In recent years, Radio Frequency Energy Harvesting (RFEH) has matured into a trustworthy and consistent method of obtaining ambient energy. For this energy to be utilized, it must be collected as efficiently over a broad range of frequencies as possible. In this regard, this article introduces a quad-band low-power, highly sensitive Radio Frequency (RF) to Direct Current (DC) signal converter circuit that operates at 1.5 GHz, 2.45 GHz, 3.6 GHz, and 5.5 GHz bands. The converter circuit is realized through single and dual-band converter circuit studies. These circuits comprise an impedance matching circuit, a voltage-doubler rectifier, a DC-pass filter with a resistive load of 5 kΩ, and a DC-DC voltage booster (LTC3108). The proposed quad-band converter circuit without a voltage booster gives a DC output voltage of 118 mV, 81 mV, 56 mV, and 24 mV at the four operational frequencies on a low input power of -25 dBm, respectively. A DC voltage of 3.3 V is obtained when the converter circuit is connected to a voltage booster. Maximum conversion efficiency achieved is 48% from four tones on a power input of -10 dBm. Circuit design steps, matching conditions, and performance parameters are presented using the Advanced Design System (ADS) and LTspice simulation tools.
In this paper, a compact Ultra Wide Band (UWB) Multiple Input Multiple Output (MIMO) antenna using circular slots Electromagnetic Band Gap (EBG) structures operating in frequency band from 3.1 GHz to 10.6 GHz is presented. The size of this compact antenna is 26 × 33 mm2. In wireless communications, such as WLAN, 4G, and 5G, MIMO has become an essential element. However, the major limiting factor of MIMO systems is mutual coupling due to the smaller spacing between multiple antennas, which reduces spatial diversity, antenna gain and can also result in unwanted interference and cross-talk between antenna elements. To enhance antenna performance and reduce the mutual coupling, EBG structures are used. Incorporation of EBG structures in MIMO antenna eliminates surface wave propagation, which reduces the mutual coupling. In this work, the design of a dot notch shaped UWB-MIMO antenna with a circular slot EBG structure is proposed. Results presented here are simulated by using CST microwave software studio. From the results it can be observed that the proposed antenna has bandwidth of 3.1 GHz-10.6 GHz. It exhibits 6.72 dB peak gain and reduces the mutual coupling considerably, i.e., more than -28 dB.
This research article introduces a compact wearable antenna designed specifically for medical applications. The antenna underwent prototyping using a flexible Rogers Duroid RO3003TM material, featuring a small form factor measuring 35 × 32 × 0.5 mm3. In the initial phase of the design process, a basic P-shaped rectangular patch antenna was employed. However, during the first design iteration (Design 1), the antenna demonstrated a single resonance around 1.2 GHz, although it was not optimally matched at that frequency. To tackle this problem and achieve miniaturization involved the introduction of two rectangular patches positioned below the P-shaped patch known as Design 2. To further improve its performance, an inverted L-slot was incorporated. The frequency of operation for the antenna is 2.4 GHz, with a bandwidth measuring 25.2% ranging from (2.087-2.692) GHz. The measured radiation patterns demonstrate bidirectional properties in the E-plane and omnidirectional properties in the H-plane and maintain a high gain of 3.54 dBi and an efficiency of 91%. The SAR values are 0.018/0.013 Watt/kg on the chest. Similarly, the SAR values are 0.02/0.015 Watt/kg on the thigh, using 1/10 g of human tissue, which comply with the standards set by the FCC and the ICNIRP. Furthermore, the simulation and measurement under bending investigation and being close to the human body demonstrate excellent performance. Therefore, the suggested antenna holds significant potential as a compact solution for wearable medical applications.
