Advanced Electromagnetics

Enhancing Plasma Density through Periodic Dielectric Grating Structures-Numerical Simulations

D. Kakulia, K. Tavzarashvili, I. Noselidze, G. Kajaia — Sat, 24 Aug 2024 00:00:00 +0200

This paper proposes an idea of the use of Dielectric Resonators (DRs) as concentrators of alternating magnetic fields for plasma density control applications. The study involves numerical simulations using the Method of Auxiliary Sources (MAS) to analyze Dielectric Frequency Selective Surfaces (DFSS) composed of periodic dielectric elements. Materials with variable dielectric permittivities, including E-Glass, Plexiglass, Taconic CER-10, and Teflon are considered, and their resonance properties are investigated. Results indicate that DFSSs can create strong magnetic fields at resonance frequencies, which can be utilized for plasma density regulation in processes like thin film deposition. The results demonstrate that materials with lower dielectric permittivity, such as Plexiglass and Teflon, exhibit higher resonance quality factors, while higher permittivity materials like E-Glass and Taconic CER-10 show poorer quality factors. The study emphasizes the potential of DFSSs in enhancing plasma density and improving industrial applications, highlighting the importance of precise geometric configurations and material properties in designing effective dielectric resonators.

Offset-fed Slotted Antenna Practically Loaded with Split Ring as Water Quality Sensor for X-Band Industrial Applications

A. Varshney, D. N. Gençoğlan — Wed, 14 Aug 2024 00:00:00 +0200

This article communicates an offset-fed split ring loaded slotted-antenna design, testing, and analysis for different water quality sensor. The antenna was designed to resonate at 10GHz on a low-cost FR-4 substrate of dimensions 0.621λ_o×0.467λ_o×.053λ_o, where λ_o is the free space wavelength. The measured antenna parameters are found in excellent agreements. The antenna achieves a gain of 7.61dBi with nearly unidirectional radiation pattern and a radiation efficiency of 76% at 10GHz. Further, the research is explored to use the antenna as a water sample sensor. Different water samples are tested with the antenna by dipping the antenna into the water samples and in the second case contactless measurements at 10mm apart from the upper water level in the container. The quality of water is examined by observing the shift in the resonant frequency (f_r), antenna quality factor with different total dissolved solvents (TDS) water samples, and changes in the reflection coefficient (S₁₁) values in the water samples. It is observed that the antenna shows less than 1.5% numerical sensitivity (NS) with f_r and high NS with the S₁₁. The S₁₁ and bandwidth of the antenna vary with different water samples. This antenna is suitable for X-band industrial and microwave laboratory applications.

Radiation Pattern Correction of Faulty Planar Phased Array using Genetic Algorithm

R. A. B. Saleem, A. A. Shah , H. Munsif , A. I. Najam, S. Khattak, I. Ullah — Wed, 24 Jul 2024 00:00:00 +0200

The probability of antenna array failure or malfunctioning cannot be ruled out, and hardware replacement of faulty elements is not always a viable solution. Therefore, academic and industrial interest in self-healing phased arrays are on the rise. In this work, the phase-only genetic algorithm (GA) optimization flow for the radiation pattern correction of a 4 × 4 phase faulty planar antenna array is proposed. Initially, a reference array pattern at the desired scan angle is generated. Then random phase faults are introduced across the 1 × 4 antenna elements in any one of 4 sub-arrays to produce maximum distortion in the reference radiation pattern of 4 × 4 planar array. The proposed GA re-computes the new excitation weights for the remaining non-faulty 3 sub-arrays to correct the overall radiation pattern of 4 × 4 array. This is achieved by calculating the array output power for reference and GA computed weights. The GA corrected patterns fairly follow the desired array patterns in terms of peak gain and reducing sidelobe levels for the desired scan angle. The efficiency of the optimized radiation patterns was evaluated in full-wave HFSS model and measurements validation. In this way, maintenance cost can be reduced with recovery of acceptable level of radiation pattern using software instead of physically replacing faulty antenna elements in the array.

