Switched Polarized H-Field Forming Using a Planar Switchable Double-Dumbbell Coil Antenna for Orientation-Oblivion Wireless Power Transfer

A planar switchable multicoil transmitter (Tx) antenna is presented to eliminate angular misalignment problems in near-field wireless power transfer (WPT) applications. To power the receiver (Rx) antenna in any orientation, the previous methods of 3-D rotating
$H$
-field forming required complex feeding with multiple modulated sources. As an alternate, a switched polarized
$H$
-field is proposed, which conjoins the field-forming technique with switching control to exploit the orthogonal field components using a single excitation source. The switching periods and the corresponding
$H$
-field components are controlled to satisfy analytically derived constraints for complete mitigation of the angular misalignment problem. To generate this switched polarized
$H$
-field, the proposed antenna comprises planar single axial and double dumbbell coils optimized to provide a maximum
${S}21$
with the Rx coil such that a maximum link efficiency is obtained under the field constraint. The switching is integrated with the design using two single pole double throw (SPDT) switches and a planar cost-effective realization in printed circuit board (PCB) technology is achieved. The proposed approach and the antenna are experimentally validated and the results are corroborated showing a constant voltage induced in the Rx coil with a standard deviation of 0.0028 V. The results proved the potential of the proposed switchable Tx antenna generating switched polarized
$H$
-field for orientation-oblivion WPT applications.