A Switchable Multicoil Antenna With Booster Coil to Improve Coverage in WPT Systems

In this article, a planar distributed multicoil transmitter antenna is presented for wireless power transfer (WPT) applications. The proposed antenna is optimized to mitigate lateral misalignment problems and configured to operate in two different modes. The antenna switched to the normal mode excites a chief coil to form a concentrated
$H$
-field within the perfectly aligned receiver area. Encircling the chief coil, a set of booster coils is incorporated in the design which is switched on in enhanced mode to stretch the
$H$
-field uniformity whenever the receiver is misaligned. As a result, the proposed design evolves into a switchable planar distributed multicoil (SPDMC) antenna. Using a field forming technique based on a minimum mean square error algorithm, dimensional parameters of the proposed antenna are optimized. The proposed antenna improves stability in the power transfer efficiency which is verified by measuring the
$S21$
parameter. The
$S21$
stability achieved in the Rx working area is 98
$\times98$
mm
²
which corresponds to a 255% improvement over an existing design of the same dimension in the literature. The proposed SPDMC antenna is proven to be highly insensitive to lateral misalignment and a good antenna candidate for various short- and medium-range WPT applications.