Resonant Frequency Of Antenna Research Articles

Antenna-Based Popup Vapor Sensor Guided by Controlled Compressive Buckling

A novel highly stretchable gas sensor is reported that is based on popup antenna reconfiguration due to the strain induced by the swelling of a polydimethylsiloxane (PDMS) substrate when exposed to diethyl ether. When the swollen substrate is removed from the volatile solvent environment, the PDMS volume increase is reversed leading to compressive stress in an attached antenna transforming a 2D structure to a 3D structure through mechanically induced shaping. This provides a low cost and simple route to tune the antenna resonant frequency and gain in direct response to a chemical stimulus. Our proposed solvent sensor is able to measure 0 to 60% PDMS swelling corresponding to diethyl ether concentrations up to 1620 ppm via a resonant frequency shift from 4 to 2.4 GHz. A fatigue life study indicated 103.5 life cycles which demonstrates the durability of these sensors to accommodate large strain and repeatability of the sensing process. Multiphysics Finite Element Method (FEM) modelling of the mechanical and RF simulations along with analytical results based on an equivalent circuit model were in good agreement with experimental data and demonstrate the potential of these structures as sensors.

Flexible and miniaturized design of microstrip patch antenna with improved cross-polarized radiation

A simple and miniaturized design of rectangular microstrip patch antenna (RMPA) is presented with improved cross-polarization (XP) purity. This design approach is much more flexible to tune the resonance frequency of the antenna for its optimum performance. A complete design guideline based on theoretical analysis has been provided to estimate the antenna resonance frequency and corresponding resonant mode. The higher-order spurious mode, orthogonal to the co-polarized fields, has been identified as the source of XP radiation. The physical insight into the XP suppression has been thoroughly discussed and successfully applied for an optimum design. An improved antenna configuration has been realized without any perturbation in the radiating patch or the ground plane. Size, gain, and impedance matching of the proposed antenna have also been considered along with the suppression of XP value. This may be applicable to any conventional working RMPA by introducing very small possible changes. As much as 16 dB suppression of XP radiation is realized in the H-plane without affecting the co-polarized peak-gain value of 5.27 dBi. The proposed concept has been experimentally validated using a set of antenna prototypes. Measured results are closely corroborated with the simulated predictions.

Design of a Novel Passive Wireless Integrated SAW-Based Antenna Sensor for Structural Health Monitoring

A novel passive wireless integrated SAW-based antenna sensor for strain sensing is presented in this paper. A SAW delay line scheme is proposed for signal modulation, which could distinguish the backscattered data from environmental clutter in time domain. The theoretical relationship between the antenna resonance frequency shifts, the temperature, and the applied strain was established. A multiphysical coupled simulation process is proposed to improve the simulation accuracy. By comparing the phase shift of adjacent echoed data which is generated by SAW reflective grating, the temperature information could be extracted exactly and the effect of temperature fluctuation on the resonance frequency could be compensated. A more accurate passive (battery-free) wireless strain sensing could be provided by this proposed integrated antenna sensor than the previous proposed methods. Simulation and experimental results demonstrate the effectiveness of the sensor.

DTC-Enabled Frequency-Tunable Inverted-F Antenna for IoT Applications

In this letter, an integrated frequency-tunable inverted-F antenna is presented. Thanks to a reconfigurable circuit using a digitally tunable capacitor (DTC), the antenna resonant frequency can be shifted over 32 different positions from 600 to 960 MHz. This tunability is used to compensate the frequency detuning caused by the change in the antenna close surrounding. The small dimensions as well as the digital control and the low power consumption of the reconfiguration circuit make the proposed antenna a good candidate for Internet of Things applications.

Effects of Textile Weaving and Finishing Processes on Textile-Based Wearable Patch Antennas

In this paper, we analyze the effects of textile weaving and finishing processes on the performance of textile-based wearable antennas. Several textile-based patch antennas operating at 2.4 GHz were designed and fabricated for evaluation. All of them had the same geometry comprising a 1-mm-thick felt substrate in the middle, and silver ink screen-printed polyester fabric as the ground and patch at the bottom and on top. However, polyester fabric, the bare textile material for the conductive ground and patch was subjected to different weaving and finishing (tentering, scouring, and calendering) processes. It was observed that the antenna resonant frequency, bandwidth, radiation efficiency, and peak gain were varied by these processes, although the antenna geometry and screen-printing method were identical to each other. The best antenna exhibits a peak gain of 5.2 dBi and a radiation efficiency of 42.4%, while the worst shows corresponding values of 4.17 dBi and 34.8%. This implies that the weaving and finishing processes considerably impact textile-based wearable antenna performances.

