Ca microfon este folosit un difuzor de mici dimensiuni cu impedanta 4 sau 8 ohmi. Difuzorul este cuplat printr-un transformator de iesire la baza tranzistorului (EFT353). Cand nivelul undelor acustice…
Cuprind undele electromagnetice cu lungimea de undă între 10 şi 100 m (frecvenţa de 3 MHz pînă la 30 MHz) şi, respectiv, benzile de radioamatori de la 10 la 80…
În cazul acestor unde, energia propagată la suprafaţa solului, respectiv unda directă, este absorbită de sol cu atît mai mult cu cît lungime de undă scade. în general, unda directă…
Undele kilometrice, mai ales cele cuprinse în gama de radiodifuziune, se propagă în condiţii aproape identice atît ziua cît şi noaptea, ocolesc obstacolele prin fenomene de difracţie. Acea parte din…
Undele electromagnetice se propagã traversînd aerul, materialele izolante sau spaţiile dintre planete, cum o demonstreazã comunicaţiile radio şi de televiziune, ca şi reflexiile de pe Lunã sau Venus, ori recepţia…
Carte publicata in Bucuresti, 1977 - Editura SPORT-TURISM - Autor: Ing. GHEORGHE STÃNCIULESCU Cateva cuvinte din carte: ropagarea undelor electromagnetice Undele electromagnetice se propagã traversînd aerul, materialele izolante sau spaţiile…
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