Printed Slot Antenna Fed by CPW Supported by Broadband Planar Artificial Magnetic Conductor with Enhanced Features

A low profile printed slot antenna (PSA) backed by broadband planar artificial magnetic conductor (AMC) is introduced in this study. Firstly, a suggested PSA with the radiating tapered slots excited by coplanar-waveguide (CPW) is used to expand the bandwidth in the measured range of 9–11 GHz (S₁₁ ≤ –10 dB). Then, the suggested planar AMC surface as the ground plane of the antenna is inserted into the PSA to gain improved radiation efficiency. The realized result from the PSA with the 5 × 7 planar AMC array exhibits ‒10 dB measured impedance bandwidth from 6.63 to 13.70 GHz (almost 70%). The suggested PSA with AMC compared to the PSA without AMC exhibits a size reduction of 59.7%, enhanced bandwidth of almost 50%, and excellent impedance matching with uni-directional radiation patterns. The novel AMC unit cell is realized to operate at 10.14 GHz with an AMC bandwidth of 8–12.35 GHz (43.1%) for X-band operation. Besides, by introducing a specific method based on the reflection results of the equivalent waveguide feed, the number of AMC unit cells is investigated to obtain an optimal AMC array. In this approach, an equivalent waveguide feed corresponding to the center operating frequency is considered to choose the number of AMC array reflector.

Keywords: artificial magnetic conductor (AMC); electromagnetic band gap (EBG); printed slot antenna; planar AMC; wideband AMC

Copyright comment ISSN 1064-2269, Journal of Communications Technology and Electronics, 2022, Vol. 67, No. 4, pp. 375–386. © Pleiades Publishing, Inc., 2022.

INTRODUCTION

In most studies, electromagnetic band gap (EBG) structures have been employed in many wireless networks and a wide variety of electromagnetic equipment due to the unique and remarkable characteristics. They exclude the surface wave's propagation in a determined frequency gap. The EBG structures are studied and recognized as the photonic band gap (PBG) structures with periodic arrangements [[1]–[4]]. As is known, the artificial magnetic conductor (AMC) structures introduce a privilege like a perfect magnetic conductor (PMC) with in-phase reflection response entire the certain range. Based on this, multiple low profile antennas and mode prevention designs are applied AMCs as diverse surfaces to augment the distinguishing features [[5]–[10]]. The results presented in [[9]] show a broadband patch array by loading diverse EBG-AMCs into the ground plane. Also, a miniaturized uni-planar metamaterial-based EBG for parallel-plate mode prevention of the switching noise in digital circuits is described in [[10]].

The uses of AMC periodic surfaces in distinct combinations are provided to show better efficiency [[11]‒[18]]. Among these works, a mushroom-shaped AMC structure as a beneficial approach is usually applied for diverse arrangements to achieve the low profile structures with a higher efficiency [[11]]. In this method, used vias in periodic arrangements cannot create an easy accomplishment in the printed circuits and devices due to the drilled holes in a substrate. In the recent work, an EBG mushroom surface with a dual-layer is reported to attain a size reduction of more than 60% for multiple patch microstrip antennas [[16]]. This study is designed to present diverse two and four-element patch antennas at 2.5 GHz. It is noted that a narrow AMC bandwidth in designing broadband microwave technologies and antennas is a drastic drawback [[19]]. Therefore, there are few types of research for working on broadening the bandwidth of AMC structures [[20]–[23]]. Based on the frequency selective surface (FSS), an AMC design for RFID applications is proposed in [[22]]. In [[23]], a bandwidth of 4.4% at the resonance of 6.2 GHz is demonstrated to acquire a compact AMC unit cell with relatively acceptable angular stability.

In recent years, by increasing the extension of wireless networks and satellite applications, microstrip patch antennas have attracted a great deal of attention owing to their charming specifications, like a low profile structure, light weight and simple implementation. Although a limited impedance bandwidth of the introduced antennas is accounted a notable issue in most studies. Diverse approaches in previous works have been developed to ameliorate the bandwidth of microstrip antennas [[24]–[26]]. Recently, by ameliorating the variety of integrated circuit technologies, the broadband AMC surfaces in the low profile antennas and microwave devices are impressively utilized with the improved features [[27]–[37]]. In [[29]], a low profile circular polarized antenna with the AMC surfaces like a reflector plate is reported to provide a broadband antenna with a higher gain. This antenna with AMC includes the impedance bandwidth from 1.19–2.37 GHz (66.3%) with the axial ratio AR bandwidth of 1.25–1.97 GHz (44.7%).

