自1920年美国在世界上首先从事无线电广播以来,至今已整整的六十年了。六十年在人类的历史长河中只不过是短短的一瞬间。然而就在这短暂的岁月里,作为电子技术的一个分支的广播技术以及由此而建立的广播事业却已获得了突飞猛进的发展。从广播事业的规模来看,无线电广播已由美国的独家经营普及到世界上156个国家;电视广 It has been six decades since the United States first started radio broadcasting in the world in 1920. Six decades have been only a brief moment in the long history of mankind. However, in this short time, the broadcasting technology as a branch of electronic technology and the broadcasting business established by it have made rapid progress. From the perspective of the scale of broadcasting businesses, radio broadcasting has been spread to 156 countries in the world exclusively by the United States; television