Antenna Unit Cell Research Articles

Design and analysis of SRR based metamaterial loaded circular patch multiband antenna for satellite applications

Satellite communication has reached a turning point in transmitting data quickly and receiving signals clearly in faraway places. This paper presents a metamaterial-based antenna for distant and military applications that overcomes restrictions and performs unmatched. This project explores metamaterials to create a unique antenna. Expect to be astounded by its power to bend electromagnetic waves, miniaturize, and change our relationship with the universe. The feeding mechanism of this antenna is a modified co-planar waveguide. At 5.6 GHz, the proposed antenna unit cell measures 0.076λ0×0.2λ0, making it small thanks to its MTM characteristic. CP radiation is made when two orthogonally polarized modes are stimulated at the same time and two composite right- and left-handed transmission line unit cells are placed orthogonally. Reduced size, increased bandwidth, and improved Learn how this discovery opens new doors for high-resolution photography, broadband internet, and space exploration. One nanostructure that makes up a metamaterial is the Split Ring Resonator (SRR). SRR dimensions must be smaller than the resonance wavelength, making them crucial for near-infrared and optical responses. This effort examined nanoscale SRR characteristics in the infrared and visible ranges. SRRs composed of aluminum (Al) and gold (Au) were produced on silicon and silica substrates using electron beam lithography (EBL). The proposed structure consists of a microstrip-line-supplied SRR, a parasitic patch that is perpendicular to the ground plane, and two via holes connected by two split rings that feed the patch indirectly. Choosing the right material parameter for all such antennas depends on the planned structure. Fabrication and testing of the antenna matched simulations. Dimensions: 23.7 mm × 16.2 mm × 1.6 mm; substrate dielectric constant: 4.4. Experimental data are detailed and compared to analytical calculations. Simulation results show that metamaterials have negative permittivity and permeability in a certain frequency range, which can be predicted by an analytical method. Simulations indicated eight BRS, WiMAX, radar, and mobile phone resonance frequencies. Radiation is dipole-like in the omnidirectional in the H-plane and E-plane. 10 dB return loss and 3 dB axial ratio bandwidths are 38.6.7% and 8.1%, respectively.

Design and analysis of ultra-wideband microstrip patch antenna with various conductive materials for terahertz gap

The paper explores the design and analysis of a wideband microstrip patch antenna with a metallic patch and a 3 × 3 split ring resonator (SRR) array operating in the 0.1–5 THz frequency range. The antenna's structure incorporates different conductive materials such as gold, silver, and graphene as a metallic patch. The dimensions of the metallic patch and SRR are calculated to achieve wideband operation within the desired THz range. The SRR array enhances electromagnetic resonance, thereby improving bandwidth and radiation characteristics for medical imaging. The study discusses the equivalent circuit and design equations for the microstrip patch antenna and SRR unit cell. For designing and analyzing the proposed antenna, CST Microwave Studio 2019 software have been used. Performance parameters such as return loss, bandwidth, gain, efficiency, directivity, VSWR, and radiation pattern have been evaluated. The advantages and limitations of each conductive material are evaluated to determine their suitability for THz-based medical imaging applications. The goal is to maximize the antenna's bandwidth, gain, and image resolution for medical imaging purposes. The findings highlight the performance characteristics of gold, silver, and graphene as conductive materials for medical imaging applications, facilitating the development of high-resolution, non-invasive imaging systems with improved diagnostic capabilities.

Split ring resonator geometry inspired crossed flower shaped fractal antenna for satellite and 5G communication applications

This work suggests a fractal antenna in the shape of a crossed flower with a split ring resonator geometry. This suggested antenna serves the Sub-6 GHz 5G and satellite repeater applications for wireless devices operating in the frequency range of 4.01–4.82 and 7.6–7.94 GHz, respectively. The suggested antenna's performance parameters have been empirically confirmed by creating a printed prototype. The antenna geometry is based on a lower-cost FR4 substrate and consists of a mix of crossed floral square-shaped split-ring resonators organized in a Minkowski fractal configuration. A thorough examination of both manufactured and simulated antennas is conducted to demonstrate the uniqueness and edge over traditional dual-band antennas. The suggested fractal antenna's overall physical dimensions measure 0.90λ x 0.96λ at a lower resonant frequency. The response of the unit cell antenna is recorded when Split Ring Resonators are grouped in a fractal antenna with a flower shape. The measured findings verify that the proposed and constructed antenna has an electrical impedance bandwidth of −10 dB at lower frequency band (18.80 %, 4.01–4.82 GHz) and upper frequency band (4.41 %, 7.6–7.94 GHz) of −10 dB. The simulated and fabricated prototypes exhibit good agreement with respect to the stable gain and radiation patterns. Because of its consistent radiation efficiency in the realized resonating bands, the suggested prototype is a strong contender for 5G Sub-6 GHz and X band satellite applications.

