A modified Hilbert fractal resonator based rectenna design for GSM900 band RF energy harvesting applications

This article proposes a novel rectenna design based on modified Hilbert fractal shaped microstrip antenna and Villard voltage doubler rectifying circuit for RF energy harvesting applications operating at Global System for Mobile Communications (GSM) 900 MHz band. The energy harvesting antenna is numerically optimized and fabricated on a Rogers RO4003 substrate of thickness 1.52 mm with a compact overall physical sizes of 80 mm × 82 mm (λ₀/4.16 × λ₀/4.06). Various geometric parameters and circuit component values of the proposed energy harvesting system are optimized in order to achieve a matched input impedance with good radiation performance of high gain for the input power level less than ?20 dBm. The numerical and experimental results point out the technical potential of the proposed rectenna design to be utilized in DC power supply modules of low voltage, low power electronic devices.     

A novel RF energy harvesting cube based on air dielectric antenna arrays

In this article, a new 2 × 2 circular microstrip antenna array with air dielectric layer for ambient RF energy harvesting has been proposed. Two pairs of arc‐shaped slots located close to the boundary of the circular microstrip patch have been designed for achieving dual‐band response and extending the frequency bandwidth. The antenna has a frequency bandwidth from 1.85 to 1.93 GHz and from 2.0 to 2.1 GHz which can cover GSM‐1800 and UMTS‐2100 bands. At the frequency of 1.89 and 2.05 GHz, the measured gain is 5.3 and 6.6 dBi, respectively, and high gain of 3.8‐9.3 dBi has been achieved over the whole band. Also, a broadband rectifier that can cover all the bandwidths of the antenna array is designed for the rectenna, which has the maximum rectifying efficiency of 53.6%. Finally, a cube device formed of four antenna and four rectifiers is designed to harvest RF energy, whose maximum output DC voltage is 2.3 V and the maximum output power is 4 mW that can drive four LEDs and an electronic watch.     

Design of a compact size tag antenna based on split ring resonator for UHF RFID application

In this article, a new design of miniaturized split‐ring resonator antenna using a meander line technique with a simple impedance matching method applicable to UHF‐RFID tags is presented. The new approach is based on the integration of a meander line into the radiating element of SRR to reduce the electrical tag size and a theoretical demonstration to calculate the conjugate impedance matching and directly attach the antenna with the chip. The new SRR antenna, which is printed on the flexible substrate Arlon CuClad 250LX, is designed using Alien Higgs 3 RFID ASIC whose input impedance is 25‐j190. The prototype antenna has a low‐cost compact size (18.28 mm × 18.28 mm) with a read range higher than 4 m within the RFID UHF band and with a roughly 4.2‐m peak range at 915 MHz. As a proof of behavior, a tag prototype is fabricated and measured to operate at a UHF RFID band. Based on some works' results, an optimized design is obtained with a 48% size reduction compared with the classic split ring resonator antenna and with a good impedance matching the antenna with RFID ASIC without the need for any external matching network.     

A radio frequency and vibration energy harvesting antenna based on piezoelectric material

This article proposes a novel hybrid energy harvesting antenna that can be used to harvest radio frequency (RF) and vibration energy in ambience. A microstrip antenna is designed on the piezoelectric film with the material of polyvinylidene fluoride (PVDF). Due to the high dielectric constant of PVDF, the antenna size can be reduced efficiently. The shape of designed microstrip antenna is trapezoidal, the final antenna size is reduced to 50 mm × 30 mm × 0.2 mm. To improve the efficiency, the rectifier with matching network is optimized and the modes of the piezoelectric film are analyzed. The experimental results show that the frequency bandwidth of the antenna is 2.1 to 2.5 GHz. For a RF source at distance of 1 m away, with a 0.25 W EIRP 2.4 GHz transmitter, the output power of the antenna can reach 17.2 μW. While under 17 Hz vibration excitation, the output voltage and power can reach 1.44 V and 15.3 μW, respectively.     

A novel meander line integrated E‐shaped rectenna for energy harvesting applications

In this article, design of a novel meander integrated E‐shaped rectenna is presented. The designed rectenna operates at ISM frequency range from 2.2 to 2.5 GHz with acceptable reflection coefficients, gain and VSWR values. The designed rectenna is simulated using HFSS 15 (High Frequency Electromagnetic Field Simulation) and FR4 epoxy material is used in rectenna design for low cost having dielectric constant of 4.4 and thickness of 1.6 mm. In the rectifying stage full wave voltage doubler circuit is designed for DC power generation with SMS7630 Schottky diode and lumped circuit elements. The impedance matching circuit between the antenna and the rectifier is designed and simulated using advanced design system (ADS) software for efficient power transmission from the antenna to the load. The simulation and measurement results with different load and input power levels prove that the designed and implemented system can be used for low power energy harvesting applications in order to feed electronic components and battery free sensor networks.     