Utilizing deep learning to replace numerical simulation solvers for electromagnetic wave propagation is a promising approach for the rapid design of photonic devices. However, to realize the advantages of deep learning for rapid design, it is essential to apply it to a general device structure. In this study, we propose a method that employs deep learning to assist in fast design of a general grating coupler structure. We use a modified 1D-ResNet18(1D-MR18) to predict the coupling efficiency of various grating couplers at different wavelengths. After comparing and selecting the optimal combination of learning rate, activation functions, and batch normalization size, the 1D-MR18 demonstrates remarkable accuracy (MSE: 2.18×10-5, R2: 0.969, MAE: 0.003). By integrating the 1D-MR18 with the adaptive particle swarm algorithm, we can efficiently design periodic and nonuniform grating couplers that meet various functional requirements, including single-wavelength grating couplers, multi-wavelength grating couplers, and robust grating couplers. The time for designing a single device is no more than 2 minutes, and the shortest is only 17 seconds. This novel approach of employing deep learning for the fast and efficient design from standard photonic device structures offers valuable insights and guidance for photonic devices design.
The exponential increase of data traffic in next generation wireless communication attracts optimized design of antenna arrays (AAs) to be deployed in RANs. The traditional antenna array synthesis techniques have become exhaustive leading to the introduction of machine learning assisted new binary optimization algorithm. In this paper, three specific AA features are given particular attention: peak sidelobe level (PSLL), first null beam width (FNBW), and broad sector null in interference directions. These contrast each other, and a multi-objective new binary cat swarm optimization (MO-NBCSO) with a novel mutation probability is developed to derive the best-compromised solutions among them. The computational complexity is approximated as O(MN2) (here, M and N represent the number of objectives and population size, respectively). Hence, a 20×20 planar antenna array is considered for synthesis and pareto fronts are generated alongside state-of-the-art MO algorithms. A fuzzy-based decision approach is introduced to choose the best trade-off solutions. A detailed comparative performance study is carried out by the two-performance metrics, namely, I-metric and S-metric. Numerical results illustrate that MO-NBCSO is a better candidate to produce the best antenna arrays in terms of array characteristics over other algorithms.
Methods of manual analysis for infrared image and temperature detection of power transmission and transformation equipment typically have problems, such as low efficiency, strong subjectivity, easy to make mistakes and poor real-time feedback. In this paper, a high temperature anomaly detection method based on SegFormer in infrared image of power transmission and transformation equipment is proposed. Many infrared images of power transmission and transformation equipment are collected and preprocessed, and the temperature information of each infrared image is read out using the DJI sdk tool to construct the temperature data matrix. In the segmentation stage, the SegFormer network is used to segment the key parts of the power transmission and transformation equipment to obtain the mask for detection. The maximum values of the temperature data in the mask area are calculated, and the high temperature anomaly detection atthe key parts of the power transmission and transformation equipment is realized. The test results on the test set show that the overall performance of the method is the highest as compared to other methods such as FCN, UNet, SegNet, DeepLabV3+, and an automatic temperature recognition can be realized, which has important practical value for the detection of high temperature anomaly at the key parts of power transmission and transformation equipment.
This paper designs a miniaturized, wide stopband microstrip filtering coupler based on coupled resonators. Firstly, a short-stub loaded uniform-impedance resonator (SSLUIR) is proposed, , and the size of the SSLUIR is reduced by adjusting the impedance ratio of the stubs and bending them. Then, the resonance performance of SSLUIR during electrical and magnetic coupling is studied. By adjusting the electrical length of the short stubs, higher harmonics are suppressed, and the upper stopband is widened. Finally, a 3 dB 180° microstrip filtering coupler is designed based on SSLUIRs. The measurement results show that the center frequency of the filtering coupler is 2.43 GHz, with a relative bandwidth of 6.6%. It can suppress harmonics within the 8.2f0 range by more than 18 dB and has a size of 0.23λg×0.33λg. The correctness of the design method for miniaturized and wide stopband filtering coupler has been verified.
