A Wideband High Front-to-Back Ratio Directional Filtering Slot Antenna and its Application in MIMO Terminals

In this paper, a directional filtering slot antenna with a wideband high front-to-back (F/B) ratio is proposed, which aims to improve the anti-interference capability of the unit antenna in the spatial and frequency domains and reduce the coupling between MIMO units. The fundamental structure of this antenna is a transformed defective ground slot antenna, featuring superior filtering attributes in the frequency domain. To achieve a wideband F/B, boost the directional characteristics, and further augment the anti-interference capabilities of the filtering slot antenna, the leading terminal and slot are, respectively, integrated into the filtering antenna. A 2×2 MIMO antenna ensemble is also designed, utilizing the directional filtering slot antenna as the element. This antenna not only exhibits commendable filtering proficiency across the frequency and spatial domains but also effectively inhibits the surface wave and space wave coupling between MIMO antenna units. The simulated and measured results show that the operating bandwidth of the directional filtering slot antenna is 2.8-11.3 GHz, the F/B of the radiation pattern is larger than 15 dB, and the isolation between the 2×2 MIMO antenna units is greater than 20 dB without any decouplingstructure.