The present study reports a detailed discussion of the new broadband AMC design for applying at the suggested PSA. At first, a planar AMC is introduced to resonate at 10.14 GHz (8–12.35 GHz) for broadband application. In the following, a low profile broadband PSA backed by the planar AMC surface is introduced. For this purpose, two radiating tapered slots fed by CPW broaden the impedance bandwidth in X-band. Then, a broadband 5 × 7 planar AMC reflector is developed under the antenna to obtain the ameliorated radiation efficiency. It presents the measured ‒10 dB impedance bandwidth in 6.63–13.70 GHz with the measured bandwidth of 69.6%. Also, the proper impedance matching and broad bandwidth with excellent compactness are achieved. Meanwhile, the performance of the AMC surface inserted in PSA is studied by introducing an equivalent waveguide feed in the position of the one half-wavelength of the radiating slot. Based on the reflection results of the equivalent waveguide feed, the optimal AMC array is determined.

SUGGESTED PRINTED SLOT ANTENNA WITH BROADBAND AMC SURFACE

3D view and top view of suggested PSA backed by planar AMC surface is drawn in Fig. 1. Two radiating slots with tapered slots are placed on FR4 substrate with 1.6 mm thickness. The 5 × 7 periodic patch of AMC surface is placed underneath the ground plane which is made from substrate thickness (FR4) of h1 to couple the energy to the top layer of PSA. The dimensions of width and length of slots with tapered slots are 22 mm, and they etch on the substrate by sizes of 53 × 75 mm2. The CPW feeding system of PSA for 50-Ω input impedance is utilized. The main design parameters select as thickness h1 = 2.4 mm, and h2 = 1.6 mm, εr = 4.4 and tan δ = 0.02 for FR4 substrates. A 50-Ω CPW feed is employed with the width of the strip 3 mm and the width of the slot 0.3 mm to provide the optimum impedance matching. Also, the value of LCPW = 23.5 mm for CPW length is optimized. The arrangement of the 5 × 7 AMC periodic ground plane is developed below the PSA as the reactive coupling to conclude a broader bandwidth.

Graph: Fig. 1. Structure of the suggested PSA backed by the broadband planar AMC reflector.

The suggested antenna excites by a 50-Ohm SMA connector from the center of the structure. The parametric studies are employed to determine the optimum dimensions and slots' length. The sizes of the suggested structure with AMC are listed in Table 1. The image of the fabricated cases of the PSA backed by the planar AMC reflector are shown in Fig. 3.

Table 1. Sizes of suggested PSA backed by the AMC

Parameters	Values, mm
W	22
W1	1.5
L	22
Lt	4.3
LCPW	23.5
WCPW	3
h1	2.4
h2	1.6
m	0.5
l	6.3
n	1.75
k	0.8
p	2.75

Graph: Fig. 2. (a) Equivalent circuit for simple patch. (b) Equivalent circuit for PSA with tapered slots.

Graph: Fig. 3. Images of fabricated cases of the PSA backed by the planar AMC reflector.

The proposed PSA is introduced based on tapered slots for achieving different resonances [[4]]. The length, width and position of slots into the tapered slot patch result in a broad bandwidth. By incorporating two slots into the patches with tapered shapes, various resonances occur and thus the impedance bandwidth can be broadened.

The conventional microstrip patch antenna is modelled as a simple resonant circuit L1C1, as seen in the Fig. 2 (a) with the presented lumped elements [[3]]

1

Graph

2

Graph

3

Graph

4

Graph

where y0, Le, fr, h and εe are the distance of feed point from the edge, the effective length of the patch, the frequency of operating band and substrate characteristics, respectively. When two slots incorporate into the patch as a taper, an additional series inductance ΔL and an additional capacitance ΔC can be modelled as shown in Fig. 2b. Thus, different inductive and capacitive couplings in the proposed PSA design result in the wide impedance bandwidth with multiple resonances.