Expedited Yield Optimization of Narrow- and Multi-Band Antennas Using Performance-Driven Surrogates

Uncertainty quantification is an important aspect of engineering design, also pertaining to the development and performance evaluation of antenna systems. Manufacturing tolerances as well as other types of uncertainties, related to material parameters (e.g., substrate permittivity) or operating conditions (e.g., bending) may affect the antenna characteristics. In the case of narrow- or multi-band antennas, this usually leads to frequency shifts of the operating bands. Quantifying these effects is imperative to adequately assess the design quality, either in terms of the statistical moments of the performance parameters or the yield. Reducing the antenna sensitivity to parameter deviations is even more essential when increasing the probability of the system satisfying the prescribed requirements is of concern. The prerequisite of such procedures is statistical analysis, normally carried out at the level of full-wave electromagnetic (EM) analysis. While necessary to ensure reliability, it entails considerable computational expenses, often prohibitive. Following the recently fostered concept of constrained modeling, this paper proposes a simple technique for rapid surrogate-assisted yield optimization of narrow- and multi-band antennas. The keystone of the approach is an appropriate definition of the optimization domain. This is realized by considering a few pre-optimized designs that represent the directions of the major changes of the antenna resonant frequencies and operating bands. Due to a small volume of such a domain, an accurate replacement model can be established therein using a small number of training samples, and employed to improve the antenna yield. Verification results obtained for a ring-slot antenna, a dual-band and a triple-band uniplanar dipoles indicate that the optimization process can be accomplished at low cost of a few dozen of EM simulations: 62, 74 and 132 EM simulations, respectively. Result reliability is validated through comparisons with EM-based Monte Carlo simulations.

Miniature microstrip antenna for IoT application

Wireless technology is greatly influenced by the advanced technological development of the antenna. With the rapid expansion of Internet of Things (IoT) application in the modern communication system, the demand for micro antennas is increasing. Microstrip patch antennas are generally used in IoT applications due to itscompatibility. The key benefit of the microstrip antenna is that it allows easy integration into IoT devices. Thus, in this work, rectangular microstrip patch antenna is designed and the performance was analysed. In this work,the antenna resonant frequency range was 100 MHz and 5.8 GHz, which is appropriate for IoT application was used. The antenna was designed with FR-4 substrate material. For this work, CST software (version 2014) was used as simulation software. In this work, two types of antenna were designed, which was conventional microstrip antenna and optimized microstrip antenna containing U-shaped structure. The performance of these two antennas was compared in terms of bandwidth, gain and return of loss. The key results of this work showed that the optimized U-shaped antenna improved the bandwidth from 134.1 MHz to 167.6 MHz, gain from 1.83 dB to 2.54 dB and return of loss-20.32 dB to −26.56 dB compared to the conventional antenna. In addition, the optimized antenna achieved operating frequency of 5.755 GHz, which is suitable for IoT applications.

CSRR-Based Microwave Sensor for Dielectric Materials Characterization Applied to Soil Water Content Determination.

A new and compact sensor based on the complementary split-ring resonator (CSRR) structure is proposed to characterize the relative permittivity of various dielectric materials, enabling the determination of soil water content (SWC). The proposed sensor consists of a circular microstrip patch antenna supporting a 3D-printed small cylindrical container made out of Acrylonitrile-Butadiene-Styrene (ABS) filament. The principle of operation is based on the shifting of two of the antenna resonant frequencies caused by changing the relative permittivity of the material under test (MUT). Simulations are performed enabling the development of an empirical model of analysis. The sensitivity of the sensor is investigated and its effectiveness is analyzed by characterizing typical dielectric materials. The proposed sensor, which can be applied to characterize different types of dielectric materials, is used to determine the percentage of water contained in different soil types. Prototypes are fabricated and measured and the obtained results are compared with results from other research works, to validate the proposed sensor effectiveness. Moreover, the sensor was used to determine the percentage of water concentration in quartz sand and red clay samples.

