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.

Size Reduction of Wilkinson Power Divider using a Combination of Parallel Coupled Lines and Defective Microstrip Structures

B. P. Eppe, A. Ghosh, P. Mondal — Tue, 29 Oct 2024 00:00:00 +0100

This work describes a miniaturized power divider (PD) using the combination of two symmetrical parallel coupled lines (PCL) and a defective microstrip structure (DMS). The proposed PD is intended for 2.4 GHz wireless local area network (WLAN) applications. DMS structures are used to improve PD performance while also decreasing its size. Initially, to reduce the circuit size, quarter-wavelength lines were replaced with PCL’s. It is observed that the size of PD is 0.42λgX0.53λg, representing a 25.3% decrease. Furthermore, four DMS structures are integrated into the design to reduce the overall size by 43% as compared with conventional Wilkinson PD at 2.4 GHz. The final size of PD is 0.35λgX0.47λg. Required equations are provided for the optimization of the DMS structure. The proposed PD has a return loss, isolation performance, and power division of around 16 dB, -15 dB, and -3.3 dB, respectively. The designed PD is fabricated on the substrate of Rogers RT/duroid 5880 with εr=2.2.

Performance analysis of patch-type UHF-RFID tag antennas in the presence of mutual coupling

K. F. Gbamélé — Thu, 07 Nov 2024 00:00:00 +0100

In a context of high-density deployment of UHF RFID patch-type tag antennas, mutual coupling can have an impact on the detection rate due to the degradation of the link budget between certain tags and the reader. The aim of this paper is to analyze the performance of a system that takes account of electromagnetic mutual coupling as a function of the random positions of UHF RFID patch-type tag antennas in complex environments. The design of the patch-types tags, including the extraction of the Y admittance parameters, was studied using the HFSS electromagnetic simulation software. To validate the study approach, the results obtained were compared using MATLAB software. The results obtained provide additional information needed to gain an in-depth understanding of UHF RFID patch-type tag antenna systems to make them reliable and practical in a dense environment. Future research and development work may be inspired in the design of UHF RFID patch-types tag antennas for miniaturized applications.

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.

Analytical Circuit-based Model for Low Thickness Tunable Metasurfaces Design

C. Legrand, P. Ropa — Thu, 07 Nov 2024 00:00:00 +0100

An analytical model of metasurfaces made of a rectangular array deposited on a low thickness (10-150 µm) grounded dielectric layer is presented. The surface impedance and the equivalent circuit are extracted from full wave simulations. Contrary to previous works on higher thickness metasurfaces, the absorption corresponds to the first resonance under the patch. The equivalent circuit is made of a parallel resonant RLC circuit in series with an inductance L_s. The analytical expressions of the RLC components and of the quality factors are established from the study of the influence of the different parameters. The inductance L_s is attributed to the non-metallized part of the mesh. The impedance of the resonant circuit expresses as the product of a proportionality factor, the impedance of a single patch and a periodicity factor. The model is validated on different examples. Specific properties are evidenced like the quasi-independence of the equivalent circuit resistance versus the length of the patch, the total absorption condition and the extension of the model to a two patches metasurfaces. Giving a better understanding of the role of the different parameters, the model is useful in view of new applications development notably electrically driven tunable metasurfaces.

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.