Daasari Surender, Md. Ahsan Halimi, Taimoor Khan, Fazal A. Talukdar, Nasimuddin, Sembiam R. Rengarajan
IMAGE LICENSED BY INGRAM PUBLISHING
In this article, we present an overview of the 5G rectifying antenna and its primary elements for applications in millimeter-wave (mm-wave) energy harvesting (EH) and wireless power transmission (WPT). The wide spectrum available for 5G communication bands have attracted significant attention for extensive applications. The power received by the harvesting antenna relies on the size of the antenna. Hence, the realization of antenna and rectenna systems with good efficiency at 5G mm-wave is a challenge. This review article highlights the recent advances in 5G rectenna systems for different applications at the component and structure levels. The primary objectives of the article are 1) to explore the potential advances of mm-wave rectenna systems and the feasibility of their designs to attain desired characteristics and 2) to present a comparative assessment of performance parameters of existing rectenna systems.
Demands for extremely high data rates, large network capacity, and flawless connectivity have increased globally as wireless technologies, such as 5G cellular systems, the Internet of things (IoT), and machine-to-machine, machine-to-human, and human-to-machine communications, have advanced. 5G communication has been considered an appealing approach for meeting energy demands. The prime objective of 5G communication systems is to supply cellular consumers with higher data rates, lower power consumption, and better quality of services consistently. The frequency spectrum of 5G communication has been divided into several bands, including lower-band 5G (<1 GHz), midband 5G (3.1–6 GHz), and higher-band 5G (24.25–52.6 GHz) [1], [2], [3].
The rapid growth of the IoT and smart cities with increased data rates necessitates the deployment of millions of IoT devices with sensors. This could affect a large number of batteries that need to be charged and changed regularly. As a result, the design and implementation of autonomous self-powered systems, i.e., the unremitting IoT, is essential [4]. A radio-frequency (RF) EH technique is one potential means of achieving these goals. Researchers are now interested in the RFEH approach because of its unique features, such as maximum conversion efficiency and environmental independence, compared to other EH approaches. The rectenna is a specialized device designed exclusively for RFEH applications. The basic elements of the rectenna are the antenna and the rectifier [5]. The rectenna was investigated for WPT applications initially and also explored in RFEH applications [6]. The 5G/mm-wave bands are studied extensively in the outside atmosphere, due to increased energy demands. As a result, establishing 5G mm-wave rectenna systems for mm-wave EH/WPT applications is desirable.
Many review articles on rectennas for mm-wave EH/WPT applications have been reported in the literature; however, their scope has been limited [7], [8], [9], [10], [11]. Wagih et al. [7] have reviewed rectennas at mm-wave, including the higher band of 5G for mm-wave EH/WPT applications. Wagih et al. [8] have reviewed applications of rectennas in RFEH and WPT in view of antenna impedance bandwidth and radiation properties. Sleebi et al. [9] have reviewed the rectenna, its design challenges, and different rectifier topologies suitable for rectenna system design. Hassani et al. [10] have reviewed an RFEH approach for IoT systems. They highlighted the design requirements of RFEH for 5G systems and design constraints. Surender et al. [11] have reviewed various rectenna systems based on their frequencies of application. However, the reported review articles are not focused on rectenna systems operating at the frequency bands of current interest, such as 5G/mm-wave operating bands. To the best of the authors’ knowledge, there is no publication addressing 5G/mm-wave rectennas for EH/WPT applications and their performance enhancement.
5G is frequently referred to as the Internet’s enabler for everyone, everywhere, and everything. One of the technological goals of 5G is to increase cellular network capacity by a factor of 100 as compared to 4G (to generate a maximum data rate of >10 Gb/s) [12]. To meet the urgent demands for increased data rates and larger capacity, new spectrum usage techniques, including licensed, unlicensed, and shared spectra, are being researched. Sub-6-GHz (450 MHz–6 GHz) and mm-wave bands (24.25–52.6 GHz) spectrum are now assigned to 5G communication [13]. Sub-6-GHz bands are used to provide more coverage while maintaining reasonable data speeds. They can keep interoperability with 4G at the same time. The 5G standard’s mm-wave bands are intended for ultrahigh-data-rate communication among devices in close proximity.
By 2025, it is expected that there will be over 35 billion linked devices, with over 20 billion of those being machine-to-machine configurations. As a result, one of the most significant tasks of 5G is to enable IoT communications with the ability to run the network independently for accessing services uninterruptedly. On this front, EH is increasingly recognized as a promising solution. The eternal IoT with the design and execution of energy-independent self-powered systems is thus extremely desirable. mm-Wave EH and WPT are possible techniques to achieve these objectives. The mm-wave energy available in 5G wireless mobile bands (above 24 GHz) is a significant source of RF scavenging. This highlights the ability of 5G to construct a useful wireless power network or power grid.
W.C. Brown first proposed the concept of the rectenna in the 1960s, intending to drive a model helicopter (Figure 1). WPT and helicopter technology have been successfully coupled to create a flying aircraft that is powered purely by a microwave beam [14], [15]. The significance of microwave-powered helicopter research goes far beyond its ability to give a new and practical capability in aerospace. The improved microwave energy-generating technology at superpower levels has enabled WPT over long distances for remote energization of objects and vehicles without the use of cables. WPT applications are explored in the fields of sensing, implantable devices, self-powered sensors, and so on. The rectenna is a device that helps to perform various applications of WPT.
Figure 1. The wireless powered transmission experimental setup with a flying drone model by W.C. Brown. (a) The basic elements of a microwave- powered helicopter system [6]. (b) First WPT-aided flying drone experiment. [14].
Rectennas are composed of an antenna, an impedance matching network (IMN), a rectifier, and a dc pass filter, as illustrated in Figure 2. The amount of power input to the rectenna system may affect the overall rectenna system output. The power input to the rectenna system can be increased by a suitable antenna, which is possible because of the high-gain, multiresonance, broadband resonance, and wide coverage characteristics of the antenna. A rectifier is one of the essential components of a rectenna system. The performance of the rectifier mainly relies on the selection of an appropriate diode and suitable rectifier topology. Schottky diodes are found suitable at RF power levels, due to their fast switching speed and low turn-on voltage. The diode is usually chosen based on the level of RF power input to the rectifier circuit and the operating frequency of the received RF energy. Generally used rectifier topologies are a half-wave rectifier (shunt/series), a voltage doubler rectifier (VDR), a full-wave bridge rectifier (FWR), and a Greinacher rectifier. The fundamental performance characteristics of the rectenna for both RFEH and WPT applications are presented in Table 1. Various design approaches to mm-wave EH/WPT systems for 5G applications are discussed in the following sections in detail.
Figure 2. A rectenna system. LPF: low-pass filter.
Table 1. The performance characteristics of rectenna systems.
This section illustrates various approaches to RFEH/WPT systems to operate at 5G within the frequency band of 0.5–6 GHz. The primary intention of any rectenna system is to harvest as much power from an ambient/dedicated source as possible and to increase the rectenna system output. Different classification-based strategies are explored in this part to suit the criteria of RFEH/WPT systems.
An irregular diamond shape of the radiator was adopted for multiresonance characteristics, including 5G [16]. A monopole antenna with a circular geometry and equally spaced rectangular strips has been investigated for reconfigurability at the operating band [17]. A modified E-shaped microstrip antenna [18], a fan-shaped structure with a coplanar waveguide (CPW) feed [19], and a slit-loaded bow tie antenna fed by a pair of microstrip lines [20] were employed for 5G RFEH applications. A notch included a slotted-ground plane [21] and a hexagonal slot embedded in a circular monopolar antenna [22], widening the operating range. A back-to-back approach to the patch helps achieve wide angular coverage [23] (see Figure 3).
