The present study investigates the design, fabrication, and validation of an FSS reflector-based antenna for enhancing the eficiency of Vehicle-to-Vehicle (V2V) communication in Internet of Things (IoT) applications. The proposed design integrates a compact antenna of size 24 mm × 30 mm × 1.6 mm with an FSS unit cell of 10 mm × 10 mm × 1.6 mm. The combination results in a significant improvement in gain, increasing from 1.46 dB to 6.42 dB at 5.9 GHz, along with a broader bandwidth of 738.86 MHz. The research highlights the efectiveness of FSS technology in amplifying antenna gain and bandwidth, demonstrating its potential to enhance V2V communication systems within IoT environments. A prototype of the proposed design is fabricated, and the measurement results validate the simulated outcomes, confirming the efectiveness of the FSS reflector-based antenna for V2V communication in IoT applications.
Research on the Internet of Vehicles (IOV) [1], including vehicle-to-everything (V2X), vehicle-to-vehicle (V2V), vehicle-to-network (V2N), and vehicle-to-information (IVI) communication, has flourished [ 2, 3] as a result of the continuous increase in demand for antennas for use in automotive communication systems. Through the connection of the Internet of vehicles and the base station, the Intelligent Transportation System (ITS) will be able to obtain real-time trafic information in the future, including information about pedestrians, road conditions, and information about roads. This information will also help to improve driving safety, prevent trafic jams, and increase the eficiency of transportation [4]. Moreover, cars are becoming a more integral part of our lives and are used by people to get to their destinations more and more frequently. The development of intelligent vehicle technology is a result of the above-mentioned reasons why increasing road trafic safety is a crucial concern [ 5]. The swift advancement of new technology and the Internet of Vehicles (IOV) have greatly facilitated our lives and transportation. Along with enhancing road safety, it has assisted governments in numerous nations and areas in eficiently managing the use of roads and highways. Additionally, V2X and satellite communication antennas in the ITS have drawn a lot of attention as vehicle communication technology has advanced [6].
Every car has a satellite link in addition to a V2V connection with adjacent vehicles and roadside units (RSUs) [7]. The main technologies of the existing vehicle communication system advance research on LEO satellite antennas for vehicle-to-vehicle connections [8, 9]. Apart from ensuring enhanced safety during driving, like vehicle distance and remote driving, the V2X communication system further encompasses vehicle-to-infrastructure (V2I) connections. In order to predict the safest driving conditions and the shortest route to a destination, it ofers numerous advanced features, including blind spot detection, emergency vehicle approach warning, forward distance warning, and road condition data. However, for these features to function properly, a high-performance antenna is necessary [10, 11].
Furthermore, due to the antenna’s limited area of usage, building antennas for specific substrates like car windows or windshields is also dificult. Because of this, only extremely thin conductive strips can be utilized, which adds to the complexity of the antenna’s design and installation [15]. Whatever the wireless communication product, antenna design ought to be given high importance. As a result, antenna engineers need to have a clear vision when making design selections. This includes considering factors like cost, area, and future achievability. There will be a high need for wireless data mass transit in the future. Antennas occupy a bigger space for communication between vehicles and low-orbit satellites than integrated circuits for data processing and analysis due to the coexistence of many wireless network broadcasts. In order to be more afordable and practical for today’s multi-band wireless communication systems, the designed antenna must be small, multifunctional, and multi-band [16].
Many antennas used in LEO communication applications are constructed with multi-band and broadband in mind, in order to increase the diversity of the operational frequency of the antenna. These innovations include the use of tapered-angle power dividers and patch antennas. A dual-band efect can be achieved by increasing the bandwidth by 109% while maintaining a 2 dBi reduction in overall gain [10]. Bending the monopole antenna and adding branches has allowed for multi-band use. Multi-band use has been accomplished by increasing the dual-band bandwidth by 31.22% and 65.29% with a progressive adjustment in impedance [13]. Broadband can be achieved with a loop patch antenna design that uses partially slotted ground planes and rectangular slots. Enhancing antenna performance is the primary objective of employing parasitic loop elements [17]. In this design, the surface current at the operating frequency between the patch antenna elements is eficiently blocked or absorbed through the elliptical patch, the grounding branch, and the T-shaped branch, decreasing the mutual influence and creating a broadband efect [ 18]. The antenna can generate resonance at diferent frequencies by merging two bow-tie-like curves, which secures the multi-frequency efect. The antenna operates at a lower frequency due to the prolonged twists and turns [19].