On the basis of the transmission line model for the rectangular radiating patch, the basic width (W) and length (L) of the patch at the resonant frequency are determined using equations (5)–(8) [[26]]:

5

Graph

6

Graph

7

Graph

8

Graph

where, εeff, h and ΔL are effective permittivity coefficient, thickness and additional length due to fringing fields, respectively. Similarly, the basic width and length of printed microstrip dipole antenna are designed based on the equations (5)–(8) for determined operating frequency at X-band. In this case, dielectric constant substrate, εr = 4.4 is considered. The optimum sizes of the proposed PSA such as different lengths and total height of the patch are optimized by full-wave simulator with the parametric study.

The arrangement of the 5 × 7 AMC periodic ground plane is developed below the PDA as the reactive coupling to conclude a broader bandwidth and enhancement of radiation properties. The parametric studies are employed in the full-wave simulator to determine the optimum dimensions and arms' length.

Figure 4 demonstrates the geometry of a suggested rhomboid AMC unit cell. The regular patches are combined with different slots. The relative permittivity and thickness of εr = 4.4 and h = 2.4 mm, respectively are selected to realize on an FR4 substrate. The dimension of the unit cell equal to 7.3 × 7.3 mm2 and the size of the ground plane is selected 10.6 × 10.6 mm2. The electrical and structural specifications of the rhomboid AMC are the main factors on obtaining the enhanced bandwidth. The structural specification of the broad AMC bandwidth acquires from the reactance couplings for arms, slots and parasitic patches. The optimum AMC bandwidth is gained by choosing the suitable electrical specification as h and εr. Based on this, the angular stability should remain without variation for broadband applications. Indeed, various parts with slots insert into the rhomboid AMC design, lead to an extra inductance and capacitance and an extensive AMC bandwidth is obtained [[26]].

Graph: Fig. 4. (a) Structure of suggested planar design and simulation box by using Floquet theory and (b) equivalent circuit model.

Graph: Fig. 5. Flow chart of the design process for the proposed structure.

The mushroom-type EBG structure is formed by a via-loaded metal patch which can be characterized by an equivalent parallel LC resonator with a resonant frequency fr = 1/(2π√LC). The inductance L is obtained by the current path between the patch surface and ground plane through via. Besides, the capacitance C represents the gap effect between two adjacent patches (see Fig. 4b). The values of LC resonator and the frequency band gap in terms of the EBG parameters can be determined by the following formulas [[11]]:

9

Graph

10

Graph

11

Graph

where, ɛ0, μ0, WEBG, and g are the permittivity and permeability of free space, patch width and gap between unit cells respectively. Also, η is the free space impedance which is 120π.

The electromagnetic properties of the suggested AMC are analyzed based on the finite element method (FEM) for periodic arrangements. As shown in Fig. 4a, an infinite model is fulfilled with a periodic boundary condition (PBC) at the surrounding faces. For this purpose, different scan angles of incident waves (θ) are performed to recognize a wideband performance with angular stability for reflection phase (see Fig. 4a) at operating band. Moreover, the infinite model by applying Floquet port helps to determine the operational bandwidth of AMC at a given ±90° reflection phase.

According to Fig. 5, the flow chart of the design process is introduced in the different steps. It shows the comprehensive model to attain an optimum proposed design for wideband performance.

EXPERIMENTAL AND SIMULATION RESULTS

An investigation of reflection responses of the periodic AMC is discussed in this section. Also, the printed slot antenna backed by the planar AMC surface is tested to achieve low profile broadband antenna.

Infinite AMC Unit Cell with Simulation Results

The finite element method based on the Floquet theory is utilized in Ansoft High-Frequency Structure Simulator (HFSS) to simulate the AMC designs. Figure 6 plots the reflection phase of the suggested AMC by radiating the perpendicular TE/TM waves. The frequency range for reflection phases between +90° to −90° is ordinarily considered as an AMC operation bandwidth [[11]]:

2

Graph

where, fup is the frequency at which reflection phase equals –90°, flo is the frequency at which reflection phase equals +90°, and fc is the center frequency where reflection phase equals 0°.

Graph: Fig. 6. Reflection magnitude and phase of TE/TM responses of planar AMC for indirect incident waves in φ = 0° and 90°.

