This paper presents the design and simulation of a 32element microstrip patch antenna array operating at 24 GHz for millimeter-wave applications. The proposed array is designed on a Rogers RT5880 substrate. A compact Wilkinson power divider is employed to achieve uniform power distribution with excellent impedance matching and high port isolation. The simulated results demonstrate a reflection coefficient better than $\mathbf{- 3 0 ~ d B}$ for the single patch antenna, while the Wilkinson divider exhibits S11 below - 19 dB, equal power split of - 3 dB, and an isolation level of -20 dB between output ports. When integrated into the complete 32-element antenna array, the system maintains a strong impedance matching with a return loss around $-\mathbf{2 5 ~ d B}$ at $\mathbf{2 4 ~ G H z}$. The radiation characteristics confirm high directivity and improved gain, making the proposed antenna array suitable for automotive radar, millimeter-wave communications, and highfrequency wireless systems.

This paper presents the design of a highly reconfigurable interdigital bandpass filter (BPF) developed through a three-stage design approach. In the first stage, the influence of four low-loss dielectric substrates on the filter response is systematically analyzed to identify the optimal configuration. The selected substrate demonstrates excellent performance, achieving an input return loss of −38 dB, an insertion loss of −0.9 dB at 4.30 GHz, and a wide passband corresponding to a bandwidth (BW) of 2.20 GHz. In the second stage, two variable capacitors were incorporated into the baseline geometry, enabling manual tuning of the center frequency (f0) from 5.10 to 6.34 GHz, with (S11) better than −25 dB and (S12) close to −0.60 dB. In the final stage, the capacitors were replaced by SMV1413 varactor diodes, transforming the design into a fully voltage-controlled tunable filter. This configuration provides continuous frequency agility from 4.70 to 5 GHz without modifying the physical structure, while achieving (S11) levels down to −40 dB and insertion loss as low as −0.7 dB. The proposed architecture offers a compact, low-loss, and electrically reconfigurable solution, making it a promising solution for next-generation RF front-ends, adaptive wireless systems, and cognitive radio applications. Two independent Electromagnetic solvers (EM) were employed to validate the filter’s performance: an EM based on the Finite Integration Technique and the Advanced Design System 2026 (ADS) solver using the Method of Moments (MoM). The close agreement between the results produced by both platforms confirms the accuracy and robustness of the proposed reconfigurable bandpass filter structure.

This paper presents the design and performance evaluation of a circularly polarized antenna array intended for rectenna integration. A slot antenna element is first developed and optimized to achieve circular polarization with an axial ratio (AR) below 3 dB in the 5.8 GHz ISM band. To enhance the gain and improve power reception, a $2 \times 2$ antenna array configuration is then implemented. The effect of the substrate choice on antenna performance is investigated by considering three different materials: Rogers RO4003C ($\varepsilon_{r}=3.38, \tan \delta= \mathbf{0. 0 0 2 7}$, thickness $\boldsymbol{=} \mathbf{1. 5 2 ~ m m}$), RT/duroid $\mathbf{5 8 8 0}$ (RT1) with 1.02 mm thickness $\left(\varepsilon_{r}=2.2, \tan \delta=0.0009\right)$, and RT/duroid 5880 (RT2) with 1.57 mm thickness $\left(\varepsilon_{r}=2.2, \tan \delta=0.0009\right)$. Full-wave simulations are carried out to analyze key parameters, including reflection coefficient (S11), axial ratio bandwidth, and peak gain. The results demonstrate that the substrate properties strongly affect impedance matching, circular polarization bandwidth, and radiation efficiency. Comparative analysis highlights the trade-offs between low dielectric loss and physical thickness, providing useful guidelines for substrate selection in rectenna applications. The proposed design shows promising characteristics for efficient wireless power transfer and energy harvesting systems.