Figure 3. Antenna configurations for sub-6-GHz RFEH applications.
A CMOS-based multistage rectifier with two different paths for low and high input power levels was designed for harvesting applications [24]. For designing a dual-band rectifier, a Greinacher rectifier topology was investigated in [25]. A shunt diode rectifier using a high-impedance microstrip line was designed in [26]. A dc feedback loop was created for enhancing the rectifier performance at low input power levels and also to operate the rectifier efficiently across a wide range of input power levels (see Figure 4).
Figure 4. Rectifier topologies for sub-6-GHz RFEH applications. BPF: bandpass filter; MSL: microstrip line, SBD: shottky barrier diode.
Rectenna performance was investigated with different combinations of rectifier array circuits, such as 1 × 1, 2 × 2, 4 × 4, and 8 × 8 [27]. It is noticed that the number of elements in an antenna array affects the output voltage more than the efficiency, as shown in Figure 5. A rectenna using a modified E-shaped microstrip antenna and a two-stage voltage multiplier [28] as well as an optical rectenna system using a solar cell antenna [29] were designed for IoT applications. A flexible keyhole shape of an antenna and a VDR were used in the rectenna design [30]. A rectifier consisting of two tapered lines connected at the core of the rectifier circuit enhanced the rectifier power conversion efficiency (PCE) and output voltage performance.
Figure 5. A performance comparison: (a) efficiency and (b) output power [27]. dBm: decibels referenced to 1 mw.
A CPW-fed circular patch antenna deposited on a transparent polyethylene terephthalate substrate for efficient operation in both indoor and outdoor conditions was designed in [31]. In [32], a dual-band rectenna was developed using an antenna with a slots-loaded ground plane and a series-connected rectifier circuit. A rectenna with a combination of a stub-loaded planar antenna and a half-wavelength shunt rectifier has been presented [33]. The length of the stubs controls the operating frequency of the antenna circuit. A spiral-slot antenna integrated into a diplexer and transponder circuitry was chosen for designing the rectenna [34].
The sub-6-GHz grid in 5G communication allows for ubiquitous exposure, but it runs into spectrum scarcity, making it difficult to sustain a considerable rise in the number of wireless appliances in 5G and beyond. There is growing interest in putting 5G mm-wave cells beneath existing sub-6-GHz cells to provide appropriate network capacity and widespread coverage. Due to its vast spectrum of resources at higher frequencies, mm-wave has been widely exploited for long-distance communication in terrestrial and satellite applications, resulting in extremely high data rates. Designing an EH/WPT system at the mm-wave 5G band is highly desirable due to its increased availability and its ability to design a harvesting system with a compact dimension (see Figures 6–8).
Figure 6. Rectenna designs for sub-6-GHz RFEH/WPT applications.
Figure 7. The |S11| plots of antenna configurations for sub-6-GHz RFEH/WPT applications.
Figure 8. The radiational characteristics of antenna configurations for sub-6-GHz RFEH/WPT applications.
This section discusses various design approaches to mm-wave EH systems for 5G mm-wave applications.
A dual-patch antenna configuration [35], a two-leg Yagi antenna [36], and a pair of concentric ring slots [37], described in Figure 9, were investigated for mm-wave EH applications. A flexible mm-wave antenna is designed by printing a triangular-shaped patch on a flexible field-effect transistor (FET) substrate [38]. A reconfigurable Y-shaped patch antenna [39] and an asymmetric antipodal Vivaldi antenna (AVA) [40] were developed for mm-wave EH applications. In [39], the reconfigurability is achieved by integrating two p-i-n diodes with the microstrip patch radiator. A flexible textile antenna integrated into an electromagnetic bandgap (EBG) structure was designed for on-body applications in [41].
Figure 9. The antenna geometries for mm-wave EH applications.
In [42], a W-band zero-bias detector from Virginia Diodes was found suitable to operate efficiently up to a frequency of 81 GHz. A multi-IMN consisting of a T-section impedance transformer and a series shunt stub was investigated for tri-band rectifier design in [43] (see Figure 10).
Figure 10. Rectifier configurations for mm-wave EH applications. TL: transmission line; Virtual SC: virtual short circuit.
The performance of a receiving rectifying element (RRE) with different combinations of antenna array cells, such as quadrupoles, double dipoles, collinear wire, and mesh, was investigated [44]. A better rectification efficiency performance of the RRE was achieved with double dipoles and quadrupoles. A mm-wave EH RFID tag was designed with CMOS technology in [45]. A monopole antenna with a three-stage inductive peak rectifier in [46], a CMOS-based rectenna with a dipole antenna and a single-stage Dickson rectifier in [47], and an array of antenna elements in [48], [49], and [50] were investigated for rectenna system design. The array of antennas enhances the antenna gain, thereby increasing the harvested power. Enhanced rectifier performance in terms of PCE was observed using a metal–insulator–metal (MIM) diode at the V band [51]. A graphene FET (GFET)-based rectenna was implemented to increase the impedance bandwidth of the rectifier circuit [52], [53].
A compact harvesting system that is immune to the wireless link parameters and loading variations was designed for biomedical implants [54]. A packaged integrated harvester system operated at 26 GHz was designed to be embedded within 3D-printed multilayer flexible packaging structures [55]. A graphene self-switching diode-based rectenna was investigated experimentally for the first time using a patch antenna array [56]. The graphene diode is designed for the maximum possible nonlinearity in the current–voltage curve. A textile-based rectenna is implemented using an AVA and a VDR for wearable applications [57].
Several mm-wave rectenna configurations for WPT systems have been proposed in recent decades. This section delves into the advancements in rectenna design techniques that have occurred over time. These techniques lower transmission costs and design complexity, provide a high level of power utility, and allow for the installation of a battery management facility.
A coplanar stripline-fed folded dipole in [58], a lens-based antenna for low diffraction loss [59], and a dual-port electromagnetically coupled square patch array antenna in [60] were investigated for WPT applications. The array elements are rotated by 45° to reduce the mutual coupling among the elements. An array of antenna elements is used to achieve a high gain [61], [62]. A metasurface superstrate enhances the harvested power [63], while a metasurface array antenna exhibits a wide angular coverage [64]. A flexible textile antenna with an inset microstrip feed was designed for mm-wave WPT applications in [65]. A triple L-arms patch slotted antenna with a diamond-shaped ground was implemented for 5G applications [66].
A VDR circuit with microstrip technology was developed for WPT applications [67]. To enhance the rectifier PCE, a harmonic harvesting rectifier circuit was implemented using a ${\lambda}$/4 open circuit stub resonator [68]. Transmission line (TL)-based impedance transformers are used to match the real impedance of the antenna and rectifier circuits [69]. An integral form of a double compact microstrip resonant cell low-pass filter and a CPW feedline with CMOS technology have been developed to design a very small-sized rectenna [70]. A TL-based VDR was designed for dual-band characteristics at 28- and 38-GHz frequencies [71]. A CMOS technology-based rectifier was implemented for WPT applications at the W and Ka bands [72]. A performance comparison of the rectifier at two mm-wave frequencies is presented in Figures 11 and 12.
Figure 11. Antenna/rectifier configurations for mm-wave EH applications.
