Antenna Gain Research Articles

Miniaturized tapered‐slot ultra‐wideband Vivaldi antenna for ice sounding radar

AbstractThis paper presents a novel high‐gain, miniaturized, and ultra‐wideband tapered‐slot Vivaldi antenna (TSVA) for ice‐sounding radar applications. To miniaturize the antenna and improve the impedance matching and antenna gain of conventional TSVA, tapered slot edge, circular cavity, rectangular cavity, inner circular patch, and rectangular slit structures are newly designed and introduced. The simulation results show that the size of the designed Vivaldi antenna is reduced by 15% and increases the peak realized gain by up to 5.1 dBi, compared to the conventional Vivaldi antenna. The optimized Vivaldi antenna was fabricated and characterized for its antenna performance. The simulated results are in good agreement with the measured results.

Broadband and high gain coupled and cascaded square ring antenna for RADAR applications

Gain and bandwidth are the two primary performance characteristics of an antenna that dictate its role and utilization. In this paper, the design and fabrication details of a coupled and cascaded square ring antenna for S-band (2–4 GHz) radar communications such as navigation applications are presented. The design is employed by two square coupled rings for bandwidth enhancement and two in-phase cascaded square rings for enrichment in gain. The fabricated antenna has delivered 33% (2.52–3.52 GHz) of 10-dB bandwidth and 11.2–13.1 dBi of broadside gain. The in-phase cascading ring technique improved the antenna's gain without increasing reflector size and ring height. Thus, the proposed design is compact, with a height of 0.2λ and a total planar area of 2λ2. Moreover, the performance of the antenna is presented for variations in the geometrical parameters also.

Reconfigurable biconcave lens antenna based on plasma technology

This article is focused on the application of plasma technology for the development of microwave lens antennas with electronically controllable radiation gain. With this aim, the analytical background and design procedure for designing a biconcave lens based on plasma dielectric material are presented. The procedure is used to design a plasma lens antenna with a pyramidal horn feed. The effect of switching the designed lens ON and OFF on the radiation gain of the lens antenna is investigated. It is also shown that the plasma frequency of the lens can be used to dynamically adjust the radiation gain. A one-dimensional version of the proposed plasma lens operating at 10 GHz has been developed to validate the concept. Experimentally measured characteristics of a fabricated prototype of the lens antenna based on commercially available fluorescent lamps confirm the presented design procedure and numerical results. The results also show that changing the plasma frequency of the lens can be used to adjust the radiation gain of the proposed lens antenna.

High transmittance Huygens' metasurface with 360° phase coverage and its metalens application

Huygens' metasurfaces, as a class of artificial electromagnetic surfaces, have garnered significant interest due to their ability to effectively manipulate electromagnetic wave fronts. In this article, a Huygens' element with a simple design is discussed. The structure comprises a dielectric substrate sandwiched between a reverse-opening resonant ring and a pair of single-opening resonant rings. The proposed structure enables independent modulation of the electrical and magnetic response, particularly delivering transmittance amplitude of at least 0.8 and 0°–360° phase control simultaneously in a single double layer without vias. Based on this structure, we create a Huygens' metasurface focusing lens that gathers plane waves at the focal point. Then, a patch antenna is mounted onto this metalens to transform the radiated spherical waves into plane waves, increasing the antenna gain by up to 11 dBi. The experimental and simulated results demonstrate excellent agreement, demonstrating the usefulness of the proposed metalens and the importance of the designed Huygens-atom for metalens applications.

