An Improved Topology for Adaptive Agile Impedance Tuners

Abstract

Mobile devices are used in unpredictable dynamic environments making favorable antenna performance a challenge. There is great interest in antennas that can operate over a wide range of frequencies in a multitude of environments. To accommodate the range of possible antenna impedances for tuning, it is required to use reconfigurable agile matching circuits. Many existing tuning topologies seek to minimize | <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> | of the matching network. While this is suitable for less demanding tuning systems, such a network can potentially maximize circuit losses in aggressively agile systems. In this letter, we present an understanding of circuit-loss mechanisms along with tuning topologies that maximize a circuit's efficiency for agile systems. It is demonstrated that proper sensing with directional couplers is necessary to maximize power delivered to the load. Validations are provided through fabrication and measurement of an agile tuning network operating at UHF.