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Vol. 121, 157-167, 2023
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A Novel Balanced-to-Unbalanced All-Port Reflectionless Filtering Power Divider Without Loading Additional Absorptive Branches at Input and Output Ports
Qi Chen , Huabin Zhang , Zhongbao Wang , Hongmei Liu and Shao-Jun Fang
A novel balanced-to-unbalanced (BTU) all-port reflectionless filtering power divider without loading additional absorptive branches at input and output ports is proposed in this paper. The proposed power divider includes two reflectionless filtering networks, four transmission lines, a phase inverter, and two isolation resistors. Unlike the existing filtering power dividers that require additional absorptive branches to be loaded at each port to achieve reflectionlessness at all ports, the proposed power divider achieves all-port reflectionlessness by embedding only two reflectionless filtering networks in the BTU power dividing circuit. Meanwhile, this reflectionless filtering network also introduces two transmission zeros located at the lower and upper sides of the passband, respectively, for high selectivity. To validate the proposed power divider topology, a 2.0-GHz BTU filtering power divider is designed and fabricated with a 3-dB filtering bandwidth of 40.1%. The 10-dB reflectionless bandwidth for the balanced port is 98.7% from 0.940 to 2.772 GHz and that for the unbalanced ports covers the entire measurement frequency from 0.5 to 3.5 GHz, achieving good all-port reflectionless characteristics.
A Novel Balanced-to-unbalanced All-port Reflectionless Filtering Power Divider without Loading Additional Absorptive Branches at Input and Output Ports
Vol. 121, 147-156, 2023
download: 77
Design, Modeling and Analysis of Low Cross Polarization Level Low Radar Cross Section Conformal Ultra Wideband Absorber Based on Resistive Metasurface
Saurabh Kumar Srivastava , Rahul Dubey and Manoj Kumar Meshram
In this paper, a low cross-polarization level, low radar cross section (RCS), conformal, ultrawideband, polarization-insensitive absorber utilizing sinusoidal periphery annular ring (SPAR) resonator based novel resistive metasurface is presented. The proposed absorber operates with more than 90% absorptivity over the frequency range 7.68 GHz-24.90 GHz encompassing X-, Ku- and major portion of K-bands. The absorber consists of two sinusoidal peripheries annular rings embedded with lumped resistors, placed on top of a 0.1 mm thin low cost FR-4 substrate which is supported by metal backed foam. The sinusoidal periphery on the annular rings improves the absorption bandwidth and miniaturizes the proposed structure. Cross-polarized reflected component from the absorber is also investigated and included in the estimation of absorptivity to validate that the proposed structure functions as an absorber and not as a reflective type polarization converter. An equivalent circuit analysis based on the transmission line model is also presented. Novelty of the proposed article's lies in the design approach for the proposed absorber in which flexibility is incorporated to choose unit cell geometrical parameters as per the limiting frequencies (upper and lower) of desired band along with some miniaturization aspects of the absorbing structure. Furthermore, 10 dB RCS reduction is discussed, and the formula is derived by including cross-polarized reflection component of the incident wave in estimation. The proposed absorber is validated through theoretical, simulation, and experimental studies for planar and conformal applications.
Design, Modeling and Analysis of Low Cross Polarization Level Low Radar Cross Section Conformal Ultra Wideband Absorber based on Resistive Metasurface
Vol. 121, 139-146, 2023
download: 105
Skin Sarcoma Detection by Antenna Resonance Scale
Dozohoua Silue , Fethi Choubani and Mondher Labidi
In this paper, a small antenna is proposed to diagnose skin sarcoma from the embryonic stage to the metastasis stage. The prototype consists of a new antenna structure with a surface of 31.3 x 15.65 mm2 and a 35 μm copper sheet engraved on a 1.6 mm FR-4 substrate. The diagnosis is based on the shift in resonance frequency when the antenna is positioned on malignant tissue. For the simulations, a three-layer body Phantom (skin, fat, and muscle) and a half-sphere tumor Phantom were considered. Simulations of antenna performances showed that for a tumor of 26.17 mm3, the resonance frequency decreases by 7.5 MHz. Measurements made on the prototype of the designed antenna show an adequacy between the results of the measurement and those of the simulation.
Skin Sarcoma Detection by Antenna Resonance Scale
Vol. 121, 127-137, 2023
download: 107
A Phase Noise Optimized FMCW Radar System for Data Transmission
Andreas Wanjek , Linus Hampel , Thomas Schäfer and Thomas Zwick
This paper presents a method for using a 120 GHz frequency-modulated continuous wave (FMCW) radar system for communication. The transmitting unit of the FMCW radar partly consists of a phase locked loop (PLL) control. Through modification, the functionality of this structure is extended for data transmission. The two modes of operation, i.e. radar measurement and data transmission, impose different requirements on the design of the PLL, such as the necessary bandwidth. We show how the phase noise and hence the quality of data transmission can be improved by varying the charge pump (CP) current of the PLL. Simulation results and measurements prove the data transmission potential of the presented method for industrial applications in the field of short-range communication.
