Dual-Functional Electrically Small Huygens Antenna System

© 2018 KIEES. A dual-functional electrically small Huygens antenna system is introduced for wireless power transfer (WPT) and communication applications at 915 MHz. This dual-functional system is facilitated by using two orthogonally-oriented electrically small Huygens linearly polarized (HLP) dipole subsystems. Each HLP antenna consists of two metamaterial-inspired near field resonant parasitic (NFRP) elements, i.e., the capacitive loaded loop (CLL) and the Egyptian axe dipole (EAD). A rectifier circuit is integrated with one of the HLP antennas to facilitate its function as a rectenna for WPT applications. The other HLP antenna serves the communication applications. Due to the large isolation (> 30 dB) between these two HLP subsystems, their functionalities are independent. A successfully fabricated and measured prototype demonstrates that this highly-integrated dual-functional antenna system has excellent performance characteristics. It is electrically-small (ka < 0.77) and produces unidirectional Huygens (cardioid) broadside realized gain patterns with broad beamwidths. It has a high AC to DC conversion efficiency. The antenna system is an excellent, practical candidate for wireless Internet-of-Things (IoT) applications

Eletrically-Small Rectenna with Huygens Radiation Pattern for Wireless Power Transfer Applications

© 2018 IEEE. An electrically-small Huygens rectenna is reported that operates at 915 MHz in the ISM band for wireless power transfer (WPT) applications. The rectenna consists of an electrically-small Huygens linearly-polarized (HLP) antenna and a rectifier circuit. The HLP antenna is developed by systematically combining two near-field parasitic resonant (NFPR) elements: an Egyptian axe dipole (EAD) and a capacitively loaded loop (CLL), together, with a small dipole antenna. The designed HLP antenna is electrically-small (ka < 0.89), low profile (0.0420), and produces cardioid-shaped directivity patterns with a very satisfactory peak realized gain value (4.4 dBi), wide half power beamwidth (136°), and high front-to-back ratio (26 dB). A rectifier circuit is designed and integrated with the HLP antenna to realize the rectenna. The rectifier consists of one HSMS286 Schottky diode and three lumped elements. The rectenna achieves a maximum RF to DC conversion efficiency: 86%, and a 2.4 V output DC voltage for a -5.0 dBm input power. Owing to its compact footprint and excellent radiation performance, this electrically-small rectenna is suitable for wirelessly powering sensors and unmanned aerial vehicles (UAVs)

Compact, omni-directional, circularly-polarized mm-Wave antenna for device-to-device (D2D) communications in future 5G cellular systems

© 2017 IEEE. A simple, compact, omni-directional, circularly-polarized (CP) millimeter-wave antenna for Device-to-Device (D2D) communications in the next generation (5G) cellular systems is reported. It is a CP omni-directional antenna operating at 28 GHz for mobile terminals. The antenna combines a vertical electric monopole element with four magnetic elements to coherently excite parallel electric and magnetic dipoles. This combination generates the omni-directional CP radiation. The overlapping -10-dB impedance and 3-dB axial ratio (AR) bandwidth is from 27 to 28.5 GHz, which covers the 28 GHz frequency band proposed for 5G mobile cellular networks (i.e., from 27.5 to 28.35 GHz). The antenna has an omni-directional radiation pattern at 28 GHz whose peak realized RHCP gain is 2.08 dBic and whose 3-dB AR beamwidth is wide, from elevation angles 3° to 136°. Mass production of the antenna is possible by PCB manufacturing technologies. The overall size is 3.44 mm × 3.44 mm × 1 mm (ka = 1.1017). Consequently, it could be embedded in many current popular, smart wireless devices such as cell phones, laptops, digital watches, and smart glasses as well as their future versions for operation in 5G cellular networks

Electrically Small Huygens Antenna-Based Fully-Integrated Wireless Power Transfer and Communication System

