Rectenna Application Research Articles

Electrical Characteristics of Gated Anode Diodes Based on Normally Off Recessed‐Gate GaN High‐Electron‐Mobility Transistors for Rectenna Applications

AlGaN/GaN high‐electron‐mobility transistor (HEMT)‐based gated‐anode diodes (GADs) for a 5.8 GHz rectenna application are proposed. An anode of the GAD is formed by connecting a gate and a drain of a normally off GaN HEMT. Herein, a wide recessed HEMT structure reported in the previous article is modified to a buried‐type recessed gate HEMT structure. The gate‐to‐cathode distance is optimized to maximize device performance. Typical direct current (DC) characteristics of the HEMTs are a threshold voltage (Vth) of +0.4 V and a maximum drain current (Imax) of 450 mA mm−1. GADs using the HEMTs show the characteristics of maximum forward current (If) of 600 mA mm−1and reverse breakdown voltage (BVr) of more than 100 V. The GAD using the recessed gate structure HEMT is shown to significantly improveIfandBVrsimultaneously compared to the previous work using the wide recessed gate structure. The rectifying performance of a bridge‐type rectifier simulated with SPICE model of the GAD shows radio frequency (RF)–DC conversion efficiency of 84% and RF input power of 13 W at 5.8 GHz using four GADs with each gate width (Wg) of 400 μm.

Theoretical and experimental study of shear mode bulk acoustic wave transformer based on c-axis zigzag ScAlN multilayer for rectenna application

The wireless power transfer with rectennas for sensors has attracted much attention in recent years. Although a charge pump is commonly used for voltage transformers in rectennas for RF voltage amplification, it is large, has low efficiency, and has poor impedance matching. Here, we propose small bulk acoustic wave piezoelectric transformers based on c-axis zigzag polarization-inverted ScAlN multilayers. The capacitive impedance ZC of an n-layer c-axis zigzag multilayer resonator is n times larger than that of a single-layer resonator. A piezoelectric transformer can, therefore, be obtained by the combination of a c-axis tilted monolayer and a c-axis zigzag multilayer. Glancing angle-sputtering deposition enabled c-axis highly oriented zigzag multilayer growth. The transformers exhibited an experimental voltage gain approaching +10 dB in the 0.5 GHz range. The experimental results agreed well with the theoretical model calculated using the electromechanical transmission line model, including the effect of the polarization-inverted structure. Furthermore, a simple formula expressing the voltage gain and simple equivalent circuit model for the transformer was derived, which is precise near the resonant frequency. In contrast to the finite element method model, this model described by lumped components makes it possible to simulate easily the entire performance of a rectenna, including an antenna and a rectifier, using a common circuit simulator.

A Novel Design of Circularly Polarized Aperture-Coupled Antenna with Harmonic Rejection for Rectenna Application

This paper presents a novel design of stacked antenna that operates at 2.45 GHz. The proposed antenna applies a new aperture coupling slot of right triangle which is fed by a single microstrip line and coupled to the radiated patch etched on the top substrate. The two layers of a low-cost FR-4 substrate with relative permittivity of er= 4.4 are separated by an air gap to enhance the antenna gain to >7 dB. The proposed antenna with right triangular aperture coupling slot has achieved high order harmonic rejection at 4.5 GHz and 6.6 GHz, and circular polarization with an axial bandwidth of 40.8%. Experimentally, the measurement results show a good agreement with the simulated ones, which makes this antenna a good candidate for rectenna applications.

Enhanced Antenna Design for Rectenna Application in the 2.45 GHz ISM Band

In this paper a two layers microstrip antenna design at 2.45 GHz ISM band with Harmonic rejection filter embedded on the ground plane is presented. The two roger substrates with relative permittivity of 2.2 are separated by an air gap which enhances the antenna gain. The design is simulated using Computer Simulation Technology (CST) Studio Suite 2015. Different aperture couplings slots such as rectangular and triangular aperture coupling slots are studied and compared. It is found that the antenna with triangular aperture coupling slot enhances the antenna performance by suppressing 2 nd and 3 rd harmonics at 5 GHz and 8 GHz, respectively, increasing the antenna gain and providing a better circular polarization behavior. The simulated antenna design achieves a gain of 9 dB, return loss of -23.6dB, axial ratio of 1.27dB and axial-ratio bandwidth of 40.8% (2 ~ 3 GHz). The proposed antenna shows an enhancement in the antenna performance which makes it a suitable candidate for rectifying antenna or rectenna application as it can increase the total conversion efficiency resulting in a high output DC voltage used to power low power electronic and electrical devices such as wireless sensor.

Design of Circular Polarization Antenna With Harmonic Suppression for Rectenna Application

A microstrip antenna design that effectively attains circular polarization (CP) and harmonic suppression is proposed. By modifying the size and position of two peripheral cuts, two orthogonal modes that have equal amplitude and are 90 out of phase are simultaneously excited. The four right-angle slits embedded in the antenna can block the second- and third-order harmonic signals. This property is especially suitable for nonlinear circuit applications, such as active integrated antenna (AIA) and rectifying antenna (rectenna). The adopted CP antenna built on a low-cost FR4 substrate has a measured bandwidth of 137 MHz (10-dB return loss) and a 30-MHz CP bandwidth (3-dB axial ratio). A rectenna that comprises the proposed antenna and a rectifying circuit is built for verifying the characteristics of the proposed antenna. The measured results of the proposed antenna are in good performances and steady efficiency.

Effects of Dielectric Deposition on the Electrical Characteristics of MIM Tunnel Junctions

In this research, the effects of varying the reactive gas ratio during insulator deposition of MIM junctions have been observed and studied. Junctions with 100×100 μm area have been realized using Ni-NiO-Cr electrodes for Rectenna application. The electrical properties of the tunnel junctions exhibited improved tunneling response with reduced O2 gas ratio. It is theorized that a surplus of O2 ions facilitates tunneling, as does a deficiency of O2 ions due to charge transport by ions or vacancies. The devices fabricated with 1:1 and 1:3 gas ratios both exhibited high electrical responses with the latter exhibiting higher, while 1:2 exhibited the lowest response, suggesting that an increased or decreased density of traps within the barrier results in changes in the tunneling current. The dependence of voltage linearity on trap-densities within a dielectric has been shown and is discussed in this article.