Quantum sensing (QS) exploits non-classical physical phenomena for advanced measurement, with growing relevance to infrastructure monitoring. Despite laboratory-level progress, real-world deployment remains uneven, shaped by integration complexity, digital connectivity, and technological maturity. This article presents a systematic review of QS technologies focused on deployability within infrastructure monitoring architectures. Following PRISMA 2020 guidelines, searches were conducted across six bibliographic databases, covering the 2017-2025 period. An initial dataset of 3636 records was retrieved and reduced through a multi-stage screening pipeline which progressively narrowed the corpus to a final set of 80 peer-reviewed publications retained for detailed analysis. Studies were classified by QS modality, readout architecture, physical platform, and application domain encompassing geophysical and subsurface monitoring, civil and structural health monitoring, transport systems, and urban and environmental sensing. A cross-modality performance comparison was conducted using reported quantitative metrics including sensitivity, resolution, and bandwidth to benchmark quantum sensor technologies against classical sensing baselines, contextualizing their deployment feasibility. Readiness for real-world deployment was assessed using an adapted quantum technology readiness level framework, emphasizing system-level integration, operational sustainability, and compatibility with internet of things enabled and digitally connected monitoring infrastructures. Results reveal heterogeneous maturity trajectories across quantum sensor subtypes and highlight the critical roles of hybrid quantum-classical architectures, edge processing, and secure data integration for scalable deployment. This review positions QS as an enabling component within digitally integrated monitoring systems and provides a realistic perspective on the conditions under which quantum sensor technologies can contribute effectively to future infrastructure monitoring applications.

This paper presents a novel U-slotted microstrip patch antenna integrated with a defected ground structure (DGS) for 15 GHz 6 G mid-band applications. The proposed antenna is designed to achieve enhanced impedance bandwidth, improved gain, and compact size suitable for future wireless communication systems. The U-slot introduced on the patch improves impedance matching and bandwidth performance, while the defected ground structure alters the current distribution, resulting in gain enhancement and reduced mutual coupling. The antenna is designed and simulated using CST electromagnetic simulation software. Simulation results demonstrate that the proposed antenna operates efficiently at 15 GHz with a reflection coefficient below -10 dB, stable radiation characteristics, and satisfactory gain and radiation efficiency. These characteristics make the proposed antenna a promising candidate for 6 G mid-band wireless communication applications.

This paper introduces a new coplanar bandpass filter (BPF) designed for the 5.8 GHz frequency band, targeting wireless communication and Internet of Things IoT applications. The filter design, which is based on CPW technology with a Complementary Split-Ring Resonator CSRR, is mounted on a Rogers RO4003C substrate. This substrate has a thickness of 1.52 mm, a dielectric constant of 3.38, and a low loss tangent of 0.0027.The BPF operates with a center frequency of approximately 5.8 GHz, covering a bandwidth from 5.7 GHz to 5.88 GHz. Its performance is excellent, featuring a low insertion loss of 1.78 dB and a high return loss of 22 dB. The design was validated using two different electromagnetic solvers, both of which confirmed the filter’s low insertion loss within the passband and its strong rejection of out-of-band signals. With a compact size of just 16.07 × 21.20 mm2, the filter is a promising solution for miniaturized devices. The 5.8 GHz frequency is part of the widely used Industrial, Scientific, and Medical (ISM) band. The filter’s ability to isolate this specific frequency makes it essential for optimizing connection quality and performance in various applications. For instance, some IoT devices that require higher bandwidth utilize the 5.8 GHz band, and this filter is critical for ensuring reliable and stable communication.

This paper presents the design, analysis, implementation, and validation of a high-performance 64-element planar patch antenna array tailored explicitly for sub-6 GHz fifth-generation (5G) communication systems. Operating at 3.5 GHz and constructed on an FR4 substrate, the antenna array exhibits a high gain of approximately 17.5 dB, with excellent input impedance matching and radiation efficiency. To further enhance the system's performance, the antenna array was integrated with a custom-designed power amplifier based on the BFP640ESD bipolar transistor. This integration enabled the achievement of an active antenna system, improving both transmission power and overall system efficiency. The power amplifier was designed using the Advanced Design System (ADS) software. To ensure reliable operation, key parameters such as power efficiency, input/output impedance matching, and stability were analyzed and optimized. Integrating the power amplifier, the active antenna array was thoroughly tested and validated in the 3.5 GHz frequency band. The results demonstrate that the system not only meets the required specifications for 5G applications but also offers enhanced performance in terms of signal strength and matching input impedance across a wide bandwidth. This study confirms the benefit of incorporating an active power amplifier in a planar antenna array for modern wireless communication systems.