Design and Simulation of Microstrip Antenna Array Operating at S-band for Wireless Communication System

In this article, different design configurations of rectangular microstrip patch antenna (RMSA) array operating at S-band frequency are presented. The substrate material utilized in the designs is Rogers-RT-5800 with dielectric permittivity (Ԑr= 2.2), thickness of (h=1.6 mm), and loss tangent of (δ = 0.009). The performances of a single element, (1×2), (2×2) and (1×4) array elements operating at (3.6 GHz) are investigated using the CST and HFSS numerical techniques. The simulation results indicates that the antenna gain of (8.68, 10.35, 10.43 and 10.52) dB, VSWR (1.045, 1.325, 1.095 and 1.945), return loss (-34.91, -17.15, -27.42 and -12.26) dB, and bandwidth (85.00, 200.00, 215 and 106.4) MHz are achieved with the implementation of HFSS for advanced single element, (1×2), (2×2) and (1×4) array elements, respectively. Besides, the corresponding antenna parameter values provided by CST are, gain (7.36, 9.8, 9.87 and 10.30) dB, VSWR (1.011, 1.304, 1.305 and 1.579), return loss (-44.97, -17.58, -17.55 and -14.01) dB, and bandwidth (92.28, 204, 229.49 and 129.12) MHz, respectively. The results also reveals that the higher gain and wider bandwidth are, respectively, achieved with (1×4) and (2×2) array configuration arrangement and with both simulation techniques. Additionally, a good agreement and an advancement between the obtained results with the ones previously studied for the same array types operating at S-band frequencies are also observed.

Design and analysis of split ring resonator engraved metamaterial broadband and high gain patch antenna for THz applications

We propose a new split ring resonator engraved metamaterial MIMO patch antenna design which applies in 6–11 THz frequency band. Four different THz antennas are investigated and their results are compared to find the optimized antenna design with superstrate. The four antenna designs evolved by adding superstrate layers and metamaterials in the form of complementary split ring resonators are investigated. They are THz patch antenna (TPA), THz complementary split ring resonator patch antenna (TCPA), THz patch antenna with complementary split ring resonator superstrate (TPACS), and THz complementary split ring resonator patch antenna with complementary split ring resonator superstrate (TCPACS). The results show that the complementary split ring resonator metamaterial added in the patch as well as in the superstrate affects the antenna gain and bandwidth while the addition of the superstrate affects the multiband and gain characteristics. All four designs are optimized and show the multiband response. The TCPACS design exhibits the highest bandwidth of 900 GHz 8.88%) and the highest gain of 9.19 dB. The TCPA design is having highest bandwidth of 530 GHz (5.3%) and the highest gain of 8.05 dB. The TPACS design is having highest bandwidth of 300 GHz (3%) and the highest gain of 7.47 dB. The TPA design is having highest bandwidth of 60 GHz (0.6%) and the highest gain of 6.42 dB. The proposed antenna design with multiband, broadband, high-gain and optically transparent characteristics can be used in Terahertz Wireless Area Networks, Terahertz Wi-Fi, 6 G, Internet of Things, Sensing and Imaging applications. Availability of data and materialsThe data supporting the findings in this work are available from the corresponding author with a reasonable request.

Dual-Band Metamaterial-Based EBG Antenna for Wearable Wireless Devices

In this paper, a wearable dual-band T-shaped antenna using a coplanar waveguide (CPW) fed operating at 2.4 GHz and 5.2 GHz bands is proposed for onbody wireless communications applications. Without the metamaterial-based electromagnetic bandgap (EBG) layer, the original antenna covers two bands from 1.96 GHz to 2.77 GHz and from 5.07 GHz to 5.35 GHz. The antenna efficiency decreases when it is placed on the human arm due to the interference from the human body to the antenna, as shown by a high specific absorption rate (SAR) value. These SAR values are reduced to 77.1% at 2.4 GHz and 91.7% at 5.2 GHz by the proposed EBG. The antenna gain is therefore improved to 1.4 dBi at 2.4 GHz and 6.25 dBi at 5.2 GHz. The antenna prototype is evaluated using a Wi-Fi wearable device, resulting in an improved signal-to-noise ratio (SNR) of 6-12 dB.

Resonance Analysis and Gain Estimation Using CMA-Based Even Mode Combination Method for Flexible Wideband Antennas.

