Radiation Performance Of Antenna Research Articles

ANN modeling for predicting muscle-implanted antenna performance for skin and fat thickness variations at 2.45 GHz

Abstract Implantable antenna is embedded in implantable medical devices to communicate with external world for continuous patient monitoring. The implantable antenna performance may vary with patients due to their different skin and fat thickness owing to their environment, location and concentration of collagen in skin, estrogen and testosterone concentration, age, diseases like obesity, Gottron syndrome etc. Estimation of IMA performance requires a proper description of its dependence on variable skin and fat thickness which is not studied extensively in previous related works. In this article, we have designed a muscle-implanted antenna at 2.45 GHz to examine its performance dependence on variable skin and fat thickness values. In this study, we have designed an artificial neural network (ANN) for prediction of antenna performance parameters at 2.45 GHz for wide range of skin and fat thickness variations. The designed ANN model can predict antenna performance with ∼0.99 % error. Here, accurate dependence analysis of radiation performance of implantable antenna in terms of S 11, realized gain, bandwidth and operating frequency on skin and fat thickness variations is performed which has not been studied yet and use of ANN in this field for accurate prediction is also a novel approach.

Performance optimization for magnetoelectric antennas based on a multi-field coupling analysis model

This paper presents a multi-field coupling model for magnetoelectric (ME) antennas, encompassing a ME film, electrode layers, and a substrate featuring a cavity structure. This model accounts for the nonlinear magnetoelastic coupling within the radiation layer and employs a combined DC and AC simulation methodology to capture the antenna's radiation mechanism. Leveraging this multi-field coupling model, performance differences between the ME antenna and an ideal ME composite film are analyzed. By exploring optimization schemes based on multi-physics fields, electrode materials, and structural design, the ME antenna's radiation performance is significantly enhanced. The findings demonstrate that the complete antenna structure, with its increased thickness and cavity design, exhibits a lower resonance frequency and a higher converse ME (CME) coefficient compared to the ideal ME film. The optimal CME effect is achieved under proper external stimuli, leading to a broader 3 dB bandwidth. Expanding the cavity dimensions enhances the CME coefficient by 42% and reduces the resonance frequency due to decreased acoustic wave loss. Adopting electrode materials with higher acoustic impedance elevates the CME coefficient, yet narrows the bandwidth. Conversely, using silver (Ag) electrodes promotes a broader bandwidth. Additionally, ME antenna arrays are designed to broaden the bandwidth by 300%.

A low-profile 3-D printable metastructure for performance improvement of aperture antennas

In order to increase the radiation performance of aperture-type antennas, this paper demonstrates a low-profile, planar, single-layer, three-dimensional (3-D) printable metastructure. The proposed hybridized metastructure is highly transparent as it is made out of novel hybrid meta-atoms having transmission coefficient magnitudes greater than – 0.72 dB and fully complies with the near-field phase transformation principle. The hybridized design approach makes the metastructure planar, low-profile, light in weight, and compatible with additive printing technology. For the proof-of-concept, such metastructure is developed and numerically verified to enhance the radiation performance of a resonant cavity antenna (RCA). With the proposed metastructure, the peak directivity of the RCA is improved by 8.6 dBi (from 11.4 dBi to 20 dBi) at the operating frequency of 12.4 GHz. The aperture efficiency and 3-dB directivity bandwidth of the RCA with the metastructure are 41.46% and 16.5%, respectively. Using readily accessible thermoplastics or polymers and copper with cost-effective fused deposition modeling (FDM) 3-D printing technology, the proposed planar hybridized metastructure can be prototyped commercially.

Enhanced performance of microstrip antenna fabricated on a composite dielectric substrate coupled with multiple dielectric superstrates

In this study, we introduce a unique geometrical design of a rectangular patch antenna for sub-6 GHz 5G applications. The proposed antenna is designed at 5.2 GHz, and design criteria and performance characteristics have been investigated through numerical simulations and verified using measured data. A composite structure is suggested to overcome the restrictive parameters of conventional antennas. Two different materials, Rogers RT5880, and RT5870, are utilized, achieving a maximum gain of 6.210 dB, and a 90.2% radiation efficiency was attained. Four layers of superstrates are placed above the antenna to enhance the antenna's radiation performance further. The fabricated antenna is evaluated by measuring its radiation characteristics and return loss. The final antenna prototype offers a maximum bandwidth of about 896 MHz at a −10 dB reflection coefficient with a maximum gain of 9 dB. The proposed model achieved ultimate efficiency as high as 89% by employing four superstrates. The results showed good impedance matching (S11, VSWR), high efficiency, and appropriate radiation patterns. The outcomes from simulation and measurement are well aligned, making this antenna suitable for high-performance 5G applications.