A Phase Noise Optimized FMCW Radar System for Data Transmission
Vol. 121, 117-125, 2023
download: 180
An Ultra-Wideband and Translucent Metasurface Absorber Based on Water
Chaobiao Chen , Tianhang Chen , Min Huang , Huan Lu and Bin Zheng
Electromagnetic metasurface has become the focus of researchers in the field of electromagnetic absorption in recent years because of its thin thickness, simple structure and high absorption rate. With high real and imaginary parts of the permittivity in the microwave frequency regime, water plays a crucial role in absorbing materials. This work demonstrates a water-based translucent metasurface with 5.2 mm, which is fabricated by 3D printing. By changing the conductivity of water, a metasurface with good absorption performance is obtained, which can realize ultra-wideband absorption in 5.85-23.1 GHz and 5.85-14.8 GHz under the oblique incidence of 40˚. The metasurface has the characteristics of thin thickness, wide-band absorption, and translucency.
An Ultra-wideband and Translucent Metasurface Absorber Based on Water
Vol. 121, 107-115, 2023
download: 100
Research on Anti-Offset Performance of the Wireless Power Transfer System with Asymmetric Coupling System
Xiangyang Shi , Jianwei Kang , Deyu Zeng and Yang Shi
Coupling system is important for a Wireless Power Transfer (WPT) system, and it directly affects the efficiency and reliability of the WPT system. In some special applications, such as implantable medical devices, the size of the receiving coil of the WPT system is strictly limited. Coupling coils of equal size will not meet the application requirements. When being applied in implantable medical devices, equal-size coupling coils suffer from shortcomings such as poor anti-offset performance and cumbersome design process. In view of the above problems, in this paper we design a coupled coil structure asymmetrically, so that parameters such as the outer diameter and the number of turns of the transmitting and receiving coils are no longer equal. In this paper, we first analyze the effect of tightly wound and loosely wound coils on the WPT system when they are used separately as transmitting coils, and find that the two different types of coils have different characteristics of the magnetic induction intensity distribution. Then we use the genetic algorithm to optimize the transmission coil and design a new asymmetric coupling system. Finally, we experimentally demonstrate that the optimized coupled system is able to maintain the stability of the output current and the transmission efficiency within a certain range in the presence of the offset, which indicates that the coupling system has a certain ability of anti-offset.
Research on Anti-offset Performance of the Wireless Power Transfer System with Asymmetric Coupling System
Vol. 121, 95-105, 2023
download: 72
Leaky Mode Analysis of Solid Dielectric Horn Antenna
Shreya Sudhakaran Menon , Shubham Kalra , Surya Kumar Pathak , Nalesh Sivanandan and Supriya M. Hariharan
Solid dielectric horn antennas have a directional radiation pattern and high gain. However, even when a solid dielectric horn antenna is excited with the fundamental mode metallic waveguide, there is a possibility that higher order modes in the guided region will be generated. Also, the energy can leak from the normal direction to the dielectric horn generating a leaky mode. It is one of the reasons that higher-order guided modes and leaky modes analysis of horn becomes important. In this paper, propagation characteristics for solid dielectric horns are derived and computed for fundamental and higher-order guided and also leaky modes in a solid dielectric horn antenna. We have also analyzed the radiation characteristics of the leaky mode and guided mode of a solid dielectric horn. Finally, radiation equations for a solid dielectric horn antenna that were deduced earlier by some of the authors, but omitted for brevity are given and compared with numerical and measured results. These results have been further verified by comparing them with the already reported literature on guided mode radiation characteristics of the solid dielectric horn. From the plotted graphs given in the paper, we can infer that the proposed propagation constant equations and radiation equations predict dispersion characteristics and the radiation pattern of guided and leaky modes well, respectively.