In the renewable energy sector, the management of protective equipment (PPE and collective safety systems) is a crucial priority to reduce workplace risks and ensure the safety of operations. This article presents the design and optimization of a novel UHF RFID tag operating at 868 MHz, featuring an original structure inspired by a wind turbine shape. This tag is specifically designed to be integrated into industrial safety helmets made of polycarbonate, a material characterized by a dielectric constant εr = 2.9 and a loss tangent tanδ = 0.01. The tag aims to enhance equipment tracking and traceability. The antenna is adapted to an Alien H4 UHF RFID chip, which has an internal impedance of Z = 23.37 - j203.3 Ω at the chosen frequency, ensuring optimal power transfer. Simulation results demonstrate that the tag offers high readability and efficiency while respecting the mechanical and dielectric properties of polycarbonate. This study highlights the potential of innovative UHF RFID tag designs for tracking safety equipment in industrial environments, offering a robust solution to improve workplace safety and operational efficiency.

This paper presents an advanced microstrip diplexer specifically engineered for radio frequency (RF) energy harvesting. As key elements in multi-band harvesting setups, diplexers allow for the concurrent capture and conversion of ambient RF power across several frequency bands, leading to a substantial increase in the total harvested energy. The proposed design incorporates two band-pass filters, tuned to 5.8 GHz and 2.26 GHz, and constructed on a 1.6 mm thick FR-4 substrate (with a dielectric constant of 4.4 and a loss tangent of 0.025). A thorough evaluation of the filters' architecture and performance confirms their capability to convert ambient RF energy effectively. The diplexer efficiently segregates these frequency bands, enabling independent processing and rectification of the captured energy at each frequency. Such separation is essential for achieving maximum energy harvesting efficiency by reducing interference between bands and allowing the implementation of optimized rectifier circuits tailored to each band. Simulated S-parameters corroborate crucial performance indicators, including excellent impedance matching (low S11), minimal insertion loss (high S21 and S31), and significant isolation between ports (low S23 and S32), all of which are paramount for successful RF energy harvesting.

This paper proposes a deep learning (DL)-based high-resolution hybrid time-division multiplexing (TDM) and code-division multiplexing (CDM) multiple input multiple output (MIMO) automotive radar to enhance the discrimination capabilities of the radar in a cluttered environment. The hybrid TDM-CDM approach is implemented by partitioning the transmit and receive arrays into subarrays, applying CDM across the subarrays, while TDM is used within each subarray. On the other hand, the DL-based scheme utilizes the SqueezeNet deep convolutional neural network (DCNN), which treats the angle, range, and Doppler estimations of the extracted targets as a multi-label classification problem. Compared to CDM-MIMO radars, this approach requires fewer spreading codes, alleviating the challenge of spreading and despreading over each element. Compared to TDM-MIMO radars, it requires fewer time slots, increasing the refresh rate. Our approach outperforms existing DL-based TDM-MIMO radar systems and performs similarly to DL-based CDM-MIMO radar systems but with reduced complexity. Simulation results show that an angular resolution of 0.25° was achieved using 12-element transmit and receive arrays, each partitioned into three subarrays.

This paper presents the design and simulation of a Band-Pass Filter (BPF) specifically designed for RF energy harvesting applications at 5.8 GHz. Using microstrip technology, the BPF is compact and suitable for integration into RF energy harvesting systems. It enables effective signal processing by allowing desired frequencies to pass while suppressing higher-order harmonics. The design was optimized and validated using the Advanced Design System (ADS) solver, the proposed structure is mounted on an FR-4 substrate with a thickness of 1.6 mm, a dielectric constant of 4.4, and a loss tangent of 0.025. The results highlight the filter's good performance, with a narrow passband centered at 5.8 GHz, low reflection, and transmission losses, demonstrating its potential to improve the efficiency and reliability of RF energy harvesting systems for low-power applications such as IoT sensors and wearable devices.