Design of circularly polarized antenna with wide overlapped axial‐ratio and gain beamwidths for upper hemispherical coverage

AbstractIn this letter, a circularly polarized antenna with wide overlapped axial ratio and gain beamwidth is proposed for upper hemispherical coverage. By bending half of the dipoles to the vertical direction, and connecting eight metal columns to the ground, the half‐power beamwidth (HPBW) of all cut planes can be increased effectively. On the basis, one reactive impedance structure is applied as the reflector to achieve unidirectional radiation, as well as increase the 3‐dB axial ratio beamwidth (ARBW) of the antenna. Miniaturized four‐feed networks are utilized to provide excitation, and the shielding technique is applied to reduce its influences on the antenna radiation performances. Measurements show that the proposed antenna can operate in the range of 1.51–1.59 GHz, which covers the upper band of global navigation satellite system (GNSS). Besides, at 1.561 GHz, the measured HPBWs and 3‐dB ARBWs are larger than 131° and 135° in all cut planes. The wide overlapped beamwidth of the proposed antenna with small size indicates the potential applications in high‐precision GNSS navigations.

Low-RCS electromagnetic metasurface antenna based on shared-aperture technique

In this paper, a novel shared-aperture method of electromagnetic metasurface and antenna is proposed to obtain low radar-cross-section (RCS) performance. In this method, the low-RCS metasurface is first designed, then this metasurface is combined with traditional antenna to obtain novel low-RCS antenna based on shared-aperture technique. Besides, the analysis and corresponding local structure modification are also conducted to ensure that the antenna has good radiation performance while reducing broadband RCS. Using this method, a dual-layer polarization rotation unit cell is first proposed and its broadband working principle is investigated by both theoretical analysis and numerical comparison. Based on this unit cell, a broadband low-RCS metasurface is constructed. Then an initial shared-aperture metasurface antenna is obtained by substituting the middle cells in the metasurface with traditional patch antenna directly. Through careful analysis of surface current in radiation mode, the gain decrease of this metasurface antenna is revealed. On this basis, a finite removal strategy is put forward and some metasurface cells in the antenna are removed by using the electric current analysis. Consequently, an improved shared-aperture metasurface antenna is proposed. This improved antenna works in a frequency range from 6.3 to 7.48 GHz, which is slightly wider than the traditional patch antenna. Its gain is also higher than that of traditional antenna, with a maximum improvement of 1 dB. Meanwhile, the apparent RCS decreases from 6 to 16 GHz for any polarized incident wave, and the reduction peak is larger than 20 dB. Finally, fabrications and measurements are conducted. The measurement results and numerical calculations are in good agreement. The well-behaved radiation performance and broadband low-RCS property of this metasurface antenna verify the effectiveness of the proposed method. Unlike most of reported design methods of low-RCS antennas directly from traditional antennas, the proposed method adopts reverse thinking to transform scattering optimization into radiation optimization, realizing the integration between metasurface and antenna, thus making low-RCS antenna design easier and faster.

Composite metamaterial antenna with super mechanical and electromagnetic performances integrated by three-dimensional weaving technique

The integration of structure and function was crucial for the application of microstrip antennas. Layered microstrip antennas were prone to delamination, which severely limits their performance stability. The textile conformal microstrip antenna with integrated structure design prevented the layered failure and greatly improved the damage resistance of the antenna. However, textiles had an inherent deficiency in suppressing surface waves due to their discontinuous mesh structure, critically deteriorating the radiation performance of microstrip antennas. Electromagnetic metamaterial with a specific pattern resonated in the excitation of electromagnetic waves to form a forbidden bandgap, which was expected to suppress surface wave radiation of microstrip antennas. In this study, a textile-based microstrip antenna integrated with electromagnetic metamaterials (MA-EBG) was proposed by embedding conductive copper wires in three-dimensional (3D) spacer fabric to form an integrated structure. Due to the function of the forbidden bandgap in metamaterial structure, the surface wave radiation was suppressed and the gain of antenna was increased from 5.1 dB to 9.6 dB. Owing to the tight physical binding, MA-EBG retained its structural integrity with proper electromagnetic performance under the impact of 24 J. The application of electromagnetic metamaterials elevated the gain of textile-based microstrip antennas, which provided a new method for the design of high-gain textile-based microstrip antennas with excellent mechanical properties.