응답시간이 개선된 액정 기반 능동 반사 배열 안테나 단위 셀 구조

This paper presents a unit cell structure for liquid crystal (LC)-based reconfigurable reflective arrays, aimed at improving the imbalance in response time. Conventional LC-based reflectarray antenna unit cells, which have been widely used as high-gain beam-steerable antennas, have an imbalance in response time because of different alignment of LC molecules during the rise and decay times. By separating the metal layers in contact with the LC layer and applying four bias voltages, we generated both horizontal and vertical electric field. Accordingly, the decay time was improved by unifying the methods in which the LC molecules were aligned during the rise and decay times. Our measurements confirm that the decay time can be reduced to approximately 1/3 compared to the conventional structure, indicating the possibility of resolving the imbalance.

Printed leaky‐wave antenna with stable gain and reduced cross polarization

AbstractA printed leaky‐wave antenna with stable gain and reduced cross‐polarization level is presented in this letter. The proposed antenna has the property of continuous backward‐to‐forward beam scanning with symmetrical scanning. The proposed antenna's unit cell consists of two unequal inclined stubs connected to a microstrip line. The angle between the stubs and their dimensions is designed optimally to obtain improved antenna performance. The antenna provides stable gain with peak gain 14.4 dBi and gain variation 2.55 dBi in the operating band 9.5–15 GHz. The maximum value of cross‐polarization level along the main beam is −30 dB. The design gives a scanning angle of 73° from −36° to +37° through broadside. Another important feature of the proposed antenna is that there is no gain reduction at the broadside radiation.

Metamaterial-Based Compact Antenna with Defected Ground Structure for 5G and Beyond

In this paper, a unit cell of a single-negative metamaterial structure loaded with a meander line and defected ground structure (DGS) is investigated as the principle radiating element of an antenna. The unit cell antenna causes even or odd mode resonances similar to the unit cell structure depending on the orientation of the microstrip feed used to excite the unit cell. However, the orientation which gives low-frequency resonance is considered here. The unit cell antenna is then loaded with a meander line which is parallel to the split bearing side and connects the other two sides orthogonal to the split bearing side. This modified structure excites another mode of resonance at high frequency when a meander line defect is loaded on the metallic ground plane. Specific parameters of the meander line structure, the DGS shape, and the unit cell are optimized to place these two resonances at different frequencies with proper frequency intervals to enhance the bandwidth. Finally, the feed is placed in an offset position for better impedance matching without affecting the bandwidth The compact dimension of the antenna is 0.25 λL × 0.23 λL × 0.02 λL, where λL is the free space wavelength with respect to the center frequency of the impedance bandwidth. The proposed antenna is fabricated and measured. Experimental results reveal that the modified design gives monopole like radiation patterns which achieves a fractional operating bandwidth of 26.6%, from 3.26 to 4.26 GHz for |S11|

Design and Performance Analysis of a Compact Quad-Element UWB MIMO Antenna for Automotive Communications

This paper presents the design and analysis of a planar ultra-wideband (UWB) multiple-input-multiple-output (MIMO) antenna for modern vehicular communication systems. The proposed unit cell antenna structure was designed using modified elliptical radiators on a Rogers RO3003 substrate, has a size of 22 × 22 × 0.76 mm3, and covers an impedance bandwidth (S11 ≤ −10 dB) of 3.14 GHz to 12.24 GHz. The peak gain and efficiency of the unit cell prototype are 5.1 dBi and 81%, respectively. The unit cell was further developed into a MIMO antenna configuration with four elements placed orthogonal to each other in a single plane measuring 50 × 50 × 0.76 mm3. The measured isolation between the antenna elements was greater than 20 dB. The measured envelope correlation coefficient (ECC) of the MIMO antenna was less than 0.004, the diversity gain (DG) was greater than 9.67 dB, the total active reflection coefficient (TARC) was <−10 dB, and the mean effective gain (MEG) ratio was > 0.99. The characteristics of the proposed unit cell and the MIMO antenna were investigated for housing effects in order to validate the consistent performance of the antenna in the presence of conducting bodies. In addition, the radiation characteristics of the antenna when mounted on a vehicle were analyzed using a virtual model of the car. The results show that the proposed quad-element UWB MIMO array is compact, has good performance, and is well-suited for automotive applications.