The simulated result of 8–12.35 GHz (43.1%) for normal TE/TM waves is provided. This AMC resonates at resonances of 10.14 GHz. As compared to the known researches [[11]], [[20]–[23]], the suggested AMC expresses the acceptable characteristics. It indicates the symmetric unit cell design with the same response for TE/TM waves, considerably broader bandwidth and tuning ability of the significant factors to gain diverse outputs for broadband application. Figure 6 plots the reflection phases of the planar AMC for diverse inclined incident waves (θ) from 0° to 60° in two polarization angles of φ = 0° and 90°. A good agreement between the outcomes of TE and TM waves is identified. Thus, it can be concluded that the planar AMC design covers X-band for wideband operation.

Measurement and Simulation Results of Printed Slot Antenna Loaded with AMC Surface

The measured and simulated S-parameters of the suggested PSA design without AMC are illustrated in Fig. 7. The PSA without AMC surface includes the measurement range of 9–11 GHz (20%) for S11 < –10 dB. As seen from Fig. 8, the suggested antenna with the planar AMC reflector indicates the –10 dB measured bandwidth of 69.6% in 6.63–13.70 GHz. It is concluded that the PSA with the 5 × 7 AMC reflector presents the bandwidth enhancement of almost 50% versus the PSA without the AMC reflector. On the other hand, the decrease in frequency leads to suitable miniaturization.

Graph: Fig. 7. Measurement and simulation results of S-parameters of the suggested PSA without AMC.

Graph: Fig. 8. Measurement and simulation results of S-parameters of the suggested PSA with planar AMC.

The total dimensions of the PSA without AMC reflector are 1.59λL, 2.25λL and 0.048λL, respectively (λL is the wavelength at the lower frequency). Whereas, the total dimensions of the PSA with the planar AMC surface are 1.171λL, 1.65λL and 0.088λL, respectively. It is clear that by utilizing AMC the operating frequency of antenna reduce to the lower frequencies and consequently, a compact antenna with the reduced size is achieved. Thus, by introducing the planar AMC reflector in the suggested PSA size reduction of 59.7% gains compared with the PSA without the AMC. As an interesting note, at the PSA with the AMC reflector a minimum impedance matching of almost –40 dB occurs over the obtained bandwidth. The suggested PSA with the AMC reflector in comparison with the PSA without AMC has excellent matching.

Figure 9 plots the surface current density on the patch of the printed antenna and AMC surfaces at various resonant frequencies. As seen from Fig. 9a at the lower resonance of 8.3 GHz of suggested design with planar AMC, a current distribution dominates on the CPW feed line and the sections of the AMC unit cells that are located under the CPW feed line. It is obtained that in Fig. 9b at the higher resonance of 12.2 GHz, the current density distributes on most unit cells of the AMC and around the tapered slots.

Graph: Fig. 9. Surface current density on the patch of the proposed antenna with planar AMC at: (a) 8.and 3 (b) 12.2 GHz.

The measurement and simulation results of radiation patterns in the xz-plane and yz-plane for the suggested PSA with the planar AMC reflector are plotted in Fig. 10. It is well found out that suitable accordance of the results is appointed. Simultaneously, the suggested design presents acceptable unidirectional radiation patterns. The maximum gain of the suggested PSA with planar AMC surface within the operational bandwidth is 8.96 dBi, as seen in Fig. 11. Thus, the gain of the structure is impressively increased over obtained impedance bandwidth compared to the antenna without AMC.

Graph: Fig. 10. Measurement and simulation results of radiation patterns of the suggested PSA with the planar AMC surface for co and cross-polarization (a) 8.3 GHz and (b) 12. 2 GHz.

Graph: Fig. 11. Simulated and measured gain of the suggested design with and without AMC surface.

The comparative behavior of the proposed design is depicted in Table 2. It well presents the remarkable features of the suggested structure which includes considerable size reduction, wider bandwidth and enhanced maximum gain. The suggested design compared with the previous research works with planar AMCs like [[31]–[34]] introduces a broader bandwidth with more size reduction and enhanced impedance matching over the operating bandwidth.

