This paper presents a wideband, low-profile and semi-flexible antenna for wearable biomedical telemetry applications. The antenna is designed on a semi-flexible material of RT/duroid 5880 (E r = 2.2, ...tanδ = 0.0004) with an overall dimensions of 17 mm × 25 mm × 0.787 mm (0.2λ 0 × 0.29λ 0 × 0.009λ 0 ). A conventional rectangular patch is modified by adding rectangular slots to lower the resonant frequency, and the partial ground plane is modified to enhance the operational bandwidth. The final antenna model operates at 2.4 GHz with a 10-dB bandwidth (fractional bandwidth) of 1380 MHz (59.7 % at the centre frequency of 2.4 GHz). The proposed antenna maintains high gain (2.50 dBi at 2.4 GHz) and efficiency (93 % at 2.4 GHz). It is proved from the simulations and experimental results that the antenna has negligible effects in terms of reflection coefficient, bandwidth, gain, and efficiency when it is bent. Moreover, the antenna is simulated and experimentally tested in proximity of the human body, which shows good performance. The proposed wideband antenna is a promising candidate for compact wearable biomedical devices.
In this paper, a long-range dual-band rectenna for harvesting ambient radio frequency (RF) energy from GSM/900 and GSM/1800 is presented. Theoretical analysis of the proposed dual-band impedance ...matching network (IMN) is conducted using a modified <inline-formula> <tex-math notation="LaTeX">\Pi </tex-math></inline-formula>-section matching network (MN). The RF-rectifier is integrated with a dual-band inverted-F monopole antenna. The rectenna circuit complexity is minimized by introducing a dual-band IMN, which plays a significant role in improving the harvester RF-to-dc power conversion efficiency (PCE). Measurement results of the proposed design achieved a peak RF-to-dc PCE of 12.93% and 8.0% for an input power of −30 dBm at 0.9 GHz, and 1.8 GHz, respectively. The RF harvester ambiance measurement attained an output dc voltage of 0.374 V. The circuit generates 0.747 V using a low-powered bq25504-674 evaluation module (EVM). Thus, adequate energy management of the proposed rectenna can be used to power many low-powered devices from the harvested ambient RF energy.
Abstract
This paper described a four-band implantable RF rectifier with simplified circuit complexity. Each RF-rectifier cell is sequentially matched to the four operational frequencies to accomplish ...the proposed design. The proposed RF rectifier can harvest RF signals at 1.830, 2.100, and white space Wi-Fi bands between 2.38 to 2.68 GHz, respectively. At 2.100 GHz, the proposed RF harvester achieved a maximum (radio frequency direct current) RF-to-DC power conversion efficiency (PCE) of 73.00% and an output DC voltage
$$V_{DC}$$
V
DC
of 1.61 V for an RF power of 2 dBm. The outdoor performance of the rectenna shows a
$$V_{DC}$$
V
DC
of 0.440 V and drives a low-power bq25504-674 evaluation module (EVM) at 1.362 V. The dimension of the RF-rectifier on the FR-4 PCB board is 0.27
$$\lambda _{g}$$
λ
g
$$\times$$
×
0.29
$$\lambda _{g}$$
λ
g
. The RF-rectifier demonstrates the capacity to effectively utilize the frequency domain by employing multi-band operation and exhibiting a good impedance bandwidth through a sequential matching technique. Thus, by effectively controlling the rectenna’s ambient performance, the proposed design holds the potential for powering a range of low-power biomedical implantable devices. (BIDs).
LiDAR is a technology that uses lasers to measure the position of elements. Measuring the laser travel time and calculating the distance between the LiDAR and the surface requires the calculation of ...eigenvalues and eigenvectors of the convergence matrix. SVD algorithms have been proposed to solve an eigenvalue problem, which is computationally expensive. As embedded systems are resource-constrained hardware, optimized algorithms are needed. This is the subject of our paper. The first part of this paper presents the methodology and the internal architectures of the MUSIC processor using the Cyclic Jacobi method. The second part presents the results obtained at each step of the FPGA processing, such as the complex covariance matrix, the unitary and inverse transformation, and the value and vector decomposition. We compare them to their equivalents in the literature. Finally, simulations are performed to select the way that guarantees the best performance in terms of speed, accuracy and power consumption.
