Resonant Frequency Of Antenna Research Articles

Strain-invariant stretchable radio-frequency electronics.

Wireless modules that provide telecommunications and power-harvesting capabilities enabled by radio-frequency (RF) electronics are vital components of skin-interfaced stretchable electronics1-7. However, recent studies on stretchable RF components have demonstrated that substantial changes in electrical properties, such as a shift in the antenna resonance frequency, occur even under relatively low elastic strains8-15. Such changes lead directly to greatly reduced wireless signal strength or power-transfer efficiency in stretchable systems, particularly in physically dynamic environments such as the surface of the skin. Here we present strain-invariant stretchable RF electronics capable of completely maintaining the original RF properties under various elastic strains using a 'dielectro-elastic' material as the substrate. Dielectro-elastic materials have physically tunable dielectric properties that effectively avert frequency shifts arising in interfacing RF electronics. Compared with conventional stretchable substrate materials, our material has superior electrical, mechanical and thermal properties that are suitable for high-performance stretchable RF electronics. In this paper, we describe the materials, fabrication and design strategies that serve as the foundation for enabling the strain-invariant behaviour of key RF components based on experimental and computational studies. Finally, we present a set of skin-interfaced wireless healthcare monitors based on strain-invariant stretchable RF electronics with a wireless operational distance of up to 30 m under strain.

RBFNN-based UWB 4×4 MIMO Antenna Design with Compact Size, High Isolation, and Improved Diversity Performance for Millimeter-Wave 5G Applications

Abstract The millimeter-wave spectrum has emerged as a compelling solution to address the pressing need for high-datarate
capabilities in the development of 5G technology systems. Spanning between 20 GHz and 40 GHz, this spectrum
encompasses several prominent frequency bands crucial for advancing 5G applications. In light of this, our study
presents a thorough investigation into the design and performance of a compact cross-shaped slot broadband antenna,
complemented by a 4×4 Multiple-InputMultiple-Output (MIMO) configuration tailored for 5G operations at
28 GHz. The primary objective of this study is to develop an antenna system capable of achieving an extended bandwidth
ranging from 20 GHz to 40 GHz, effectively covering the crucial frequency bands essential for 5G millimeterwave(
mmWave) operations. To accomplish this, the optimization of antenna performance is meticulously carried out
using the Radial Basis FunctionNeuralNetworks (RBFNN) model. The RBFNNmodel serves as a robust tool for establishing
the intricate relationship between antenna dimensions, resonant frequency, and bandwidth. Subsequently,
the developed RBFNN model is employed to predict optimal antenna dimensions, ensuring resonance at 28 GHz and
meeting specified bandwidth targets. The single antenna is designed with a rectangular patch and a cross-shaped
slot and is constructed on the low loss Rogers RT Duroid 5880 substrate. This design reaches an outstanding bandwidth
of 19.5 GHz, and exhibits excellent radiation characteristics, with a high radiation efficiency of up to 99% and a
corresponding gain of 5.75 dB. The antenna’s design and performance are rigorously designed using HFSS software,
which is then compared to the results acquired using CST software. In addition, the proposed MIMO configuration
offers excellent performance in terms of key features such as small size (16 × 16.2 mm2), very wide bandwidth of 20
GHz, good gain of 6.75 high isolation exceeding 35 dB, and significant improvements in diversity performance measures
such as Envelope Correlation Coefficient (ECC), Diversity Gain (DG), Channel Capacity Loss (CCL), Total Active
Reflection Coefficient (TARC), and Mean Effective Gain (MEG). The potential of the proposed MIMO configuration
for high-speed applications is particularly remarkable. Practical verification of the MIMO configuration is carefully
carried out by fabrication andmeasurement. Experimental results strongly confirmthe effectiveness of the proposed
antenna design, establishing it as a competitive challenger for 5G technology.