Reconfigurable Metamaterial Antenna based an Electromagnetic Ground Plane Defects for Modern Wireless Communication Devices

T. A. Elwi, A. A. M. Al-Shaikhli, H. H. Al-Khaylani, R. K. Abdulsattar — Tue, 28 May 2024 00:00:00 +0200

In this paper, a design of a microstrip antenna based on metamaterial (MTM) and electromagnetic band gap (EBG) arrays. The patch is structured from 5×3 MTM array to enhance the antenna bandwidth gain product. The individual unit cell is structured as a split ring (SRR) with a T-resonator. The ground plane is defected with an EBG to suppress the surface waves diffraction from the substrate edges. The antenna is printed on a Roger substrate with permittivity of 10.2 and 1 mm thickness. It is found that the proposed antenna provides a frequency resonance around 2.45 GHz and 3.5 GHz with another band between 4.6 GHz to 5.6 GHz which are very suitable for Wi-Fi and 5G networks. Nevertheless, the antenna gain is found to vary from 3.5 dBi to less than 6 dBi. The antenna size is reduced enough to λ/5 of the guided wavelength to fit an area of 12 mm×20 mm. The proposed antenna performance is controlled with two PIN diodes for reconfiguration process. The antenna frequency resonance bands are found to be well controlled by stopping the current motion at the particular band. The antenna is fabricated and tested experimentally. Finally, the simulated results are compared to those obtained from measurements to provide an excellent agreement to each other with error of less than 3%.

Metal Mesh Metasurfaces as Dual-Band Bandpass Filters for Terahertz Frequencies

A. Perov — Wed, 14 Aug 2024 00:00:00 +0200

In the paper, we propose a new strategy to design of metal mesh filters (MMFs) based on spatial symmetry analysis of bound states in the continuum(BICs) and manipulating and control with resonances, when BICs transformed to the resonances due to spatial perturbations in the MMF structure. The design of a dual-band polarization-insensitive terahertz bandpass filter with wide upper stopband characteristics using a single conducting layer patterned with rectangular holes is presented. The transmission response of the MMF with two poles is obtained to realize dual-band characteristics and three zeros to suppress the stopband. The proposed design has achieved broadband bandpass transmission characteristics under both TE and TM polarizations with canter frequencies at 0.516THz and 0.734THz and 3dB bandwidths of 25% and 17%, respectively, and upper stopband from 0.887THz to 1.6THz with over 10dB suppression.

Compact CPW-fed Antenna with Controllable WLAN Band-rejection for Microwave Imaging

M. Mokhtari, R. Oussaid, A. Mansoul, M. Challal — Wed, 24 Jul 2024 00:00:00 +0200

This work presents the design and experimental validation of a compact frequency reconfigurable coplanar waveguide (CPW)-fed ultra-wideband (UWB) antenna with a capability to on-demand reject WLAN frequencies within the range of 5.15 GHz to 5.85 GHz, specifically tailored for applications in microwave imaging. The design and experimental results are presented and discussed. The bandwidth enhancement is obtained by using T-shaped slots between the feedline and the ground plane of the antenna, and the WLAN band is rejected by using an open loop resonator (OLR) placed on the antenna backside. Switching between UWB with and without WLAN band-notched modes is performed using a PIN diode and a bias circuit. The simulation results corroborate well with the experimental data and clearly showed an interesting frequency reconfigurable behavior for use in microwave imaging applications. An antenna performance simulation and analysis model is presented for breast tumor detection, and the tumor effect has been noticed for both operating modes of the antenna.

Modified Inverted CSRR and Stepped Impedance Stub based Bandstop Filter with wide passband

A. Mandal, T. Moyra, P. Kumar Deb — Sat, 24 Aug 2024 00:00:00 +0200

This paper presents a compact bandstop filter (BSF) with a wide passband range (0.1 GHz – 3.7 GHz) and low insertion loss in microstrip technology. The design includes two modified inverted complementary split ring resonators (CSRRs) etched from the bottom plane and L-shaped defected structures along with two stepped impedance stubs placed symmetrically in the top plane. The stop rejected filter has a center frequency of 5.35 GHz which attenuates the signal in the C-band with a fractional bandwidth of 44 %. The designed filter has a circuit size of 0.08 lamda g square with a maximum insertion loss of 0.3 dB. The lumped equivalent circuit of the presented filter has been derived and the proposed fabricated BSF structure has also been validated finally with experimental results. This filter is applicable for ISM band (5250 MHz – 5350 MHz) and Wi-Max (2300 MHz – 2500 MHz) applications.

