A Novel Wideband Decoupling Network for Two Antennas Based on the Wilkinson Power Divider

In this article, a wideband decoupling network (DN) is presented based on the Wilkinson power divider (WPD). The DN is composed of 2 two-way unequal WPDs, three transmission lines (TLs), and two reactive components. Two techniques are introduced for the wideband performance: 1) by using the WPD with high output isolation, the antenna matching becomes independent of antenna decoupling. So, the decoupled antennas with the proposed DN could perform broad impedance bandwidths without using matching networks and 2) the DN is designed to minimize antennas' coupling coefficients at two frequencies, which collectively contribute to a broader decoupling bandwidth. In addition, rigorous design formulas are presented along with systematic design procedures. Based on this, the TL lengths and component reactances can be precisely calculated instead of being fitted to achieve high antenna isolation. Two decoupling cases using the proposed DN and its simplified model are presented and compared to give an intuitive illustration of the wideband mechanism. The measurement results for decoupling case #1 show that a very wide isolation bandwidth of 23.7%, total efficiency over 65%, and the envelope correlation coefficients (ECCs) less than 0.05 can be achieved simultaneously using the proposed DN.