Transducer是什么？

A transducer is a device that converts one type of energy to another. Energy types include (but are not limited to) electrical, mechanical, electromagnetic (including light), chemical, acoustic or thermal energy. While the term transducer commonly implies the use of a sensor/detector, any device which converts energy can be considered a transducer.

简单地说，transducer就是换能器，把输入能量转化为另一种输出能量的物质或者装置。

在《功率吸收钳 Transducer 计算方法》一文中，附录中公式
Level [dBμV]=Level[dBm]+107  就是电压和功率之间换算的transducer推导过程，如果电阻是恒定的50欧姆，则计算过程是不变的。

在EMC测量中，transducer一词还包括修正值，即修正因放大器或衰减器的存在对测得值的影响。所以，放大器的tranducer factor是负值，而衰减器的tranducer factor则是正值。例如，一套辐射测试系统的transducer就需要涉及天线的Factor、Cable loss、Amplifier修正值，传导测试系统的transducer需要涉及Lisn factor、Cable loss、attenuator修正值。

附：Applications
Electromagnetic:
Antenna – converts electromagnetic waves into electric current and vice versa Cathode ray tube (CRT) – converts electrical signals into visual form
Fluorescent lamp, light bulb – converts electrical power into visible light.

Magnetic cartridge – converts motion into electrical form
High altitude wind power's airborne wind energy conversion systems – convert the kinetic energy of the wind into electricity, sound, heat, mechanical pumping motion, or light.

Photodetector or photoresistor or light dependent resistor (LDR) – converts changes in light levels into resistance changes
Tape head – converts changing magnetic fields into electrical form.

Hall effect sensor – converts a magnetic field level into electrical form only an antenna is an electrical device which converts electric currents into radio waves, and radio waves into electric currents. It is usually used with a radio transmitter or radio receiver.

In transmission, a radio transmitter applies an oscillating radio frequency electric current to the antenna's terminals, and the antenna radiates the energy from the current as electromagnetic waves (radio waves). In reception, an antenna intercepts some of the power of an electromagnetic wave in order to produce a tiny voltage at its terminals, that is applied to a receiver to be amplified. An antenna can be used for both transmitting and receiving.

看看。。。