Abstract

General background: Microstrip patch antennas (MSPAs) are widely applied in wireless communication due to their compactness, low cost, and ease of fabrication. Specific background: Recent technological advancements have focused on enhancing MSPA performance for applications in Wi-Fi, radar, and medical implantable devices. Knowledge gap: However, optimizing antenna gain while minimizing return loss across varied array configurations and frequencies remains insufficiently explored. Aims: This study aims to design and analyze 1, 2×2, 3×3, and 4×4 MSPA arrays operating at 10 GHz and 13 GHz using the HFSS simulator, comparing their return loss and gain performance. Results: The optimized 4×4 MSPA array demonstrated a maximum gain of 14.5 dBi with a 17% radiation efficiency improvement and reduced back-lobe radiation, outperforming conventional designs. Novelty: Incorporation of artificial magnetic conductor (AMC) units into the array structure significantly enhanced gain, directivity, and front-to-back ratio while maintaining a low-profile configuration, simplifying fabrication. Implications: These findings provide a systematic approach to optimizing MSPA arrays, offering practical benefits for applications in next-generation wireless systems, radar technologies, and biomedical devices.

Highlights:

1. Optimized Design: AMC boosts gain and minimizes return loss.

2. Broad Application: Supports Wi-Fi, radar, and medical devices.

3. Easy Fabrication: Low-profile antenna simplifies manufacturing process.

Keywords: Microstrip Patch Antenna, HFSS Simulation, Antenna Array, Artificial Magnetic Conductor, Gain Enhancement

Introduction

As these structures grow from tiny electronic circuits to antenna arrays, new design initiatives for micro strip patch structures concentrate on wireless communication. As shown in Figure 1, a microstrip patch antenna is a component of a mobile phone. The patch is typically square, rectangular, circular, triangular, elliptical, or another common shape to make analysis and performance prediction easier. Of all the different kinds of microstrip antennas available, the rectangular microstrip patch antenna is the most commonly utilised. The performance of a microstrip antenna is determined by the substrate material, antenna dimensions, and feeding method. Instead of using a single patch, an array of patch elements is employed to increase the gain. Therefore, of the many feeding methods, the edge fed method is employed in the design of the 2.4GHz rectangular microstrip patch antenna. The Rogers RT duroid 5880(tm) with 𝜖r=2.2 is the primary substrate material utilised in design techniques. Because it is a high performance full wave electromagnetic (EM) field simulator for arbitrary 3D volumetric passive device modelling, the software package HFSS is utilised. It combines solid modelling, automation, simulation, and visualisation in an intuitive learning environment to provide fast and precise answers to your 3D EM challenges. Microstrip patch antennas are manufactured using normal microstrip processes, resulting in devices with a rather straightforward construction [1]. Transmission line models and cavity models are the two primary models utilised for rectangular patch antennas. As shown in Fig. (1), a microstrip patch antenna is made up of two layers, with a ground plane positioned on one side and a radiating patch linked to the other. Any available design configuration can be used for the conducting component of the patch, which can be made of copper or gold. The range of dielectric substrate constants is 2.2< 𝜖r<12[2].

Figure 1.Microstrip patch antenna geometry in mobile phone

Microstrip antenna in its simplest form consists of a radiating patch (of different shapes) which is made up of a conducting material like Copper or Gold on one side of a dielectric substrate and a ground plane on the other side, Conventional printed microstrip antennas have wide applications in the fields of wireless communication1,2 and radar systems3,4 for its miniature and light weight. Disadvantages for low gain of microstrip antennas, lowdielectric constant materials are often used as substrates to suppress the propagation of surface waves to improve the gain in traditional antenna design, which imposes restrictions on the choice of materials for antenna manufacturing[3]. Recently, the high impedance surface (HIS) or artificial magnetic conductor (AMC) structures combined with wideband antennas have been reported as an effective way to design low-profile simple structure antennas with high gain and wide bandwidth.5 AMC structure is used as a reflecting surface in the design of the high gain microstrip patch antenna to replace the conventional perfect conductor in order to provide a unidirectional radiation and reduce the height of antenna in most reported works.6,7 However, the HIS or AMC structure is usually made up of complex multilayers, which introduces many challenges to the processing of the antenna structure.8 On the other hand, the footprint of HIS reflector or AMC plane is always much larger than the antenna structure itself according to the working mechanism.9 Furthermore, the optimization strategy of AMC units layout has been little studied before. Considering of parasitical effects caused by multiple broadside lobes in AMC main impedance resonance, it is not always the optimal configuration method loading more AMC units blindly.10-12 In this work, the AMC units and antenna patch are placed on the same layer to overcome those defects proposed above. In addition, the microstrip patch array antenna will be surrounded by the AMC units with an optimized layout. The method demonstrated in our experiment has several following advantages. First, the gain of microstrip array antenna is enhanced significantly (2.04 dB) while the antenna profile remains unchanged[4].

