Miniature mesa extension for a planar submicron AlGaN/GaN HEMT gate formation

In this letter, a novel approach is presented to overcome issues in AlGaN/GaN high elec- tron mobility transistors (HEMTs), such as metal discontinuity of the gate stemmed from conven- tional mesa isolation. This usually requires a careful mesa etch process to procure an anisotropic mesa-wall profile. An alternative technique is the use of ion implantation for device isolation instead of conventional mesa for a planar device formation. However, ion implantation is a costly process and not always easily accessible. In this work, the proposed method is to simply extend the mesa below the gate just enough to accommodate the gatefeed, thereby ensuring the entire gate is planar in structure up to the gatefeed. The newly developed device exhibited no compromise to the DC (direct current) and RF (radio frequency) performance. Conversely, it produced a planar gate con- figuration with an enhanced DC transconductance (approximately 20% increase is observed) and a lower gate leakage while the etch process is considerably simplified. Similarly, the RF transconduct- ance of proposed device (device B) increased by 80% leading to considerable improvements in RF performance

A frequency reconfigurable folded antenna for cognitive radio communication

In this work, a spectrum-sensing monopole antenna was used to operate in different frequency bands for cognitive radio applications. The proposed antenna consists of a folded monopole antenna with a partial ground plane, and it can be used for various wireless technologies operated at various frequencies from 1.5 to 3.5 GHz. The suggested antenna was printed on a RO4003 substrate with 3.38 permittivity and an overall size of 60 × 60 × 0.813 mm3. To achieve reconfigurability of the antenna, PIN diodes (HPND-4005) were inserted at different lengths along the antenna to obtain the desired performance. The antenna was fabricated and experimentally tested to validate the simulation outcomes, and distinct consistency between the simulation and measurement outcomes was obtained. Computer simulation tool (CST) software was used to design and simulate the suggested antenna and then the model was fabricated to validate the simulation outcomes

A pattern reconfigurable antenna using eight-dipole configuration for energy harvesting applications

A pattern reconfigurable antenna, composed of eight elements, is proposed for energy harvesting applications. Pattern reconfigurable antennas are a promising technique for harvesting from different wireless sources. The radiation pattern of the proposed antenna can be steered electronically using an RF switch matrix, covering an angle range from 0 to 360 degrees with a step size of 45 degrees. The proposed antenna primarily consists of an eight-dipole configuration that shares the same excitation. Each dipole is excited using a balun comprising a quarter-wavelength grounded stub and a quarter-wavelength open-circuit stub. The proposed antenna operates in the frequency range of 4.17 to 4.5 GHz, with an impedance bandwidth of 7.6%. By switching between the different switches, the antenna can be steered with a narrower rotational angle. In addition, the antenna can work in an omnidirectional mode when all switches are in the ON state simultaneously. The results demonstrate a good agreement between the numerical and experimental findings for the reflection coefficient and radiation characteristics of the proposed reconfigurable antenna

The optimization and analysis of a triple-fin heterostructure-on-insulator fin field-effect transistor with a stacked high-k configuration and 10 nm channel length

The recent developments in the replacement of bulk MOSFETs with high-performance semiconductor devices create new opportunities in attaining the best device configuration with drive current, leakage current, subthreshold swing, Drain-Induced Barrier Lowering (DIBL), and other short-channel effect (SCE) parameters. Now, multigate FETs (FinFET and tri-gate (TG)) are advanced methodologies to continue the scaling of devices. Also, strain technology is used to gain a higher current drive, which raises the device performance, and high-k dielectric material is used to minimize the subthreshold current. In this work, we used stacked high-k dielectric materials in a TG n-FinFET with three fins and a 10 nm channel length, incorporating a three-layered strained silicon channel to determine the short-channel effects. Here, we replaced the gate oxide (SiO2) with a stacked gate oxide of 0.5 nm of SiO2 with a 0.5 nm effective oxide thickness of different high-k dielectric materials like Si3N4, Al2O3, ZrO2, and HfO2. It was found that the use of strained silicon and replacing only the SiO2 device with the stacked SiO2 and HfO2 device was more beneficial to obtain an optimized device with the least leakage and improved drive currents

Design of a modified MIMO antenna based on tweaked spherical fractal geometry for 5G New Radio (NR) band N258 (24.25–27.25 GHz) applications

