摘 要：調幅發射機目前正廣泛應用于無線電廣播系統中，課題以電子線路課程設計實踐為背景，通過查閱大量教學文獻，并結合專業基礎課程教學需要，以原教學內容為基礎，完成了小功率調幅發射機從設計、仿真到安裝、調試等一系列完整設計工作。

　　　發射機的主要任務是完成有用的低頻信號對高頻載波的調制，將其變為在某一中心頻率上具有一定帶寬、適合通過天線發射的電磁波。

　　　所謂調幅，就是指使振幅隨調制信號的變化而變化，嚴格的講，就是指載波振幅與調制信號的大小成線性關系，而它的頻率和相位不變。振幅調制分為4種方式：AM（普通調幅）、DSB（抑制載波雙邊帶調幅）、SSB（單邊帶調幅）、VSB（殘留邊帶調幅）。本設計調幅發射機指的是AM調幅發射機。

　　　文中系統的設計了振蕩器、音頻放大器、振幅調制器和諧振功率放大器等系統單元電路，并通過具有射頻仿真模塊的軟件Mμltisim，試驗和仿真優化了系統電路。

關鍵詞：調幅發射機；振蕩器；音頻放大器；調幅調制器；功率放大器

Abstract：AM transmitters are now widely used in radio broadcasting systems， this thesis as the background of electronic circuit，Through access to a large number of teaching literature, combined with teaching needs, based on the original teaching, completed the low-power AM transmitters from the design, simulation to the installation and commissioning of a full range of design work.  

　　The main task of the transmitter is complete the useful signal frequency modulated high frequency carrier. to turn it into a center frequency at a certain bandwidth, suitable for electromagnetic waves emitted by the antenna.

　　The so-called spinodal means make the amplitude with the modulation signal changes, strictly speaking, refers to the carrier amplitude modulated with signal size linearly, but its frequency and phase constant. Amplitude modulation is divided into 4 ways: AM ( amplitude ), DSB ( bilateral with carrier suppression modulation ), SSB ( single sideband modulation ), VSB ( VSB ). The design of AM transmitters is referred to as AM am transmitter.

　　Oscillator, audio amplifier, power amplifier and resonant amplitude modulator is designed by the system using software Multisim circuit simulation and optimization of the system.

Key words：Low-power AM transmitters; Oscillator; Audio amplifier; Amplitude Modulator; Power amplifier.