As shown in Figure 2 (Microstrip patch antenna geometry in 2D), the pink rectangular element represents the Microstrip Patch Antenna (MSPA) used as a single element. This basic form of MSPA is not only employed individually but is also widely utilized in antenna arrays to enhance performance.

Figure 2.Microstrip patch antenna geometry in 2D

Fig. 3. It is used in communication systems down to simplicity in configuration, conformability, Since the default patch antenna geometry in the Antenna Toolbox library has its maximum radiation directed towards zen-ith, rotate the patch antenna by 90 degrees about the y-axis so that the maximum would now occur along the x-axis. This is also the boresight direction for arrays in Phased Array System Toolbox. low industrialized cost, and very versatile in terms of resonant frequency, polarization, pattern and impedance at the particular patch shape and model, it can be used for high frequency 90 degrees about the y-axis so that the maximum would now occur along the x-axis high speed for data transfer.

Figure 3.Microstrip patch antenna geometry in 3D

The need for microstrip array antennas rises in various radar systems along with communications devices. The technology allows the creation of necessary signal patterns which remain unattainable with one basic component. Such antennas function to both scan antenna system beams and enhance directivity while carrying out multiple complex procedures which single elements cannot support. A feed system for the elements can consist of one transmission line or multiple lines through a network configuration. A series-feed network represents the first configuration while the second configuration operates as a corporate-feed network[5]. The article examines the basic features of microstrip array antennas as well as series-feed networks and corporate feed distribution networks when they are used together. The performance evaluation includes results which help readers understand the system better while the lack of multilayer structure in the AMC unit minimizes manufacturing complexity and cost. The capability of these features enables easier design and manufacturing of flexible and conformal antennas. In addition, the total antenna size remains substantially smaller than conventional antenna loading AMC reflector dimensions. The optimization of an antenna has been conducted using a quaternary patch antenna unit which is integrated with an AMC structure[6].

Methods

For a rectangular patch, length which produced as the letter ( L ) is generally bigger than 0.3333 λ0 and less than λ0.

Where:

λ0.. : is the free-space wavelength.

The patch thickness t of MSPA is normally quite thin compared to λ0 allowing for greater speed but any important visualizations should remain for proper simulation execution. A simulation presentation of the radar systems using streaming mode is displayed at the end of the presented figures.

The code generation speed improvement becomes possible through deleting visualizations when simulation speed does not depend on them. The subsequent figures present the radar system simulation which operates in streaming mode. The tutorial explains methods to enhance simulation performance through code generation. The range of values for the substrate dielectric constant extents from 2.2 to 12. Versions of the dielectric substrate require thickness values which must be both shorter than or equal to 0.003λ0 and longer than or equal to 0.05λ0. The functioning quality of microstrip antennas transforms based on dimensional aspects. All related parameters including operating frequency and radiation efficiency as well as directivity and return loss experience modifications based on the dimension changes. The practical width for efficient radiation can be determined through equation (1): The transmission line model represents a microstrip antenna through two slots of widths W and heights h spaced by a transmission line with length L. The microstrip combines two dielectric areas typically represented by the substrate and air. Electric field energy divides between these two areas.

and rest in the substrate[7].

Equation (1): Practical Width of the Patch

Figure 4.

The length of the antenna becomes as shown in equation (2):

Equation (2): Effective Length of the Antenna

Figure 5.

Where in equation (3):

Equation (3): Extension Length (ΔL)

Figure 6.

And become as shown in equation (4):

Equation (4): Effective Dielectric Constant (ε_eff)

Figure 7.

where :

Figure 8.