Angularly stable frequency selective surface for the gain enhancement of isolated multiple input multiple output antenna

AbstractA metasurface is highly useful for improving the performance of patch antennas and reducing their size due to their inherent and unique electromagnetic properties. In this research work, we design a wideband bandstop reflector‐based frequency selective surface (FSS). It consists of a periodic array of circular shape metallic rings with four stubs. The FSS unit cell resonates over a frequency band from 7.2 to 9.2 GHz and has excellent stability under different polarizations and incident angles. A microstrip patch‐based isolated multiple input multiple output (MIMO) antenna is designed that operates over a frequency band of 7.9GHz to 8.7 GHz. The MIMO antenna and FSS are printed on the one face of a substrate. The radiation performance such as gain and directivity of the antenna is improved due to parasitic radiation of the surface and coherent‐ superposition of energy in the far‐field, between the antenna and FSS unit cells. Where the other parameters such are efficiency, radiation pattern and isolation are well preserved. The designed structure shows low complexity during fabrication. The simulated and experimental results confirm the predicted antenna performance and gain enhancement.

An Equivalent-Circuit Topology for Lossy Non-Symmetric Reciprocal Two-Ports

An equivalent-circuit topology for two-port lossy non-symmetric reciprocal networks is proposed. The circuit topology is based on the eigenstate decomposition. The proposed circuit consists of two immittances and two transformers with a single complex turns ratio, all obtained from the eigenvalues and eigenvectors of the admittance or impedance matrix of the network in a straightforward way. The interconnection of the circuit elements is simple and compact, and the real parts of its immittances are always positive. To verify its behavior, the equivalent circuit of two different leaky-wave antenna unit cells is extracted: a series-fed coupled patch radiating element, and the complementary strip-slot. Simulated and measured data are provided for the study cases, highlighting the satisfactory behavior of the equivalent circuit over a very broad bandwidth. A simple asymmetry model is also proposed that can be used advantageously in the analysis and design of non-symmetric two-ports, like unit cells of leaky-wave antennas.

Design of a transmissive metasurface antenna using deep neural networks

This article presents design methods for a transmissive metasurface antenna composed of four layers of meta-structures based on the deep neural network (DNN). Owing to the structural complexity as well as side effects such as couplings among the adjacent meta-structures, the conventional design of metasurface unit cell strongly relies on the researcher’s intuition as well as time-consuming iterative simulations. A design method for a metasurface antenna unit cell with a size of a quarter wavelength operating at a frequency of 5.8GHz is presented. We describe two unique implementations for designing the target metasurfaces: 1) utilizing the inverse network 2) data augmentation by the forward network and a random search algorithm. With the usage of the two DNNs, the average transmittance of the unit cells is improved by about 0.024 than that of the unit cells designed by the conventional approach. This research invokes the application of DNN in designing antennas and other structures operating at radio frequency.

Scalable Planar Active Array Antenna Integrated With Distributed Amplifying Transistors for High-Power Applications

A scalable planar 2-D active array antenna configuration that can realize amplified radiation through co-existing active devices is proposed, studied, and demonstrated in this work. The input and output of these amplifying active devices are directly integrated with the feed network and array elements, respectively, thereby eliminating the matching networks typically required in an amplifier circuit. A comprehensive analysis of the rectangular patch antenna (RPA) performance with different feeding techniques is initially analyzed and the choice of nonradiating edge feed RPA as array elements is justified for not only realizing the maximum radiation efficiency but also facilitating the direct active device integration. Subsequently, a physical arrangement of these array elements is devised to reduce cross-polarization. The design of 4×2 active array antenna unit cell operating at 5.8 GHz is then discussed through extensive analysis of active devices, optimization procedure, potential excitation signal control, and influence of faulty transistors. From simulations, this active array scheme has realized a higher matching bandwidth and exhibited an amplifier gain of around 13.6 dB, compared with its passive counterpart. Eventually, these unit cells are integrated through an equal power hybrid feed network for realizing an 8×8 active array antenna configuration that is fabricated and measured. The measured results of the experimental prototype match reasonably well with the simulation results, thereby confirming the proposed integration technique. The resulting paralleled configuration promises efficient handling of greater powers, making them suitable for high-power applications.

