ABSTRACT Small‐signal model of a MOSFET is an equivalent circuit that represents its electrical components and specifies the device's electrical characteristics. The non‐quasi‐static (NQS) model is among the most precise small‐signal models utilized in the design of analog and RF circuits. This work introduces an innovative device design known as Gate Stack Silicon on Insulator Schottky Barrier (GS‐SOISB CGAA) cylindrical MOSFET and analog/RF characteristics are extracted utilizing the Silvaco 3D device simulator. An analytical model of GS‐SOISB CGAA is also introduced and validated against the simulation findings. The NQS model of the GS‐SOISB cylindrical MOSFET is formulated to ascertain the extrinsic and intrinsic parasitic components utilizing Y ‐parameters in both the on and off states, respectively. The analog/RF characteristics and NQS model parameters of the GS‐SOISB cylindrical MOSFET have been compared with those of the SOISB cylindrical MOSFET and the SB cylindrical MOSFET. The revolutionary device has a lower gate‐source capacitance ( C GS ) of 7.95% and 8.79%, a gate‐drain capacitance ( C GD ) of 7.22% and 4.57%, and an overall gate capacitance ( C GG ) of 7.91% and 8% than SB and SOISB cylindrical MOSFETs. Compared to conventional SB cylindrical and SOISB cylindrical MOSFET structures, the proposed device shows reduced extrinsic parameters of the NQS model by 7.93% and 3.99% in C gde and C gse , respectively, and 33.4% and 23.9% in R D and R S . The revolutionary device's intrinsic gate‐drain capacitance ( C gd ) reduces by 7.13% and 4.29%, and its intrinsic gate‐source capacitance ( C gs ) reduces by 7.93% and 8.79% as compared to SB and SOISB cylindrical MOSFETs.

ABSTRACT In this article, ultra‐wideband (UWB) single‐element and two‐port multiple‐input‐multiple‐output (MIMO) antenna structures with circular polarization (CP) characteristics are designed to support numerous modern wireless systems. The basic CP element is designed to obtain an ultra‐wide operating bandwidth. In the design process, a circular stub is integrated into the ground plane, and a circular slot is structured into the patch to achieve CP. On the other hand, a rectangular stub is used to improve the axial ratio bandwidth (ARBW). The elemental antenna achieves an impedance bandwidth (IBW) of 97.96% (4.13–12.06 GHz), an ARBW of 49.62% (5–8.3 GHz), a peak gain of 5.75 dB, and a minimum efficiency of 80%, maintaining small dimensions of 20 mm 20 mm 1.6 mm (0.275 λ 0 × 0.275 λ 0 × 0.022 λ 0 ). Meanwhile, a two‐element UWB MIMO radiator of 20 mm 44 mm 1.6 mm (0.275 λ 0 × 0.606 λ 0 × 0.022 λ 0 ) is designed and experimentally validated. It addresses the challenges of achieving wide impedance and axial‐ratio bandwidths while maintaining a compact size and high isolation for MIMO operation with attractive diversity performance. It achieves an impressive ultrawide IBW of 100% (4–12 GHz), ARBW of 42.73% (4.6–7.1 GHz), and 10.90% (7.8–8.7 GHz) while offering improved isolation. The MIMO geometry exhibits outstanding diversity performance, with an envelope correlation coefficient (ECC) < 0.01, diversity gain (DG) > 9.92 dB, total active reflection coefficient (TARC) < 10 dB, and channel capacity loss (CCL) < 0.2 bits/s/Hz. These features render the proposed UWB MIMO antenna exceptionally appropriate for various wireless communication uses, such as microwave C‐band (4–8 GHz), WiMAX (5.725–5.850), WLAN (5.150–5.825 GHz; 5.925–7.125 GHz), and satellite communication in X‐band (downlink: 7.25–7.745 GHz and uplink: 7.9–8.4 GHz).

ABSTRACT A harmonic‐included canonical section‐wise piecewise linear (CSWPL) model with both bias and frequency information is presented in this study. This new model is verified by means of fundamental and harmonic load‐pull simulation data for a 10‐W gallium nitride (GaN) packaged transistor considering a wide range of input power. According to the proposed model, the harmonic behavior of the device under test (DUT) can be captured more accurately than what is currently available in the existing fundamental‐only CSWPL model, which is very helpful for the designers of power amplifiers (PAs). Further, the proposed model is implemented in Keysight advanced design system (ADS) simulator by using a frequency‐domain defined device (FDD), which is then applied to the design of a single‐ended broadband PA. In accordance with the results achieved, the GaN‐based PA has a power added efficiency (PAE) greater than 60% and an output power greater than 40 dBm over the frequency range of 2 to 3 GHz. A very good match exists between the simulation results of the proposed model and the actual measurements of real PAs, which demonstrates the suitability of the presented model for practical PA applications.

ABSTRACT Gallium nitride (GaN) high electron mobility transistors (HEMTs) inherently demonstrate nonlinear behavior due to input capacitance modulation and bias‐dependent variations at elevated power levels, resulting in significant phase distortion and diminished intermodulation performance in power amplifiers (PAs). This paper presents a distinctive parallel R–C loaded matching technique aimed at mitigating these nonlinearities in GaN monolithic microwave integrated circuit (MMIC) PAs designed for frequency‐modulated continuous‐wave (FMCW) radar applications. The intrinsic device‐level sources of nonlinearity are examined, and the efficacy of the proposed network in suppressing amplitude‐phase (AM–PM) distortion and enhancing intermodulation distortion (IMD) characteristics is comprehensively assessed. Utilizing this technique, a 15–20 GHz three‐stage GaN MMIC PA is designed and simulated, achieving over 30 dB small‐signal gain, 23%–31% power‐added efficiency (PAE), and a peak power of 39.3 dBm at 17 GHz. The PA demonstrates excellent linearity, with AM–PM variation constrained within ±2° at saturation. The final design occupies a compact 3.37 × 2.59 mm 2 footprint, rendering it highly suitable for high‐throughput FMCW radar transmitters. Additionally, full electromagnetic (EM) co‐simulation, including quad flat no‐lead (QFN) packaging and bond‐wire parasitics, is conducted to validate performance robustness under practical integration constraints.