Leaky Mode Analysis of Solid Dielectric Horn Antenna
Vol. 121, 83-93, 2023
download: 152
A Hierarchical PHM Framework for Phased Array Radar Systems
Delanyo Kwame Bensah Kulevome , Hong Wang , Zian Zhao and Xuegang Wang
Phased array radar (PAR) systems are critical for modern defense and surveillance applications, but their reliability and availability are affected by various factors, including physical and performance degradation. Furthermore, implementing prognostics and health management (PHM) framework for the whole radar system is challenging. To address these issues, this paper proposes an efficient solution by hierarchically implementing PHM frameworks in an active PAR (APAR) system. The proposed framework subsumes device-level, subsystem-level, and system-level health prediction models to enable comprehensive health monitoring and maintenance decision-making. This approach addresses the unique challenges involved in implementing PHM for the APAR system and facilitates the transition from traditional reactive maintenance practices to a predictive maintenance approach, thereby improving the overall system. Mathematical models that relate the radar's physical degradation to its performance deterioration are formulated, analyzed and presented. Subsequently, a Bayesian long short-term memory (BayesLSTM) architecture is developed and integrated into the proposed framework for estimating the remaining useful life (RUL) of critical devices/subsystems. The effectiveness of the proposed deep learning-based prognostic framework is evaluated through simulations and experimental studies. The proposed hierarchical framework has the potential to be applied to other radar systems that require effective health monitoring strategy.
A Hierarchical PHM Framework for Phased Array Radar Systems
Vol. 121, 73-81, 2023
download: 107
Modification of Fast Inverse Laplace Transform for Transient Response Analyses
Koki Watanabe
The fast inverse Laplace transform (FILT) proposed by Hosono is recently applied to various transient response problems in electromagnetics. The frequency-domain methods have been the mainstream of electromagnetic simulation for many years, and a lot of knowledge has been accumulated. The FILT makes it possible to utilize frequency-domain techniques to transient analyses, and it is expected to provide reliable transient response analyses. Since the evaluation points of the image function in the conventional FILT depend on the observation time, the scope of application is sometimes limited when evaluation of the image function takes a relatively long computation time. This paper modifies the FILT so that the evaluation points are independent of the observation time, and the number of image function evaluations is reduced.
Modification of Fast Inverse Laplace Transform for Transient Response Analyses
Vol. 121, 63-72, 2023
download: 98
A Focused Circular Array with Variable Focal Length
Khalil Sayidmarie and Mohammed Z. Mohammed Fwzi
Focused arrays are attracting increased interest because of their wide range of applications. Focusing the antenna's radiation in the near field requires proper phase distribution of the array elements that must be fed through many phase shifters. This work presents a design idea for a focused circular array antenna, whose focal distance can be varied by only a single variable phase shifter. The idea is implemented on a dual-ring circular array having a six-wavelength diameter and focused at five wavelengths by using a single fixed phase shifter. Theoretical analysis and computer simulations of a sample design using MATLAB and CST Microwave Studio show that a phase change of 0.9π leads to a four-wavelength change in the focal distance. A formula for the estimation of the depth of field DOF is derived. The proposed array offers a simple method to vary the focal length continuously by a single variable phase shifter. This idea can be utilized in hyperthermia, RFID, and imaging applications, where the position of the focal spot needs to be moved along the normal to the array.
A Focused Circular Array with Variable Focal Length
Vol. 121, 49-62, 2023
download: 106
A Low Profile Circularly Polarized Microstrip Antenna with Equilateral Triangular Patch and Parasitic Elements for Dual Application Band
Murari Shaw
In this research work, a low-profile microstrip patch antenna has been designed with broad circularly polarized resonant bandwidth. The designed antenna consists of an equilateral triangular-shaped radiating patch with two triangular coplanar parasitic elements along with a square-shaped ground plane. The unique feature of this antenna design is a generation of circularly polarized radiation by only optimum corner truncation of the two parasitic elements along with a small portion of the driver patch. The designed antenna can be used for (5.725-5.850 GHz) WLAN and (5.85-5.925 GHz) dedicated short-range communication applications with circularly polarized radiation property. The overall resonant bandwidth for (S11 ≤ -10 dB) is 1.52 GHz 24.75% with a frequency range (5.38-6.90 GHz), and the circularly polarized resonant bandwidth for (Axial ratio ≤ 3 dB) is 240 MHz 4.13% with a frequency range (5.69-5.93 GHz). The gain of the antenna is 4 dB at 5.81 GHz and almost remains the same for the entire resonant bandwidth. The complete design of the antenna has been done using theoretical calculation and HFSS ver13 simulation software. After that, it has been fabricated, and different parameters have been measured using Vector Network Analyser. It has been found that the measured results are very much similar to the simulated results.
A Low Profile Circularly Polarized Microstrip Antenna with Equilateral Triangular Patch and Parasitic Elements for Dual Application Band
Vol. 121, 39-47, 2023
download: 122
Optimizing Detection in MIMO OFDM Radar: Methods for Eliminating Distance-Angle Coupling in Beamforming
Doudou Huang , Yurong Wu , Mingliang Shen , Longshan Xu and Jun Tang
This study investigates beamforming and optimization in Multiple-Input-Multiple-Output Orthogonal-Frequency-Division-Multiplexing (MIMO OFDM) radar systems. The objective of this research is to mitigate the range-angle coupling effect in MIMO OFDM radar systems by adopting range compensation and distance-angle decoupling methods, which is to ensure that the signal processing during radar waveform formation does not impact the aforementioned coupling effect. In distance compensation, the CVX toolbox is used to minimize peak sidelobe after distance compensation is performed in the angle dimension. A mathematical model is established, and an optimal set of transmission frequencies is achieved through the use of the Alternating-Direction-Method-of-Multipliers (ADMM) algorithm in the context of distance-angle decoupling. Both methods effectively eliminate distance-angle coupling and enhance detection and identification capabilities of MIMO OFDM radar systems.
