Computers, Materials & Continua Tech Science Press DOI:10.32604/cmc.2021.018292 Article Design of a Five-Band Dual-Port Rectenna for RF Energy Harvesting Surajo Muhammad1,*, Jun Jiat Tiang1, Sew Kin Wong1, Jamel Nebhen2 and Amjad Iqbal1 1Centre for Wireless Technology, Faculty of Engineering, Multimedia University, Cyberjaya, 63100, Malaysia 2College of Computer Science and Engineering, Prince Sattam Bin Abdulaziz University, Alkharj, 11942, Saudi Arabia *Corresponding Author: Surajo Muhammad. Email: [email protected] Received: 02 March 2021; Accepted: 04 April 2021 Abstract: This paper proposed the design of a dual-port rectifier with multi- frequency operations. The RF rectifier is achieved using a combination of L-section inductive impedance matching network (IMN) at Port-1 with a multiple stubs impedance transformer at Port-2. The fabricated prototype can harvest RF signal from GSM/900, GSM/1800, UMTS/2100, Wi-Fi/2.45 and LTE/2600 frequency bands at (0.94, 1.80, 2.10, 2.46, and 2.63 GHz), respectively. The rectifier occupies a small portion of a PCB board at 0.20 λg × 0.15 λg. The proposed circuit realized a measured peak RF-to-dc (radio frequency direct current) power conversion efficiency (PCE) of (21%, 22.76%, 25.33%, 21.57%, and 22.14%) for an input power of −20 dBm. The RF harvester attains a measured peak RF-to-dc PCE of 72.70% and an output dc voltage of 154 mV for an input power of 3 dBm at 2.46 GHz. Measurement of the proposed rectifier in the ambiance gives a peak dc output voltage of 376.1 mV from the five signal tones. Similarly, a low-powered bq25504-674 evaluation module (EVM) is integrated with the rectifier. The module boost and drive the rectifier output dc voltage to 945 mV. The performance of the proposed rectifier in the ambiance environment makes it a suitable module for low-powered RF applications. Keywords: RF energy harvesting; impedance matching network; power conversion efficiency; multi-band rectifier 1 Introduction The evolution and advancement of wireless communications technology contribute immensely to the exponential growth of wireless devices in our day-to-day activities [1]. The emergence of technologies for low-powered applications in the field of security surveillance, health care systems, agriculture, along with other vital application drivers, attracted the attention of researchers in the area of wireless power transfer (WPT) and RFEH [1–3]. A reliable energy source is one of the key challenges with the growing ultra-low-powered devices [4]. To overcome the challenges of battery-based conventional devices. RFEH technology is considered to provide direct power and battery recharging from the electromagnetic (EM) energy [4]. In order to address the limi- tation of the conventional battery-based devices of charging, maintaining, or replacing a battery. This work is licensed under a Creative Commons Attribution 4.0 International License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 488 CMC, 2021, vol.69, no.1 The propagation of EM wave in space that carries an EM radiant energy from various sources makes it applicable as an additional source of energy for low-powered devices [3]. The RFEH circuit is accomplished through a rectifying antenna (rectenna) comprising a receiving antenna, an IMN, a rectifying diode, a dc-pass filter, and a terminal load [5]. The RFEH antenna picks relatively low AC signals. Hence, a conditioning circuit for max- imum transfer of power between the antenna and the rectifying diode to the load terminal is of paramount importance [2,5]. The RF rectifier is a vital component of the RFEH circuit that matches and converts the received AC signal from the antenna to the equivalent dc output through an IMN, a rectifying diode, a dc-pass filter, the load terminal. Rectenna operates at a designated frequency with a significant RF power density to ensure a reliable operation of the circuit [1,6]. Various researchers have reported works on RFEH circuits for single-band [7,8], dual-band [9], and multi-band [1,6–10], operations. The authors in [6] present a quad-band (1.3, 1.7, 2.4, 3.6 GHz) rectifier using a distributed T-section IMN. The authors in[11] reported a triple-band (0.94, 1.95, and 2.44 GHz) RF rectifier control by a 4-stage single dual-diode matched through a single L-section IMN. A four-band (0.95, 1.83, 2.45, and 2.62 GHz) RF harvester using two- branches of 4-stage voltage multiplier is reported by the authors in [12]. The RFEH harvester in [6,11], and [12] are suitable for high-power applications because of the complexity of the circuits that increase the parasitic capacitance across the junction of the diode. In [13], the