Dynamic Antenna Impedance Tuning for Sub-GHz Systems

In all wireless systems, high power transfer from the RF front-end (RFFE) to the antenna is required. To achieve this, impedance matching between the RFFE and the antenna is necessary. Most applications assume a static antenna impedance for a given frequency band and thus only require a single static matching network per band. In reality, changing near-field conditions (e.g. due to human interaction) require a rapid adaption or in-band mismatch requires a finer change in impedance matching. This work introduces and compares several topologies that allow dynamic adaptive antenna impedance tuning in sub-GHz applications. They even permit a strong mismatch with a voltage standing wave ratio (VSWR) of 20:1 with a high power rating suitable for transmission in mobile applications.