controller and the central of the mobile system. Besides the mobile phone and the base station there are also one ore more antennas, which transmit electromagnetic waves (radiation) into the space and receive electromagnetic waves from the space. The only two sources of highfrequency nonionized electromagnetic radiation are the mobile phone and the base station. This is the reason why there are regulations and standards which determine the limited value for the size of electromagnetic fields. Most regulations over different countries base on the recommendations of Internation Commission on Non- Ionizing Radiation Protection (ICNIRP). The purpose of this thesis is to measure electromagnetic field intensity of different mobile phones with different values of SAR in the proximity of the antenna tower. Measurements are taken with a broadband measuring instrument PMM 8053. The result of a measurement like this is one measured value, which represents the biggest EMS value in certain measuring frequency area. |