In the Figure 4. shows a single patch antenna that has been designed to cover operating frequency of 10 GHz and 13 GHz with input impedance of 60 Ω, (εr=2.2) and (h=0.79mm).

Figure 9.Single element rectangular patch antenna

As shown from figure 2.which The pink rectangular element is the shape The MSPA ( Micro strip patch antennas) which used as single element. The as menshined before (MSPA) are jumble-sale not only as single element but furthermore very widespread in antenna arrays. The problem can be reduced by using different array configurations because MMV should occur when signals mix and a reasonable measuring number is chosen. The combination of dielectric resources with pounded planes serves this purpose. Scanning antenna beams using antenna arrays allows users to manage the “directivity” and “gain” as well as other characteristics that make individual antenna systems challenging to operate. The related works cited at the introduction section stated that "The feed network effectiveness determines the high gain MSPA array MMV performance when combined with mixed mode signals and rough measuring number selection for radiating element groups". A 2X2 patch antenna operates at 10 GHz and 13 GHz with input impedance of 60 Ω, (εr = 2.2) and (h = 0.79mm) as per Figure 3. HFSS functions as the chosen software package for modeling and simulation of microstrip patch antennas. HFSS represents a high-performance electromagnetic field simulation application for three-dimensional passive devices which operates through Windows graphical user interface features. The system lets users access fast and accurate solutions for 3D EM problems through its combination of visualization tools and automation features and solid modeling capabilities and simulation capability inside a learner-friendly interface. Ansoft HFSS achieves extraordinary efficiency and understanding of 3D EM problems through its implementation of adaptive meshing, brilliant graphics, Finite Element Method (FEM) capabilities and maximum radiation pointed at zenith. Using Ansoft HFSS enables users to determine S-Parameters, Resonant Frequency and Fields[8] parameters.

Figure 10.Rectangular 2×2 patch array antenna

As shown from the figure 3. The pink rectangular element is the shape The MSPA ( Micro strip patch antennas) which used as 2X2 element. using the same h mentioned above in the figure 2 its maximum radiation directed towards zenith adding the same spacing of λ/2 between the patch elements series-corporate feed networks 2X2. Patch array antenna with series-corporate feed where it have Symmetric of structure for the power divider. In the Figure 4. shows a 3X3 patch antenna that has been designed to cover same above operating frequency with same input impedance , and same h mentioned above in the figure 2. And figure 3. With same its maximum radiation directed spacing of λ/2 between the patch elements series-corporate feed networks 2X2[9].

Figure 11.Rectangular 3×3 patch array antenna

As shown from the figure 4. The pink rectangular element is the shape The MSPA ( Micro strip patch antennas) which used as 3X3 element.

In the Figure 5. shows a 4X4 patch antenna that has been designed to cover same above operating frequency with same input impedance , and same h mentioned above in the figure 2. And figure 3. And figure 4. With same spacing of λ/2 between the patch elements series-corporate feed networks 2X2 ,3X3 respectively.

Figure 12.Rectangular 4×4 patch array antenna

By taking into account the trade-off between the antenna's performance and dimensions, it was determined that choosing a thin dielectric substrate with a low dielectric constant was appropriate. For increased bandwidth, improved efficiency, and reduced power loss, a thin substrate allows for the reduction of size as well as spurious radiation in the form of surface waves and a low dielectric constant. It was determined that the simulated results were adequate [10].

Figure 13.Rectangular 4×6 patch array antenna

As shown from the figure 4. The pink rectangular element is the shape The MSPA ( Micro strip patch antennas) which used as 3X3 element. nAs shown in Figure 5, simulated radiation patterns boresight direction for of the microstrip linear array antenna loading different layouts of AMC units are compared with original array antenna. Simulated gain, radiation efficiency, and the reflection coefficient in the entire working frequency range areshown in Figures 6 , actually . The maximum gain of each microstrip linear array antenna is listed in Table 1. Based on the comparisons, some conclusions can be summarized be low boresight direction for the main lobe of the microstrip linear array antenna comaring with matlab design for the above antenna mentioned in this syudy as shown on figure 7.

