Small Antennas bandwidth enhancement Using Network Characteristic Modes

With the rapid development of wireless communication, antenna miniaturization is still a field of intense research activities with remarkable achievements, where nowadays a wireless device is supposed to carry multiple antennas operating at different frequencies and standards. Extensive studies were conducted to miniaturize and enhance the performance of small antennas, by designing complex structures addressing the issue of enhancing the bandwidth/efficiency of small antennas. In this context, input matching networks were adapted to match the antenna in a specified bandwidth. Nevertheless, these networks are passive and are limited by the gain and bandwidth [1, 2]. Multiport antenna systems can be regarded as N-port networks, which can be analyzed using the theory of network characteristic modes (NCMs). Due to the profound physical insights provided by an NCM, a desired antenna performance can be achieved by properly manipulating the modes through reactive loading at specified ports.