Figure 12. The |S11| plots of antenna configurations for mm-wave EH applications.
It has been shown that it is essential to improve the diode performance for enhancing the rectifier performance at sub-terahertz frequencies [73]. At the W band, the TL-based approach to the matching network shows low loss [74]. The tunnel diode-based rectifier exhibits better conversion efficiency over the Schottky diode-based rectifier for input power levels of <1 dB referenced to 1 mW (dBm) [75], as illustrated in Figure 13(a). A hybrid form of technology involving a two-stage Dickson charge pump/voltage multiplier and gallium arsenide technology was found to be suitable for enhancing the rectifier performance [76] (see Figure 14).
Figure 13. The radiational characteristics of antenna configurations for mm-wave EH applications.
Figure 14. Antenna geometries for mm-wave WPT applications.
The design and development of mm-wave rectennas and power beaming systems were presented in [77]. The diode characteristics at 2.45 and 35 GHz were investigated [78]. An array-based rectenna system exhibits better output voltage performance [79]. A full-wave rectifier-based rectenna with a tapered slot and finite-width ground CPW (FGCPW) TLs using CMOS technology was implemented in [80]. The FGCPW TLs help to reject harmonic components. An adjustable stub and a resonator included after the diode in a shunt topology increase the PCE [81]. Hatano et al. found that the rectenna with a class F load showed better performance than the conventional rectenna with a capacitive load and that the performance increases with an increase in the number of diodes, as revealed in Figure 13(b) [82].
A mm-wave rectifier circuit as a monolithic microwave integrated circuit was fabricated to reduce the rectifier dimension and also to increase the rectifier PCE [83]. A substrate integrated waveguide (SIW) technology of rectenna design reduces the losses [84]. An SIW cavity-backed antenna was integrated into a self-biased rectifier to create a rectenna [85]. The SIW cavity-backed antenna array enhances the gain and also achieves circular polarization (CP). A high-efficiency rectifier was designed using two output class F dc pass filters and a high-gain Fabry–Perot resonator antenna [86]. A rectenna with a grid type of antenna integrated into a complementary cross-coupled oscillator-like rectifier was designed [87]. A simple rectenna was implemented using a dipole antenna and a single diode element [88]. A rectenna using a microstrip patch antenna and a rectifier circuit was designed with microelectromechanical system technology [89]. A fin line transfer circuit was used in the design process for reducing losses. A 35-GHz rectenna was developed using a patch antenna fed by a coupling slot and MA4E1317 diode-based shunt rectifier circuit in [90] (see Figure 15).
Figure 15. A performance comparison: (a) 35 GHz and (b) 94 GHz [72].
A rectenna was implemented by a bow tie-shaped antenna coupled to a MIM diode [91]. A flexible rectenna system for a conformal surface was designed using a flexible cylindrical patch antenna array and a flexible rectifier circuit [92]. In [93], a slot-coupled patch antenna array with SIW cavity back feeding was used for enhanced gain with proper isolation among the elements (see Figures 16 and 17). The performance of rectennas was analyzed for two rectifier topologies using two different diodes at 24 GHz [94]. A performance comparison of two rectenna arrays is investigated in [95], as revealed in Figure 18. A transparent optical rectenna was investigated for the first time for harvesting purposes [96]. A rectenna was designed using a tapered slot antenna and a CMOS switching rectifier to increase the antenna gain, radiation efficiency, and PCE [97]. A similar output performance to that presented in Figure 18 was observed with the increased number of rectenna array elements [98]. The rectenna system was experimentally demonstrated with a free-flight AR Drone at an altitude of 800 mm [99] (see Figures 19 and 20).
Figure 16. Rectifier topologies for mm-wave WPT applications. MN: matching network.
Figure 17. The rectenna performance: (a) Vout [75] and (b) PCE [82].
Figure 18. The rectenna array performance variation: (a) a 1 × 2 rectenna array and (b) a 2 × 2 rectenna array [95].
Figure 19. Antenna/rectifier configurations for mm-wave WPT applications.
Figure 20. The |S11| characteristics of antenna/rectifier configurations for mm-wave WPT applications.
To direct the radiated energy from the base station antenna array to the end user while overcoming increasing path losses, beam steering antennas will be required as 5G moves into higher frequencies (see Figure 21). Beam steering permits a signal to be concentrated in one direction instead of radiating over 120º, as it would do typically. Electronically steerable antennas (ESAs) control the signal, allowing for more precise propagation and a faster more reliable connection than would be possible otherwise. This reduces the propagation loss and extends the range of 5G in mm-wave frequencies. The Rotman lens is a unique and economical way to do mm-wave beam steering.
Figure 21. The radiational characteristics of some antenna configurations for mm-wave WPT applications.
Dense mm-wave networks may provide comparable coverage and data rates to traditional microwave networks [100]. Advanced beamforming techniques that allow multiuser transmission can be used to generate a large gain. A hybrid power combining approach that adapts a beamforming matrix was proposed for achieving both a large dc output and wide angular coverage [101]. A 4 × 4 Butler matrix has been investigated for beam scanning and power transmission applications [102]. Larger antenna arrays have been used at mm-wave frequencies to realize higher gain values [103]. A beamforming network was investigated for WPT applications to enhance the output power [104]. WPT with a scalable array-based passive beamforming system was investigated to support concurrent multidirectional full field of view power transfer [105]. Different combinations of RF power combining and dc power combining approaches were investigated [106].
The following conclusions are presented:
The commonly used dc combining technique does not raise the overall rectenna system’s turn-on sensitivity. To overcome the tradeoff between angular coverage and sensitivity, the Rotman lens has been used between the antenna and rectifier [107], [108], [109], [110].
A performance comparison of different sub-6-GHz antennas is presented in Table 2. It is understood that a bow tie shape offers better gain, and slotted and partial ground-based structures help to achieve multiresonance and broadband characteristics. A few rectifier circuits reported in the literature for the sub-6-GHz band are compared in Table 3. The HSMS-285x series diodes are found to be suitable for sub-6-GHz applications operating at moderate to high input power levels. Table 4 presents a performance comparison of different sub-6-GHz rectennas. From [29], [30], and [31], it is found that the dimensions of the rectenna also affect its gain value. We also observe that the half-wave rectifier (HWR) offers better PCE at low input power levels.
Table 2. A performance analysis of 5G Sub-6-GHz antennas for RFEH systems.
Table 3. A performance analysis of 5G Sub-6-GHz rectifiers for RFEH applications.
Table 4. A performance analysis of 5G Sub-6-GHz rectennas for RFEH systems.
Table 5 compares the performance of different rectenna designs. Hybrid and antipodal structures are designed for a wide impedance bandwidth of the antenna, but a hybrid system offers a comparatively low gain. Limited articles on rectifier circuits for 5G mm-wave are provided in Table 6, which is self-explanatory. Table 7 reveals the performance of various rectenna systems designed for RFEH 5G mm-wave applications. It may be noted that at high frequencies, the HWR circuit is the most-adopted rectifier topology. Also, a GFET-based rectenna shows better PCE performance and output voltage.
Table 5. A performance analysis of 5G mm-wave antennas for mm-wave EH systems.
Table 6. A performance analysis of 5G mm-wave rectifiers for mm-wave EH systems.
Table 7. A performance analysis of 5G mm-wave rectenna for mm-wave EH systems.
