无线电测向是通过测试无线电电磁波的参数，获知无线电发射源方位的技术。对于一个固定测向站来说，在30MHz以上频段，通常只测试电波在水平面上的来向；在HF的频段，通常还要测量它的仰角。由于无线电波具有特定的电波传播规律，根据两个以上站点测得的电波来向，或者一个站点测得的来向、仰角和跳次数据，或者三个以上站点测到的电磁波到达的时间差，可以得知无线电发射台的位置。 根据不同无线电测向的原理，有幅度测向法、相位测向法、空间谱估计测向法和到达时间差测向法等常用方法。

A radio direction finder (RDF) is a device for finding the direction, or bearing, to a radio source. The act of measuring the direction is known as radio direction finding or sometimes simply direction finding (DF). Using two or more measurements from different locations, the location of an unknown transmitter can be determined; alternately, using two or more measurements of known transmitters, the location of a vehicle can be determined. RDF is widely used as a radio navigation system, especially with boats and aircraft.