This study presents the design and analysis of a compact circularly polarized rectenna operating at 2.45 GHz, intended for wireless power transmission (WPT) applications. The proposed structure includes a 2x2 patch array antenna and a voltage doubler rectifier circuit, both optimized to maximize RF-DC conversion efficiency. Simulations, carried out using ADS and another electromagnetic solver show excellent performance with a reflection coefficient (S₁₁) below -10 dB, an axial ratio below 3 dB in the ISM band, and a maximum gain of 11.14 dB for the antenna array. The RT5880 substrate (εᵣ = 2.2, tanδ = 0.0009) and 35 μm metal thickness were chosen to balance performance and simplicity of design. The results show an RF-DC conversion efficiency of up to 73.69% at 27 dBm, confirming the potential of this design for mobile WPT applications such as powering drones.

This paper presents the design and analysis of a novel microstrip bandpass filter (BPF) using square split ring resonators (SRRs) as resonating elements. The proposed filter architecture comprises a modified microstrip line section coupled to microstrip lines on either side, with an integrated SRR positioned centrally. The SRR elements are strategically designed and optimized to achieve the desired frequency response. The filter is fabricated on an FR-4 substrate with a thickness of 1.6 mm, a dielectric constant of 4.4, and a loss tangent of 0.025. It features a compact size of 9x26.3mm².This study will initially present the simulation results of the designed filter. Subsequently, the filter will be transformed into a tuneable configuration. one approache will be investigated a reconfigurable structure where the variable capacitance is varied to adjust the bandwidth while maintaining the filter's physical dimensions, The integration of capacitance enables dynamic tuning capabilities for the bandpass filter. This design represents a significant advancement in filter technology, with promising applications in next-generation communication systems that require high levels of flexibility and performance. This filter is designed for wireless power transmission and is compatible with applications operating in the vicinity of 2.4GHz to 2.5GHz.

This paper proposes a compact and highly selective coplanar waveguide bandpass filter (BPF) optimized for ISM band applications around 2.4 GHz. The filter is based on coplanar waveguide (CPW) technology and is constructed on Rogers RT/duroid 5880 substrate, which has a thickness of 0.51 mm, a dielectric constant of 2.2, and a loss tangent of 0.0009. The filter demonstrates return and insertion losses of $\mathbf{2 4 ~ d B}$ and $\mathbf{1. 0 5}$ dB, respectively, with a center frequency near 2.4 GHz and an operating bandwidth ranging from 2.18 GHz to 2.64 GHz, resulting in a bandwidth of $\mathbf{4 6 0 ~ M H z}$. The design was simulated using two electromagnetic solvers based on different physical principles, both showing low insertion loss across the passband and strong signal rejection outside it. The overall size of the filter is $19.7 \times 22.05 \mathrm{~mm}^{2}$, making it a promising option for wireless communication and radio frequency signal processing applications. Notably, the 2.4 GHz ISM band is widely used, appearing in devices such as microwave ovens, Wi-Fi routers, and Bluetooth gadgets.

This paper introduces the design of a new frequency-reconfigurable ultra-high frequency radio frequency identification (UHF RFID) antenna, demonstrating an innovative approach that enables dynamic adjustment of its resonance frequency. The proposed antenna design features a central dipole structure, enhanced by two hexagonal split-ring resonators (H-SRR) at each end. A T-match network is integrated into the center of the dipole, which is essential for achieving impedance matching between the antenna and the Alien Gen2 H4 RFID microchip. The antenna is designed using a Rogers 4350B substrate, a high-performance dielectric material ideal for RFID applications. With dimensions of 68×32.6×1.524 mm3, the compact antenna maintains full UHF band (860 MHz to 930 MHz) coverage compliant with International Telecommunications Union (ITU) RFID standards. This ensures that the antenna can be used in different regions around the world, offering broad compatibility with various RFID systems. The antenna's frequency reconfigurability is achieved through the integration of localized capacitors with variable values, which plays a key role in enabling precise adjustments to the antenna's center frequency across the entire UHF band. Extensive simulation results validate the effectiveness of this reconfigurable design, demonstrating that the antenna can dynamically adjust its frequency while maintaining excellent performance metrics, including impedance matching, radiation efficiency, and bandwidth. This makes the proposed antenna an ideal choice for modern RFID applications.