Optimizing Detection in MIMO OFDM Radar: Methods for Eliminating Distance-angle Coupling in Beamforming
Vol. 121, 27-37, 2023
download: 110
Series-Fed Antenna Array Without Beam Deterioration Using Miniaturized Bandpass Filters for Phase-Slope Balancing
Huanhuan Shi , Xin Guo and Wen Wu
A design of a series-fed antenna array without beam deterioration using miniaturized bandpass filters (BPFs) is proposed. The BPFs are connected behind branches of series feed network (SFN) to compensate the varied phase slope of paths, resulting in constant phase difference between elements across the bandwidth. Hence, the beam deterioration versus frequency is removed. The closed-form equations of the phase slopes for BPFs are deduced, and thus they can be designed quantitatively for phase slope balancing. The proposed SFN has advantages of compactness, simplicity, and low loss. For validation, an 8-element antenna array is designed and measured. The gain and sidelobe level are 12.2-12.39 dBi and 11.67-12.65 dB within the bandwidth of 5.2-5.8 GHz. As comparison, the gain and sidelobe level are 12.85-13.77 dBi and 7.18-12.75 dB using conventional feed network. Therefore, the designed antenna array has stable radiation pattern including beam direction, sidelobe level, and gain.
Series-fed Antenna Array without Beam Deterioration Using Miniaturized Bandpass Filters for Phase-slope Balancing
Vol. 121, 13-26, 2023
download: 83
Low-Frequency Magnetic Shielding of a Cavity Formed by Two Imperfectly Conducting Sheets: Effect of Sheet-to-Sheet Distance and Comparison with the Single-Sheet Configuration
Fubin Pang , Shi Chen , Jianfei Ji , Yiyi Jing , Sijia Liu and Chongqing Jiao
In standard measurement methods such as NSA 94-106, the low-frequency magnetic shielding effectiveness of a shielding enclosure is tested using the near field of loop antenna. Under this near-field configuration, there is no analytical or closed-form solution for volumetric shielding like box/cavity except for planar shielding like a sheet of infinite extension. Exploring the correlation between volumetric shielding and planar shielding can provide simple prediction methods for volumetric shielding based on planar shielding. As a taste to this end, this article explores the difference between the shielding effectiveness of a double-sheet cavity and a single sheet under the NSA 94-106 standard. We derived the exact solution in integral form for electromagnetic fields inside the cavity and calculated the curves of shielding effectiveness on the frequency with different sheet material, thickness, and sheet-to-sheet distance. The results show that when the distance from the receiving antenna to the back sheet is greater than the diameter of the loop antenna, the results of a double-sheet cavity tend to be consistent with a single-sheet configuration. When the distance is less than the diameter, the difference between the two depends on material type and sheet thickness.
Low-frequency Magnetic Shielding of a Cavity Formed by Two Imperfectly Conducting Sheets: Effect of Sheet-to-sheet Distance and Comparison with the Single-sheet Configuration
Vol. 121, 1-11, 2023
download: 85
Multi-Physics Analysis and Loss Evaluation of High Frequency Transformer with Non-Sinusoidal Excitation
Sherin Joseph , Shajimon Kalayil John , Kudilil Prasad Pinkymol , Jineeth Joseph and Kappamadathil Raman Muraleedharan Nair
High Frequency Transformer (HFT) acts as the key element of a Solid State Transformer (SST), which is a mandatory equipment in smartgrid system. SST replaces power frequency transformer by providing control and communication in power system. The design of an HFT matching the design of conventional distribution transformer is done in this paper. It is done by developing an iterative algorithm using Brute Force technique. The optimum design is selected by taking minimization of total owning cost as objective function. The algorithm takes eight design variables and four design constraints for shortlisting the optimum design. The optimum design developed is validated in finite element analysis software. The multi-physics analysis of the design is done by interconnecting electromagnetic, mechanical, thermal, and power electronics components of the system. The analytical and numerical analysis follow the same pattern by conducting a case study on the design of HFT with ratings 1000 kVA, 11 kV/415 V, three phases.
Multi-physics Analysis and Loss Evaluation of High Frequency Transformer with Non-sinusoidal Excitation