This work presents an efficient design and optimization method based on characteristic mode analysis (CMA) to predict the resonance and gain of wideband antennas made from flexible materials. Known as the even mode combination (EMC) method based on CMA, the forward gain is estimated based on the principle of summing the electric field magnitudes of the first even dominant modes of the antenna. To demonstrate its effectiveness, two compact, flexible planar monopole antennas designed on different materials and two different feeding methods are presented and analyzed. The first planar monopole is designed on Kapton polyimide substrate and fed using a coplanar waveguide to operate from 2 to 5.27 GHz (measured). On the other hand, the second antenna is designed on felt textile and fed using a microstrip line to operate from about 2.99 to 5.57 GHz (measured). Their frequencies are selected to ensure their relevance in operating across several important wireless frequency bands, such as 2.45 GHz, 3.6 GHz, 5.5 GHz, and 5.8 GHz. On the other hand, these antennas are also designed to enable competitive bandwidth and compactness relative to the recent literature. Comparison of the optimized gains and other performance parameters of both structures are in agreement with the optimized results from full wave simulations, which process is less resource-efficient and more iterative.

Capacity Analysis of Holographic MIMO Channels With Practical Constraints

Holographic Multiple-Input and Multiple-Output (MIMO) is envisioned as a promising technology to realize unprecedented spectral efficiency by integrating a large number of antennas into a compact space. Most research on holographic MIMO is based on isotropic scattering environments, and the antenna gain is assumed to be unlimited by deployment space. However, the channel might not satisfy isotropic scattering because of generalized angle distributions, and the antenna gain is limited by the array aperture in reality. In this letter, we aim to analyze the holographic MIMO channel capacity under practical angle distribution and array aperture constraints. First, we calculate the spectral density for generalized angle distributions by introducing a wavenumber domain-based method. And then, the capacity under generalized angle distributions is analyzed and two different aperture schemes are considered. Finally, numerical results show that the capacity is obviously affected by angle distribution at high signal-to-noise ratio (SNR) but hardly affected at low SNR, and the capacity will not increase infinitely with antenna density due to the array aperture constraint.

Double Band MIMO Antenna Design for WLAN, IoT and LTE Applications

This paper presents a double band multiple-input multi-output (MIMO) antenna design for UWB applications, WLAN 2.4 GHz, WiMAX 3.3 – 3.6 GHz, Internet of Things (IoT) and LTE 9/24 38/41 48/52 bands. Two circular patches form the MIMO antenna array with an “I” shaped EBG structure inserted between the patch antennas to improve the isolation between elements. The The low frequency band spectrum is from 1.03 GHz to 5.03 GHz, and the high frequency band spectrum is from 6.13 GHz to 11.62 GHz. The maximum isolation between ports at 3.8 GHz and 6.9 GHz are 7 dB and 8 dB, respectively. The antenna gain at 7 GHz reaches 4.05 dB.

Performance analysis of pixelated antennas employing shifted cross‐shaped elements

AbstractThis article presents a detailed analysis of pixelated antennas employing shifted cross‐shaped elements optimised by evolutionary algorithms. Although, the size and number of the involved pixels, as well as the overall antenna size strongly influence performance of such antennas, detailed investigations on the interplay of geometrical considerations and their influence on parameters such as gain are missing from literature. Thus, the influence of various geometrical parameters on the performance of pixelated antennas for the first time, resulting in valuable design considerations is presented in this study. A maximum cross size could be found, for which an optimisation is viable. Based on this, a dataset consisting of 400 pixelated antennas was created, for different pixel‐ and antenna sizes and investigated certain parameters such as bandwidth and antenna gain. Most notably, a directly proportional dependence from the pixel‐on the antenna size for the optimisation of electrically large antennas was found. For small antennas, this dependency begins to deviate, leading to the fact that smaller pixels are needed to successfully optimise an antenna. Furthermore, the authors find that multi‐objective optimisation is a necessity to optimise matched antennas with a defined bandwidth and gain. The antenna gain shows a dependency on the cross size for electrically small antennas. From these results, design considerations for pixelated antennas can be derived. In addition to the extensive simulations, the dataset was verified in laboratory measurements.