Table 2. Comparison of suggested designs with other studies

Proposed design	Bandwidth without AMC	Bandwidth with AMC and impedance matching	Size of antenna (width × length × height)	Maximum gain
Suggested PSA with planar AMC	9–11 GHz (20%)	6.63–13.70 GHz (69.6%) Minimum Matching: –40 dB	53 × 75 × 4 mm3	8.96 dBi
Bow-tie antenna with AMC in [33]	1.67–2.06 GHz	1.64–1.94 GHz (16.8%) Minimum Matching: –25 dB	50 × 70 × 25 mm3	6.5 dBi
Antenna with AMC in [34]	7.25–7.75 GHz	6.9–7.9 GHz (13.5%) Minimum Matching: –25 dB	76 × 76 × 7 mm3	13 dBi
Bowtie dipole antenna with AMC in [19]	3.1–3.9 GHz	3–4.1 GHz (31%) Minimum Matching: –30 dB	75 × 75 × 12.7 mm3	7.1 dBi
Antenna with AMC in [31]	2.06–2.89 GHz	1.83–2.72 GHz (39%) Minimum Matching: –23 dB	120 × 120 × 16 mm3	6 dBi
Antenna with AMC in [32]	5.2–6.5 GHz	4.8–6.6 GHz (32%) Minimum Matching: –23 dB	42 × 24 × 6.8 mm3	7 dBi
Antenna with EBG-MTM in [36]	9.45–9.75 GHz	8.7–11.7 GHz (29.4%), 11.9–14.6 GHz Minimum Matching: –40 dB	37 × 70 × 1.6 mm3	9.15 dBi
2 × 2 array with EBG in [37]	8.4–8.78 GHz	8–9.25 GHz (14.5%) Minimum Matching: –15 dB	96 × 96 × 1.6 mm3	7 dBi
Antenna with AMC in [20]	9.65–9.70 GHz	5.80–6.1 GHz, 8.94–9.18 GHz (3%) Minimum Matching: –21 dB	64 × 64 × 1.6 mm3	7.9 dBi
Antenna with AMC in [6]	8.25–8.45 GHz	6.98–8.57 GHz (20.4%) Minimum Matching: –31 dB	68 × 68 × 33.6 mm3	9.3 dBi

The proposed structure is considered a following design process to show an acceptable performance:

— Suggesting a wideband AMC design in 8–12.35 GHz (43.1%) for X-band operation and investigation of their properties in the infinite condition.

— Designing a broadband printed slot antenna using tapered slots fed by CPW in X-band (9–11 GHz).

— Designing a low profile printed antenna loaded with the planar AMC surface for wideband applications with improved radiation performance.

For this purpose, The suggested design compared with the previous research works with planar AMCs like [[6], [19], [29], [31]–[37]] introduces a broader bandwidth of almost 70% and a higher gain of 8.96 dBi with enhanced impedance matching over the operating bandwidth until –40 dB. For example, a proposed MIMO array in [[19]] with the size of 75 × 75 × 12.7 mm3 indicates a wide bandwidth of 3–4.1 GHz and maximum gain of 7.1 dBi. Also, a reported array with EBG in [[37]] introduces a bandwidth of 8–9.25 GHz (14.5%) with 96 × 96 × 1.6 mm3 and high gain of 7 dBi. Thus, it can be concluded that the propose design introduces a compact wideband antenna with enhanced gain for X-band operation.

CONSIDERATIONS ON AMC UNIT CELLS OF SUGGESTED DESIGN

The performance of the planar AMC surface developed in PSA is studied by applying an equivalent waveguide feed in the position of the one half-wavelength of the radiating slot element on the basis of applied method in [[35]]. Based on the reflection results of the equivalent waveguide feeding, the optimal AMC reflector is determined. In this section, a new method of determining the patch's numbers to fulfill the AMC ground plane is introduced. It contributes to reduce the radiated power from the cavity structure within the operating band. This test setup consists of a waveguide feed including dielectric with the cavity which is organized by the slot conducting plate, the antenna substrate and AMC surface. The sizes and location of the waveguide feed are selected as a λ/2 radiating slot. The proposed method is developed in the center operating frequency of 10 GHz due to the operation of the suggested PSA without AMC in X-band. In the suggested test setup, an equivalent waveguide feed is chosen with the dimensions and location as λ/2 radiating slot which corresponds to the tapered slot, according to Fig. 12. It includes a waveguide feed in proportion to the tapered radiating slot. The waveguide port is stimulated with a dominant waveguide mode to calculate the reflection responses.

Graph: Fig. 12. Equivalent waveguide feed setup with the dielectric-filled rectangular waveguide.

At the same time, to recognize the number of unit cells in the reflector, the reflection properties of four planar AMC surfaces are studied. The features of four AMC surfaces are analyzed (see Fig. 13): (a) Design#1; 4 × 7 AMC reflector, (b) Design#2; 5 × 6 AMC reflector, and (c) Design#3; 5 × 7 AMC reflector.