Wireless communication systems have developed significantly over the last few decades. Due to the saturation of lower frequencies of microwave spectrum (3-30 GHz) and the increasing need for high speed, emerging systems for consumer or professional use are progressively shifting to upper microwave and millimeter waves. Our study proposes a methodology for evaluating and classifying losses on a vertically polarized millimeter wave link at 80 GHz. To achieve this, we simulated the link budget of a Nokia 80UBT millimeter wave link operating in its real propagation space (with overground) with Pathloss 5.1 Design tool. Then we built a 3.58 km full-scale link in the Tongo-Bassa watershed of the coastal city of Douala in Cameroon. Analysing data collected over the period from December 06, 2020 to December 16, 2021 under Power BI allowed us to characterize the response of the millimeter signal in free space, during dry and rainy seasons. We then challenge ITU-R P.837-7 and ITU-R.P.838-3 Recommendations on statistical models of rainfall for propagation modeling, especially for millimeter signals propagated in an equatorial climate with heavy rainfalls. The study estimated a rainfall rate for 0.01% of the time at 110.1 mm/h, with a millimeter link cut-off for a rainfall rate greater than 64.8 mm/h, with a specific attenuation due to rain of 6.5 dB/km.
Generalized Mie theory provides a theoretical solution to the extinction cross-section curve of an electromagnetic scattering event with a multiparticle aggregate, given the configurational information of the constituent particles. However, deducing the configuration of the aggregate from the extinction cross-section curve is a non-trivial inverse problem that can be cast as a global optimization problem. To address this challenge, we propose a computational scheme that combines global optimization search algorithms with a calculator known as the Generalized Multiparticle Mie-solution The scheme is tested using mock scattering cross-section curves based on randomly generated aggregate configurations. The scheme successfully reproduces the scattering curve by minimizing the discrepancy between the two scattering curves. However, the ground-truth configuration is not reproduced, as initially expected. This is due to the inability of the global optimization algorithm scheme used in the present work to correctly locate the global minimum in the high-dimensional parameter space.Nonetheless, the partial success of the proposed scheme to reconstruct the mock curves provides an instructive experience for future attempts to solve the inverse electromagnetic scattering problem by fine-tuning the present approach.
A wide band circularly polarized planar antenna of high radiation efficiency is proposed in the present work for future generations of wireless communications requiring circular polarization in the X-band of the microwave spectrum. The main radiating part of the antenna is a rectangular turn-shaped strip that is capacitively loaded by two corner-shaped parasitic elements. The antenna is fed through coplanar waveguide (CPW) region whose ground structure is defected by etching two rectangular annular slots. The purposes of both the corner-shaped parasitic elements and the rectangular annular slots of the CPW ground plane are to increase the impedance matching and the 3 dB axial ratio (AR) bandwidth, and to enhance the antenna efficiency. The design is achieved through complete parametric study to find the optimum dimensions of the antenna. A prototype of the proposed antenna is fabricated for experimental assessment of its performance. The results obtained by both simulation and experimental measurements show that the impedance matching bandwidth is about 5.3 GHz (8-13.3 GHz); the 3 dB AR bandwidth is about 3.1 GHz (8-11.1 GHz); the maximum gain ranges from 4.5 to 5.5 dBi; and the radiation efficiency is higher than 98% over the operational frequency band.
In order to support 5G communication, this article suggests a small, four-port MIMO antenna with a G slot. This antenna has an electromagnetic band gap (EBG) in the shape of an S that is engraved on the substrate in the space between consecutive pairs of radiating patches. The recommended MIMO antenna is constructed from an FR4 substrate and measures 48x48x1.6 mm3. Between antenna elements 1 and 2, the integrated EBG structure of the MIMO antenna can reduce mutual coupling by 10.5 dB. The suggested four port G slot MIMO antenna with an S-shaped EBG structure displays the performance in terms of ECC less than 0.0002 and diversity gain larger than 9.99 with consistent frequency band extending from 3.3 GHz to 3.7 GHz. The proposed four port MIMO antenna is designed using HFSS software, and its simulation results are measured using anritsu combinational analyzer MS2037C vector network analyzer.