Compact Rhombus Ring Dual Frequency Microstrip Antenna for Wireless Applications

In paper, a low profile microstrip patch antenna with rhombus model is designed at an running frequency at 2.4 GHz, 5.2 GHz. Microstrip Patch Antenna are suited to non-plane and plane areas, uncomplicated and effortless to design by used Printed Circuit Technology, it is a mechanically vigorous when it is ascended on rigid places and when the particular patch design model and dimension were selected, it has adjustable in view of resonance frequency, radiation design, impedance and polarization. High Frequency Structural Simulator (HFSS) is a definite component method solver for structures of EM (electromagnetic). The outcome values are discussed and analyzed in view of S11 (Return Loss), 3D Polar Plot, Radiation design and Gain. The value of S11 comes out to be -14.16dB for the designed antenna. The antenna measured length is nearly half wavelength in the dielectric, it is a highly censorious parameter, which governs the antenna resonant frequency. And the final values are simulated using High Frequency Structural Simulator

A new design micropatch antenna for GPS applications on vehicle navigation systems

A new design of the micropatch antenna for GPS applications is studied. 70 antenna iterations working around the L1 band (1575 MHz) with different sized quarter-circular slots on the patch are designed and simulated. In parallel, “design dimensional parameters (“r” slot radius and “h” substrate thickness) and antenna resonant frequencies according to parameters” are applied to curve fitting algorithm and an equation for resonance frequency is obtained based on r and h. The resonance frequency values obtained by proposed equation are compared with simulations.

Open/short circuit terminations of efficient ACS-fed CRLH small antennas

A design of asymmetric coplanar strip-fed (ACS) CRLH antennas for multiband operation is presented in this paper. Two different possible termination of the antenna is discussed. Comparison between ACS short circuit and ACS open circuit termination confirm that the open circuit termination has extra resonance band. The antenna resonance frequencies were optimized for WIMAX/WLAN frequencies. The antennas have compact size of 13.5 × 26.5 mm2 thanks to the asymmetric configuration. The antenna has size reduction up to 50% as compared to the patch antennas which are operated as the same frequency bands. The antennas are tested experimentally to validate the agreement between simulated and measured data.

Lumped Elements and Its Existence in Quasi Lumped Element Resonator Antenna

In this paper, the Quasi Lumped Element Resonator Antenna is reviewed. It is composed of Lumped elements. Lumped Elements are passive components whose size across any dimensions should be small to make it a lumped element. The various researches that have been done to come about the various types of basic building blocks of the lumped element are staged in this write up. This review is towards accomplishing the derivation of the component elements used in the design of the Quasi Lumped Element Resonator Antenna. These elements are the interdigital capacitor, inductor and pad capacitors. The pertinent formulae for determining each one of them were all expressed in this review. The formula for calculating the resonance frequency of the Quasi Lumped Element Resonator Antenna was expressed in this review. The equivalent circuit model for the lumped elements were all reviewed and presented. This review brings about how the lumped elements are involved in the design of the Quasi Lumped Element Resonator Antenna.

Microstrip patch antenna for simultaneous temperature sensing and superstrate characterization

This paper investigates a microstrip patch antenna for measuring the thickness and dielectric constant of the medium above the antenna (i.e. the superstrate) as well as the temperature. The intended application is simultaneous sensing of ash accumulation and temperature inside a boiler, with the aim of enhancing safety, improving efficiency, and reducing downtime associated with maintenance. A patch antenna, consisting of a dielectric substrate, a radiation patch, and a ground plane, functions as an electromagnetic resonator with specific fundamental frequencies. A dielectric medium placed above the patch antenna changes its effective dielectric constant and thus its resonant frequencies. Meanwhile, temperature also influences the antenna frequencies because of the thermal expansion of the conductors (i.e. the radiation patch and ground plane), and the dielectric constant of dielectric materials due to their temperature dependency. Since a rectangular patch antenna has two fundamental frequencies, it enables determining these two parameters simultaneously. Once the temperature and superstrate thickness are determined, the dielectric constant of the superstrate and its temperature dependency can also be extracted. To demonstrate this capability, a dual-frequency patch antenna was designed, fabricated, and characterized with a superstrate of various thicknesses and at different temperatures. By fitting the antenna resonant frequencies as functions of the superstrate thickness and temperature, these two parameters were inversely determined from the measured antenna frequencies. Using ash from charcoal briquettes as a superstrate, the measurement uncertainties were determined to be ±0.58 °C and ±58.05 μm for the temperature and the superstrate thickness respectively. The dielectric constant of the ash was found to be 2.64 at room temperature and its thermal coefficient of dielectric constant (TCDk) was found to be 918 ppm °C−1.