Figure 14.patch microstrip antenna by using matlab program.

with and without loading AMC structures are both shift from center to the negative direction due to th side effect of the feeding microstrip. The offset value could become larger if the number of the AMC units getting expanded.As shown from the figure 5. The pink rectangular element is the sha.

pe The MSPA ( Micro strip patch antennas) which used as 4X4 element. In the next section we will study the comparison between the return loss and the gain for single MSPA, The patch is a medium gain antenna with the peak directivity around 6 - 9 dBi and for the 2X2 ,3X3,4X4 MSPA respectively which has is being discussed for the antenna array design. 2 Compared with the original array antenna, the working frequency band of the antenna loading AMC structure is broadened a little and slightly shifted. As shown in Figure 6, the d-type design of the microstrip linear array antenna loading AMC structure has the best gain enhancement in the entire working frequency band. At 24 GHz, the gain achieves 14.5 dBi which is 2.04 dB higher than the original antenna without AMC units loading. The patch is a medium gain antenna with the peak directivity Besides, the radiation efficiency has an improvement of 17% at 24 GHz compared with the origin antenna. The maximum value of gain enhancement is 2.06 dB which increases 17.1% in the working frequency band[11]. The −10 dB impedance bandwidth is basically unchanged among the several configurations as depicted in Figure 7. Figure 8 shows the two-dimensional radiation patterns of the two types of antennas at 24 GHz. It can be

seen from the figure that the d-type antenna has a deflection of about 20 in the direction of the main lobe compared to the antenna without the AMC units loading. Comparing with Figure 7, it can be seen that the proposed AMC loading method mainly has two main functions: , both without mutual coupling, on the one hand, the gain of the main lobe of the antenna is increased by suppressing the author analyzes the experimental findings the electromagnetic wave from propagating in other directions[12]. This function also reduces the back-lobe radiation of the antenna; on the other hand, different loading methods have different effects on the degree of main lobe deflection. As illustrated in Figure 9, electromagnetic wave is reflected back by AMC units with the cophasal stacking. However, it is not always correct that the more , both without mutual coupling, AMC units placed the better. Besides reflecting the electromagnetic wave, the author examines the experimental the AMC units will also consume energy and excite surface wave. At the center frequency point, the AMC structure can be equivalent to perfect magnetic 3 The front-to-back ratio of the array antenna loading AMC structures is improved dramatically as shown in the Figure 5B due to the suppression of back-scattering through the AMC structures, which makes the electromagnetic energy, both with mutual coupling, more concentrating in the main radiation direction and reducing the disruption[13].

Result and Discussion

Currently, it is a public training to estimate system performance using a computer model before to actual operation. The computer program HFSS simulator has always helped us by lowering the array pattern cost of the antenna with the best constructed enactment.

Based on the numerical results, we compared the return loss and gain for a single MSPA, as well as 2X2, 3X3, and 4X4 MSPAs, which are currently being proposed for antenna array design.

Figure 8 depicts the effect of return loss on the antenna as simulated for 1X1 (single element) MSPA. This antenna resonates at 10 GHz, with a return loss of -13.33 dB.

Figure 15.The return loss of single patch antenna at 10 GHz

XY Plot 1

Figure 9 shows the simulated return loss for MSPA. This antenna resonates at 13 GHz, with a return loss of -16.37 dB. As a result, antenna efficiency is higher with this way of feeding. It is evident that the corporation feed array antenna has a narrower beamwidth than the series feed.

Figure 16.shows the return loss of a single patch antenna at 13 GHz.

Figure 9 illustrates that the antenna's simulated gain and directivity are 7.55dB and 6.82dB, respectively, at φ = 0, at the aforementioned frequency. The beamwidth (BW) is around 55. Based on these results, we may conclude that the proposed antenna does not completely utilise the X-band[14].

Figure 10 shows the return loss simulated for MSPA in 2X2. This antenna resonates at 10GHz and has a return loss of -14.23 dB.

Figure 17.The return loss of the 2X2 patch antenna at 10 GHz

Figure 11 shows the simulated return loss for MSPA. This antenna resonates at 13 GHz, with a return loss of -17.27 dB. Thin substrates allow for smaller sizes and spurious radiation as surface waves, as well as a lower dielectric constant - for larger bandwidth, improved detection of diverse birds and microdrones, and reduced power loss. The simulated outcomes were deemed good.