A coplanar waveguide (CPW) structure X-band patch antenna that can be directly attached to the antenna and transmit receiver modules without the need for extra wire is suggested. As a result, unneeded movement can be stopped and antenna performance degradation can be minimized when external causes interfere [20]. Impedance bandwidth can also be obtained using rectangular slot patches by stacking perforated cylinders and etching a rectangular slot on the ground side. An antenna that combines the operating frequencies is called a broadband hybrid dielectric resonator antenna. As an alternative, the same aperture can be utilized on two frequency bands by combining array design with shared aperture technology [21, 22]. In patch antennas, the necessary radiation is produced by shorting pins and slots, which are cut into the surface to create resonance [23]. The rectangular microstrip patch can be truncated to produce broadband characteristics, and the electromagnetic bandgap structure can be used to produce notch features [24]. Loss can be decreased by the coplanar waveguide structure. Broadband can be achieved with a patch antenna and a wide impedance bandwidth by optimizing the radiation patch and the ground plane [25]. Broadband performance can be achieved with a defective ground structure (DGS) and a rectangular microstrip antenna. The antenna is 60 × 60 mm2 in total [26]. In order to create a patch that is distinct from the conventional rectangle, they employ patch antennas and modify the structure. The broadband efect is achieved by using an elliptical radiator design. Reconfigurable circular polarization can be used to achieve 10.8–11.8 GHz and 14–15.4 GHz in dual-frequency bands for satellite communication applications, with bandwidths of 7.6% and 4.3%, respectively [27]. The entire antenna is built using substrate-integrated waveguides (SIWs), which result in a 9.85 GHz mixed-mode resonance. Dual resonances at 14 GHz result from cutting the short slit into the top of the cavity. Peak gains of 6.62 dBi and 6.44 dBi, respectively, were recorded by the antenna at 9.85 GHz and 14 GHz [28].
The document’s remaining sections are organized as follows: The design and simulations of the antenna element are shown in Section II, along with a discussion of the proposed FSS unit cell’s geometry. In Section III, the antenna’s simulation results with and without the FSS are evaluated. A 4 × 4 periodic design of the FSS is employed as a reflector to boost gain. The part also contains the measurement results to support the simulated outcomes. Lastly, the paper’s closing observations are given in Section IV.
The proposed microstrip antenna design is illustrated in Figure 1. The antenna dimensions were carefully optimized using CST Microwave Studio’s parametric sweep function to achieve the desired resonance at 5.9 GHz while maintaining a compact size.
(a) (b)
The length () is 30 mm, and the width ( ) is 24 mm. The substrate thickness (ℎ) is 1.6 mm. An FR4 substrate with a relative permittivity of = 4.3 and a loss tangent of 0.025 was chosen for its cost-efectiveness and availability as shown in Tabe 1.
Dimensions of the proposed microstrip antenna.
Parameter 1 1 2 2 1 2 ℎ
Based on the proposed microstrip antenna, Figure 2 shows how the reflection parameter S11 varies with frequency.
Figure 3 presents the dimensions of the proposed Frequency Selective Surface (FSS) decagonal unit cell, which were optimized through parametric studies using CST Microwave Studio. This novel layout functions as a reflector, guiding electromagnetic waves toward a main lobe of operation.
The FSS structure is fabricated on an FR-4 substrate with a thickness of 1.6 mm, a dielectric constant of = 4.3, and a loss tangent of 0.025. The unit cell consists of two concentric decagons, with outer and inner diameters 1 = 6.8 mm and 2 = 5.8 mm, respectively. The total surface area of each unit cell is 15 mm × 15 mm.
11) of the antenna with and without the FSS reflector.
The inclusion of the FSS significantly improves the antenna’s impedance matching and overall perforof 5.9 GHz. This substantial reduction indicates enhanced energy transfer and reduced reflection. mance. Specifically, the 11 value is reduced from − 25.16 dB to − 46.34 dB at the operating frequency
− 10 dB bandwidth of 738.86 MHz centered around 5.9 GHz.
This bandwidth is well-suited for V2V communication operating within the Dedicated Short Range Communication (DSRC) system band, making the design efective for vehicular communication applications. The Frequency Selective Surface (FSS) is structured as a 4 × 4 grid of unit cells. Each cell measures 60 mm × 60 mm and is arranged with a periodicity of 2 mm. The dimensions of the unit cells are consistent with those of the overall array, ensuring uniform electromagnetic behavior and facilitating constructive interference in the desired frequency band.
In this section, a thorough analysis is conducted on the antenna’s reflection coeficients, gain, and radiation pattern within the context of IoT communication. The arrangement of a Frequency Selective Surface (FSS) array positioned behind the antenna is illustrated in Figure 5. It is observed that the optimal reflection occurs when the distance between the antenna and the FSS array is equal to the wavelength corresponding to the resonant frequency of 5.9 GHz.
The concept of constructive interference plays a key role in enhancing antenna performance. The phase diference between the direct and reflected waves is calculated using the equation:
A phase diference of 4 (or any multiple of 2 ) ensures that the direct and reflected waves are in phase, resulting in constructive interference. This phenomenon leads to an increase in the overall gain of the antenna.