Graph: Fig. 13. Three different rhomboid AMC reflectors used in suggested PSA; (a) Design#1: 4 × 7 AMC surface, (b) Design#2: 5 × 6 AMC surface, (c) Design#3: 5 × 7 AMC surface (main case).

The simulated reflection coefficients S11 for the waveguide port of the equivalent waveguide feed are plotted in Fig. 14. It clearly indicates that among four suggested cases for planar AMC array surfaces, Case#3 has the maximum reflection response around the resonance of 10 GHz. Accordingly, the reflection coefficients of the Design#1 and Design#2 are almost close to each other, whereas its difference with Design#3 is significant. Therefore, Case#3 is chosen for optimal design to apply in the suggested printed slot antenna. It can be concluded that by increasing the number of patches used to the AMC array, the variations in reflection coefficients are slight over the operating bandwidth.

Graph: Fig. 14. S-parameters of the suggested design by using the suggested waveguide feeding method at 10 GHz.

The simulated S-parameters of the suggested design with different planar AMC surfaces in Fig. 13 are plotted in Fig. 15. It confirms the introduced method of the equivalent waveguide feed to recognize the optimal numbers of unit cells in the proposed structure. According to the results, the optimum Design#3 leads to wideband performance with better impedance matching.

Graph: Fig. 15. S-parameters of the suggested design for different AMC unit cells.

CONCLUSIONS

The novel design of the planar AMC unit cell is introduced to provide a broadband response, in this study to include 8–12.35 GHz (43.1%). The introduced AMC indicates distinguished properties with proper stability within the AMC bandwidth. It is verified that the planar AMC is helpful in broadband applications by investigating the reflection responses at the different polarization angles for diverse incident waves. The suggested PSA with tapered slots backed by AMC reflector introduces the low profile broadband structure for X-band operation. By adding planar AMC surface into the PSA the –10 dB impedance bandwidth of 6.63–13.70 GHz is achieved. The proper impedance matching until –40 dB, excellent compactness and broader bandwidth were obtained from the suggested PSA with AMC compared with the PSA without AMC. Besides, the uni-directional radiation patterns with a high gain are achieved. From experimental results, the acceptable efficiency is reported and it is concluded that the suggested design can be used for broadband systems. Finally, the efficiency of the AMC reflector inserted in the PSA is studied utilizing an equivalent waveguide feed in the position of the λ/2 radiating slot. In this method, to select the number of AMC patches, an equivalent waveguide feed corresponding to the center frequency is considered.

CONFLICT OF INTEREST

The authors declare that they have no conflict of interest.