This paper presents the design and simulation of a semi-lumped low-pass filter with finite-frequency attenuation poles at 10 GHz for integration into a 35 GHz harmonic harvesting rectifier in wireless power transmission (WPT) systems. Implemented on an RT6002 substrate, the filter enhances RF-to-DC conversion by suppressing unwanted harmonics, ensuring stability and efficiency. The design, optimized for compactness and high selectivity, is validated through ADS and CST simulations, confirming sharp roll-off and strong stopband attenuation. This work contributes to renewable energy harvesting by improving rectenna-based WPT systems for self-powered IoT and sustainable energy applications.

This paper introduces the design and evaluation of a wideband fractal antenna intended for RF energy harvesting applications operating near 5.8 GHz. The antenna employs a coplanar waveguide (CPW) feed, enhancing impedance matching and simplifying integration into RF systems. To achieve improved bandwidth, gain, and radiation efficiency while maintaining a compact form factor, a fractal structure is mounted on a 1.6 mm thick FR4 substrate with a dielectric constant of 4.4 and a loss tangent of 0.025. Simulations carried out using Advanced Design System (ADS) and CST Microwave Studio, both full-wave electromagnetic solvers, demonstrate a broad input impedance bandwidth. These results confirm the antenna’s effective operation within the Industrial, Scientific, and Medical (ISM) band, positioning it as a strong candidate for wireless power transfer, lo-power IoT devices, and sensor network applications.

This paper introduces a multi-section coupler designed using coupled-line structure to achieve optimal coupling characteristics, which is a critical aspect in high-frequency applications such as radar and microwave systems. The coupler's design incorporates a symmetric structure, chosen to enhance isolation and optimize performances. Operating at a frequency of 24 GHz, the proposed structure has a compact size and exceptional directivity, making it a more efficient alternative to conventional designs. The integration of multi-section coupled-line structures allows for better control over the coupling process, which is crucial for high-performance applications. The coupler is mounted on an RO4830 substrate, a material known for its suitability in microwave and RF circuits. The substrate has a thickness of 0.127 mm, a dielectric constant of 3.24, and a low loss tangent of 0.0033, ensuring minimal signal loss and maintaining the integrity of the transmitted signals. Simulations of the coupler's behavior were carried out using the Advanced Design System (ADS) solver.

This work introduces a rectenna operating in the 2.45 GHz ISM band for RF energy harvesting. By utilizing a differential rectifier structure combined with a microstrip patch antenna, the design removes the need for power splitters and voltage adders, thereby minimizing ohmic losses and signal leakage. Fabricated on an FR-4 substrate with a thickness of 1.6 mm, dielectric constant of 4.4, and loss tangent of 0.025, the prototype demonstrates a peak power conversion efficiency of 73.69%.

This paper presents a new configuration of a coplanar compact low pass filter (LPF) for terahertz applications based on coplanar-waveguide (CPW). It features a compact size with dimensions of 84.38 by 125.60µm2. The filter is mounted on a GaAs substrate having a thickness of 30 µm, a dielectric constant of 12.9 and loss tangent of 0.0001. The filter's cut-off frequency is 0.45 THz, and it exhibits a rejection outside the bandwidth below 20 dB. The design's validity is confirmed through simulations using two independent electromagnetic solvers, highlighting its potential for applications in terahertz imaging, non-destructive testing, satellite communications, medical diagnostics, and biosensing.