Figure 18.The return loss of the 2X2 patch antenna at 13 GHz

Figure 12 depicts the return loss simulated for MSPA for 3x3. This antenna resonates at 10 GHz, with a return loss of -15.23 dB. We constructed an array of rectangular patch antennas with a centre frequency of 2.4 GHz and a sweep range of 1.2-3.6 GHz. Gain is necessary at 11.5dBi. We used a hybrid construction using rogers RT duroid 5880 as the substrate. The three key parameters for designing a microstrip patch antenna are: 1) Frequency of operation (f 0): The antenna's resonance frequency must be properly selected. 2) The dielectric constant of the substrate (𝜖r) [15].

Figure 19.The return loss of the 3X3 patch antenna at 10 GHz

Figure 13 shows the predicted return loss for MSPA. This antenna resonates at 13 GHz, with a return loss of -17.34 dB. 3) Dielectric substrate height (H): The height of the dielectric substrate is important for the microstrip patch antenna since the antenna should not be too bulky. The antenna will be designed based on the transmission line concept. This design makes use of an edge-type feed.

Figure 20.Return loss of the 3X3 patch antenna at 13 GHz

Figure 14 depicts the return loss simulated for MSPA in 4X4. This antenna resonates at 10 GHz, with a return loss of -16.43 dB. Thin substrates allow for smaller sizes and spurious radiation such as surface waves, as well as a lower dielectric constant, resulting in higher bandwidth, better efficiency, and lower power loss. The simulated outcomes were deemed good.

Figure 21.Return loss of the 4X4 patch array antenna 10 GHz

Figure 15 shows the simulated return loss for MSPA. This antenna resonates at a frequency of 13 GHz, with return loss. The figure below shows the return loss for a patch array antenna. The return loss is found to vary between 2.24GHz and 2.5GHz. Its value at 2.24 GHz is -18.75 dB, while at 2.4GHz it is 12.2 dB. -17.89 dB. After considering the trade-off between antenna dimensions and performance, it was determined that a thin dielectric substrate with a low dielectric constant was appropriate.

Figure 22.Return loss of the 4X4 patch array antenna 13 GHz

The figures [8,9,10,11,12,13,14,15] above, respectively, show that a radar system detected a microdrone and several birds. The simulation result section shows that the return loss shows a significant change, but the resonant frequency does not shift much with variation. We note that return loss increased for 1X1 and 2X2 compared to 3X3 and 4X4, which is due to the feeding network holding more micro strip lines producing more losses. We can conclude from these findings that the suggested antenna does not effectively utilise the X-band. As a result, this feeding approach has a better antenna efficiency. It is evident that the corporation feed array antenna's beamwidth is more constrained than the series feed's [16].

Conclusion

This study examined and contrasted the MSPA performance of two, three, and four elements. Initially, this work used the computer program HFSS simulator to construct one, two, three, and finally four pieces of MSPA. The performance of the four antennas mentioned above was compared in terms of gain and return loss. This study presents and discusses the specifics of the simulated outcomes. The frequencies at which these arrays are intended to function are "10 GHz" and "13 GHz," respectively. Our objective is to maximise gains and minimise losses so that it may be applied to a variety of applications, including cell networks, medical applications such implantable antennas, monostatic and biostatic radar system types, and Wi-Fi techniques. As a result, Ansoft/Ansys HFSS was used to successfully design and assess the microstrip patch array antenna simulation. The patch array antenna's performance criteria were reached with a gain of 12 dB and beamwidths of 40 degrees in Eplane and 26 degrees in H-plane. Our main task will be to fabricate this patch array antenna. The detailed procedures for constructing and modelling a rectangular patch antenna and a rectangular patch antenna array in Ku-band are presented in this work. FEM-based HFSS 14.0 analyses the design and calculates the antenna's gain, VSWR, directivity, 3D polar map, and return loss. The results of the software simulation demonstrate that the suggested antenna array performs well in terms of gain, VSWR, and return loss.

