Mobile device antenna design & isolation technologies

Abstract

Mobile device antenna design and isolation technologies are thoroughly investigated in this thesis. The antenna design parameters for mobile devices are quantified using practical restraints by analyzing almost 60 mobile handsets and the effect of materials, human tissue, manufacturing, and antenna type/placement on antenna design and then mapped into Wheeler-space that correlates the spherical wave modes with the antenna performance. The isolation technologies with mutual coupling anti-resonances are unified by a single performance parameter to distinguish them from the more traditional isolation technologies. This unifying performance parameter is the group delay between two antennas where high group delay indicates the presence of a bandstop filter in the form of either a PCB or an antenna modification. This thesis analyzes both PCB and antenna modifications with high group-delay and demonstrates these types of antennas can be placed in close proximity without affecting other performance parameters. It is also shown that both the PCB and antenna modifications contain two isolation methods where each isolation method is a mirror complement of the other method. Some antenna geometries can also increase the mutual coupling in order to improve the antenna performance using a phenomena called over-coupling. These over-coupled antenna systems can result in lower SAR for the cellular antennas and decreased array sizes for NFC/RFID/wireless-power antennas, resulting in better performance of antennas inside mobile devices.