Design of Rocket‐Borne Data Transmission System for Sounding Rocket

The design of a rocket‐borne data transmission system is presented in this article. This data transmission system is used for Meridian Space Weather Monitoring Project II sounding rocket. The major function of this data transmission system is to transmit payload data and rocket telemetry data to ground station. The data transmission system achieves power greater than 4 W (36 dBm). The amplitude unbalance is 1.60% (0.14 dB) and the phase unbalance is 1.74°. Total power consumption of the data transmission system is less than 24 W (28 V power supply). The radiation performance of the data transmission antenna is good. Based on the actual condition of solid rocket, the relevant heat dissipation and vibration reduction measures are designed under the demand of miniaturization. The data transmission system has been tested by performance test, environmental simulation test, system integration test, and other tests; the test results show that it has good working performance, good stability, and high reliability.

A novel dual-band–high-gain terahertz MIMO antenna

In this study, a terahertz dual-band–high-gain, multi-input–multi-output (MIMO) antenna with two and four input ports was realized, with gain values of up to 7.16[Formula: see text]dBi and 6.44[Formula: see text]dBi, respectively. This represents an increase in gain of 102.4% and 81.8%, respectively, compared to single-input port antennas. By calculating and analyzing the voltage standing wave ratio (VSWR), gain, envelope correlation coefficient (ECC), and diversity gain, the two MIMO antennas achieved perfect impedance matching at their resonance points. Moreover, the interference between the elements of the MIMO antenna was small, and an isolation effect between the units was realized. These MIMO antennas can achieve multiple input signals to regulate the antenna radiation performance and improve signal strength and quality. In addition, they possess good development prospects for achieving high-speed data transmission in the terahertz band and in mobile communication.

A low profile perturbed CDRA with convex conformal ground plane excited by differential feed

A low profile, Convex Conformal Cylindrical Dielectric Resonator Antenna (CCCDRA) with perturbation excited by dual coaxial probes in Differential Feed Arrangement (DFA) with TM11δ and TM21δ modes being observed at 7.7 GHz, and 8.7 GHz respectively, is presented and examined in this paper. The radiation performance of the bent Cylindrical Dielectric Resonator Antenna (CDRA) is investigated and it can be observed that at the bent angle of φ1 = 24°, high broadside gain is obtained therefore it is chosen for the proposed design. Investigation on the DFA is carried out and it is observed that the differentially driven CDRA offers a low cross polarization as well as directional broadside radiation pattern. Wide impedance bandwidth is achieved by perturbing the CDRA in such a way so as to maximize the Surface Area to Volume (S/V) ratio, resulting in lowering the Q-factor. A high-gain of 9.6 dBi at 8 GHz for wideband wireless applications, featuring 30.5 % fractional bandwidth is achieved. Additionally, the proposed CDRA has a height of 0.16 λ0 with a low profile. The simulation results are found to be in good agreement with the experimental measurements performed on a fabricated prototype.

Design and Performance Analysis of Rectangular Microstrip Patch Antennas Using Different Feeding Techniques for 5G Applications

In this article, the design and performance of a novel rectangular microstrip patch antenna (RMPA) utilizing the dielectric substrate material FR4 of relative permittivity (Ԑr = 4.3) and thickness (h = 0.254 mm) is proposed to operate at (fr = 28 GHz). Three different feeding techniques (microstrip inset line, coaxial probe, and proximity coupled line) are investigated to improve the antenna radiation performance especially the antenna gain and bandwidth using Computer Simulation Technology (CST) and High Frequency Structure Simulator (HFSS). The simulated frequency responses generally reveal that the proximity-coupled fed provides extremely directive pattern and maintain higher radiation performance regardless of its antenna size which is larger than the other considered feeding ones. With the presence of the three feeding techniques, the gain is improved from 5.50 dB to 6.83 dB additionally, the antenna bandwidth is improved from 0.6 GHz to 3.60 GHz at fr = 28 GHz when the reflection coefficient S11= -10 dB. Compared to the previously designed RMPA, the proposed design has the advantages of reliable size, larger bandwidth and higher gain, which make it more suitable for many 5G application systems.

