Load impedance estimation for fast and accurate configuration of tunable matching networks

The use of tunable matching networks (TMNs) for antenna tuning and efficiency enhancement is well-known. However, finding the optimum TMN state or configuration is not an easy task and an incorrect process may lead to a poor performance. If we are able to estimate the load impedance, the TMN state choice can be done quickly and properly with some previous off-line calculations. In this paper we propose a new technique to estimate a complex load impedance with scalar measurements at three different states of the TMN. With an appropriate calibration process, following the idea of six-port measurements, accurate load estimation will be obtained, leading to an optimum TMN state configuration.