This article describes a fractal-based MIMO antenna for 5G mm-wave mobile applications with micro-strip feeding. The proposed structure is a fractal-based spherical configuration that incorporates spherical slots of different iterations on the patch, as well as rectangular slots on the ground plane. These additions are meant to reduce patch isolation. The two-element MIMO antenna has closely spaced antenna elements that resonate at multiple frequencies, 9.5 GHz, 11.1 GHz, 13.4 GHz, 15.8 GHz, 21.1 GHz, and 26.6 GHz, in the frequency range of 8 to 28 GHz. The antenna’s broadest operational frequency range spans from 17.7 GHz to 28 GHz, encompassing a bandwidth of 10,300 MHz. Consequently, it is well-suited for utilization within the millimeter wave (mm wave) application, specifically for the 5G new radio frequency band n258, and partially covers some other bands X (8.9–9.9 GHz, 10.4–11.4 GHz), and Ku (13.1–13.7 GHz, 15.4–16.2 GHz). All the resonating bands have isolation levels below the acceptable range of (|S12| > −16 dB). The proposed antenna utilizes a FR4 material with dimension of 28.22 mm × 44 mm. An investigation is conducted to analyze the effectiveness of parameters of the antenna, including radiation pattern, surface current distributions and S parameters. Furthermore, an examination and assessment are conducted on the efficacy of the diversity system inside the multiple input multiple output (MIMO) framework. This evaluation encompasses the analysis of key performance metrics such as the envelope correlation coefficient (ECC), diversity gain (DG), and mean effective gain (MEG). All antenna characteristics are determined to be within a suitable range for this suggested MIMO arrangement. The antenna design underwent experimental validation and the simulated outcomes were subsequently verified

A parasitic patch loaded staircase shaped UWB MIMO antenna having notch band for WBAN applications

A staircase-shaped quasi-fractal antenna is presented to meet the requirements of compact electronics operating in UWB or E-UWB spectrum. A conventional broadband monopole antenna is converted into UWB antenna utilizing three iterations of fractal patches. The resultant antenna offers wide impedance bandwidth ranges 2.3–17.8 GHz, having a notch band at 6.1–7.2 GHz. Afterwards, a two-port MIMO antenna is created by placing the second element orthogonally with an edge-to-edge distance of 8.5 mm, that is λ/15 where λ corresponds to free space wavelength at the lowest cut-off frequency. Hereafter, a meandered line-shaped stub is inserted to reduce the mutual coupling between closely spaced MIMO elements to less than −25 dB. As the intended application of the proposed work is On-body, Specific Absorption Rate (SAR) analyses are carried out at 2.4, 5.8 and 8 GHz, showing an acceptable range for both 1-g and 10-g averaged tissues standards. Moreover, various parameters of the MIMO antenna are studied, and a comparison is made between simulated and measured results as well as those of the state of the art

Development of compact bandpass filter using symmetrical metamaterial structures for GPS, ISM, Wi-MAX, and WLAN applications

This article describes the development of a compact microstrip bandpass filter (BPF) for multiple wireless communication utilizations. The proposed bandpass filter consists of metamaterial unit cells that are symmetrical in shape. The design process involves the placement of four symmetrical split-ring resonators (SRRs) on the top plane of the BPF. It exhibits improved filter characteristics through the implementation of these SRRs. The filter was modeled and fabricated and its performance was evaluated using a Vector Network Analyzer. The designed bandpass filter shows a 5 GHz bandwidth covering the frequency band spanning from 1 to 5.2 GHz, with a quality factor value of 1.85 across 1.9 GHz, 3.3 across 3.3 GHz and 5.1 across 5.1 GHz. The metamaterial analysis was carried out using ANSYS ELECTRONIC DESKTOP. The proposed filter measures 20 × 18 × 1.6 mm3, which is significantly smaller than current filters. The designed bandpass filter occupies 50% of the space of a conventional filter. The designed bandpass filter exhibits a distributed surface current of 84 A/m, and 94 A/m across the wide- and narrow-band operating frequency. The simulated and measured results indicate that the suggested metamaterial filter is well-suited for multiband wireless applications like GPS (1.57 GHz), WLAN (2.4, 3.6, and 5.2 GHz), Wi-MAX (2.3, 2.5, and 3.5 GHz), and ISM (2.5 GHz)

Wireless insights into cognitive wellness: A paradigm shift in Alzheimer's detection through ultrathin wearable antennas

