Electrically Small, Low-Profile, Highly Efficient, Huygens Dipole Rectennas for Wirelessly Powering Internet-of-Things Devices

Abstract

Wireless power transfer (WPT) technologies are a major trend for emerging Internet-of-Things (IoT) applications. Because they negate the need for heavy, bulky batteries and can power multiple elements simultaneously, WPT systems enable very compact, ubiquitous IoT wireless devices. However, the realization of high performance, ultra-compact (electrically small) rectennas, i.e., the rectifying antennas that enable mid-range and far-field WPT, is challenging. We present the first electrically small (ka < 0.77) and low profile (0.04 λ0) linearly (LP) and circularly (CP) polarized WPT rectennas at 915 MHz in the IMS band. They are facilitated by the seamless integration of highly efficient rectifiers, i.e., RF signal to DC power conversion circuits, with electrically small Huygens dipole LP and CP antennas. Their optimized prototypes have cardioid, broadside radiation patterns and effective capture areas larger than their physical size. Experimental results validate that they achieve an 89% peak ACto-DC conversion efficiency, effectively confirming that they are ideal candidates for many of the emerging IoT applications. Index Terms-Electrically small rectennas, Huygens radiation pattern, internet-of-things (IoT), rectifier circuits, wireless power transfer.

Custom-Designed Electrically Small Huygens Dipole Antennas Achieve Efficient, Directive Emissions Into Air When Mounted on a High Permittivity Block

“…The achieved radiation efficiencies are quite high and are inline with those previously demonstrated with measured HDA prototypes [23]- [29]. In anticipation for an actual experiment at RF or lower millimeter wave (mm-wave) frequencies, the high permittivity material was selected to be a well-known low loss copper-cladded board material.…”

“…Circularly polarized (CP) properties would further enhance their performance since they facilitate mitigation of any polarization mismatch issues. CP HDAs [17] and HDA-based rectennas [29] related to the customdesigned ones reported herein have been developed recently. The demonstration that NFRP HDAs can overcome a common OCA bottleneck coupled with their proven versatility of being tailorable to a variety of application environments such as on human bodies and their demonstrated high efficiencies suggest they have the potential to meet a variety of prerequisites of 5G wireless SoC-based and other IoT devices.…”

A Metamaterial-Inspired Approach to Mitigating Radio Frequency Blackout When a Plasma Forms Around a Reentry Vehicle

“…Ultimately, a unidirectional antenna is highly desired for any "sub-exterior surface" antenna system. The electrically small Huygens dipole antennas developed in [31][32][33][34] are advantageous in this regard. The linearly-polarized Huygens antenna is made up of three major components: a capacitively loaded loop (CLL), an Egyptian axe dipole (EAD), and a smaller dipole that excites these near-field resonant parasitic (NFRP) elements by coupling energy into them.…”

Design of a Rectenna Array Without a Matching Network

“…Such rectenna system is an integral and critical part of Wireless Power Transfer systems (WPT). Since their main goal is to deliver energy wirelessly to a load, rectennas enabled numerous applications such as Space Solar Power [1], [2], energy harvesting/scavenging [3]- [5], remote sensing [6], [7], Internet Of Things (IOT) [8]- [10], wireless battery charging [11], and infrared detection [12], [13].…”