Which type of coupling is typically involved in measuring VSWR?

Directional coupling is the correct choice for measuring Voltage Standing Wave Ratio (VSWR) because it allows for the identification of the direction of power flow in a transmission line. In a directional coupler, there are two ports – one for the input signal and another for the output signal.

This design enables the measurement of reflected power, while isolating the forward power. VSWR is determined by comparing the forward power and the reflected power, making directional couplers essential for accurately assessing the performance of antennas and transmission lines. By isolating these two types of power flow, you can effectively calculate the standing wave ratio, which is critical for ensuring efficient transmission and minimizing losses.

Other coupling types such as unidirectional filtering, resistive coupling, and inductive coupling do not provide the directional capability necessary for measuring reflected and forward power in the same way. This lack of ability to differentiate between the flow of transmitted and reflected signals makes them unsuitable for the precise requirements needed in VSWR measurement.