The performance of various antennas designed for 5G mm-wave WPT applications is given in Table 8, which is self-explanatory. Table 9 reveals that a VDR using a DMK2790 diode exhibits better PCE over a VDR with other possible diodes of the rectifier circuit. Table 10 presents the performance of 5G mm-wave rectenna systems for WPT applications. It is noticed that there is a need to develop rectenna systems with polarization-insensitive characteristics. It is observed that, at the same input power level, the maximum possible conversion efficiency is observed with an HWR topology, and the maximum output voltage is achieved with the VDR topology [92], [94]. The mm-wave rectenna systems are found to operate efficiently at high input power levels rather than low input power levels. From the analytical results, it can be concluded that large gain values are possible with mm-wave communication bands.
Table 8. A performance analysis of 5G/mm-wave antennas for WPT applications.
Table 9. A performance analysis of 5G/mm-wave rectifiers for WPT systems.
Table 10. A performance analysis of 5G/mm-wave rectennas for WPT systems.
This article has presented a comprehensive review of the current literature on 5G/mm-wave rectenna systems for wireless power transfer and EH systems. A comparative assessment of the performance of various published rectenna systems has also been presented. The applications of 5G have been increasing due to the technology’s increased energy density in the ambient environment; hence, 5G bands are highly preferred for RFEH at present. Among various 5G bands, 5G mm-wave bands overcome the spectrum scarcity issues that arise in the sub-6-GHz 5G band and also provide a high data rate and widespread coverage.
For WPT applications, a high-gain antenna and CP characteristics are preferred, and for RFEH applications, omnidirectional and all polarization characteristic antennas are highly preferred due to multisource harvesting. Applications at a 3.5-GHz frequency in the sub-6-GHz 5G band and 24/35-GHz frequencies in the mm-wave 5G band are found more than at other frequencies. At sub-6-GHz 5G band frequencies, HSMS-285x series diodes are found to be suitable for moderate to high input power levels. At mm-wave 5G frequencies, a Schottky diode with a low junction capacitance is found suitable; hence, the MA4E1317 Schottky diode is the most adopted for rectifier design. Low PCE and output voltage performances are observed at high RF frequencies over low RF frequencies.
The wide angular coverage of the rectenna helps to increase the harvesting power. The Rotman lens-based beamforming network is widely used for wide angular coverage in mm-wave EH applications. The writers have done their best to compile the most recent contributions from the global research community; nonetheless, if any significant article(s) is/are overlooked unintentionally, the authors humbly apologize.
This work was supported by the Science and Engineering Research Board, Government of India, under the Visiting Advanced Joint Research scheme (grant VJR/2019/000009).
Daasari Surender (surender.daasari@gmail.com) is an assistant professor in the Department of Electronics and Communication Engineering, Vaageswari College of Engineering, Karimnagar 505527 India. His research interests include planar antennas, dielectric resonator antennas, and radio-frequency energy harvesting systems. He is a Member of IEEE.
Md. Ahsan Halimi (ahsanhalimi@gmail.com) is pursuing his Ph.D. degree in the Department of Electronics and Communication Engineering, National Institute of Technology Silchar, Silchar 788010 India. His research interests include radio-frequency energy harvesting, microwave rectifiers, and ultrawideband and reconfigurable antennas. He is a Student Member of IEEE.
Taimoor Khan (ktaimoor@ieee.org) is an associate professor in the Department of Electronics and Communication Engineering, National Institute of Technology Silchar, Silchar 788010 India. His research interests include printed microwave circuits, dielectric resonator antennas, artificial intelligence paradigms, and radio-frequency energy harvesting systems. He is a Senior Member of IEEE.
Fazal A. Talukdar (fatalukdar@gmail.com) is a professor in the Department of Electronics and Communication Engineering, National Institute of Technology Silchar, Silchar 788010 India. His research interests include signal processing, communication, power electronics, and analog circuit design. He is a Senior Member of IEEE.
Nasimuddin (nasimuddin@i2r.a-star.edu.sg) is a scientist with the Institute for Infocomm Research, Agency for Science, Technology, and Research, Singapore 138632, Singapore. His research interests include multilayered microstrip-based structures, millimeter-wave antennas, ultrawideband antennas, and metamaterials-based microstrip antennas. He is a Senior Member of IEEE.
Sembiam R. Rengarajan (sembiam.rengarajan@csun.edu) is a professor in the Department of Electrical and Computer Engineering, California State University, Northridge, Northridge, CA 91330 USA. His research interests include applications of electromagnetics to antennas, scattering, and passive microwave components. He is a Life Fellow of IEEE.
[1] N. A. Muhammad et al., “Stochastic geometry analysis of electromagnetic field exposure in coexisting sub-6 GHz and millimeter wave networks,” IEEE Access, vol. 9, pp. 112,780–112,791, Aug. 2021, doi: 10.1109/ACCESS.2021.3103969.
[2] D. Wang et al., “A 24-44 GHz broadband transmit–receive front end in 0.13-μm SiGe BiCMOS for multistandard 5G applications,” IEEE Trans. Microw. Theory Techn., vol. 69, no. 7, pp. 3463–3474, Jul. 2021, doi: 10.1109/TMTT.2021.3069858.
[3] T. A. Khan et al., “Millimeter wave energy harvesting,” IEEE Trans. Wireless Commun., vol. 15, no. 9, pp. 6048–6062, Sep. 2016, doi: 10.1109/TWC.2016.2577582.
[4] D. Surender et al., “2.45 GHz Wi-Fi band operated circularly polarized rectenna for RF energy harvesting in smart city applications,” J. Electromagn. Waves Appl., vol. 36, no. 3, pp. 407–423, Aug. 2021, doi: 10.1080/09205071.2021.1970030.
[5] D. Surender et al., “Key components of rectenna system: A comprehensive survey,” IETE J. Res., vol. 20, pp. 1–28, May 2020, doi: 10.1080/03772063.2020.1761268.
[6] W. Brown et al., “An experimental microwave-powered helicopter,” in IRE Int. Conv. Rec., New York, NY, USA, Mar. 1966, pp. 225–235, doi: 10.1109/IRECON.1965.1147518.
[7] M. Wagih et al., “Millimeter-wave power harvesting: A review,” IEEE Open J. Antennas Propag., vol. 1, pp. 560–578, Oct. 2020, doi: 10.1109/OJAP.2020.3028220.
[8] M. Wagih, A. S. Weddell, and S. Beeby, “Rectennas for radio-frequency energy harvesting and wireless power transfer: A review of antenna design [Antenna Applications Corner] ,” IEEE Antennas Propag Mag., vol. 62, no. 5, pp. 95–107, Oct. 2020, doi: 10.1109/MAP.2020.3012872.
[9] S. K. Divakaran et al., “RF energy harvesting systems: An overview and design issues,” Int. J. RF Microw. Comput. Aided Eng., vol. 29, no. 1, p. e21633, 2019, doi: 10.1002/mmce.21633.
[10] S. E. Hassani et al., “Overview on 5G radio frequency energy harvesting,” Adv. Sci. Technol. Eng. Syst. J., vol. 4, no. 4, pp. 328–346, 2019, doi: 10.25046/aj040442.
[11] D. Surender et al., “Rectenna design and development strategies for wireless applications,” IEEE Antennas Propag. Mag., early access, Aug. 12, 2021, doi: 10.1109/MAP.2021.3099722.
[12] A. Inoue, “Millimeter-wave GaN devices for 5G: Massive MIMO antenna arrays for sub-6-Ghz and mm-wave bandwidth,” IEEE Microw. Mag., vol. 22, no. 5, pp. 100–110, May 2021, doi: 10.1109/MMM.2021.3056936.