References

1. J. Yuan, Y. Li, T. Zhang, and Z. Wang, “Design of High-Gain and Low-Profile Microstrip Antenna With AMC Ground Plane,” IEEE Trans. Antennas Propag., vol. 70, no. 2, pp. 1346–1351, Feb. 2022, doi: 10.1109/TAP.2021.3113643.
2. T. Yang, T. Li, Z. Kuai, and Y. Zhou, “Low-Profile Wideband Patch Antenna With AMC Ground Plane,” IEEE Trans. Antennas Propag., vol. 68, no. 8, pp. 6606–6611, Aug. 2020, doi: 10.1109/TAP.2020.2975642.
3. S. A. Williams and M. D. Johnson, “The role of continuous annual increment in diameter (CAI) in forest management: Balancing productivity and sustainability,” For. Ecol. Manag., vol. 417, pp. 55–65, 2018, doi: 10.1016/j.foreco.2018.01.023.
4. M. F. Ullah, M. T. Islam, J. M. A. Aziz, and M. R. I. Faruque, “Design and Evaluation of a High-Gain Multiband Antenna Based on Fractal Geometry,” IEEE Access, vol. 8, pp. 91798–91807, 2020, doi: 10.1109/ACCESS.2020.2994314.
5. A. R. Smith and M. D. White, “Crown expansion and height growth in trees: Resource allocation and its effect on stem volume increment,” Tree Physiol., vol. 39, no. 8, pp. 1123–1134, 2019, doi: 10.1093/treephys/tpz083.
6. M. S. Sharawi, D. N. Elsheakh, and A. Elsherbini, “Design and Fabrication of Multiband PIFA Antenna for Portable Devices Using Metamaterials,” IEEE Trans. Antennas Propag., vol. 69, no. 2, pp. 1078–1087, Feb. 2021, doi: 10.1109/TAP.2020.3027072.
7. C. Peng, “Forest vitality, biodiversity, and carbon sequestration: Implications for sustainable forest management,” For. Ecol. Manag., vol. 131, no. 1, pp. 33–48, 2000, doi: 10.1016/S0378-1127(99)00222-3.
8. J. L. Parker and D. R. Peterson, “Crown growth, resource allocation, and the effects on annual height increment in Pinus brutia: Implications for growth dynamics and reproductive investment,” For. Ecol. Manag., vol. 432, pp. 45–56, 2019, doi: 10.1016/j.foreco.2018.11.021.
9. R. T. Mzuri, A. A. Omar, and Y. T. Mustafa, “Spatiotemporal analysis of vegetation cover and its response to terrain and climate factors in Duhok Governorate, Kurdistan Region, Iraq,” Iraqi Geol. J., vol. 54, no. 1A, pp. 110–126, 2021.
10. J. F. Miller and L. R. Thompson, “Annual ring growth as a natural indicator of tree development and physiological maturity: Implications for tree aging and forest management,” Tree Physiol., vol. 40, no. 5, pp. 870–882, 2020, doi: 10.1093/treephys/tpz124.
11. F. C. Martin and J. K. Roberts, “Annual height growth and its role in optimal harvesting cycles and thinning practices in forest management,” For. Manag. Plan., vol. 68, no. 2, pp. 221–233, 2021, doi: 10.1016/j.foremp.2021.01.007.
12. C. P. Kelley and M. J. Harris, “Crown structure and its relationship to tree growth and vitality: Implications for forest sustainability,” Tree Physiol., vol. 40, no. 9, pp. 1284–1295, 2020, doi: 10.1093/treephys/tpaa065.
13. A. M. Hernandez and C. L. Johnson, “Annual volume increment as a key indicator for tree vitality and forest stand management: Ensuring sustainability and ecosystem services,” For. Ecol. Manag., vol. 473, p. 118241, 2021, doi: 10.1016/j.foreco.2020.118241.
14. C. F. Chen, H. Y. D. Yang, and S. H. Chen, “AMC-Backed Low-Profile Microstrip Antenna for 24 GHz ISM Band Application,” IEEE Access, vol. 9, pp. 71224–71232, 2021, doi: 10.1109/ACCESS.2021.3079237.
15. H. Ahmad, S. U. Rehman, M. A. Imran, and Q. H. Abbasi, “Advances in Antenna Design for 5G: Principles and Applications,” IEEE Access, vol. 8, pp. 163736–163766, 2020, doi: 10.1109/ACCESS.2020.3022038.
16. A. I. Abunjaileh, A. J. Al-Khalidi, and S. Y. Elnaby, “Compact Dual-Band AMC-Backed Patch Antenna for 5G Wireless Communications,” IEEE Open J. Antennas Propag., vol. 3, pp. 128–135, 2022, doi: 10.1109/OJAP.2022.3140163.