Comparison of two measurement methods on net power delivery with dual directional couplers

A directional coupler is typically utilized to monitor the power flow for RF and microwave systems; therefore, accurate net power measurement is essential for different field strength standards systems which are utilized to calibrate field probes. This paper describes two methods to accurately calculate the net power with dual directional coupler. One is based on the scalar coupling coefficients, VSWR and directivity of a coupler; and the other one is a transfer method which can be traced back to the power standard system. A comparison is made with the two methods, and both methods are proved practicable. At the end, the criterion about the choice of two methods is given.