A miniaturized passive wireless patch antenna sensor for structural crack sensing

This paper presents a miniaturized patch antenna sensor for structural crack sensing, and the patch antenna sensor can be interrogated wirelessly. The proposed patch antenna sensor can detect the expansion of structural crack through relative movement between antenna components, and the relationships between the antenna resonant frequency and the crack width were studied. By using Rogers RO3010 laminate with high dielectric constant as the dielectric substrate of the antenna, the size of the proposed antenna sensor is significantly reduced, and higher sensing sensitivity is achieved. Furthermore, the wireless interrogation methods of the patch antenna sensor were also studied. The resonant frequency of the patch antenna sensor was wirelessly interrogated using linearly polarized wide-band antennas. Compared with the previous patch antenna sensor, the overall area of the proposed antenna sensor has been reduced to 33.4%, and the miniaturized patch antenna sensor shows a sensing sensitivity of 116.1 MHz/mm, which is 2.6 times higher than the previous patch antenna sensor. A series of simulations and experiments have demonstrated the feasibility of the proposed patch antenna sensor for structural crack sensing and the effectiveness of wireless interrogation methods.

Bolt loosening detection method based on double-layer slotted circular patch antenna

An innovative bolt loosening detection method based on double-layer slotted circular patch antenna is proposed. By integrating the patch antenna with the bolt, the longitudinal length variation of the bolt can be transformed into a change in the air gap thickness of the antenna and cause the resonant frequency to vary. Thus, we can detect the bolt loosening through the resonant frequency shift of the double-layer circular patch antenna. Furthermore, the circular radiation patch of the antenna is slotted to increase the effective length of current flow, thus achieving the miniaturization of the antenna sensor for bolt loosening detection. The proposed double-layer slotted circular patch antenna sensor can be as small as a coin with a high sensing sensitivity of 626.57 MHz/mm, and it can be interrogated either wired or wirelessly. A series of simulations and experimental tests demonstrate the feasibility and effectiveness of the proposed antenna sensor for bolt loosening detection. The experimental results show that the relationship between the bolt preload and the antenna resonant frequency is relatively linear, and the resonant frequency of the antenna shifts 18 MHz for an M24 bolt from completely loosened to fully fastened.

Simultaneous crack and temperature sensing with passive patch antenna

This article presents a novel passive patch antenna sensor for simultaneous crack and temperature sensing, and the antenna sensor has the ability of temperature self-compensation. The passive patch antenna sensor consists of an underlying patch and an overlapping sub-patch. The off-center feeding activates resonant modes in both transverse and longitudinal directions. The resonant frequency shift in transverse direction is used for environmental temperature sensing, while the structural crack width can be sensed by the longitudinal resonant frequency shift after temperature compensation. Furthermore, the unstressed design of the antenna can also eliminate the issue of incomplete strain transfer ratios. In this article, the relationships between the antenna resonant frequencies, the environmental temperature, and the structural crack width were studied. Simulations were conducted to determine the optimal off-center fed distance of the patch antenna sensor. Furthermore, a series of experimental tests were also conducted, where the passive patch antenna was fabricated and installed on the concrete components as well as an actual building. Continuous monitoring was performed for several days to test the temperature sensing ability of the passive patch antenna, and the sensed crack width after temperature compensation was compared with the actual results. The results of these experiments demonstrate the feasibility of using the passive patch antenna for simultaneous temperature and crack sensing.

Substrate effect and structure optimization of fabric-based circularly polarized dipole antenna for radio frequency energy harvesting

Radio frequency energy harvesting on textiles is seen as a method of enabling sustainable battery-free operation for wearable devices, while few works have clarified the influence of fabric properties on antenna performance. To prepare successfully a fabric-based circularly polarized antenna for radio frequency energy harvesting, this paper will clarify the effect of key fabric characteristics (such as dielectric properties and fabric thickness) on antenna performance by a finite element simulation. The simulated results showed the antenna resonant frequency is inversely proportional to the half square of the fabric’s dielectric constant, and the antenna radiation efficiency and gain are inversely proportional to the square of its dielectric loss tangent and thickness. Then, for the typical fabric substrates, the structure parameters of the existing circularly polarized antenna are optimized to work in the expected working frequency band, and the dominating structure parameter of the antenna in performance was identified. The optimized antenna prototype has excellent performance. The antenna has a bandwidth of 350 MHz and a maximum transmission distance of 190 cm. The received signal strength indication per unit area is 2.35 mW/cm2 and the output voltage is 1.19 mV/cm2 at a distance of 100 cm. It is concluded that the flexible size-minimized wide bandwidth circularly polarized radio frequency energy harvesting antenna screen-printed on fabric was derived from a commercial circularly polarized antenna with fiber-reinforced epoxy plate (FR4) substrate, and the critical geometrical and material parameters of the fabric substrate for this antenna performance as well as the affecting mechanism were identified.