ABSTRACT In this work, authors have deeply investigated a combination of gallium nitride (GaN) and gallium oxide (Ga 2 O 3 ) semiconductors, which are considered strong potential candidates for solar‐blind ultraviolet (UV) photodetectors. Using Silvaco TCAD software, the proposed structure contains platinum as a Schottky contact on the top of the Ga 2 O 3 absorbed layer. An intermediate GaN layer was deposited on the sapphire (Al 2 O 3 ) substrate, and it has a crucial role in increasing the photogeneration rate of the used photodetector. The proposed device shows distinct current–voltage behavior under dark and illumination conditions. A high responsivity in the deep UV region has been demonstrated. Different parameters, such as doping concentration, work function, traps, and temperature effect, have been investigated to highlight the potential of the proposed structure for the next generation of UV‐Schottky photodetectors with excellent spectral selectivity and self‐powered effect.

ABSTRACT Current unmanned aerial vehicle (UAV)‐based remote sensing systems for soil moisture detection face several challenges, including large antenna size, low efficiency, and measurement errors caused by non‐overlapping dual‐polarization coverage. To address these issues, this study proposes an efficient and compact L‐band shared‐aperture dual‐polarized microstrip antenna design. The key innovation lies in the integration of four techniques. First, an air gap between parasitic patches and the dielectric substrate broadens the operational bandwidth. Second, a high‐impedance surface (HIS) structure suppresses surface waves, significantly improving efficiency, gain, and radiation characteristics. Third, metallic patches combined with a Chebyshev impedance matcher provide precise frequency tuning and wideband impedance matching. Finally, a compact stacked structure with a multilayer symmetric feed network enables a shared‐aperture dual‐polarized layout, overcoming coverage misalignment and size limitations typical of non‐coaxial airborne antennas. The proposed antenna achieves excellent performance in the target frequency band. It demonstrates an average efficiency of 95%, a voltage standing wave ratio (VSWR) below 1.37, a peak gain of 13.42 dB, a 3‐dB beamwidth of 44.1°, and a sidelobe level below −12.79 dB. Comparative analysis shows that this shared‐aperture design offers substantial performance improvements and establishes a new benchmark for efficient, compact dual‐polarized microstrip antennas in low‐altitude L‐band remote sensing applications.

ABSTRACT This paper proposes a design method for broadband power amplifier (PA) using irregular matching structure based on an improved multi‐objective optimization algorithm, aiming at expanding its operating bandwidth. Initially, the gravitational search algorithm is enhanced by reconstructing the gravitational constant function for improving its global optimization capability. Subsequently, a fast non‐dominated sorting mechanism combined with a crowding distance strategy is introduced for multi‐objective optimization problems. Furthermore, to effectively overcome the bandwidth limitations that are inherent in conventional PA, the proposed multi‐objective gravitational search algorithm is employed for optimizing the irregular structure matching network. For verification, a broadband high‐efficiency PA is designed and fabricated, covering a frequency range of 0.4–4.0 GHz with a relative bandwidth of 163%. Measurement results show that the PA with the irregular matching structure maintains an efficiency of 59.1%–64.4% across the entire operating band, with a saturated output power of 40.3–41.8 dBm.

ABSTRACT Nuclear magnetic resonance (NMR) spectroscopy is a powerful technique for molecular analysis, yet its widespread use is limited by the bulky size and high cost of conventional radio frequency (RF) coils, which restrict portability and accessibility in clinical and field applications. To address this challenge, we propose a miniature birdcage coil implemented on a flexible printed circuit board (F‐PCB) with a Flame Retardant‐4 (FR‐4) substrate. The compact design, with a thickness of only 0.25 mm, enables the development of portable and user‐friendly NMR spectrometers without compromising performance. The coil generates a highly homogeneous magnetic field with 95% uniformity across a wide range of Larmor frequencies and achieves a magnetic field strength of 327 μT. Unlike traditional fixed‐frequency coils, the proposed design incorporates a programmable band‐pass function controlled by variable capacitors and a microcontroller, allowing electronic tuning across 1–13 MHz without hardware modifications. Finite element method (FEM) simulations confirm the coil's ability to maintain field homogeneity and high signal‐to‐noise ratio (SNR) over diverse operating conditions. Compared to existing RF coil designs such as planar, Helmholtz, or conventional birdcage coils, the proposed mini‐birdcage coil offers superior portability, tunability, and uniform excitation, thereby enhancing NMR signal acquisition and broadening applicability. This advancement holds promise for medical, pharmaceutical, biological, and geological applications, enabling portable NMR systems that improve diagnostic capabilities and expand accessibility in resource‐limited environments.

ABSTRACT To further enhance the precision of transistor modeling, the bidirectional long short term memory‐long short term memory (BiLSTM‐LSTM) neural network is utilized for the inverse modeling of the scattering parameters (S‐parameters) for the gallium arsenide pseudomorphic high electron mobility transistor (GaAs pHEMT) here. The modeling results show that the optimal mean square error (MSE) is up to 0.0001, the coefficient of determination ( R 2 ) is 0.9972 with the optimal mean absolute error (MAE) of 0.0049. Therefore, BiLSTM‐LSTM has superior advantage for the nonlinear relationship modeling for the S‐parameters of GaAs pHEMT.