Patch-Loaded Semicircular Dipolar Antenna for Metal-Mountable UHF RFID Tag Design

A compact tag antenna, which has a geometrical dimension of 40 mm x 40 mm x 3.048 mm (0.1224λx 0.1224λ x 0.0093λ), is proposed for metal-mountable applications in the UHF band. The antenna structure comprises a pair of semicircular microstrip dipolar patches which are orthogonally loaded with another pair of similar patches on the top. Rotating the orientation of the top-loading patch is found to be able to effectively tune the tag antenna's resonant frequency and its impedance. The capacitive and inductive effects introduced by the top-loading patches are crucial for bringing the resonant frequency of the tag antenna down to the useful UHF band. Conjugate impedance matching is achieved between the antenna and the microchip. An equivalent circuit has been constructed to study the impedance characteristics. Measurements show that the proposed tag antenna is able to achieve a read distance of 12.25 m at the Effective Isotropic Radiated Power of 4 W. The operating frequency of the patch-loaded dipolar patches is found to be insensitive to changes in the size of the backing metal plate, which is very useful for designing a stable radio frequency identification (RFID) tag.

Frequency invariance, gain improvement, and fast design in 3D‐printed photonic band gap antennas with quadratic holes

AbstractThe use of photonic band gap (PBG) substrates with noncylindrical holes in microstrip antennas is little reported in the literature. In this article, a 3D printer was used to produce two PBG antennas in acrylonitrile‐butadiene‐styrene (ABS) substrate: one with cylindrical holes and the other with quadratic prism holes, both with the same volume in the holes and in the total composition. The proposed PBG antenna with quadratic prism holes maintains the same resonance frequency of antenna with cylindrical holes, that is, 2.64 GHz. In addition, the proposed antenna greatly reduces the project time in the simulation phase, which is very onerous in conventional PBG antennas. The PBG antennas improved the distribution of surface current and increased the gain in relation to the antenna without PBG. Thus, the obtained results were as follows: the gain and efficiency of radiation were 3.75 dB and 55% for the antenna without PBG, 4.5 dB and 60% for the antenna with cylindrical holes, and 5 dB and 62% for the antenna with quadratic holes. All antennas maintained an approximate bandwidth of 3%. These antennas were built, simulated, and measured. A schematic of the build structures, return loss, Smith's chart, radiation diagrams, and computational simulation time was analyzed throughout this article.

Efficient and Compact Near-Field Coupled Hybrid Antenna Using a Single Radiating Subwavelength Split-Ring Resonator

Modern applications in the realms of wireless communication and mobile broadband Internet increase the demand for compact antennas with well defined directivity. Here, we present an approach for the design and implementation of hybrid antennas consisting of a classic feeding antenna that is near-field-coupled to a subwavelength resonator. In such a combined structure, the composite antenna always radiates at the resonance frequency of the subwavelength oscillator as well as at the resonance frequency of the feeding antenna. While the classic antenna serves as impedance-matched feeding element, the subwavelength resonator induces an additional resonance to the composite antenna. In general, these near-field coupled structures are known for decades and are lately published as near-field resonant parasitic antennas. We describe an antenna design consisting of a high-frequency electric dipole antenna at f d = 25 GHz that couples to a low-frequency subwavelength split-ring resonator, which emits electromagnetic waves at f SRR = 10.41 GHz. The radiating part of the antenna has a size of approximately 3.2 mm × 8 mm × 1 mm and thus is electrically small at this frequency with a product k · a = 0.5 . The input return loss of the antenna was moderate at − 18 dB and it radiated at a spectral bandwidth of 120 MHz. The measured main lobe of the antenna was observed at 60 ∘ with a − 3 dB angular width of 65 ∘ in the E-plane and at 130 ∘ with a − 3 dB angular width of 145 ∘ in the H-plane.

