Recent developments in the field of microwave planar sensors have led to a renewed interest in industrial, chemical, biological and medical applications that are capable of performing real-time and non-invasive measurement of material properties. Among the plausible advantages of microwave planar sensors is that they have a compact size, a low cost and the ease of fabrication and integration compared to prevailing sensors. However, some of their main drawbacks can be considered that restrict their usage and limit the range of applications such as their sensitivity and selectivity. The development of high-sensitivity microwave planar sensors is required for highly accurate complex permittivity measurements to monitor the small variations among different material samples. Therefore, the purpose of this paper is to review recent research on the development of microwave planar sensors and further challenges of their sensitivity and selectivity. Furthermore, the techniques of the complex permittivity extraction (real and imaginary parts) are discussed based on the different approaches of mathematical models. The outcomes of this review may facilitate improvements of and an alternative solution for the enhancement of microwave planar sensors’ normalized sensitivity for material characterization, especially in biochemical and beverage industry applications.

This paper introduces a new compact Chair-shaped MIMO antenna with two radiating elements and a single layer of frequency-selective surface (FSS) for 5G Sub-6GHz communication systems. They use two techniques, Parasitic element, and (FSS), for isolation and gain enhancement, respectively. The 1 × 2 MIMO antenna using a coplanar waveguide (CPW) fed. Moreover, an FSS array structure consisting of (a 68-unit) Square-shaped structure with Circular Slot (SCS) shaped cells is employed using a new technique (Surround Technique) to enhance the gain and isolation between the elements of the MIMO antenna. The proposed MIMO antenna system is printed on a Rogers 4350B substrate with a thickness of 0.508 mm. The antenna’s performance is evaluated using S-parameters, radiation properties, and MIMO characteristics. The MIMO antenna system works in the Sub 6-GHz 5G band, which ranges from 3 to 6 GHz. Adding the FSS layer enhances the MIMO’s antenna gain to a peak measured gain of 7.96 dBi and it also improves the MIMO antenna’s isolation. The performance metrics of the proposed MIMO antenna were also investigated, including measures values of ECC = 0.004, DG = 9.99 dB, CCL = 0.2 bit/s/Hz, MEG = -3.13 dBi, and TARC = > 0dB) exhibits advantageous antenna characteristics. The observed radiation characteristics of the suggested MIMO antenna system indicate its suitability for the upcoming 5G communication systems.

With the rapid changes in wireless communication systems, indoor wireless communication (IWC) technology has undergone tremendous development. Antennas are crucial components of IWC systems that transmit and receive signals within indoor environments. Thus, the development of indoor technology is highly dependent on the development of indoor antennas. However, indoor environments with limited space require the fewest indoor antenna units and the smallest indoor antenna sizes possible. Hence, indoor antennas with compact size and broad applications have become widely preferred. In an IWC system, circularly polarised (CP) antennas are generally important, especially in dense indoor environments, because compared with linearly polarised (LP) antennas, CP antennas reduce polarisation mismatch and multipath losses. This paper combs through the existing studies related to three-dimensional (3D) geometry (nonplanar) or waveguide indoor antennas and the two common approaches to two-dimensional (2D) geometry (planar) indoor antennas, namely, broadband CP printed monopole antennas (BCPPMAs) and broadband CP printed slot antennas (BCPPSAs). The advantages, disadvantages and limitations of previous works are highlighted as well. These research works are summarised, compared and analysed to understand the recent specifications of BCPPMAs and BCPPSAs to generate the most appropriate design structure suitable for current IWC systems.

A new broadband circular polarization (CP) monopole antenna with simple structure is proposed. The antenna consists of a P-shaped monopole and modified ground plane with rectangular stub, and results demonstrated that the 10 dB impedance bandwidth (ZBW) is 118.5% (1.6-6.25 GHz) and the 3 dB axial-ratio bandwidth (ARBW) is 104.4% (1.9-6.05 GHz). Procedures to improve the proposed antenna design and the CP mechanism analysis were performed. The performance of different parameters is presented. The advantages of the proposed antenna are broader ZBW and ARBW, simpler structure, and compact size.

Urban centers are grappling with increasing traffic congestion, which hampers mobility and reduces the effectiveness of emergency responses. Current traffic management systems struggle to dynamically prioritize emergency vehicles during peak congestion, highlighting the need for an advanced solution that improves both everyday traffic flow and emergency response efficiency. Traditional traffic light systems typically follow either fixed schedules (“Fixed” approach) or make real-time adjustments without achieving long-term efficiency (“Greedy” approach), often failing to effectively balance regular traffic dynamics with emergency needs. We propose the “Avg Log“ method, an adaptive Q-learning strategy that enhances conventional traffic management systems by incorporating an emergency-aware module. This module uses real-time data to prioritize emergency vehicles and adjust traffic signals accordingly. Additionally, our approach employs a multi-objective optimization algorithm to strengthen communication infrastructure, optimizing latency, throughput, and reliability. Through simulations in a multi-intersection urban setting, we compared the performance of our method against the standard “Greedy” and “Fixed” approaches. Key metrics assessed included average waiting times, system throughput, and the efficiency of emergency vehicle passage. The “Avg Log” method outperformed traditional methods, showing superior long-term adaptability and learning. It demonstrated lower average waiting times and effectively managed emergency situations, significantly reducing delays for emergency vehicles compared to both control methods. This method provides an efficient balance between overall traffic flow and emergency prioritization, suggesting a scalable solution for complex urban environments.

This paper presents a novel design of a modified ultrawideband (UWB) antenna array integrated with a multimode resonator bandpass filter. First, a single UWB antenna is modified and studied, using a P-shape radiated patch instead of a full elliptical patch, for wide impedance bandwidth and high realized gain. Then, a two-element UWB antenna array is developed based on this modified UWB antenna with an inter-element spacing of 0.35 λ_L, in which λ_L is the free space wavelength at the lower UWB band edge of 3.1 GHz, compared to 0.27 λ_L of a reference UWB antenna array designed using a traditional elliptical patch shape. The partial ground plane is designed with a trapezoidal angle to enhance matching throughout the UWB frequency range. The mutual coupling reduction of a modified UWB antenna array enhances the reflection coefficient, bandwidth, and realized gain, maintaining the same size of 1.08 λ₀ × 1.08 λ₀ × 0.035 λ₀ at 6.5 GHz center frequency as that of the reference UWB antenna array. The UWB antenna array performance is investigated at different inter-element spacing distances between the radiated elements. To add filtering capability to the UWB antenna array and eliminate interference from the out-of-band frequencies, a multimode resonator (MMR) bandpass filter (BPF) is incorporated in the feedline while maintaining a compact size. The measurement results showed a close agreement with simulated results. The proposed UWB filtering antenna array design achieved a wide fractional bandwidth of more than 109.87%, a high realized gain of more than 7.4 dBi, and a compact size of 1.08 λ₀ × 1.08 λ₀ × 0.035 λ₀ at 6.5 GHz center frequency. These advantages make the proposed antenna suitable for UWB applications such as indoor tracking, radar systems and positioning applications.