Simulation and Measurements of VSWR for Microwave Communication Systems

Nowadays, microwave frequency systems, in many applications are used. Regardless of the application, all microwave communication systems are faced with transmission line matching problem, related to the load or impedance connected to them. The mismatching of microwave lines with the load connected to them generates reflected waves. Mismatching is identified by a parameter known as VSWR (Voltage Standing Wave Ratio). VSWR is a crucial parameter on determining the efficiency of microwave systems. In medical application VSWR gets a specific importance. The presence of reflected waves can lead to the wrong measurement information, consequently a wrong diagnostic result interpretation applied to a specific patient. For this reason, specifically in medical applications, it is important to minimize the reflected waves, or control the VSWR value with the high accuracy level. In this paper, the transmission line under different matching conditions is simulated and experimented. Through simulation and experimental measurements, the VSWR for each case of connected line with the respective load is calculated and measured. Further elements either with impact or not on the VSWR value are identified. Interpretation of simulation and experimental results allows to judge about improving the VSWR, and consequently increasing the microwave transmission systems efficiency.