authors reported a triple-band (2, 2.5, and 3.5 GHz) rectenna. The authors in [14] present a four-band (0.89, 1.27, 2.02, and 2.38 GHz) rectifier comprising a series diode D1 and a combination of shunt field-effect transistor (FET) with a second diode D2. The Circuit in [14] is matched through a cross-shaped stub and a stepped impedance microstrip line. The rectifier operating frequency by the authors in [6] at 3.6 GHz, [13] at (2 and 3.5 GHz), and [14] at (1.27 and 2.02 GHz) contributes little RF power density to the RF harvester. The authors in [10] reported a multi-port rectenna with the ability to explore spatial domain through multiple receiving antennas. A single band (98 MHz) low-frequency frequency modulated (FM) RF harvester is slotted into a triple-band (0.88, 1.7, and 2.370 GHz) four-cornered multi-port rectenna. The narrow bandwidth associated with the design does not sufficiently exploit the frequency domain of the EM spectrum, besides the two-level dc-combiner that introduces additional losses into the transmission line. It is worth mentioning that most of the rectenna and RF rectifiers reported from the literature have limited operational bandwidth between (20–40 MHz). Besides operating at a high input power, some works presented have insignificant RF power density to harvest and manage by the rectifier. In this paper, a compact dual-port rectenna with the ability to cover most of the EM spectrum with a significant RF power density is proposed. The proposed rectifier operates at (0.94, 1.80, 2.10, 2.46, and 2.63 GHz) matched through a 2.5 k load terminal. The proposed rectenna harvests RF signals from GSM/900, GSM/1800, UMTS/2100, Wi-Fi/2.45, and LTE/2600 frequency bands. Improvements in compactness, operational bandwidth, and the overall RF-to-dc PCE were seen in the proposed design. The design is a promising candidate for many applications in low-powered systems. In this paper, the design of the rectifier circuit is discussed in Section 2, and Section 3 presents the performance of a dual-port rectifier. Section 4 highlights the design of a wideband antenna to complete a rectenna. The rectenna measurement results in the ambiance environment are reported in Section 5, and Section 6 concludes the work. 2 Rectifier Design An RFEH system requires a rectifying diode to handle a low input power at high frequency with minimum losses [5,7]. A single diode RF rectifier configuration shows a better performance CMC, 2021, vol.69, no.1 489 at low input power than its equivalents single or multi-stage voltage multiplier [2]. Hence, a single- series diode circuit topology is considered here in this work to minimize junction parasitic and ensure a faster switching time [4,15]. Fig. 1 presents a typical single-series RF rectifier topology using a shunt capacitor filter. To minimize the passage of higher-order harmonics into the load, a shunt dc-pass filter is added between the diode and the load terminal (RL). Figure 1: A Conventional single series RF rectifier topology Fig. 2 presents the model layout of the proposed dual-port wideband rectifier. Two IMN design approach is adopted at each port to reduce circuit complexity and ensure a compact harvester. The first section of the proposed rectifier (Rectifier1) is designed at 0.93 GHz using a second-order L-section matching network (MN) for harvesting GSM/900 available power. Rectifier-1 is connected through Port-1. Port-2 is used to connect the second segment ofthe rectifier (Rectifier-2), comprising three cell branches matched through an impedance transformer network. Each cell branch is matched to a single series diode D2–D4 at 1.8, 2.1, and 2.45 GHz, respectively. The rectifier sections are designed on a high-frequency single-series HSMS-2850 low-powered Schottky barrier diode from Avago. The diode exhibit a small junction capacitance of 0.18 pF, a forward biasing voltage of 150 mV. SOT-323 provides the diode physical configuration layout [1,5]. The proposed rectifier is designed and constructed on a 1.6 mm thick FR-4 substrate (witha dielectric constant of 5.4 and a loss tangent of 0.02). The dual-port RF rectifier is terminated with a 50 source through a transmission line at Port-1 and Port-2. The input impedance of Rectifiers-1 and 2 are first computed without an MN comprising only a rectifying diode, dc-pass capacitor filter, and a load terminal. The dc-pass capacitor filter is designed to smoothing the peaks from the output of the rectifying diode and also reject higher- order harmonics [16]. A source pool simulation using a harmonic balance (HB) solver is executed to determine a suitable value of RL in advance design system (ADS).