Abstract:
A dual-purpose radial-array rectenna is presented
as a potential sensor candidate for RF-energy harvesting (EH)-
enabled Internet of Things (IoT) nodes along with orientation
sensing capability. The proposed design comprises eight rectenna
elements placed radially in azimuth to capture RF energy from
entire 360◦ angular region to improve tolerance for angular
misalignment and make the design orientation-oblivious. As dualpurpose, the capability to sense its own orientation with respect
to the transmitter is additionally provided. Each rectenna consists
of a horizontally polarized compact planar scoop-shaped antenna
designed at 5.8 GHz having endfire radiation pattern with 7-dBi
gain. The dc power patterns of the proposed design are calibrated
and used to estimate orientation using minimum mean square
error (MMSE) method. The design is verified experimentally,
and the results indicate average orientation estimation error of
1.0822◦ with 0.9242◦ standard deviation and improved stability
in energy-harvesting compared to single rectenna element for
varying orientation of IoT nodes.