[13] J. Lan, Z. Yu, J. Zhou, and W. Hong, “An aperture-sharing array for (3.5, 28) GHz terminals with steerable beam in millimeter-wave band,” IEEE Trans. Antennas Propag., vol. 68, no. 5, pp. 4114–4119, May 2020, doi: 10.1109/TAP.2019.2948706.
[14] N. Shinohara, Wireless Power Transfer: Theory, Technology, And Applications. Six Hills Way, U.K.: Institution of Engineering and Technology, Michael Faraday House, 2018.
[15] W. C. Brown, “The microwave powered helicopter,” J. Microw. Power, vol. 1, no. 1, pp. 1–20, 1966, doi: 10.1080/00222739.1966.11688626.
[16] Z. Wang et al., “A multiband rectenna for self-sustainable devices,” in Proc. Int. SoC Design Conf. (ISOCC), Nov. 12–15, 2018, pp 178–179, doi: 10.1109/ISOCC.2018.8649903.
[17] D. N. Elsheakh, “Frequency reconfigurable and radiation pattern steering of monopole antenna based on graphene pads,” in Proc. 2019 IEEE-APWC Topical Conf. Antennas Propag. Wireless Commun., Granada, Spain, pp. 436–440, doi: 10.1109/APWC.2019.8870446.
[18] A.D. Boursianis et al., “Dual-band single-layered modified e-shaped patch antenna for RF energy harvesting systems,” in Proc. Eur. Conf. Circuit Theory Design (ECCTD), Bulgaria, Sep. 7–10, 2020, pp. 1–4, doi: 10.1109/ECCTD49232.2020.9218354.
[19] T. G. Ali, X. Bai, and L. J. Xu, “Dual-band energy harvesting antenna based on PVDF piezoelectric material,” in Proc. 9th Asia-Pacific Conf. Antennas Propag. (APCAP), Xiamen, China, Aug. 4–7, 2020, pp. 1–2, doi: 10.1109/APCAP50217.2020.9245943.
[20] A.D. Boursianis et al., “Modified printed bow-tie antenna for RF energy harvesting applications,” in Proc. IEEE Microw. Theory Techn. Wireless Commun., 2020, pp. 67–71, doi: 10.1109/MTTW51045.2020.9245049.
[21] D. Surender, T. Khan, and F. A. Talukdar, “A triple-band hexagonal-shaped microstrip patch antenna for RF energy harvesting in smart city applications,” in Proc. IEEE Int. Conf. Comput., Power Commun. Technol. (GUCON), Oct. 2020, pp. 389–393, doi: 10.1109/GUCON48875.2020.9231228.
[22] T. Gayatri, N. Anveshkumar, and V.K. Sharma, “A hexagon slotted circular monopole UWB antenna for cognitive radio applications,” in Proc. Int. Conf. Emerg. Trends Inf. Technol. Eng., Vellore, India, Feb. 24–25, 2020, pp. 1–5, doi: 10.1109/ic-ETITE47903.2020.447.
[23] P. Zhang et al., “Back-to-back microstrip antenna design for broadband wide-angle RF energy harvesting and dedicated wireless power transfer,” IEEE Access, vol. 8, pp. 126,868–126,875, Jul. 2020, doi: 10.1109/ACCESS.2020.3008551.
[24] J. S. Gaggatur and S. F. S. Vajrala, “An 860MHz - 1960MHz multi-band multi-stage rectifier for RF energy harvesting in 130nm CMOS,” in Proc. IEEE Int. Conf. Electron., Comput. Commun. Technol., Bangalore, India, Jul. 2–4, 2020, pp. 1–4, doi: 10.1109/CONECCT50063.2020.9198677.
[25] M. S. Papadopoulou et al., “Dual-band rectifier design for ambient RF energy harvesting,” in Proc. 3rd World Symp. Commun. Eng., Thessaloniki, Greece, Oct. 9–11, 2020, pp. 7–11, doi: 10.1109/WSCE51339.2020.9275569.
[26] R. Kashimura et al., “Rectifying circuit with high impedance microstrip line for wide dynamic range characteristics,” in Proc. IEEE Wireless Power Transfer Conf. (WPTC), Taipei, Taiwan, May 10–12, 2017, pp. 1–4, doi: 10.1109/WPT.2017.7953855.
[27] S. D. Assimonis et al., “RF energy harvesting with dense rectenna-arrays using electrically small rectennas suitable for IoT 5G embedded sensor nodes,” in Proc. IEEE MTT-S Int. Microw. Workshop Ser. 5G Hardware Syst. Technol., 2018, Ireland, pp. 1–3, doi: 10.1109/IMWS-5G.2018.8484384.
[28] A. D. Boursianis et al., “Advancing rational exploitation of water irrigation using 5G-IoT capabilities: The AREThOU5A project,” in Proc. 29th Int. Symp. Power Timing Modeling, Optim. Simul., Greece, Jul. 1–3, 2019, pp. 127–132, doi: 10.1109/PATMOS.2019.8862146.
[29] C. Bahhar, C. Baccouche, and H. Sakli, “A novel 5G rectenna for IoT applications,” in Proc. 20th Int.Conf. Sci. Techn. Autom. Control Comput. Eng., Tunisia, 2020, pp. 287–290, doi: 10.1109/STA50679.2020.9329349.
[30] A. K. M. Z. Hossain et al., “A planar antenna on flexible substrate for future 5G energy harvesting in Malaysia,” Int. J. Adv. Comput. Sci. Appl., vol. 11, no. 10, pp. 151–155, 2020, doi: 10.14569/IJACSA.2020.0111020.
[31] S. M. K. Azam et al., “Monopole antenna on transparent substrate and rectifier for energy harvesting applications in 5G,” Int. J. Adv. Comput. Sci. Appl., vol. 11, no. 8, pp. 84–89, 2020, doi: 10.14569/IJACSA.2020.0110812.
[32] D. Surender et al., “Circularly polarized DR-rectenna for 5G and Wi-Fi bands RF energy harvesting in smart city applications,” IETE Tech. Rev., vol. 12, pp. 1–15, May 2021, doi: 10.1080/02564602.2021.1923079.
[33] Y. Shinki et al., “Wireless power transmission circuit on a small planar wide-band antenna,” in Proc. Int. Conf. IEEE Region, China, 2013, pp. 1–4, doi: 10.1109/TENCON.2013.6718459.
[34] X. Gu et al., “Diplexer-based fully passive harmonic transponder for sub-6-GHz 5G-compatible IoT applications,” IEEE Trans. Microw. Theory Techn., vol. 67, no. 5, pp. 1675–1687, May 2019, doi: 10.1109/TMTT.2018.2883979.
[35] R. H. Rasshofer, M. O. Thieme, and E. M. Biebl, “Circularly polarized millimeter-wave rectenna on silicon substrate,” IEEE Trans. Microw. Theory Techn., vol. 46, no. 5, pp. 715–718, May 1998, doi: 10.1109/22.668688.
[36] K. Issa and H. Fathallah, “High performance 60 GHz antenna for electromagnetic energy harvesting,” in Proc. Int. Conf. Inf. Commun. Technol. Res., 2015, pp. 13–15, doi: 10.1109/ICTRC.2015.7156409.
[37] P. Burasa et al., “On-chip dual-band rectangular slot antenna for single-chip millimeter-wave identification tag in standard CMOS technology,” IEEE Trans. Antennas Propag., vol. 65, no. 8, pp. 3858–3868, Aug. 2017, doi: 10.1109/TAP.2017.2710215.
