Wideband Six-Port Reflectometer for Microwave Applications.

In this paper, a wideband reflectometer based on six-port technology is presented. The designed six-port junction is built by using a modified ring power divider and three identical 90-degree hybrid couplers. The main difference from its initial application as a conventional six-port reflectometer is the addition of a fourth qi point. Here, the four power detectors are used to find the reflection coefficient (4 qi points) and a fifth detector is added as a reference. To simplify the fabrication process and minimize the cost, the six-port circuit is designed on a single-layer PCB. The measured results of the six-port junction reveal high performance over a large frequency band from 2.2 to 3.55 GHz. In order to evaluate its performance for real-time measurements, the proposed six-port reflectometer is then tested by measuring the reflection coefficient of different devices under test (DUTs). The measured results are then corrected by a simplified calibration method to have optimal results. Compared to conventional six-port calibration methods, the proposed calibration process is simple and allows accurate reflection coefficient measurements. After calibration, there is a great improvement in the corrected results of the reflection coefficient compared to the measured results which proves that the calibration process works perfectly from 2.6 to 3.8 GHz. [ABSTRACT FROM AUTHOR]