Broadband, Low-Profile, Planar Reflectarray Antenna Based on an Achromatic Metasurface

This paper presents a broadband, low-profile, and planar reflectarray antenna based on an achromatic metasurface. The achromatic metasurface has advantageous broadband focusing capabilities compared to conventional reflectarrays. Six types of unit cells offering versatile phase responses are employed to design an achromatic metasurface optimized by a convolutional algorithm. A broadband achromatic reflectarray antenna with a diameter of 270 mm is simulated, fabricated, and tested. The test results agree well with the simulated results. Notably, the 3-dB realized gain of the reflectarray antenna reaches a fractional bandwidth of 58.2% at a range of 8.9 GHz to 16.2 GHz. Furthermore, the reflectarray antenna significantly enhances the feeding antenna’s gain from 7.3 GHz to 17 GHz. The reflecting metasurface also has a low profile of 0.11 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> , where λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> is the wavelength in free space at 7.3 GHz. With excellent broadband performance, high gain, low profile and ease of fabrication, the developed reflectarray antenna serves as a promising device for long-distance integrated communication systems.

Integrated of proximity-coupling high-order modes patch antenna with solar cells for sustainable communication

An integration of single-layer proximity-coupling patch antenna and solar cells with bandwidth enhancement and optical energy harvesting is proposed for sustainable communication. For this purpose, many dual-function components are selected for designing the miniaturized solar cell antenna. On the one hand, by greatly affecting the current flow of the rectangular patch, vias and proximity-coupling are introduced to control the resonance modes frequency and matching, respectively, for wideband application, and the radiation performance property can be achieved by high-order mode. On the other hand, vias and proximity-coupling are beneficial to complete direct-current (DC) loop of solar cell and improve compatibility of DC-RF (radio frequency), whereas a high-order mode is beneficial to increase the area of collected light energy. To prove the working principle, fabricated and manufactured solar cell antenna. The measured and simulated results illustrate that the solar cell antenna gain is raised to as high as 9.27 dBi in 4.37 to 5.06 GHz applied to fifth generation communication (5G).

Study on microwave absorber acting as an antenna

In this study, we propose a structure that comprises both an electromagnetic wave absorber and antenna in the microwave band. The structure consists of a metallic patch layer at the top, dielectric layer in the middle, and slot layer at the bottom. The results demonstrate that the proposed structure is an electromagnetic wave absorber with a reflective property of –15 dB and an antenna gain of 4.8 dBi.

A High Gain Vivaldi Antenna with Multiple Near-Field Dielectric Lenses and Grooved Edges

In order to expand the applications of the traditional Vivaldi antenna by addressing the low gain of the traditional Vivaldi antenna, this paper combines the phase distribution of the Vivaldi antenna aperture based on the analysis of the transmission characteristics of a dielectric unit by utilizing the advantages of artificial electromagnetic material. A more reasonable method of loading a dielectric lens is proposed and utilized in combination with edge grooving. A comparison of the results shows that the antenna operates in the frequency range of 4 to 16 GHz. The low-frequency boost is approximately 3 dB, and the high-frequency boost is approximately 9.6 dB.

Metamaterial-Based LTCC Compressed Luneburg Lens Antenna at 60 GHz for Wireless Communications

In this study, a metamaterial-based LTCC compressed Luneburg lens was designed, manufactured and measured. The lens was designed at 60 GHz to utilize the unlicensed mm-wave spectrum available for short-range high-capacity wireless communication networks. The transformation optics method was applied to ensure the compression of the Luneburg lens antenna and thus maintain a low-profile structure. The two different types of unit cells for low and high permittivity regions were considered. The parametric study of the effect of compression on lens performance was presented. The antenna is implemented with a standard high-permittivity LTCC process, and details of the manufacturing process for the metamaterial lens are discussed. The low-profile lens is thinner than 2 mm and measures 19 mm in diameter. A size reduction of 63.6% in comparison with a spherical lens was achieved. The near-field to far-field mm-wave measurement technique is presented, and the measurement results show a peak antenna gain of 16 dBi at 60 GHz and a beam-scanning capacity with 1 dB scan loss within a 50° field of view.