= 2
+ ︂( 2 )︂
= 2 ︂( 2 · 3/ 4 )︂ + = 4 where represents the distance between the antenna and the FSS, and is the wavelength. When the distance is set to = 34 , the phase diference becomes:
To facilitate this constructive interference, the antenna emits a wave that propagates upward from the patch and downward through the partial ground plane. By introducing a reflector composed of FSS cells at a distance of from the antenna, the downward wave is redirected back toward the patch, acting as an additional source of radiation. The antenna then combines two waves: the primary wave emitted from the patch and the secondary wave reflected by the FSS. Since these waves are in phase, they interfere constructively, modifying the radiation pattern and enhancing both directivity and gain.
Furthermore, when integrated into an electronic circuit, the antenna serves as an efective electromagnetic shield for the ground plane. This integration significantly contributes to the antenna’s functionality in facilitating Internet of Things (IoT) communication, thereby enhancing its utility in modern applications.
The reflection coeficient ( 11) of the antenna is significantly influenced by the presence of the FSS, as illustrated in Figure 6. The graph shows a substantial decrease in the input reflection coeficient value, from − 25.16 dB to − 46.34 dB at the operating frequency of 5.9 GHz. Additionally, the antenna’s − 10 dB bandwidth, centered at 5.9 GHz, is measured at 738.86 MHz. This bandwidth is suitable for Vehicle-to-Vehicle (V2V) communication within the Dedicated Short Range Communication (DSRC) frequency band. The comparison highlights the improved impedance matching and bandwidth enhancement achieved through FSS integration.
As shown in Figure 7, the gain of the antenna is significantly enhanced when the FSS reflector is employed. The peak gain increases from 1.46 dB to 6.42 dB at 5.9 GHz. This enhancement occurs without altering the antenna’s geometry or materials, demonstrating the eficiency of using a passive FSS structure to improve radiation performance.
Figure 8 compares the far-field radiation patterns in the E-plane ( = 0∘ ) and H-plane ( = 90∘ ) at 5.9 GHz. Although the general shape of the patterns remains stable with or without FSS, notable modifications in lobe structure and directionality are observed. These variations confirm that the integration of FSS modifies the electromagnetic behavior of the antenna, leading to improved directional performance and reduced back radiation. Figure 9 demonstrates that the antenna achieves an eficiency exceeding 87.45% within the operating frequency band. This high eficiency validates the suitability of the proposed structure for IoT applications requiring reliable and energy-eficient wireless links. As illustrated in Figure 10, the Voltage Standing Wave Ratio (VSWR) at 5.9 GHz is approximately 1.17, well below the threshold value of 2. This indicates excellent impedance matching between the feed line and the antenna, ensuring maximum power transfer and minimal reflection loss.
To experimentally validate the proposed Dug-Hex antenna and FSS design, a fabrication process was carried out in a fabrication laboratory, as illustrated in Figures 11 and 12.
The fabrication followed the parameters listed previously, using FR-4 substrate and copper metallization, consistent with the CST simulation setup. Standard printed circuit board (PCB) manufacturing techniques were employed to realize the prototype.
Figure 13 shows no significant diference between the measured and simulated S-parameters for both configurations, with and without the FSS. Both sets of results align closely, indicating that the experimental data matches the theoretical predictions. This confirms the accuracy of the design and fabrication process, validating the performance of the proposed dug-hex antenna and FSS.
As observed in Figure 13, the measured results show excellent agreement with the simulations for both configurations. The close alignment of the 11 responses confirms the reliability of the design process and validates the performance enhancement achieved through FSS integration. These results demonstrate that the proposed structure is both practically realizable and efective for IoT and V2V communication applications.
(a) (b)
This study has demonstrated the efectiveness of integrating a Frequency Selective Surface (FSS) reflector with a compact antenna structure to enhance performance for Vehicle-to-Vehicle (V2V) communication in Internet of Things (IoT) environments. The proposed design achieved a significant gain improvement from 1.46 dB to 6.42 dB at 5.9 GHz, along with a broadened bandwidth of 738.86 MHz. These enhancements were achieved without negatively afecting the antenna’s transmission characteristics.
To validate the proposed architecture, a prototype was fabricated using standard PCB manufacturing techniques. The measured results closely aligned with simulation outcomes, thereby confirming the reliability and feasibility of the design.
The findings highlight the strong potential of FSS-based reflectors for improving gain and bandwidth in V2V and IoT applications. Future work may involve further optimization of the FSS geometry, as well as exploring hybrid or adaptive structures for multi-band or reconfigurable antenna systems targeted toward next-generation vehicular communication networks.
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