[38] M. T. Hafeez, S. F. Jilani, “Novel millimeter-wave flexible antenna for RF energy harvesting,” in Proc. IEEE Int. Symp. Antennas Propag. USNC/URSI Nat. Radio Sci. Meeting, Jul. 9–14, 2017, pp. 2497–2498, doi: 10.1109/APUSNCURSINRSM.2017.8073291.
[39] W. A. Awan et al., “Frequency Reconfigurable patch antenna for millimeter wave applications,” in Proc. 2nd Int. Conf. Comput., Math. Eng. Technol., 2019, pp. 1–5, doi: 10.1109/ICOMET.2019.8673417.
[40] M. Wagih, A. S. Weddell, and S Beeby, “Millimeter-wave textile antenna for on-body RF energy harvesting in future 5G networks,” in Proc. IEEE Wireless Power Transfer Conf., 2019, pp. 245–248, doi: 10.1109/WPTC45513.2019.9055541.
[41] E. M. Wissem et al., “A textile EBG-based antenna for future 5G-IoT millimeter-wave applications,” Electronics, vol. 10, no. 2, pp. 1–12, 2021, doi: 10.3390/electronics10020154.
[42] A. Eid et al., “Flexible W-band rectifiers for 5G-powered IoT autonomous modules,” in Proc. IEEE Int. Symp. Antennas Propag. USNC-URSI Radio Sci. Meeting, 2019, pp. 1163–1164, doi: 10.1109/APUSNCURSINRSM.2019.8888600.
[43] A. Riaz et al., “A triband rectifier toward millimeter-wave frequencies for energy harvesting and wireless power-transfer applications,” IEEE Microw. Wireless Compon. Lett, vol. 31, no. 2, pp. 192–195, Feb. 2021, doi: 10.1109/LMWC.2020.3037137.
[44] V. M. Shoknrlo and D. V. Gretskikh, “A model of receiving-rectifying elements of MM wave band rectennas,” in Proc. 5th Int. Conf. Antenna Theory Techn., Ukraine, May 24–27, 2005, pp. 248–250, doi: 10.1109/ICATT.2005.1496939.
[45] S. Pellerano, J. Alvarado, and Y. Palaskas, “A mmWave power-harvesting RFID tag in 90 nm CMOS,” IEEE J. Solid-State Circuits, vol. 45, no. 8, pp. 1627–1637, Aug. 2010, doi: 10.1109/JSSC.2010.2049916.
[46] H. Gao et al., “A 71GHz RF energy harvesting tag with 8% efficiency for wireless temperature sensors in 65nm CMOS,” in Proc. IEEE Radio Frequency Integr. Circuits Symp., 2013, pp. 403–406, doi: 10.1109/RFIC.2013.6569616.
[47] N. Weissman, S. Jameson, and E. Socher, “W-band CMOS on-chip energy harvester and rectenna,” in Proc. IEEE MTT-S Int. Microw. Symp. (IMS2014), Tampa, FL, USA, Jun. 1–6, 2014, pp. 1–3, doi: 10.1109/MWSYM.2014.6848243.
[48] A. Mavaddat, S. H. M. Armaki, and A. R. Erfanian, “Millimeter-wave energy harvesting using 4 × 4 microstrip patch antenna array,” IEEE Antennas Wireless Propag. Lett., vol. 14, pp. 515–518, 2015, doi: 10.1109/LAWP.2014.2370103.
[49] J. Bito et al., “Millimeter-wave ink-jet printed RF energy harvester for next generation flexible electronics,” in Proc. IEEE Wireless Power Transfer Conf. (WPTC), Taipei, Taiwan, May 10–12, 2017, pp. 1–4, doi: 10.1109/WPT.2017.7953871.
[50] C. Hannachi, S. Boumaiza, and S. O. Tatu, “A highly sensitive broadband rectenna for low power millimeter-wave energy harvesting applications,” in Proc. IEEE Wireless Power Transfer Conf. (WPTC), Jun. 3–7, 2018, doi: 10.1109/WPT.2018.8639130.
[51] M. Aldrigo et al., “Harvesting electromagnetic energy in the V-Band using a rectenna formed by a bow tie integrated with a 6-nm-thick Au/HfO2/Pt metal–insulator–metal diode,” IEEE Trans. Electron Devices, vol. 65, no. 7, pp. 2973–2980, Jul. 2018, doi: 10.1109/TED.2018.2835138.
[52] N. Singh et al., “A compact and efficient graphene FET based RF energy harvester for green communication,” Int. J. Electron. Commun., vol. 115, p. 153,059, Feb. 2020, doi: 10.1016/j.aeue.2019.153059.
[53] N. Singh et al., “A compact broadband GFET based rectenna for RF energy harvesting applications,” Microsyst. Technol., vol. 26, no. 6, pp. 1881–1888, 2020, doi: 10.1007/s00542-019-04737-0.
[54] H. Rahmani and A. Babakhani, “A dual-mode RF power harvesting system with an on-chip coil in 180-nm SOI CMOS for millimeter-sized biomedical implants,” IEEE Trans. Microw. Theory Techn., vol. 67, no. 1, pp. 414–428, Jan. 2019, doi: 10.1109/TMTT.2018.2876239.
[55] T. H. Lin et al., “Achieving fully autonomous system-on-package designs: An embedded-on-package 5G energy harvester within 3D printed multilayer flexible packaging structures,” in Proc. IEEE MTT-S Int. Microw. Symp. (IMS), Boston, MA, USA, Jun. 2–7, 2019, pp. 1375–1378, doi: 10.1109/MWSYM.2019.8700931.
[56] M. Aldrigo et al., “Graphene diodes for 5G energy harvesting: Design, simulations and experiments,” in Proc. 49th Eur. Microw. Conf., Paris, France, Oct. 1–3, 2019, pp. 7–10, doi: 10.23919/EuMC.2019.8910802.
[57] M. Wagih et al., “Broadband millimeter-wave textile-based flexible rectenna for wearable energy harvesting,” IEEE Trans. Microw. Theory Techn., vol. 68, no. 11, pp. 4960–4972, Nov. 2020, doi: 10.1109/TMTT.2020.3018735.
[58] M. Aboualalaa et al., “Compact coplanar stripline-fed folded strip dipole antenna for millimeter energy combining,” in Proc. IEEE 17th Annu. Wireless Microw. Techn. Conf. (WAMICON), Clearwater, FL, USA, Apr. 11–13, 2016, pp. 1–3, doi: 10.1109/WAMICON.2016.7483820.
[59] S. L. Liu et al., “A near field focused lens antenna for wireless power transmission systems,” in Proc. IEEE Asia-Pacific Conf. Antennas Propag. (APCAP), Auckland, New Zealand, Aug. 5–8, 2018, pp. 313–315, doi: 10.1109/APCAP.2018.8538187.
[60] S. D. Joseph et al., “A novel dual-polarized millimeter-wave antenna array with harmonic rejection for wireless power transmission,” in Proc. 12th Eur. Conf. Antennas Propag. (EuCAP 2018), Apr. 9–13, 2018, pp. 1–3, doi: 10.1049/cp.2018.0693.
[61] H. Flores-Garcia et al., “High gain wireless power transfer using 60GHz antenna array,” in Proc. SoutheastCon, Huntsville, AL, USA, Apr. 11–14, 2019, pp. 1–2, doi: 10.1109/SoutheastCon42311.2019.9020471.