High gain and enhanced isolation MIMO antenna with FSS and metasurface

This research work proposes a high gain MIMO antenna with improved isolation. The present antenna is low profile and contains four elements built with FR-4 substrate. This antenna uses a superstrate based metasurface to reduce the coupling between antenna elements and frequency selective surface (FSS) to improve the antenna gain. The suggested antenna is topped with a superstrate-based metasurface, which is positioned at a height of 15 mm below the antenna. FSS structure consists of a concentric circular ring on a single-layered FR4 substrate. The present MIMO antenna has operating band of 1.18–2.89 GHz with a peak gain of 8.44 dBi and isolation of less than − 20 dB between each antenna element. This MIMO antenna provides maximum efficiency of 96% and 92.3% reduction in the correlation coefficient. Additionally, the current structure offers a diversity gain (DG) of 9.99 and an envelope correlation coefficient (ECC) of 0.01.

A novel wideband dielectric resonator antenna with compact size

ABSTRACT In this paper, a wideband dielectric resonator antenna with compact size is presented. The proposed antenna is formed by four dielectrics. Non-adjacent dielectrics have same permittivity constant. A 50-ohm micro strip feed line is used to exciting the antenna through the coupling slot. By optimizing the dimensions and structure of the antenna, impedance bandwidth of 3.25 to 4.4 GHz is obtained. Impedance bandwidth of the proposed antenna is a very wide bandwidth compared to the previous dielectric antennas. The antenna gain is about 9.6 dB.

Reconfigurable CRLH‐inspired antenna based on Hilbert curve EBG structure for modern wireless systems

AbstractThis paper presents a novel antenna design with an enhanced gain‐bandwidth product for modern communication networks, including 5G systems. The design is consistent with 17 unit cells of a composite right/left‐hand (CRLH) structure with an electromagnetic band gap of Hilbert inclusions. Therefore, the resulting design occupies an area of 40 × 200 mm2 of a Taconic RF‐43 substrate. The maximum antenna gain is 16 dBi at 5.5 GHz, which is very applicable for long‐range communication systems. Nevertheless, the antenna performance is controlled with optical switches of light‐dependent resistors (LDR) technology. Therefore, the antenna performance is tested with different switching seniors to investigate the possibility of reconfiguration scenarios at various frequency bands. However, the antenna gain is highly affected by changing LDR switching status; for example, at 5.5 GHz, the antenna gain is varied between 7 and 16 dBi. Thus, the proposed antenna is an excellent candidate for direct amplitude modulation. Finally, the antenna simulation results and measurements agree very well with each other.

Multifunctional twelve port frequency agile diversity antenna for indoor wireless applications

The recent resurgence of new-generation reconfigurable technologies delivers a plethora of various applications in all public, private and enterprise solutions over the globe. In this paper, a frequency reconfigurable polarization and pattern diverse Multiple-Input-Multiple-Output (MIMO) antenna is presented for indoor scenarios. The MIMO antenna is comprised of twelve radiating elements, and polarization and pattern diversity is obtained by arranging them in three different planes: Horizontal Plane (HP), Vertical Plane-I (VP-I), and Vertical Plane-II (VP-II). The proposed antenna operates in mode I (wideband) and mode II (multiband), by combining two different radiators using PIN diodes. The antenna dynamically switches between Mode I (wideband) and mode II (multiband). Mode, I cover the ultra-wideband (UWB) range from 2.3 to 12 GHz, while mode II covers GSM (1.85–1.9 GHz), Wi-Fi and LTE-7 (2.419–2.96 GHz), 5G (3.15–3.28 GHz and 3.45–3.57 GHz), public safety WLAN (4.817–4.94 GHz), and WLAN (5.11–5.4 GHz) frequency bands. The peak gain and efficiency of the MIMO antenna are 5.2 dBi and 80%, respectively.