Practical approach - tunable antennas and tunable matching networks

In this paper, we perform a detailed study to compare tunable matching networks and tunable antenna elements. The study is mainly focused on ascertaining which method will help achieve the design targets in terms of system capabilities for transmitting and receiving RF power. For this study we use a practical M2M device that is currently certified with multiple carriers in North America [1]. We used both radiated power and return loss to study system performance. Both simulation and measurement results revealed that in the low frequency band, the performance with tunable matching network was better than the performance with aperture tuning. This is valid for power accepted and radiated by the antenna. In the high frequency band, the power accepted by the antenna is improved in the case of the tunable matching network over the aperture tuning method; however, the power radiated was lower. This is due to losses introduced by the reactive elements used in the matching network.