Design of a Varactor-Based Matching Network Using Antenna Input Impedance Variation Knowledge

It is commonly assumed that the antenna input impedance remains static during the transmission and reception process. However, in a real scenery the impedance value is a dynamic parameter, affected by the user and the environment, that can be very different compared to the static situation. With a statistical approach, the impedance variation can be characterized in the matching domain. This information can be very useful for the design of efficient adaptive matching circuits. In this paper, we propose the design and optimization of a varactor-based tunable matching network (VMN) to improve the antenna matching, using the previous knowledge of the antenna input impedance variations. Improvements in power transmission greater than 3 dB for the originally unmatched region, and reduced power losses (under -0.5 dB) in the originally matched area can be achieved using this circuit.