This paper presents a unique antenna that is designed to be efficient, with improved gain and partial flexibility, for use in wearable biomedical telemetry applications. The antenna design utilizes a ...semi-flexible RO5880 substrate material (dielectric constant, ε r = 2.2, loss tangent, (tan δ) = 0.0009) with physical dimensions measuring 0.47λ g × 0.47λ g . The model involves the incorporation of rectangular inverted "C" slots, which effectively results in a reduction of the resonant frequency. Additionally, a distributed rectangular slot is introduced on the ground plane, contributing to the augmentation of the operational bandwidth. The operational frequency of the proposed antenna design is 2.40 GHz, accompanied by a bandwidth (BW) of 320 MHz at a -10 dB level. This equates to a fractional percentage bandwidth (FBW) of 13.33% centered around the frequency of 2.40 GHz. The antenna design presented in this work demonstrates the preservation of improved gain and efficiency, achieving values of 3.67 dBi and 94%, respectively, at a frequency of 2.40 GHz. The work demonstrates through simulation and experimental outcomes that the antenna exhibits minimal impact on parameters such as gain reflection coefficient (|S11|), BW, and bending efficiency. Furthermore, the antenna underwent simulation and experimental testing in close proximity to the human body, revealing favorable operational characteristics. The proposed antenna exhibits substantial potential as a viable option for wearable biomedical instruments. Thus, the proposed wearable antenna design in this study offers a wideband antenna for ISM band applications, expanding bandwidth without compromising performance. Bending the antenna minimally affects gain, bandwidth, and efficiency when worn on the body, making it suitable for wearables. It also maintains a reasonably low Specific Absorption Rate (SAR), reducing wave absorption by the body. Unique features like rectangular inverted "C" slots and a distributed rectangular slot on the ground plane enhance bandwidth while maintaining performance during bending.
This article presents an innovative method for efficiently synthesizing radiation patterns by combining the Taguchi method and neural networks, validating the results on a ten-element antenna array. ...The Taguchi method aims to minimize product and process variability, while neural networks are used to model the relationship between antenna design parameters and radiation pattern characteristics. This approach utilizes Taguchi parameters as inputs for the neural network, which is then trained on a dataset generated by the Taguchi method. After training, the network is validated using a real ten-element antenna array. Analytical results demonstrate that this method enables efficient synthesis of radiation patterns, with a significant reduction in computation time compared to traditional approaches. Furthermore, validation on the antenna array confirms the accuracy and robustness of the approach, showing a high correlation between the performance predicted by the neural network model and actual measurements on the antenna array. In summary, our article highlights that the combined use of the Taguchi method and neural networks, with validation on a real antenna array, offers a promising approach for efficient synthesis of antenna radiation patterns. This approach combines speed, accuracy, and reliability in antenna system design.
A printed and minimal size antenna having the functionality of frequency shifting as well as pattern reconfigurability is presented in this work. The antenna proposed in this work consists of three ...switches. Switch 1 is a lumped switch that controls the operating bands of the antenna. Switch 2 and Switch 3 controls the beam switching of the antenna. When the Switch 1 is ON, the proposed antenna operates at 3.1 GHz and 6.8 GHz, covering the 2.5–4.2 GHz and 6.2–7.4 GHz bands, respectively. When Switch 1 is OFF, the antenna operates only at 3.1 GHz covering the 2.5–4.2 GHz band. The desired beam from the antenna can be obtained by adjusting the ON and OFF states of Switches 2 and 3. Unique beams can be obtained by different combination of ON and OFF states of the Switches 2 and 3. A gain greater than 3.7 dBi is obtained for all four cases.
This paper proposed a broadband RF-rectifier circuit. The design is matched through a combination of a wideband resistance compression network (RCN) with a modified short-stub matching network (MN) ...for Terminal-1 (T1) and a Π-MN for Terminal-2 (T2). The RCN incorporates the two terminals using a transmission line (TL) of 50 Ω. The TL-MN parameters are analyzed and evaluated in the design using closed-form equations. The HSMS2850-based prototype model demonstrates that the peak RF-to-DC power conversion efficiencies (PCE) realized at 3 dBm input power (Pin) are (76.92%, 70.53%, 69.75%, 67.54%) for (1.82, 2.13, 2.45, and 2.67 GHz), respectively. The prototype is terminated with a 1 kΩ load terminal (RL) and attained a maximum average output DC voltage VDC of 2.52 V. The model is tested in the ambient environment and achieved a T1(T2) VDC of 0.350(0.230) V. This approach also mitigated the impact of impedance variations imposed by diode non-linearity. The RF harvester drive a low-power evaluation module (EVM) for T1(T2) at 0.600(0.470) V.
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