Miniaturization of a Microstrip Patch Antenna with a Koch Fractal Contour Using a Social Spider Algorithm to Optimize Shorting Post Position and Inset Feeding

This paper presents a social spider optimization (SSO) design of a small-size microstrip antenna. Two antenna miniaturization techniques, based on the use of a Koch fractal contour and a shorting post (connecting the patch to the ground plane), are combined to enable a major size reduction. The antenna is inset fed by a microstrip line. The developed SSO algorithm is used to find out the best radius and position of the shorting post and the length of the inset feed, to achieve the desired resonant frequency with good impedance matching. Antenna prototypes have been fabricated and measured. The good agreement obtained between numerical simulation and experimental results has validated the design procedure. Compared with a conventional rectangular patch, the antenna resonance frequency is reduced from 2.45 GHz to 730 MHz, which corresponds to a remarkable miniaturization of about 70%. The proposed antenna is suitable for applications in the 700-800 MHz frequency range, such as 4G mobile communication systems.

IMPLEMENTASI JARINGAN SYARAF TIRUAN DALAM MEMPREDIKSI FREKUENSI RESONANSI ANTENA MIKROSTRIP

The resonant frequency of an antenna is determined by the dimensional parameters and permittivity of the antenna substrate. Generally, to get the resonant frequency, a complex mathematical formula is needed to solve. For this reason, an intelligent method is offered to determine the resonant frequency more easily. In this study, an artificial neural network method with Backpropagation algorithm is used to overcome the problem. The data used were consisting of 80 training data and 15 testing data. The results have shown that the artificial neural network learning method with the backpropagation algorithm was successfully utilized to calculate the resonant frequency of microstrip antennas, where the precision of the resonant frequency obtained of 93.33% at an error of = 1%, and 100% at an error of = 2%.

A Theoretical Model of Underground Dipole Antennas for Communications in Internet of Underground Things

The realization of Internet of underground things (IOUT) relies on the establishment of reliable communication links, where the antenna becomes a major design component due to the significant impacts of soil. In this paper, a theoretical model is developed to capture the impacts of the change of soil moisture on the return loss, resonant frequency, and bandwidth (BW) of a buried dipole antenna. Experiments are conducted in silty clay loam, sandy, and silt loam soil, to characterize the effects of soil, in an indoor testbed and field testbeds. It is shown that at subsurface burial depths (0.1–0.4 m), the change in soil moisture impacts communication by resulting in a shift in the resonant frequency of the antenna. Simulations are done to validate the theoretical and measured results. This model allows system engineers to predict the underground antenna resonance and also helps to design an efficient communication system in IOUT. Accordingly, a wideband planar antenna is designed for an agricultural IOUT application. Empirical evaluations show that an antenna designed considering both the dispersion of soil and the reflection from the soil–air interface can improve communication distances by up to five times compared to antennas that are designed based on only the wavelength change in soil.

Tapered Antenna Array with Non-identical Triangular MSA Elements for FSLL Reduction

Reduced interference from nearby communication systems is an essential need in all generations of wireless communication systems. In this paper, interference is reduced by reducing the first side lobe level (FSLL) by using the concept of tapering realized with non-identical triangular elements. Resonance frequency of an Equilateral triangular microstrip antenna depends on its patch height. This property has been used effectively to realize isosceles triangular microstrip antenna with equal height, thus resonating at the same frequency. The isosceles triangular elements are designed as non-identical elements, based on its area reduction and hence gain variation, with respect to three different standard amplitude distribution functions. Six such arrays have been designed with two different inset notch feed gaps. An analysis of the non-identical elements’ antenna arrays with varying inset notch feed gaps to realize tapering in the H-plane for FSLL reduction has been presented. To verify the proposed concept, one triangular patch array using eight non-identical equilateral and isosceles triangular elements designed at 6 GHz is fabricated and tested. A reasonably acceptable agreement between the simulated and measured results validates the proposed concept.