ISM Band 2.4 GHz Wearable Textile Antenna for Glucose Level Monitoring

Wearable technology has recently attracted much interest for various uses. An essential component of the wearable system is the wearable antenna. Textile and non-textile materials have both been used to create wearable antennas. Textile antennas are very useful and widely used nowadays, particularly in body-worn applications monitoring health parameters. Fabricated using microstrip technology, textile antennas have various benefits, including small size, lightweight, simple fabrication, and ease of wear. In this study, a microstrip antenna is created utilizing a substrate made of jeans. It works between 2.4 to 2.5 GHz in the ISM (industrial, scientific, and medical) band. High-frequency structure simulator (HFSS) software was used to simulate two antennas, one with an incomplete and the other with a complete ground plane. Wearable antennas can protect the body from the impacts of RF radiation by utilizing the entire ground plane principle. Results from a vector network analyzer were obtained for the fabricated antenna (VNA). This antenna's main function is to track blood glucose levels. Blood's dielectric characteristics change when blood sugar levels fluctuate, affecting the antenna’s output frequency. There are two ways to monitor glucose levels. One method requires placing a finger on an antenna patch, while the other involves fixing an antenna to a person's arm and detecting the output frequency fluctuation. The antenna's resonant frequency raises in reaction to increased blood glucose levels. Therefore, these textile antennas are a great choice for non-blood sample monitoring of blood glucose levels.

Design and Simulation of a Square Loop Antenna for 920 MHz

This study describes design and simulation of a loop antenna. A square loop antenna is designed for 920 MHz. The loop antenna is then modelled and simulated using 4NEC2 electromagnetic (EM) modeling software. 4NEC2 is a completely free numerical electromagnetic modeling code. It is based on method of moments technique to solve electromagnetic boundary value problem. The 4NEC2 simulation of the loop antenna design predicted antenna resonant frequency to be 920 MHz, Return Loss bandwidth of 130 MHz and input impedance of 50.14 -j0.30 Ohm. The antenna radiation pattern is then simulated at 920 MHz. The Return Loss, VSWR, Input Impedance and Radiation Pattern of the antenna predicated by 4NEC2 simulation are studied for the possible development of copper or aluminium tube based loop antenna.

A novel wireless oxygen gas sensor based on silver film loaded on a patch antenna

In this work, a patch antenna loaded with sensitive silver film was employed for the detection of oxygen gas at high concentrations. SEM micrographs demonstrate that the morphology of the Ag film presents an elevated degree of porosity, confirming that the film is suitable for adsorbing O2 gas molecules on its surface. Numerical simulation performed was validated, and the values of the far-field parameters showed that the investigated device works efficiently as an antenna. During the tests carried out, it was observed that the device responds sensitively to the presence of oxygen gas demonstrating shifts of the antenna resonant frequency to higher values as a function of the O2 concentration. The antenna sensitivity was calculated, presenting a value of 0.14 MHz/O2% for the frequency at 5.968 GHz, 0.23 MHz/O2% for frequency at 8.246 GHz, and 0.15 MHz/O2% for the frequency at 10.039 GHz. Results obtained indicate that the patch antenna tested could be used as a sensor of oxygen gas in environments with elevated concentrations of this gas, such as oxygen concentrators and other medical equipment. Because the device analyzed is an antenna, it would be possible transmitting the sensing information to another device which would make it a potential candidate for application in healthcare monitoring.

2.4 G HZ MINIATURISED RECTANGULAR MPA WITH DEFECTED GROUND AND PATCH

This study aimed to develop a miniaturised rectangular microstrip patch antenna with a resonance frequency of 2.4 GHz. In order to achieve this, an initial microstrip antenna's resonance frequency was shifted from 3 GHz to a lower frequency by employing a defective ground structure (DGS) with a triangular-shaped slot into the ground plane. Also Triangular ring slots used defect the patch to improve co- and cross-polarization separation. Finally, a successful downsizing of up to 28% along the length and 18% along the width of the patch is achieved compared to the traditional 2.4 GHz microstrip antenna. The findings of the experiments have been obtained using high-frequency structure simulator software (HFSS). The substrate used in this work is RT/ Duroid 5880, which has a dielectric constant of 2.2 and a thickness of 1.575 mm.