[62] R. Gopika and C. Saha, “Millimeter wave grid array antenna for wireless power transmitter,” in Proc. IEEE Recent Adv. Geosci. Remote Sens., Technol., Standards Appl., Oct. 17–20, 2019, pp. 54–56, doi: 10.1109/TENGARSS48957.2019.8976061.
[63] K. Lee et al., “Design of a metasurface superstate for improved reception of wireless power at Ka-band,” in Proc. IEEE Wireless Power Transfer Conf., Seoul, Korea, Nov. 15–19, 2020, pp. 112–114, doi: 10.1109/WPTC48563.2020.9295624.
[64] F. Xiao et al., “High-efficiency millimeter-wave wide-angle scanning phased array using metasurface,” in Proc. IEEE MTT-S Int. Wireless Symp. (IWS), Nanjing, China, May 23–26, 2021, pp. 1–3, doi: 10.1109/IWS52775.2021.9499440.
[65] M. Wagih et al., “Millimeter-wave power transmission for compact and large-area wearable IoT devices based on a higher-order mode wearable antenna,” IEEE Internet Things J., vol. 9, no. 7, pp. 5229–5239, Apr. 2022, doi: 10.1109/JIOT.2021.3107594.
[66] D. H. Sadek, H. A. Shawkey, and A. A. Zekry, “Multiband triple L-arms patch antenna with diamond slot ground for 5G applications,” Appl. Comput. Electromagn. Soc. J., vol. 36, no. 3, pp. 302–307, Mar. 2021.
[67] S. Ladan, S. Hemour, and K. Wu, “Towards millimeter-wave high-efficiency rectification for wireless energy harvesting,” in Proc. IEEE Int. Wireless Symp (IWS), Beijing, China, Apr. 14–18, 2013, pp. 1–4, doi: 10.1109/IEEE-IWS.2013.6616819.
[68] S. Ladan, and K. Wu, “35 GHz harmonic harvesting rectifier for wireless power transmission,” in Proc. IEEE MTT-S Int. Microw. Symp., USA, Jun. 1–6, 2014, pp. 1–4, doi: 10.1109/MWSYM.2014.6848572.
[69] G. N. Tan, X. X. Yang, and C. Tan, “Design of rectifying circuit for wireless power transmission in Ka band,” in Proc. IEEE Antennas Propag. Soc. Int. Symp. (APSURSI), Memphis, TN, USA, Jul. 6–11, 2014, pp. 639–640, doi: 10.1109/APS.2014.6904650.
[70] P. Zhu, Z. Ma, G. A. E. Vandenbosch, and G. Gielen, “160 GHz harmonic-rejecting antenna with CMOS rectifier for millimeter-wave wireless power transmission,” in Proc.9th Eur. Conf. Antennas Propag., Portugal, Apr. 13–17, 2015, pp. 1–5.
[71] A. Riaz, M. Awais, M.M. Farooq, W.T. Khan, “A single cell dual band rectifier at millimeter-wave frequencies for future 5G communications,” in Proc. 49th Eur. Microw. Conf. (EuMC), Paris, France, Oct. 1–3, 2019, pp. 41–44, doi: 10.23919/EuMC.2019.8910897.
[72] P. He and D. Zhao, “High-efficiency millimeter-wave CMOS switching rectifiers: Theory and implementation,” IEEE Trans. Microw. Theory Techn., vol. 67, no. 12, pp. 5171–5180, Dec. 2019, doi: 10.1109/TMTT.2019.2936566.
[73] S. Mizojiri and K. Shimamura, “Recent progress of wireless power transfer via sub-THz wave,” in Proc. IEEE Asia-Pacific Microw. Conf. (APMC), Singapore, Dec. 10–13, 2019, pp. 705–707, doi: 10.1109/APMC46564.2019.9038353.
[74] D. Zhao, P. He, and X. Wang, “Millimeter-wave rectenna and rectifying circuits for far-distance wireless power transfer,” in Proc. 12th Global Symp. Millimeter Waves (GSMM), Sendai, Japan, May 22–24, 2019, pp. 90–92, doi: 10.1109/GSMM.2019.8797674.
[75] A. Eid, J. Hester, and M. Tentzeris, “mm-Wave tunnel diode-based rectifier for perpetual IoT,” in Proc. IEEE Int. Symp. Antennas Propag. North Amer. Radio Sci. Meeting, Canada, Jul. 5–10, 2020, pp. 1495–1496, doi: 10.1109/IEEECONF35879.2020.9329745.
[76] D. Matos, R. Correia, and N. B. Carvalho, “Millimeter-wave hybrid RF-DC converter based on a GaAs chip for IoT-WPT applications,” IEEE Microw. Wireless Compon. Lett., vol. 31, no. 6, pp. 787–790, Jun. 2021, doi: 10.1109/LMWC.2021.3058542.
[77] P. Koert and J. T. Cha, “Millimeter wave technology for space power beaming,” IEEE Trans. Microw. Theory Techn., vol. 40, no. 6, pp. 1251–1258, Jun. 1992, doi: 10.1109/22.141358.
[78] J. O. McSpadden et al., “Theoretical and experimental investigation of a rectenna element for microwave power transmission,” IEEE Trans. Microw. Theory Techn., vol. 40, no. 12, pp. 2359–2366, Dec. 1992, doi: 10.1109/22.179902.
[79] Y. J. Ren, M. Y. Li, and K. Chang, “35 GHz rectifying antenna for wireless power transmission,” Electron. Lett., vol. 43, no. 11, pp. 1–2, May 2007, doi: 10.1049/el:20071061.
[80] H. K. Chiou et al., “High-efficiency dual-band on-chip rectenna for 35- and 94-GHz wireless power transmission in 0.13-μm CMOS technology,” IEEE Trans. Microw. Theory Techn., vol. 58, no. 12, pp. 3598–3607, Dec. 2010, doi: 10.1109/TMTT.2010.2086350.
[81] N. Shinohara, K. Nishikawa, T. Seki, and K. Hiraga, “Development of 24 GHz rectennas for fixed wireless access,” in Proc. 30th URSI General Assembly Scientific Symp., Istanbul, Aug. 13–20, 2011, pp. 1–4, doi: 10.1109/URSIGASS.2011.6050505.
[82] K. Hatano et al., “Development of class-F load rectennas,” in Proc. IEEE MTT-S IMWS Innovative Wireless Power Transmission, Technol., Syst., Appl., Japan, May 12–13, 2011, pp. 251–254, doi: 10.1109/IMWS.2011.5877123.
[83] K. Hatano, N. Shinohara, T. Seki, and M. Kawashima, “Development of MMIC rectenna at 24GHz,” in Proc. IEEE Radio Wireless Symp., Austin, TX, USA, Jan. 20–23, 2013, pp. 199–201, doi: 10.1109/RWS.2013.6486687.
[84] A. Collado and A. Georgiadis, “24 GHz substrate integrated waveguide (SIW) rectenna for energy harvesting and wireless power transmission,” in Proc. IEEE MTT-S Int. Microw. Symp. Dig., Jun. 2–7, 2013, pp. 1–3, doi: 10.1109/MWSYM.2013.6697772.
[85] S. Ladan, A. B. Guntupalli, and K. Wu, “A high-efficiency 24 GHz rectenna development towards millimeter-wave energy harvesting and wireless power transmission,” IEEE Trans. Circuits Syst. I, Reg. Papers, vol. 61, no. 12, pp. 3358–3367, Dec. 2014, doi: 10.1109/TCSI.2014.2338616.