A wideband rectifier array on dual‐polarized differential‐feed fractal slotted ground antenna for RF energy harvesting

This article reports a novel wideband rectenna for RF energy harvesting applications. A wideband fractal slotted ground antenna (SGA) is adopted. The operating frequency bands of the antenna are GSM, UMTS, Wi‐Fi, and LTE2600/4G bands. The antenna is fed by a dual‐polarized and differential‐feed (DP‐DF) microstrip lines disposed with an angle of 90° each relative to the other. The feed lines are etched on the bottom side of the substrate and connected to an array of four wideband RF‐to‐DC rectifiers. A nonuniform transmission lines filter ensures wideband behavior for each rectifier. The rectenna performances are simulated and measured. The experiments show an output DC voltage of 1 V at a power density of 26.6 μW/cm² over the frequency band of operation with a peak efficiency of 50%. The proposed rectenna is suitable for energy harvesting applications in urban environments.     

An ultra‐wideband rectenna using optically transparent Vivaldi antenna for radio frequency energy harvesting

This paper presents a novel ultra‐wideband rectenna which consists of a transparent Vivaldi antenna and a wideband rectifying circuit for radio frequency energy harvesting. The antenna is realized on a 2.2‐mm‐thick soda‐lime glass substrate coated with fluorine‐doped tin oxide of thickness 650 nm. It provides an optical transmittance greater than 80% in the visible region. The rectifying circuit with a cascaded matching network and the Greinacher doubler circuit are fabricated on an FR4 substrate with a thickness of 0.8 mm. The antenna provides the best matching characteristics and the realized peak gain is 3.2 dBi. The designed matching network enables maximum power transfer from the antenna to the rectifier. The rectenna provides a peak power conversion efficiency of 69% for ?10 dBm input power. The proposed antenna can be realized on the windscreen of automobiles and glass windows without causing any obstruction to normal view.     

CPW fed miniaturized dual‐band short‐ended metamaterial antenna using modified split‐ring resonator for wireless application

A miniaturized dual‐band metamaterial (MTM) antenna has been designed in this article. The designed coplanar waveguide fed antenna has composed of inner split‐ring resonator and an outer open ring resonator with rectangular stub. The series parameter of the antenna is used to determine the zeroth order resonance frequency due to short‐ended boundary condition. The whole size of proposed structure is 20 × 25.5 mm². This MTM antenna exhibits dual‐band operation at 3.17 GHz (3.1–3.22 GHz) and 5.39 GHz (5.27–5.47 GHz). The proposed MTM structure achieves measured peak gain of 0.71 and 1.89 dB at 3.17 and 5.39 GHz, respectively. The proposed antenna can be used for recent radio communication in form of S‐band application and Wi‐MAX.     

A dual‐band efficient circularly polarized rectenna for RF energy harvesting systems

A multilayered circularly polarized (CP), dual‐band, stacked slit‐/slotted‐patch antenna with compact size and with compact rectifier is offered for RF energy harvesting systems. The compact dual‐band CP antenna size is able to achieve by stacking slotted‐circular‐patch (SCP) on the substrate above the tapered‐slit‐octagon patch (TSOP). Dual‐band CP radiation is realized by stacking the SCP on the TSOP and the microstrip feedline with metallic‐via to SCP. Eight‐tapered‐slit with length difference of 6.25% are embedded along the octagonal directions symmetrically on the TSOP from the patch's center and two unequal size circular slots are embedded in diagonal axis onto SCP to produce dual‐orthogonal modes with almost equal magnitude for CP waves. The designed antenna is realized measured gain of greater than 5.2 dBic across the band (0.908‐0.922 GHz) with maximum gain of 5.41 dBic at 0.918 GHz and gain of greater than 6.14 dBic across the band (2.35‐2.50 GHz) with maximum gain of 7.94 dBic at 2.485 GHz. An overall antenna volume is 0.36λ _o × 0.36λ _o × 0.026λ _o (λ _o is free space wavelength at 0.9 GHz). A compact composite right‐/left‐handed (CRLH) based rectifier with dual‐band at 0.9 and 2.45 GHz is designed, prototyped, and measured. The right‐handed (RH) part of the CRLH transmission line (TL) is formed by a microstrip line. The left‐handed (LH) part of the CRLH‐TL is formed by lumped components. The measured RF‐DC conversion efficiency is 43% at 0.9 GHz and 39% at 2.45 GHz with rectifier size of 0.18λ _o × 0.075λ _o × 0.0002λ _o at 0.9 GHz.     

