Vehicular communication networks is a powerful tool that enables numerous vehicular data services and applications. The rapid growth in vehicles has also resulted in the vehicular network becoming heterogeneous, dynamic, and large-scale, making it hard to meet the strict requirements, such as extremely latency, high mobility, top security, and enormous connections of the fifth-generation network. Previous studies have shown that with the increase in the application of Software-Defined Networking (SDN) on Vehicular Adhoc Network (VANET) in industries, researchers have exerted considerable efforts to improve vehicular communications. This study presents an exhaustive review of previous works by classifying them based on based on wireless communication, particularly VANET. First, a concise summary of the VANET structure and SDN controller with layers and details of their infrastructure is provided. Second, a description of SDN-VANET applications in different wireless communications, such as the Internet of Things (IoT) and VANET is provided with concentration on the examination and comparison of SDN-VANET works on several parameters. This paper also provides a detailed analysis of the open issues and research directions accomplished while integrating the VANET with SDN. It also highlights the current and emerging technologies with use cases in vehicular networks to address the several challenges in the VANET infrastructure. This survey acts as a catalyst in raising the emergent robustness routing protocol, latency, connectivity and security issues of future SDN-VANET architectures.

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 presents novel structures of planar microwave sensors for detecting and characterizing the dielectric properties in common solid materials which produce high Q-factors with capability to suppress undesired harmonic spurious. These sensors are based on novel planar symmetrical split ring resonator with spurlines filters by employing the perturbation theory, in which the dielectric properties of the resonator affect the Q-factor and resonance frequency. The proposed sensors achieve narrow resonance with low insertion loss and high-Q and sensitivity which peaked up to 652 at 2.22 GHz operating frequency. By using a specific experimental methodology, practical materials are applied as standards (Roger 5880, Roger 4350, FR4) to validate the sensitivity of the sensors for permitting potentially material characterization and detection. Accordingly, the mathematical equation is derived to extract the materials with unknown properties. The average accuracy percentage of the measured results for all cases of the designed sensors is found within 97%-98% compared with those in the literature for the same tested standard materials. It is believed that these sensors would lead for a promising solution of characterizing material particularly in determining material properties and quality, such as in food industry, bio-sensing medicine applications, and therapeutics goods detections.

In this study, a critical evaluation of analyte dielectric properties in a microvolume was undertaken, using a microwave biochemical sensor based on a circular substrate integrated waveguide (CSIW) topology. These dielectric properties were numerically investigated based on the resonant perturbation method, as this method provides the best sensing performance as a real-time biochemical detector. To validate these findings, shifts of the resonant frequency in the presence of aqueous solvents were compared with an ideal permittivity. The sensor prototype required a 2.5 µL volume of the liquid sample each time, which still offered an overall accuracy of better than 99.06%, with an average error measurement of ±0.44%, compared with the commercial and ideal permittivity values. The unloaded Q_u factor of the circular substrate-integrated waveguide (CSIW) sensor achieved more than 400 to ensure a precise measurement. At 4.4 GHz, a good agreement was observed between simulated and measured results within a broad frequency range, from 1 to 6 GHz. The proposed sensor, therefore, offers high sensitivity detection, a simple structural design, a fast-sensing response, and cost-effectiveness. The proposed sensor in this study will facilitate real improvements in any material characterization applications such as pharmaceutical, bio-sensing, and food processing 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.

This paper presents a wideband and high-gain rectangular microstrip array antenna with a new frequency-selective surface (FSS) designed as a reflector for the sub-6 5G applications. The proposed antenna is designed to meet the US Federal Communications Commission (FCC) standard for 5G in the mid-band (3.5–5 GHz) applications. The designed antenna configuration consists of 1 × 4 rectangular microstrip array antenna with an FSS reflector to produce a semi-stable high radiation gain. The modeled FSS delivered a wide stopband transmission coefficient from 3.3 to 5.6 GHz and promised a linearly declining phase over the mid-band frequencies. An equivalent circuit (EC) model is additionally performed to verify the transmission coefficient of the proposed FSS structure for wideband signal propagation. A low-cost FR-4 substrate material was used to fabricate the antenna prototype. The proposed wideband array antenna with an FSS reflector attained a bandwidth of 2.3 GHz within the operating frequency range of 3.5–5.8 GHz, with a fractional bandwidth of 51.12%. A high gain of 12.4 dBi was obtained at 4.1 GHz with an improvement of 4.4 dBi compared to the antenna alone. The gain variation was only 1.0 dBi during the entire mid-band. The total dimension of the fabricated antenna prototype is 10.32 λ_o × 4.25 λ_o ×1.295 λ_o at a resonance frequency of 4.5 GHz. These results make the presented antenna appropriate for 5G sub-6 GHz applications.