© 2013 IEEE. This paper introduces the first reported electrically small Huygens dual-functional wireless power transfer (WPT) and communication system operating in the 915-MHz ISM band. It is realized by the seamless combination of a Huygens linearly polarized (HLP) antenna and a highly efficient HLP rectenna. The configuration consists of two orthogonally oriented HLP subsystems. Each one intrinsically combines two pairs of metamaterial-inspired near-field resonant parasitic elements, i.e., an Egyptian axe dipole (EAD) and a capacitively loaded loop (CLL). Through the development of a very tightly coupled feed subsystem that includes the WPT mode's rectifier circuit and the communications mode's feedline while preserving their isolation, the independent operation of both functions is facilitated in an electrically small volume ( ka < 0.77 ). The measured results of its fabricated prototype agree well with their simulated values. The communications mode antenna resonates at 910 MHz and radiates a cardioid-shaped Huygens pattern with the peak gain of 2.7 dBi. The Huygens-based WPT rectenna achieves an 87.2% peak ac-to-dc conversion efficiency at 907 MHz. The dual-functional system is an ideal candidate for many emerging Internet-of-Things (IoT) wireless applications that require simultaneous wireless information and power transfer (SWIPT) and wirelessly powered communications (WPC)

Internet-of-Things Sensors Wirelessly Powered by Electrically Small Huygens Dipole Rectenna

© 2019 Antenna Branch of Chinese Institute of Electronics. Internet-of-Things (IoT) sensors are expected to be ubiquitous in a future smart and sustainable society. Due to the exponential growth of device numbers, powering IoT devices by far field wireless power transfer (WPT) is becoming a necessary trend. This paper introduces two IoT sensors (light and temperature) that are wirelessly powered by a highly compact and efficient electrically small Huygens dipole rectenna. The entire system seamlessly integrates two subsystems. One is the metamaterial-inspired electrically small Huygens antenna that organically combines capacitively loaded loop (CLL) and Egyptian axe dipole (EAD) radiators together. The other is the sensor-augmented rectifier in which the output DC voltage varies as a function of the sensor impedance. The developed wirelessly powered systems can sense light or temperature levels and, when attached to an alarm, can send a warning signal if a threshold value is exceeded. Their prototypes were fabricated and tested. The measured results agree very well with their simulated values. The prototypes are highly compact and electrically small (ka = 0.73). They represent ideal candidates for many emerging IoT wireless sensor applications

Wirelessly Powered Light and Temperature Sensors Facilitated by Electrically Small Omnidirectional and Huygens Dipole Antennas

Wirelessly powered, very compact sensors are highly attractive for many emerging Internet-of-things (IoT) applications; they eliminate the need for on-board short-life and bulky batteries. In this study, two electrically small rectenna-based wirelessly powered light and temperature sensors were developed that operate at 915 MHz in the 902-928-MHz industrial, scientific, and medical (ISM) bands. First, a metamaterial-inspired near-field resonant parasitic (NFRP) Egyptian axe dipole (EAD) antenna was seamlessly integrated with a highly efficient sensor-augmented rectifier without any matching network. It was electrically small and very thin, and its omnidirectional property was ideal for capturing incident AC wireless power from any azimuthal direction and converting it into DC power. Both a photocell as the light sensor and a thermistor as the temperature sensor were demonstrated. The resistive properties of the photocell and thermistor changed the rectifier's output voltage level; an acoustic alarm was activated once a threshold value was attained. Second, an electrically small, low-profile NFRP Huygens antenna was similarly integrated with the same light- and temperature-sensor-augmented rectifiers. Their unidirectional nature was very suitable for surface-mounted wireless power transfer (WPT) applications (i.e., on-body and on-wall sensors). Measurements of the prototypes of both the light- and temperature-sensor-augmented omni- and unidirectional rectenna systems confirmed their predicted performance characteristics

Electrically Small, Low-Profile, Huygens Circularly Polarized Antenna

© 1963-2012 IEEE. The design, simulation studies, and experimental verification of an electrically small, low-profile, broadside-radiating Huygens circularly polarized (HCP) antenna are reported. To realize its unique circular polarization cardioid-shaped radiation characteristics in a compact structure, two pairs of the metamaterial-inspired near-field resonant parasitic elements, the Egyptian axe dipole (EAD) and the capacitively loaded loop (CLL), are integrated into a crossed-dipole configuration. The EAD (CLL) elements act as the orthogonal electric dipole (magnetic dipole) radiators. Balanced broadside-radiated electric and magnetic field amplitudes with the requisite 90° phase difference between them are realized by exciting these two pairs of electric and magnetic dipoles with a specially designed, unbalanced crossed-dipole structure. The electrically small (ka = 0.73) design operates at 1575 MHz. It is low profile 0.04λ0, and its entire volume is only 0.0018λ03. A prototype of this optimized HCP antenna system was fabricated, assembled, and tested. The measured results are in good agreement with their simulated values. They demonstrate that the prototype HCP antenna resonates at 1584 MHz with a 0.6 dB axial ratio, and produces the predicted Huygens cardioid-shaped radiation patterns. The measured peak realized LHCP gain was 2.7 dBic, and the associated front-to-back ratio was 17.7 dB