A modified split ring resonator based printed compact monopole UWB antenna with spiked elliptical radiator having five band rejection features

A coplanar waveguide (CPW) fed printed compact monopole antenna with five band rejection features is presented. Wide bandwidth was achieved by beveling the lower part and adding a modified ellipse on the upper portion of the patch. An inverted circular arc, single circular split ring resonator (SRR) with wide opening and two symmetrical circular single SRRs were embedded for obtaining three stop‐band characteristics. Two symmetrical slits were inculcated in the ground forming defected ground structure (DGS) to get another stop‐band characteristic. Two concentric rectangular modified SRRs were etched to obtain a higher frequency stop‐band feature. The proposed antenna was designed, fabricated, and experimentally tested for the validation of results. The overall dimensions of the proposed antenna were 29 mm × 24 mm × 1.6 mm. The measured impedance bandwidth of the antenna was 2.87 to 13.3 GHz at | S₁₁ |< ? 10 dB. The measured results show that the proposed antenna has five band notches centred at 3.96, 4.35, 5.7, 8.54, and 9.95 GHz to reject WiMAX band (3.65‐4.04 GHz), ARN band (4.29‐5.18 GHz), WLAN band (5.5‐6.9GHz), ITU‐8 band (7.37‐8.87), and amateur radio band (9.2‐10.3 GHz) respectively. The proposed antenna maintains omnidirectional radiation pattern in H‐Plane and dumbbell‐shape radiation pattern in E‐plane. Further, stable gain over the whole UWB except at notched frequency bands was reported.     

The design of radio frequency energy harvesting and radio frequency‐based wireless power transfer system for battery‐less self‐sustaining applications

In this paper, the RF energy harvesting system and RF‐based wireless power transfer system are proposed and designed for battery‐less self‐sustaining application. For energy harvesting, the designed antenna array improves the received RF power effectively and also can harvest RF energy in multi‐frequency bands. For wireless power transfer, the proposed helical antenna realizes the system design in miniaturization. Subsequently, the T shape LC matching network are designed between the antenna and the rectifying circuit to obtain more power transmission. The measured results show that the proposed Wi‐Fi rectifier and 433 MHz rectifier offer a maximum conversion efficiency of 66.8% and 76% in case of the input power is ?3 dBm and 0 dBm, respectively. Finally, the performance of the RF‐based wireless power transfer system and RF energy harvesting system are attested by experimentally measurement, the measured results indicate that these systems can be used to power electronic.     

A hybrid printed monopole antenna loaded with dielectric resonator for wideband and circular polarization applications

This article presents a novel compact circularly polarized antenna with wideband operation. The proposed antenna consists of a microstrip‐line‐fed printed monopole, a finite truncated ground, and a dielectric resonator (DR). Compared to the printed monopole antenna, the proposed DR‐loaded antenna has an increased impedance bandwidth, a large axial ratio bandwidth, and a good realized gain across the desired frequency range. An antenna prototype is fabricated and experimentally tested. The measured antenna impedance match is better than ?10 dB over 90% from 4.5 to 11.8 GHz frequency band and the 3‐dB axial‐ratio bandwidth is better than 35% covering the 5.4–7.65 GHz frequency band. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE , 2012.     

A novel super compact half‐mode substrate‐integrated waveguide filter using modified complementary split‐ring resonator

A novel super compact filter based on half‐mode substrate‐integrated waveguide (HMSIW) technology loaded by the modified complementary split‐ring resonator (MCSRR) is proposed. The working principle of the proposed filter is based on the evanescent‐mode propagation technique. According to this technique, by loading the complementary split‐ring resonator (CSRR) on the metal surface of the substrate‐integrated waveguide (SIW) structure, an additional passband below the SIW cutoff frequency can be obtained. In order to miniaturize the physical size of the conventional CSRR, a new method is introduced. In the proposed MCSRR unit‐cell, the meander slots are carved inside all of the interior space of the ring. Accordingly, the length of the slot is increased which leads to an increase in the inductor and capacitor of the proposed structure without occupying the extra space. Therefore, the electrical size of the proposed MCSRR unit‐cell is reduced. Consequently, the resonance frequency of the proposed MCSRR unit‐cell is decreased compared to the conventional CSRR with the same sizes. Namely, the lower resonance frequencies can be achieved by using this technique without increasing the size of the unit‐cell. In order to confirm the miniaturization technique, two HMSIW filters loaded by the proposed MCSRR unit‐cell are designed, fabricated, and experimental verifications are provided. The results show that a miniaturization about 67% is achieved.