1 Wang Z, Sun Y, Yang J, Zhang Y. Interferograms of Votex FWM Beam for Nonlinear Spatial Filter in Photonic Band Gap. IEEE Photonics Journal. 2019; 11: 1854 2 Roseline A. A, Malathi K, Shrivastav A. K. Enhanced performance of a patch antenna using spiral-shaped electromagnetic bandgap structures for high-speed wireless networks. IET Microw. Antennas Propag. 2011; 5: 1750. 10.1049/iet-map.2010.0627 3 Foroozesh A, Shafai L. Investigation Into the Application of Artificial Magnetic Conductors to Bandwidth Broadening, Gain Enhancement and Beam Shaping of Low Profile and Conventional Monopole Antennas. IEEE Trans. Antennas Propag. 2011; 59: 4. 10.1109/TAP.2010.2090458 4 Jam S, Malekpoor H. "Compact 1 × 4 patch antenna array by means of EBG structures with enhanced bandwidth. Microw. Opt. Technol. Lett. 2016; 58: 2983. 10.1002/mop.30197 5 Malekpoor H, Jam S. Improved radiation performance of low profile printed slot antenna using wideband planar AMC surface. IEEE Trans. Antennas Propag. 2016; 64: 4626. 10.1109/TAP.2016.2607761 6 Yang W, Wang H, Che W, Wang J. A Wideband and High-Gain Edge-Fed Patch Antenna and Array Using Artificial Magnetic Conductor Structures. IEEE Antennas Wireless Propag. Lett. 2013; 12: 769. 10.1109/LAWP.2013.2270943 7 Rajagopal S, Chennakesavan G, Subburaj D. R. P, Srinivasan R, Varadhan A. A dual polarized antenna on a novel broadband multilayer Artificial Magnetic Conductor backed surface for LTE/CDMA/GSM base station applications. AEU—Int. J. Electron. Commun. 2017; 80: 73. 10.1016/j.aeue.2017.06.028 8 Malekpoor H, Hamidkhani M. Performance Enhancement of Low-Profile Wideband Multi-Element MIMO Arrays Backed by AMC Surface for Vehicular Wireless Communications. IEEE ACCESS. 2021; 9: 166206. 10.1109/ACCESS.2021.3135447 9 Nashaat D, Elsadek H. A, Abdallah E. A, Iskander M. F, Hennawy H. M. E. Ultrawide bandwidth 2 × 2 microstrip patch array antenna using electromagnetic band-gap structure (EBG). IEEE Trans. Antennas Propag. 2011; 59: 1528. 10.1109/TAP.2011.2123052 Barth S, Iyer A. K. A Miniaturized Uniplanar Metamaterial-Based EBG for Parallel-Plate Mode Suppression. IEEE Trans. Microw. Theory Tech. 2016; 64: 1176. 10.1109/TMTT.2016.2532870 Sievenpiper D, Zhang L, Broas R. F. J, Alex'opolous N. G, Yablonovitch E. High-impedance electromagnetic surfaces with a forbidden frequency band. IEEE Trans. Microw. Theory Tech. 1999; 47: 2059. 10.1109/22.798001 Deng J. Y, Li J. Y, Zhao L, Guo L. X. A Dual-Band Inverted-F MIMO Antenna with Enhanced Isolation for WLAN Applications. IEEE Antennas Wireless Propag. Lett. 2017; 6: 2270. 10.1109/LAWP.2017.2713986 Rajagopal S, Chennakesavan G, Subburaj D. R. P, Srinivasan R, Varadhan A. A dual polarized antenna on a novel broadband multilayer Artificial Magnetic Conductor backed surface for LTE/CDMA/GSM base station applications. AEU—Int. J. Electron. Commun. 2017; 80: 73. 10.1016/j.aeue.2017.06.028 Lee H, Lee B. Compact Broadband Dual-Polarized Antenna for Indoor MIMO Wireless Communication Systems. IEEE Trans. Antennas Propag. 2016; 64: 766. 3465604. 10.1109/TAP.2015.2506201 Ameri E, Esmaeli S. H, Sedighy S. H. Wide band radar cross section reduction by thin AMC structure. AEU—Int. J. Electron. Commun. 2018; 93: 150. 10.1016/j.aeue.2018.06.007 Ghosh S, Tran T. N, Ngoc T. L. Dual-Layer EBG Based Miniaturized Multi-Element Antenna for MIMO Systems. IEEE Trans. Antennas Propag. 2014; 62: 3985. 10.1109/TAP.2014.2323410 Liu X. Y, Di Y. H, Liu H, Wu Z, Tentzeris M. M. A Planar Windmill-like Broadband Antenna Equipped with Artificial Magnetic Conductor for Off-Body Communications. IEEE Antennas Wireless Propag. Lett. 2015; 15: 64. 10.1109/LAWP.2015.2429683 Almutawa A. T, Mumcu G. Small artificial magnetic conductor backed log-periodic microstrip patch antenna. IET Microw. Antennas Propag. 2013; 7: 1137. 10.1049/iet-map.2013.0028 Zhu J, Li S, Liao S, Xue Q. Wideband Low-Profile Highly Isolated MIMO Antenna with Artificial Magnetic Conductor. IEEE Antennas Wireless Propag. Lett. 2018; 17: 458. 