Reflectometer with Complete Error Correction

A reflectometer operating at 2.4 GHz with complete error correction is described in this paper. The reflectometer utilizes two gain/phase detectors AD8302 from Analog Devices to measure the reflection coefficient in the full phase range of 360 degrees. Incident and reflected signal are measured and split up into equal power to fed the detectors inputs with the help of two directional couplers and two Wilkinson power dividers. The circuits are realized in microstrip line technique. A micro-controller board using MSP430G2553 from Texas Instrument is connected to the system in order to take measurement samples and send them to a computer. In spite of collecting and calibrating data, graphical user interface (GUI) software is also designed. In addition, calibration technique using a one-port error model was programmed in GUI to perform the error correction in order to overcome systematic errors of the reflectometer. The final result points out that this reflectometer has the best accuracy in th region between 0 dB and −12 dB, in which total error is lower than 2 dB. The reachable limit of this reflectometer is −25 dB.