在电子学中，发送器（英语：Transmitter）或无线电发送器指的是一种利用天线发送无线电波的装置。无线电发送器产生交变电流，作用于天线。天线产生无线电波，并将其发送至空间。除了在无线电广播中的应用，无线电发送器还被广泛使用在各种利用无线电进行通讯的设备中。常见的应用有手机、无线局域网、蓝牙、无线对讲机等等。

无线电发送器通常仅限于指代用于无线通讯或者无线电定位系统中发射无线电波的设备。广义上的无线电波发生器，例如微波炉或者电磁炉中产生无线电的装置，一般不被称为无线电发送器，虽然它们的工作原理是类似的。

In electronics and telecommunications a transmitter or radio transmitter is an electronic device which, with the aid of an antenna, produces radio waves. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating current, the antenna radiates radio waves. In addition to their use in broadcasting, transmitters are necessary component parts of many electronic devices that communicate by radio, such as cell phones, wireless computer networks, Bluetooth enabled devices, garage door openers, two-way radios in aircraft, ships, spacecraft, radar sets and navigational beacons. The term transmitter is usually limited to equipment that generates radio waves for communication purposes; or radiolocation, such as radar and navigational transmitters. Generators of radio waves for heating or industrial purposes, such as microwave ovens or diathermy equipment, are not usually called transmitters even though they often have similar circuits.