Optimization and Comparative Analysis of Quarter-Circular Slotted Microstrip Patch Antenna Using Particle Swarm and Fruit Fly Algorithms

This paper proposes a parametric study of modified rectangular microstrip antenna in the frequency range between 1.4-2.65 GHz for wireless communication applications, incorporating with optimization methods Particle Swarm Optimization (PSO) and Fruit Fly Optimization (FOA). To design an antenna using optimization methods a fitness function of required parameters is needed. The resonance frequency of Microstrip Patch Antennas (MPAs) depends on various parameters and a standard frequency function does not exist for MPAs. In this study, a rectangular patch antenna is designed for the required resonance frequency and modified with circular quarter slots. The frequency-shift with the change of design variables, which are the substrate thickness and the radius of the slots, is observed. The resonance frequency is obtained as a function of the design variables and it is used in the optimization process to minimize the difference between the target frequency and the calculated one. The original algorithms FOA and PSO have been adapted for its application to a modified rectangular patch antenna design problem: resonance frequency and design of antenna. The design parameter values obtained via optimization and the performances of the optimization methods are presented. The results showed that both PSO and FOA find the dimensions correctly. It is also observed that the sensitivity of the FOA increases with the fruit fly population and the convergence gets faster. The outcomes of this paper show that the PSO algorithm gives better results when compared to the FOA for the proposed antenna.

Design and Minimization of Mutual Coupling Steered Array Lens Antenna for 5G Communication

Examining and evaluating the improved microstrip patch antenna to enhance the performance by the initial objectives are the main contribution of this paper. To achieve multiband operation, the patch's shape is first adjusted later microstrip patch with the slot presented. With the help of the Ansoft HFSS antenna simulator, functional analysis has been shown to examine the impact on antenna resonant frequency. A probe-driven microstrip patch antenna imprinted on FR4 epoxy substrate with 1.6mm thickness and a dielectric constant of 4.4 is developed in this work via the HFSS tool for wireless applications operating between 2 to 5GHz. To achieve multiband operation, the structure of the patch is varied. The impacts on antenna resonant frequency are examined through numerical simulations. The length, as well as the width of a traditional patch antenna, is initially computed, and further, an appropriate patch dimension of 28.3mm x 36.9mm has been determined. For multiband operation over the frequency ranging between 2 and 5GHz wireless applications, a probe-driven microstrip patch antenna imprinted on FR4 epoxy substrate with 1.6mm thickness and a dielectric constant of 4.4 is built via the HFSS tool. The proposed architecture of a traditional microstrip patch antenna is imprinted on an FR4 epoxy substrate with a 1.6mm thickness and a 4.4 dielectric constant. The proposed antenna design is illustrated for the 3D structure of the Mutual Coupling Steered Array-Lens Antenna System (MPA) with an improved patch. To achieve multiband operation, two slots are inserted on the edges of the patch, and both the slots are 2mm wide, as well as the depth of the slots is modified to see how it corresponds to the resonant frequency. This work is mainly concentrated on (i) Examining as well as evaluating the improved microstrip patch antenna to enhance its performance, (ii) Examining, evaluating, as well as assessing the performance of an improved split ring resonator metamaterial, and (iii) Exploring, analyzing, as well as evaluating the performance of dielectric lens base patch array antennas and (iv) Developing as well as analyzing the transmission line phase shifter. The groundwork for developing this work is being carried out, and a comparative study is made on (i) techniques for improving the antenna's performance through the application of a modified patch antenna, a Modified split ring resonator, a Dielectric lens structure, and Transmission line phase shifter.