Compact four port slot based MIMO antenna with isolation enhancement

ABSTRACT This paper presents the design of a compact arc shape slot antenna and its application in multiple inputs and multiple-output (MIMO) communications. The unit cell antenna has a footprint of 15 × 15 mm2. The antenna with arc shape stub loaded feedline provides broadband impedance matching extending from 3 GHz– 9.5 GHz. The antenna is made dual-polarised using orthogonal feed structure. A four-port, two-element MIMO antenna is constructed by replicating the unit cell design in a parallel fashion. Broadband isolation enhancement is achieved by using a modulated microstrip line embedded with circular patches of varying diameters. The four-port MIMO antenna provides 10 dB additional enhancement in comparison with the unmodulated microstrip line decoupling unit cell. The prototype antenna is fabricated and the simulation results are verified using experimental measurements. The antenna offers an average peak gain of 5.2 dBi and efficiency greater than 75%. The MIMO parameters such as envelope correlation coefficient, diversity gain, mean effective gain are evaluated and presented. The proposed antenna is one of the most compact 4 port solution reported in the literature.

Compact symmetrical slot coupled linearly polarized two/four/eight element MIMO bowtie DRA for WLAN applications

This paper presents a compact and low cost MIMO (Multiple-Input-Multiple-Output) Bowtie dielectric resonator antennas for two, four and eight elements for public safety entities (4.94–4.99 GHz) and indoor WLAN (5.15–5.35 GHz) applications. The fractional impedance bandwidth (4.72 GHz – 5.44 GHz) is 14.17% for all ports and strengthens the targeted frequency range gain. Two bubbled I-shape embedded inside the rectangular box defective ground structure to enhance the separation between ports by etching therefore over the operating frequency band, isolation between ports exceeds 25 dB and maximum ECC (envelope correlation coefficient) of 0.04. The designed compact unit cell antenna has a dimension of 30 × 25.6 mm2 (i.e. 0.5λ0 × 0.4 λ0 where λ0 is calculated at 5.2 GHz in the free space) and finally proposed 8-element antenna having a size of only 120 × 51.2 mm2 (2.07 λ0 × 0.88 λ0). Within their finest values, MIMO diversity performance parameters are obtained. The gain of the antenna unit cell, two, four and eight elements are 5.24 dBi, 5.49 dBi, 5.68 dBi and 6.2 dBi respectively and these gain values are most suitable for WLAN applications. To show the simulated performance, a prototype of all radiators would be manufactured and tested experimentally and measured results are good agreement with simulation result.

Novel twelve port eight element UWB‐MIMO antenna

AbstractThis article presents the design of a highly integrated twelve port ultra‐wideband (UWB) antenna array for multiple‐input multiple‐output (MIMO) communications. The proposed array consists of a unit cell element constructed using a circular arc structure excited by a simple microstrip line feed terminated by an arc‐like stub. The proposed unit cell antenna covers 3–9 GHz covering most of the third, fourth, and fifth generation communication frequencies. The 3D antenna array has an overall board size of 33 × 33 × 15 mm3 consisting of one horizontal board and two vertical boards. The vertical boards are interlocked and are directly positioned above the horizontal boards. Four antennas with dual feed excitation are deployed on the horizontal board while each vertical board is printed with two elements with single port excitation. Thus, a highly integrated twelve port antenna is realized with isolation better than 15 dB between each port. The prototype antenna offers both polarization and pattern diversity leading to enhanced MIMO performance.

Electromagnetic Response Prediction of Reflectarray Antenna Elements Based on Support Vector Regression

In this letter, support vector regression (SVR) is used to predict the electromagnetic (EM) response of a complex shaped reflectarray (RA) unit cell. The calculation of the scattering coefficients of passive RA elements with periodic intervals is firstly transformed into a regression estimation problem, and then an analysis model is established by SVR to quickly predict the EM response of the unit cells. To this end, the full-wave (FW) simulation software is used to obtain a set of random samples of the scattering coefficient matrix of the RA antenna unit cell, which is used for SVR training. Under the same conditions, the radial basis function network (RBFN) is also used to predict the EM response of the elements, and the comparison results show the effectiveness and accuracy of the proposed method.