The Proposed algorithm, designed to simulate an Alzheimer’s disease (AD) brain model across different stages, presents an invaluable opportunity for further research and in-depth study of the effects of AD. Currently, there is a notable absence of a comprehensive simulated model for the AD brain that allows the exploration of all AD biomarkers within a simulation tool. This represents a crucial advancement in the field, enabling researchers to thoroughly investigate and understand the diverse biomarkers associated with AD without resorting to highly expensive and ionizing radiation techniques. The algorithm’s capability to emulate various stages of AD in a simulated environment is an essential step toward assessing its applicability for AD patients, providing a cost-effective and safer alternative for research and study in comparison to existing methodologies and delves into the development and evolution of a patch antenna designed for the identification of distinct stages in Alzheimer’s disease (AD) detection. The antenna, equipped with ultra-wideband (UWB) capabilities, consists of a slotted circular disc antenna patch and a partial ground. The placement of rectangular slots in the ground structure aims to enhance radiation directivity, gain, and efficiency. The primary objective is to optimize the antenna’s efficacy by strategically integrating a slotted circular disc and arranging slots in the ground structure. The research aims to provide an effective solution for non-invasive tracking of Alzheimer’s disease progression. The antenna, with dimensions of $50\times 35\times 0.1$ mm3, is fabricated using a flexible laminate substrate (Ultra-lam 3850). The prototype demonstrates a remarkable bandwidth of 8.55 GHz (2.02–10.57 GHz) and exhibits nearly directional radiation characteristics. The study employs 3D CST 2019 simulator software for analysis, followed by physical fabrication and measurement of the antenna. Evaluation involves both a single antenna and a four-antenna array element around a 3D realistic-shaped Hugo head model and a six-layer brain phantom simulating various AD stages. The reported peak gain reaches 2.36 dBi and 3.1 dBi at 2.4 GHz and 7.48 GHz, respectively, with consistently high radiation efficiency (92.5% and 90.5% at 2.4 GHz and 7.48 GHz)

Quad element MIMO antenna for C, X, Ku, and Ka-band applications

This article presents a quad-element MIMO antenna designed for multiband operation. The prototype of the design is fabricated and utilizes a vector network analyzer (VNA-AV3672D) to measure the S-parameters. The proposed antenna is capable of operating across three broad frequency bands: 3–15.5 GHz, encompassing the C band (4–8 GHz), X band (8–12.4 GHz), and a significant portion of the Ku band (12.4–15.5 GHz). Additionally, it covers two mm-wave bands, specifically 26.4–34.3 GHz and 36.1–48.9 GHz, which corresponds to 86% of the Ka-band (27–40 GHz). To enhance its performance, the design incorporates a partial ground plane and a top patch featuring a dual-sided reverse 3-stage stair and a straight stick symmetrically placed at the bottom. The introduction of a defected ground structure (DGS) on the ground plane serves to provide a wideband response. The DGS on the ground plane plays a crucial role in improving the electromagnetic interaction between the grounding surface and the top patch, contributing to the wideband characteristics of the antenna. The dimensions of the proposed MIMO antenna are 31.7 mm × 31.7 mm × 1.6 mm. Furthermore, the article delves into the assessment of various performance metrics related to antenna diversity, such as ECC, DG, TARC, MEG, CCL, and channel capacity, with corresponding values of 0.11, 8.87 dB, −6.6 dB, ±3 dB, 0.32 bits/sec/Hz, and 18.44 bits/sec/Hz, respectively. Additionally, the equivalent circuit analysis of the MIMO system is explored in the article. It’s worth noting that the measured results exhibit a strong level of agreement with the simulated results, indicating the reliability of the proposed design. The MIMO antenna’s ability to exhibit multiband response, good diversity performance, and consistent channel capacity across various frequency bands renders it highly suitable for integration into multi-band wireless devices. The developed MIMO system should be applicable on n77/n78/n79 5G NR (3.3–5 GHz); WLAN (4.9–5.725 GHz); Wi-Fi (5.15–5.85 GHz); LTE5537.5 (5.15–5.925 GHz); WiMAX (5.25–5.85 GHz); WLAN (5.725–5.875 GHz); long-distance radio telecommunication (4–8 GHz; C-band); satellite, radar, space communications and terrestrial broadband (8–12 GHz; X-band); and various satellite communications (27–40 GHz; Ka-band)

A high bandwidth dimension ratio compact super wide band-flower slotted microstrip patch antenna for millimeter wireless applications

A compact high bandwidth ratio (BDR) super wide band flower slotted micro strip patch antenna (SWB-FSMPA) for super wide band (SWB) applications is presented. The SWB-FSMPA is constructed on a FR-4 substrate having a size of 16 × 22 mm2. The SWB-FSMPA incorporates a 50 Ω tapered micro strip line and a rectangular beveled defected ground structure (RB-DGS). This design enables a simulation bandwidth from 3.78 to 109.86 GHz, allowing for coverage of various wireless applications such as WiMAX (3.3–3.6 GHz), 5G (3.3–3.7 GHz), WLAN (5.15–5.825 GHz), UWB (3.1–10.6 GHz), Ku– (12–18 GHz), K– (18–27 GHz), Ka– (27–40 GHz), V– (40–75 GHz), and W– (75–110 GHz) millimeter wave bands. The SWB-FSMPA antenna exhibits a gain that varies within the range of 3.22–7.23 dBi and a peak efficiency of 93.3 %. The SWB-FSMPA possesses a bandwidth ratio (BR) of 29.1:1, a BDR of 5284 in the frequency domain, a minimal group delay (GD) fluctuation of <0.48 ns, and a linear phase in the time domain, making it well-suited for SWB applications