Simulation and Study of a Triangular Microstrip Patch Antenna

This study considers the simulation and study of a probe fed triangular microstrip patch antenna developed on a FR4 type substrate. The antenna design is first simulated using Sonnet Lite™ electromagnetic (EM) analysis software. Sonnet Lite™ is memory limited free version of commercial Sonnet™ electromagnetic analysis tool. It is based on method of moments technique to solve electromagnetic boundary value problem. The simulation predicted antenna resonant frequency to be 2360 MHz, Return Loss bandwidth of 36 MHz and input impedance of 52.72 Ohm. The antenna is then studied for its return loss (RL), voltage standing wave ratio (VSWR) and impedance (ZIn1) to determine its resonant frequency. The antenna resonant frequency is found to be 2380 MHz and its return loss bandwidth to be 60 MHz. The antenna radiation pattern is then measured at 2380 MHz. The RL, VSWR and ZIn1 of antenna predicated by Sonnet Lite™ are compared with their measurements which show a good agreement.

Electro-Geometrical Analysis of Transversal V-Fold Patch Antenna

This paper investigates an original concept of electro-geometrical analysis of flexible microstrip antenna. The research work is focused on the analysis of the innovative effect of “V”- shape folding on the resonance frequency and input impedance of microstrip patch antenna. The V-folded antenna is assumed to behave as an arm constituted by horizontal and tilted members which are geometrically characterized by the folding angle, a. The folding is characterized by the angle between the horizontal plane and the folded part of the patch antenna printed on a Kapton flexible substrate. The initially flat-configured planar antenna was designed to operate at about 2.45 GHz. The innovative design method of the V-shape folded flexible antenna is explained. Full wave electromagnetic simulations of different geometrical states of the flexible antenna were performed in the frequency range from 1 GHz to 5 GHz. Exceptional results of tilted surface radiating part of flexible patch antenna were found with a positive folding angle from amin=0° to amax=45°. It was understood for the first time in the area of antenna engineering that the resonance frequency is fluctuating according to typical sine damping in the function of the V-folding angle variation. The folded angle effect, which has never been understood before is discussed. In addition to the angle effect, the input resistance and input reactance of the V-folded flexible patch antenna is also plotted.

Analysis and synthesis of L- and T-shaped flexible compact microstrip antennas using regression-based machine learning approaches

Abstract The purpose of this study was to analyze and synthesize L-shaped compact microstrip antennas (LCMA) and T-shaped compact microstrip antennas using regression-based machine learning algorithms (TCMA). This was accomplished by simulating 3808 LCMAs and 900 TCMAs operating at UHF and SHF frequencies with different physical and electrical characteristics. The acquired data was utilized to create a data set containing the antennas’ physical and electrical characteristics, as well as their resonant frequencies in the TM010 mode. Four baseline regression models and seven machine learning models were developed to determine the resonance frequency of antennas and the values of the physical parameters required for a particular frequency. To examine the efficacy of machine learning models, three-dimensional LCMAs and TCMAs were created using polylactic acid (PLA) and felt-based flexible substrates, as well as copper tape. The results illustrate the feasibility of using machine learning models for LCMA and TCMA analysis and synthesis.

A Miniaturized Triple-Band Antenna Based on Square Split Ring for IoT Applications

This article presents a miniaturized triple-band antenna for Internet of Things (IoT) applications. The miniaturization is achieved by using a split square ring resonator and half ring resonator. The antenna is fabricated on an FR4 substrate with dimensions of (33 × 22 × 1.6) mm3. The proposed antenna resonates at the frequencies 2.4 GHz, 3.7 GHz, and 5.8 GHz for WLAN and WiMax applications. The obtained −10 dB bandwidth for the three bands of the proposed antenna are 300 MHz, 360 MHz, and 900 MHz, respectively. The measured reflection coefficient values of the proposed antenna corresponding to each resonant frequency are equal to −14.772 dB, −20.971 dB, and −28.1755 dB, respectively. The measured gain values are 1.43 dBi, 0.89 dBi, and 1 dBi, respectively, at each resonant frequency. There is a good agreement between the measured and simulated results, and both show an omnidirectional radiation pattern at each of the antenna resonant frequencies that is suitable for IoT portable devices.