Circularly Polarized Antenna with Reconfigurable Broadside and Conical Beams Facilitated by a Mode Switchable Feed Network

© 1963-2012 IEEE. A pattern-reconfigurable slot-augmented patch antenna is reported that radiates circularly polarized (CP) fields and is switchable between a broadside and a conical radiating mode. Two novel design strategies were adopted to realize these advantageous performance characteristics. First, a mode switchable feed network which includes a set of eight L-probes was developed that facilitates the proper excitation of either the patch's TM11 or TM21 mode and yields symmetric radiation patterns. Second, their operating bands were made to overlap by augmenting this patch with an annular slot. Consequently, the radiation pattern is easily switched between the broadside and the conical modes within the overlapping operational bandwidths. A prototype was fabricated and tested. The measured results are in good agreement with their simulated values, verifying the design concepts. The measured operating bandwidth, 7.8% from 2.45 to 2.65 GHz, was determined from the overlap of the impedance and axial ratio bandwidths for both modes. The measured realized gain values are stable for both radiating states within this operational bandwidth, the broadside (conical) peak value being 8.5 dBic (5.8 dBic). The CP pattern reconfigurability of this antenna with its favorable performance characteristics makes it an ideal candidate for many RFID and satellite communication applications

Circularly polarized electrically small antennas for emerging wireless applications

© Institution of Engineering and Technology.All Rights Reserved. This paper introduces three circularly-polarized (CP) electrically small antennas for emerging wireless applications including wireless power transfer (WPT), Internet-of-Things (IoT), and Device-to-Device (D2D) communications in future fifth generation (5G) systems. First, an electrically small Huygens CP (HCP) antenna operating at L-band frequencies is presented that is facilitated by two near-field resonant parasitic (NFRP) elements, a crossed Egyptian axe dipole (EAD) pair and a crossed capacitively loaded loop (CLL) pair. The HCP antenna is electrically small (ka = 0.73), low profile (~ 0.04°0), and has decent cardioid-shaped radiation patterns with a broad half power beamwidth (>120°). It is attractive for many WPT and body-centric wireless sensor network applications. Second, with the rapid development of 5G wireless networks, a corresponding 28 GHz electrically small HCP antenna is reported. The overall size of this antenna is only p (1.5)2 × 1 ˜ 7 mm3 (ka = 0.94), which can be readily integrated into the various compact platforms anticipated for 5G IoT devices. Third, unlike the above two antennas that radiate uni-directional patterns, a compact 28 GHz omni-directional CP (OCP) antenna is presented for D2D communications in future 5G systems. It is electrically small (ka = 0.95), easy to fabricate, and its performance characteristics cover the entire FCC-specified 5G, 27.5 to 28.35 GHz band

Pattern reconfigurable techniques for LP and CP antennas with the broadside and conical beams

© Institution of Engineering and Technology.All Rights Reserved. This paper presents two pattern reconfigurable techniques to realize linear (LP) and circular (CP) broadside and conical-beam switchable radiation patterns from a single antenna. First, a wideband monopolar patch and a L-probe fed patch were organically integrated together to achieve a wideband (2.25 to 2.85 GHz) broadside and conical-beam pattern reconfigurable system that radiates LP radiation. Radiation coverage and wireless channel capacity were improved significantly making the reported LP antenna a good candidate as a ceiling mounted antenna for indoor wireless communications. On the other hand, a circularly-polarized (CP) broadside and conical-beam reconfigurable antenna would be preferred for satellite communications. To realize it, we successfully excited both the TM11 and TM21 modes on a circular patch with an annular slot antenna. A reconfigurable feeding network was designed to provide the correct excitations for these two modes. CP switchable broadside and conical radiated beams were realized within the same overlapping frequency ranges from 2.45 to 2.65 GHz. Both the LP and CP antennas were fabricated and tested. Experimental results show good agreement with their simulated performance characteristics. Very good radiation performance was obtained