Distributed Mobile Antennas: A Novel Miniaturized Wideband Antenna Strategy to Maximize the Use of the Fragmented Spaces of the Mobile Terminals
Shan Gao, Le Chang, Steven Gao, Anxue Zhang
Abstract
The contradiction between numerous antennas and limited antenna space in mobile terminals has prompted the exploration of the back cover space. However, the available spaces are segmented into fragmented pieces by the electronic components inside the terminal. This article addresses the problem of how to utilize these fragmented spaces efficiently. A novel miniaturized wideband antenna strategy called distributed mobile antennas is proposed and the distributed two-element antennas are introduced. By assigning a 90° phase difference, the reflections looking toward these two antennas are equal in magnitude but opposite in phase, leading to reflection cancellation. Therefore, wideband matching can be achieved and the bandwidth can be further improved by introducing the degree of freedom of the element size consistency. When the proposed strategy is applied to a normal patch, the measured results show that the impedance bandwidths are improved by <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.6\times $ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4.6\times $ </tex-math></inline-formula> for the identical and dissimilar patch cases, respectively. When applied to a miniaturized patch, the bandwidths are improved by <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$6.0\times $ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$6.9\times $ </tex-math></inline-formula>. Moreover, due to the dispersion of hotspots by distributed two-element antennas, the specific absorption rate (SAR) achieves great average reductions of 1.4–2.4 dB. The proposed wideband strategy has great potential for applications in modern 5G mobile terminals.