Design and Simulation of Miniaturization of Triangular Shape Dielectric Resonator Antenna Using AMC Surface for 5G Applications

A Dielectric Resonator Antenna (DRA) is a radio antenna. It is built up of ceramic material into blocks of various forms and is generally suitable at frequencies larger than 1 GHz (microwave frequencies and higher than microwave frequencies). Using this Dielectric Resonator Antenna, the operating frequency is achieved at 4.8GHz for 5G applications like IOT (Internet of Things), AI (Artificial Intelligence). Here, artificial magnetic conductor (AMC) surface is used to miniaturize a triangular shaped Dielectric Resonator Antenna (DRA). There are nine tiny copper patches forms the Artificial Magnetic Conductor (AMC) surface having gap of 1.5mm between the patches. AMC is installed on FR4 substrate which has dielectric constant as 4.4. On the AMC surface, a Dielectric Resonator (DR) of dielectric constant 2.2 is placed. The surface of the Artificial Magnetic Conductor is shorted with ground metal using tiny metallic vias. Antenna characteristics such as antenna gain, resonant frequency, and efficiency will not be affected due to the usage of Dielectric Resonator. As a result, the overall volume of DRA is significantly diminishing. There are three primary aspects in this design: (a) Impedance matching using a Parasitic Metallic Strip (b) Design miniaturisation with an AMC surface (c) Simple microstrip line Feeding. Overall volume of Dielectric Resonator Antenna size reduced by 85%. In addition, when compared to the original Dielectric Resonator Antenna without the surface of Artificial Magnetic Conductor, the ground surface is lowered by 15.5 percent.

Space Diverse and Frequency MIMO Antenna with Defected Ground Structure

A four-port DGS (defective ground structure) MIMO antenna is the subject of an inquiry. The proposed design in this study operates at a range of frequencies (1.8 GHz NB-IoT band, 2.4 GHz ISM band, 3.1 GHz sub 6 GHz, Wi-Max, and 4.8 GHz 5G connectivity band). The antenna is driven by an excited microstrip transmission line. All ports of the recommended MIMO antenna are isolated by less than -15dB, and its tiny (20 cm by 15 cm) footprint. It also takes into account radiation characteristics including s-parameters, radiation pattern, directivity, gain, return loss, and bandwidth. Measurements of MIMO performance such the Envelop correlation coefficient (ECC), diversity gain (DG), total active reflection coefficient (TARC), and mean effective gain (MEG) are also employed to ensure proper diversity performance. Utilizing CST Microwave Studio, the proposed antenna is examined. The resonant frequencies of antennas 1, 2, 3, and 4 are 1.8 GHz, 2.4 GHz, 3.1 GHz, and 4.8 GHz, respectively. The greatest gain it provides is 9.15dB. There is 20 dB isolation between ports.

An off-center fed patch antenna with overlapping sub-patch for simultaneous crack and temperature sensing

This paper presents an off-center fed patch antenna for simultaneous crack and temperature sensing. The antenna sensor consists of an off-center fed underlying patch and an overlapping sub-patch. The bottom copper sheet of the sub-patch is tightly attached to the underlying radiation patch allowing the electric current to flow through the integrated patch. The off-center feeding can activate the resonant modes in both transverse and longitudinal directions. The transverse resonant frequencies of the combined patch are utilized for temperature sensing. Therefore, the crack width sensed by the longitudinal frequency shift can be adjusted, eliminating the temperature effect. In addition, this unstressed structure of the combined patch can avoid the issues of incomplete strain transfer ratio and the insufficient bonding strength of a monolithic antenna. The authors developed theoretical relationships between the antenna resonant frequencies, the temperature, and the crack width. They also developed simulations of the off-center fed patch antenna sensor as well as a series of experimental tests to demonstrate the feasibility of the proposed sensor for simultaneous crack and temperature sensing.

Feasibility study of patch antenna for monitoring moisture content of made tea

This study aims to analyze the patch antenna for moisture content measurement of made tea. The patch antenna-based system uses an air gap between the ground plane and an electrically conductive patch. The tea sample is contained in the air gap. The patch antenna design has a resonance frequency of 5 GHz. The resonance frequency and S11 parameters are measured for tea samples in the moisture range of 2–10%. The resonance frequency of the patch antenna was observed to decrease with an increase in the moisture content of tea. However, the return loss of patch antenna was observed to increase with an increase in the moisture content of made tea. Linear model parameters were calculated for the prediction of the moisture content of tea leaves.