Accurate Characterization of Graphene Reconfigurable Reflectarray Antenna Element by SVR

The analysis of the graphene reconfigurable reflectarray antenna electromagnetic (EM) response through the use of support vector regression (SVR) has been carried out in this paper. The EM response of the original graphene reflectarray antenna is transformed into a regression estimation problem by SVR. In this work, we consider up to 6 degrees of freedom: the width W and length L of the graphene patch, the graphene chemical potential μ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> , the working frequency f, and the elevation θ and azimuth angles φ of the incident field. Firstly, they are discretized separately, and then full-wave (FW) simulation software is used to calculate the reflectarray antenna unit cell under different parameters to obtain the training data set of SVR. Finally, SVR is used to obtain an alternative model of the graphene reconfigurable reflectarray antenna unit cell, which is used to quickly predict the scattering coefficient matrix in co-polarized and cross-polarized states. Through the comparison of SVR method with the radial basis function network (RBFN) and FW simulation results, the effectiveness of the proposed method in precision and efficiency is verified.

Grating Lobe Mitigation in Series-Fed Patch Periodic Leaky-Wave Antenna Using Parasitic Monopoles

It is shown that the grating lobes issue of periodic leaky-wave antennas (P-LWAs) can be mitigated using parasitic monopoles placed between the antenna's unit cells. Due to the periodicity nature of P-LWAs, infinite number of space harmonics are excited, but only one space harmonic should radiate to achieve single-beam radiation. As the beam scans to the forward direction, a second space harmonic starts to radiate creating a double beam, a main beam and a grating lobe in opposite directions. Here, we present a simple and low-cost technique to overcome the grating-lobe issue in series-fed patch (SFP) P-LWA by inserting parasitic monopoles at each unit cell to reduce its radiation in the grating lobe direction, while maintaining the main beam. Moreover, the concept of parasitic monopoles and their effect on the radiation pattern of the unit cell is addressed and later validated by full-wave simulation and measurement results for an SFP P-LWA broadside frequency at 6.1 GHz. The results show that the grating lobes are reduced by about 10 dB and therefore, the scanning range is extended in the forward direction from 15° for the conventional SFP P-LWA to 29° for the proposed SFP P-LWA with parasitic monopoles.

Design of a broadband single-layer reflectarray antenna using double hexagonal rings and a hexapole

This paper proposes a novel subwavelength single-layer reflectarray antenna unit cell operating in X-band, composed of double hexagonal rings and a hexapole. This new cell is not sensitive to TE and TM polarizations. Infinite array approach has been used to determine the reflection phase curve. The proposed element has more than 575° linear phase range in 8.5–11 GHz frequency band by varying the radius of the outer ring. The scattering parameters of an infinite reflectarray using the proposed element are measured by the waveguide simulator which takes into account the effects of the mutual coupling. A 277-element center-fed reflectarray antenna using this cell is designed, fabricated and measured to verify the broadband property of the proposed element. The measurement results show about 27.5% 3-dB gain bandwidth and 22.8 dB maximum gain at 10 GHz, which is equivalent to about 32% aperture efficiency.

Compact four-port vertically polarized UWB monopole antenna for MIMO communications

PurposeThis paper aims to present the design of a compact vertically polarized four-element UWB antenna suitable for MIMO communications.Design/methodology/approachThe unit cell antenna is constructed using a square ring radiator excited through a stepped impedance feed. The proposed antenna covers the Ultra-wideband (UWB) spectrum ranging from 2.2 to 12.3 GHz. The isolation between the unit cell antennas in the array is enhanced using a simple microstrip line resonator. The decoupling element is connected to the ground through a via.FindingsThe proposed scheme offers at least 16 dB improvement in the port-to-port coupling. Furthermore, the four-element antenna array is constructed using a specific interlocking scheme. The proposed antenna array’s Multiple Input Multiple Output (MIMO) performance metrics are analyzed.Originality/valueBy suitably selecting the excitation port, directional radiation patterns can be realized. The combined radiation pattern covers 360 degrees. A prototype antenna array is fabricated, and the simulation results are verified using real-time experiments. The proposed antenna is a suitable candidate for shark fin housing in automotive communications.

Low-Cost CMOS Active Array Solution for Highly Dense X-Band Weather Radar Network

This article presents the development of a CMOS active array antenna unit cell as a potential solution for a highly dense, low-altitude short-coverage phased array $X$ -band radar network system. The antenna uses a cross-patch differential feed structure designed in a stacked configuration for bandwidth and cross-polarization enhancement. To overcome the limitations of current CMOS RF performance, a mirroring technique was applied at the element and subarray level. A 16-element array ($4\times 4$ elements), integrated with CMOS T/R modules in a tileable architecture, was developed and characterized. Measured results demonstrate that this proposed array offers cross-polarization levels less than -32 dB across the scanning range of ±45° in the principal planes for dual-polarized alternate transmit and alternate receive (ATAR) phased array weather radar.