[86] H. Mei, X. Yang, B. Han, and G. Tan, “High-efficiency microstrip rectenna for microwave power transmission at Ka band with low cost,” IET Microw. Antennas Propag., vol. 10, no. 15, pp. 1648–1655, 2016, doi: 10.1049/iet-map.2016.0025.
[87] M. Nariman et al., “A compact 60-GHz wireless power transfer system,” IEEE Trans. Microw. Theory Techn., vol. 64, no. 8, pp. 2664–2677, Aug. 2016, doi: 10.1109/TMTT.2016.2582168.
[88] S. Daskalakis et al., “Inkjet printed 24 GHz rectenna on paper for millimeter wave identification and wireless power transfer applications,” in Proc. IEEE MTT-S Int. Microw. Workshop Ser. Adv. Mater. Processes RF THz Appl., Italy, Sep. 20–22, 2017, pp. 1–3, doi: 10.1109/IMWS-AMP.2017.8247367.
[89] K. Matsui et al., “Microstrip antenna and rectifier for wireless power transfar at 94GHz,” in Proc.IEEE Wireless Power Transfer Conf., Taiwan, May 10–12, 2017, pp. 1–3, doi: 10.1109/WPT.2017.7953902.
[90] P. Pang et al., “A high-efficiency 35GHz rectenna with compact structure for rectenna arrays,” in Proc. IEEE Asia-Pacific Conf. Antennas Propag., Aug. 2018, pp. 303–305, doi: 10.1109/APCAP.2018.8538263.
[91] M. Aldrigo et al., “Bow-tie antenna integrated with an HfO2-based MIM diode for millimetre wave harvesting,” in Proc. 48th Eur. Microw. Conf., Madrid, Spain, Sep. 25–27, 2018.pp. 769–772, doi: 10.23919/EuMC.2018.8541525.
[92] B. T. Malik et al., “Flexible rectennas for wireless power transfer to wearable sensors at 24 GHz,” in Proc. Research, Invention, Innovation Congr. (RI2C), Thailand, Dec. 11–13, 2019, pp. 1–5, doi: 10.1109/RI2C48728.2019.8999964.
[93] W. Huang et al., “A novel 35-GHz Slot-coupled patch rectenna array based on SIW cavity for WPT,” in Proc. Int. Conf. Microw. Millimeter Wave Technol. (ICMMT), Guangzhou, China, May 19–22, 2019, pp. 1–3, doi: 10.1109/ICMMT45702.2019.8992128.
[94] B. T. Malik et al., “Wireless power transfer system for battery-less sensor nodes,” IEEE Access, vol. 8, pp. 95,878–95,887, May 2020, doi: 10.1109/ACCESS.2020.2995783.
[95] Q. Chen, Z. Liu, Y. Cui, H. Cai, and X. Chen, “A metallic waveguide-integrated 35-GHz rectenna with high conversion efficiency,” IEEE Microw. Wireless Compon. Lett., vol. 30, no. 8, pp. 821–824, Aug. 2020, doi: 10.1109/LMWC.2020.3002163.
[96] C. Bahhar et al., “Optical RECTENNA for energy harvesting and RF transmission in connected vehicles,” in Proc. 17th Int. Multi-Conf. Syst., Signals Devices (SSD), Tunisia, Jul. 20–23, 2020, pp. 262–266, doi: 10.1109/SSD49366.2020.9364243.
[97] P. He et al., “A W-band 2 × 2 rectenna array with on-chip CMOS switching rectifier and On-PCB tapered slot antenna for wireless power transfer,” IEEE Trans. Microw. Theory Techn., vol. 69, no. 1, pp. 969–979, Jan. 2021, doi: 10.1109/TMTT.2020.3032971.
[98] Y. Wang, X. X. Yang, G. N. Tan, and S. Gao, “Study on millimeter-wave SIW rectenna and arrays with high conversion efficiency,” IEEE Trans. Antennas Propag., vol. 69, no. 9, pp. 5503–5511, Sep. 2021, doi: 10.1109/TAP.2021.3060120.
[99] R. Moro et al., “28 GHz microwave power beaming to a free-flight drone,” in Proc. IEEE Wireless Power Transfer Conf., San Diego, CA, USA, Jun. 1–4, 2021, pp. 1–4, doi: 10.1109/WPTC51349.2021.9458030.
[100] T. Bai et al., “Coverage and capacity of millimeter-wave cellular networks,” IEEE Commun. Mag., vol. 52, no. 9, pp. 70–77, Sep. 2014, doi: 10.1109/MCOM.2014.6894455.
[101] D. J. Lee et al., “Hybrid power combining rectenna array for wide incident angle coverage in RF energy transfer,” IEEE Trans. Microw. Theory Techn., vol. 65, no. 9, pp. 3409–3418, Sep. 2017, doi: 10.1109/TMTT.2017.2678498.
[102] J. J. Kuek et al., “A compact Butler matric for wireless power transfer to aid electromagnetic energy harvesting for sensors,” in Proc. Asia Pacific Microw. Conf., 2017, pp. 334–336, doi: 10.1109/APMC.2017.8251447.
[103] T. A. Khan et al., “Energy coverage in millimeter wave energy harvesting networks,” in Proc. IEEE Globecom Workshops, San Diego, CA, USA, Dec. 6–10, 2015, pp. 1–6, doi: 10.1109/GLOCOMW.2015.7414219.
[104] P. W. Fink et al., “Beamforming rectennas, systems and methods for wireless power transfer,” U.S. Patent 10 243 412b1, 2019.
[105] M. Y. Huang et al., “Concurrent multi-directional beam-forming receiving network for full-FoV high-efficiency wireless power transfer,” in Proc. IEEE/MTT-S Int. Microw. Symp., 2019, pp. 1511–1514, doi: 10.1109/MWSYM.2019.8700746.
[106] S. Shen and B. Clerckx, “Beamforming optimization for MIMO wireless power transfer with nonlinear energy harvesting: RF combining versus DC combining,” IEEE Trans. Wireless Commun., vol. 20, no. 1, pp. 199–213, Jan. 2021, doi: 10.1109/TWC.2020.3024064.
[107] B. Schweber. “Rotman-lens antenna system harvests 28-GHz 5G energy.” Electronic Design. Accessed: Jun. 11, 2021. [Online] . Available: https://www.electronicdesign.com/industrial-automation/article/21164377/electronic-design-rotmanlens-antenna-system-harvests-28ghz-5g-energy
[108] A. Eid et al., “A scalable high-gain and large-beamwidth mmWave harvesting approach for 5G-powered IoT,” in Proc. 2019 IEEE MTT-S Int. Microw. Symp. (IMS), Boston, MA, USA, pp. 1309–1312, doi: 10.1109/MWSYM.2019.8700758.
[109] H. Y. Hong, H. S. Park, S. K. Hong, “Design of Rotman lens for far-field wireless power transfer at Ka-band,” in Proc. IEEE Wireless Power Transfer Conf. (WPTC), Seoul, Korea, Nov. 15–19, 2020, pp. 109–111, doi: 10.1109/WPTC48563.2020.9295528.
[110] A. Eid, J. G. D. Hester, and M. M. Tentzeris, “5G as a wireless power grid,” Scientific Rep., vol. 11, no. 1, pp. 1–9, 2021, doi: 10.1038/s41598-020-79500-x.
Digital Object Identifier 10.1109/MAP.2022.3208794