10.1109/LAWP.2018.2795018 Ghosh A, Kumar V, Sen G, Das S. Gain enhancement of triple-band patch antenna by using triple-band artificial magnetic conductor. IET Microw. Antennas Propag. 2018; 12: 1400. 10.1049/iet-map.2017.0815 Othman N, Samsuri N. A, Ka M. A. Rahim, and K. Kamardin, "Low specific absorption rate and gain-enhanced meandered bowtie antenna utilizing flexible dipole-like artificial magnetic conductor for medical application at 2.4 GHz. Microw Optical. Tech Lett. 2020; 62: 3881. 10.1002/mop.32507 de Cos M. E, Álvarez Y, Heras F. L. Planar artificial magnetic conductor: design and characterization setup in the RFID SHF band. IEEE Antennas Wireless Propag. Lett. 2009; 23: 1467 Hadarig R. C, de Cos M. E, Heras F. L. Novel miniaturized artificial magnetic conductor. IEEE Antennas Wireless Propag. Lett. 2013; 12: 174. 10.1109/LAWP.2013.2245093 Sun J. Y. Y, Li H. F. F. A novel planar patch antenna with dual band and diverse pattern characteristics. Microw. Opt. Tech. Lett. 2020; 62: 453. 10.1002/mop.32036 Yang X, Ge L, Wang J, Sim C. Y. D. A Differentially Driven Dual-Polarized High-Gain Planar Patch Antenna. IEEE Antennas Wireless Propag. 2018; 17: 1181. 10.1109/LAWP.2018.2837116 Xu K. D, Xu H, Liu Y, Li J, Liu Q. H. Microstrip Patch Antennas with Multiple Parasitic Patches and Shorting Vias for Bandwidth Enhancement. IEEE Access. 2018; 6: 11624. 10.1109/ACCESS.2018.2794962 Malekpoor H. Comparative investigation of reflection and band gap properties of finite periodic wideband artificial magnetic conductor surfaces for microwave circuits applications in X-band. International Journal of RF and Microwave Computer-Aided Engineering. 2019; 29: e21874. 10.1002/mmce.21874 Cook B. S, Shamim A. Flexible and compact AMC based antenna for telemedicine applications. IEEE Trans. Antennas Propag. 2013; 61: 524. 10.1109/TAP.2012.2223449 Feng D, Zhai H, Xi L, Yang S, Zhang K, Yang D. A Broadband Low-Profile Circular-Polarized Antenna on an AMC Reflector. IEEE Antennas Wireless Propag. Lett. 2017; 16: 2840 Malekpoor H, Abolmasoumi A, Hamidkhani M. High gain, high isolation, and low-profile two-element MIMO array loaded by the Giuseppe Peano AMC reflector for wireless communication systems. IET Microw. Antennas Propag. 2022; 16: 46. 10.1049/mia2.12216 Liu J, Li J. Y, Yang J. J, Qi Y. X, Xu R. AMC-Loaded Low-Profile Circularly Polarized Reconfigurable Antenna Array. IEEE Antennas Wireless Propag. Lett. 2020; 19: 1276. 10.1109/LAWP.2020.2998493 Li G, Zhai H, Li L, Liang C, Yu R, Liu S. AMC-loaded wideband base station antenna for indoor access point in MIMO system. IEEE Trans. Antennas Propag. 2015; 63: 525. 10.1109/TAP.2014.2378316 Zhong Y. W, Yang G. M, Zhong L. R. Gain enhancement of bow-tie antenna using fractal wideband artificial magnetic conductor ground. Electron. Lett. 2015; 51: 315. 10.1049/el.2014.4017 Turpin J. P, Wu Q, Werner D. H, Martin B, Bray M, Lier E. Near-zero-index metamaterial lens combined with AMC metasurface for high-directivity low-profile antennas. IEEE Trans. Antennas Propag. 2014; 62: 1928. 10.1109/TAP.2014.2302845 Joubert J, Vardaxoglou J. C, Whittow W. G, Odendaal J. W. CPW-fed cavity-backed slot radiator loaded with an AMC reflector. IEEE Trans. Antennas Propag. 2012; 60: 735. 10.1109/TAP.2011.2173152 Alibakhshikenari M, Khalily M, Virdee B. S, See C. H, Abd-Alhameed R, Falcone F, Limiti E. Mutual Coupling Suppression between Two Closely Placed Microstrip Patches Using EM-Bandgap Metamaterial Fractal Loading. IEEE Access. 2019; 7: 23606. 10.1109/ACCESS.2019.2899326 M. Alibakhshikenari, B. S. Virdee, C. H. See, R. Abd-Alhameed, A. H. Ali, F. Falcone, and E. Limiti, "Study on Isolation Improvement Between Closely Packed Patch Antenna Arrays Based on Fractal Metamaterial Electromagnetic Bandgap Structures", IET Microw, Antennas & Propag.12 (14), 2241 (2018).

By Hossein Malekpoor and Mojtaba Shahraki

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