A compact and novel star shaped fractal microstrip patch conformal MIMO antenna suitable for WLAN, vehicular communications (5.855-5.925 GHz) and Fixed Satellite Services (FSS) applications is proposed in this paper. Analysis of planar and conformal single element and four element MIMO antennas is presented. Proposed star shaped fractal MIMO antenna is prototyped on Polyamide substrate of geometry 104 x 30 x 0.4 mm3. It achieved an impedance bandwidth (S11 < -10 dB) of 3.7 GHz operating from 4.53-7.86 GHz. Radiation patterns and surface current distribution are investigated at 5.9 GHz and 7.3 GHz center frequencies. A peak gain of 5.42 dB and 4.86 dB are obtained at 5.9 GHz and 7.3 GHz respectively. Radiation efficiency is more than 98% and MIMO performance parameters are also analyzed. Proposed conformal MIMO antenna showsfine diversity performance for WLAN, vehicular and FSS communications.
A waveguide mode solver based on boundary integral equation (BIE) method and matrix compression is developed in this study. Using an accurate discretization based on a Nystrom method and a kernel-splitting technique, the BIE method gives rise to three different formulations of a nonlinear eigenvalue problem. H-matrices are used in order to accelerate and increase the precision of the subsequent computations. Results from these investigations on a canonical photonic crystal fiber (PCF) chosen as an example demonstrate that the data sparse representation of the BIE discretization reduces the memory storage, as well as the assembly and solution times.
A compact new dual band 4-port Vivaldi MIMO (Multiple-Input-Multiple-Output) antenna is designed for 5G mmWave applications. The proposed MIMO antenna resonates at two frequencies 28 GHz and 39 GHz, and it has dimensions 22x22x0.79 mm3. The Vivaldi structure etched on ground plane acts as a defected ground structure (DGS). The proposed antenna is fabricated on Rogers RT/duroid 5880 material having 0.79 mm thickness and 2.2 dielectric material. For high frequency and broad band applications RT/duroid material is suited to maintain low dielectric loss, and it works in high temperature places also. For the proposed four port Vivaldi MIMO antenna, the isolation between any two antenna elements is obtained below -21.59 dB. The bandwidths achieved for two bands are 4.64 GHz (26.31-30.95 GHz) at 28 GHz resonant frequency and 2.69 GHz (38.35-41.04 GHz) at 39 GHz resonant frequency for 4-port MIMO antenna. The gain achieved at 28 GHz is 5.65 dB and at 39 GHz is 5.53 dB. It is possible to achieve MIMO performance parameters such as ECC < 0.003, DG = 10, CCL < 0.4 (bits/s/Hz), TARC < -10 dB, and MEG ratio is 1.01. Simulated and measured results are compared, and the antenna is designed using ansys HFSS tool.
In this communication, a compact metasurface-based circularly polarized antenna with inverted L-shaped slots engraved in the ground is proposed for biomedical applications. The prospective antenna operates in the two frequency bands covering Medical Device Radio Service (Med Radio) and Industrial, Scientific, and Medicine (ISM) bands with center frequencies of 2.45 GHz and 4.1 GHz respectively. On mounting the prototype on the body, the impedance bandwidth of 14.4% and 42.5%, peak gain of 3.04 dB, and AR bandwidth of 0.3 GHz and 1.1 GHz in the two frequency bands (2.31-2.67 GHz and 3.28-5.04 GHz) are obtained respectively. For validating the prospective design, an antenna with the size of 0.264λ0 × 0.264λ0 × 0.014λ0 was fabricated on a Rogers RT/Duroid 6002 substrate and measurements were done in different scenarios. Link budget analysis of the device was also done for ensuring its communication ability.