Dual-Band Metamaterial Microwave Absorber using Ring and Circular Patch with Slits

M. S. Sim, K. Y. You, R. Dewan, F. Esa, M. R. Salim, S. Y. N. Kew, F. Hamid — Sat, 16 Dec 2023 00:00:00 +0100

This paper proposes a dual-band metamaterial microwave absorber operating at 2.5 GHz and 5.8 GHz. The absorber consists of a ring and a circular patch with slits resonator structures printed on a FR4 dielectric substrate backed by a ground layer. The main advantage of the absorber lies in its design flexibility in which each absorption band is independent and can be individually tuned by changing the dimensions of each resonator structure. The absorber unit cell is simulated and parametrically optimized using Computer Simulation Technology (CST) software. The absorption mechanism is analyzed through surface current analysis. The absorber prototype, with dimensions of 200 × 200 × 1.6 mm³ and consisting of an array of 7 × 7 unit cells, is fabricated and experimentally investigated using antennas in free-space measurement. The absorber exhibits over 97% absorption at both resonance frequencies. Furthermore, the absorber is demonstrated to be applicable in sensing applications for dielectric constant determination. With its design simplicity, wide-angle receptive, and polarization insensitive behavior, it is envisaged that the proposed absorber will find practical use in absorbing and sensing applications.

Thinned Smart Antenna of a Semi-circular Dipole Array for Massive MIMO Systems

A. Khan, J. S. Roy — Sat, 09 Dec 2023 00:00:00 +0100

Massive MIMO (multiple-input multiple-output) is a multi-user MIMO technology that can provide high-speed multimedia services in 5G wireless networks using sub-6 GHz and millimeter wave bands. The massive MIMO (MMIMO) installs array antennas in the base stations, using hundreds of transceivers with other RF modules. One of the drawbacks of the MMIMO system is its huge power consumption, and the beamforming network with RF modules for a large number of antennas is the main contributor to the power consumption. In this paper, a novel beamforming method is proposed for the low power consumption of an MMIMO system. The proposed thinned smart antenna (TSA) of a semi-circular array produces a secure beam toward the user’s terminal with reduced interference. By thinning the antenna array, some of the antenna elements are kept off, resulting in less power consumption, while the array pattern remains the same as a fully populated array with a reduced side lobe level (SLL). The sub-6 GHz band of 5 GHz is used for the design of thinned array antennas. The genetic algorithm (GA) is used to determine the array sequence in thinning, and the adaptive signal processing algorithms least mean square (LMS), recursive least square (RLS), and sample matrix inversion (SMI) are used for the beamforming of the TSA, and the corresponding algorithms are GA-LMS, GA-RLS, and GA-SMI. The power saving of 40% to 55% is achieved using TSA. The maximum SLL reductions of 13 dB, 12 dB, and 14 dB are achieved for TSA using GA-LMS, GA-RLS, and GA-SMI algorithms, respectively.

Wireless Power Transfer System with Constant Voltage/Constant Current Output Performance

X. Yang, J. Tong — Tue, 09 Jul 2024 00:00:00 +0200

Aiming at the problem of unstable output voltage and output current caused by load fluctuation, this paper starts from the perspective of system topology and control strategy for analysis. First, the output characteristics of LCL-S (inductor-capacitor-inductor and series), LCL-P (inductor-capacitor-inductor and parallel), LCL-LCL (inductor-capacitor-inductor and inductor-capacitor-inductor), and LCL-LCC (inductor-capacitor-inductor and inductor-capacitor-capacitor) compensation topologies are analyzed. Combining the advantages of LCL-S and LCL-LCL compensation topology output characteristics, an LCL-LCL/S compensation topology is constructed, and its topology is optimized. Then the influence of parasitic resistance on the output characteristics of LCL-LCL/S compensation topology is derived. A control strategy of primary side regulation is proposed to address the issue of unstable output voltage and current caused by parasitic resistance in the system under variable loads. This method can effectively improve the stability of the output voltage and output current of the wireless power transfer system in the LCL-LCL/S compensation topology under load fluctuations. Finally, a set of experimental prototypes is built to verify the correctness of the theoretical analysis.