Analytical solutions for resonant radiation performance of bending-mode magnetoelectric antennas

This paper proposes analytical solutions for the resonant radiation performance of bending-mode magnetoelectric (ME) antennas. The strain-mediated Converse ME (CME) coupling model of bending-mode ME antennas is first established by solving nonlinear constitutive equations and bending governing equations using the elastic mechanics method. Then, the calculated magnetic flux and electric displacement are employed to propose a resonant radiation field model based on the dipole method. The numerical results for the CME coefficient show a good agreement with the experimental data. It can be observed that the volume fraction ratio of the piezoelectric layer can control the CME coefficient and radiation efficiency with the same variation trend since it can determine the bending strain via changing the location of the neutral layer of the ME antennas, which also demonstrates the strain-mediated essence of the ME antennas. In addition, the volume fraction ratio can tune the resonant frequency within a wide range. The gain of the ME antenna is stable and higher than −168 dB with the volume fraction ratio ranging from 0.2 to 0.7. The tensile stress and compressive stress have the opposite effect on the resonant frequency at low and high bias magnetic fields. Meanwhile, the tensile (compressive) stress is beneficial for both the radiation and gain in the low (high) bias field region. This model may facilitate the understanding of the bending-mode radiation mechanism of ME antennas and provide a basis for designing asymmetric ME antennas.

A Low RCS and Array-Insensitive FSS Wideband Radome

In order to further expand the RCS reduction model of the miniature broadband antenna, a four-notch shaped FSS radome insensitive to the number of array elements is designed based on the multi-layered medium Green’s function and the transflective coefficient of the finite radome is derived. The calculated results are in good agreement with the infinite array, showing broadband transmission performance in both C-band and X-band. The electric field distribution and far-field distribution of a finite FSS array are given and the effects of a 5 × 5 array in a V-shaped structure on the surface of a miniature broadband antenna on its gain coefficient and RCS reduction characteristics are calculated numerically. The results show that the designed radome exhibits good array element insensitivity and far-field scattering reduction characteristics and achieves significant in-band and out-of-band RCS accurate reduction under the premise of constant antenna radiation performance. At normal incidence, the single-station RCS in the passband and stopband are as low as −35 dB and −32.66 dB, respectively. The maximum reduction in the transmission band reaches 20.96 dB under oblique incidence and the projection size of the radome decreases with the increase in the bottom angle of the radome but the RSC reduction performance is basically unaffected and can be adjusted flexibly according to actual needs. The above results provide a theoretical basis and technical support for the application of FSS radome in RCS reduction in micro wideband antennas.

A Novel L-Shaped Metalens for Ultra-Wide Band (UWB) Antenna Gain Improvement

In this work, a novel metamaterial lens (metalens) is designed and optimized to improve the radiation performance of an antipodal Vivaldi antenna for wideband applications. The metalens is integrated into the antenna substrate, and placed close to the tapered slot in the end-fire direction, allowing the preservation of the lightweight and compactness of the antenna. The prototype has been fabricated and characterized, demonstrating good agreement with the simulations. The insertion of the metalens allows, with respect to the pristine Vivaldi, a measured maximum gain of Gmax=14.2 dB, increased by about ΔGmax=4.8 dB; an operating bandwidth of f=3÷14.7 GHz, increased by Δf=1.2 GHz; and a radiation pattern with a maximum reduction in half-power beamwidth of ΔHPBWmax=31.3°, more symmetrical in the E and H planes.

A simple decoupling method applied in gain improvement of a planar array antenna

AbstractA 4 × 4 patch array antenna based on loading shorting vias is proposed in this letter. The excitation method of the array antenna adopts stripline coupling feed, leading to a strong mutual coupling between the adjacent elements. The realized gain and impedance match are deteriorated seriously. Then, eight groups of metallic vias are introduced to the array antenna. By adjusting their number and spacing, the radiation performance of the array antenna can be improved significantly. Finally, the experiment results show that the proposed array antenna resonates at 5.4 GHz. Compared with the antenna without shorting vias, one resonance point caused by the mutual coupling can be removed within 5.34 GHz to 5.46 GHz. The gain drops unexpectedly, which is improved as well.

Analysis and Measurement of Large Circular Transmitting Arrays for Microwave Power Transmission

Phased arrays have been widely used in microwave power transmission. The efficiency of rectenna is closely related to the received power density. Therefore, it is necessary to accurately analyze the radiation performance of the transmitting array in order to achieve the high-efficiency power transmission. And in order to meet the long-distance and high-efficiency power transmission requirements, the transmitting array needs to have the characteristics of large electricity sizes. The direct numerical analysis method of entire array will bring huge cost in computing time and storage space. Subarray extrapolation is a method to reasonably account for the edge effects of arrays, but only for rectangular arrays. Aiming at the geometric characteristics of the array contour, this communication proposes an irregular contour recognition method. This method can expand the application of subarray extrapolation method and realizes the purpose of accurately evaluating the radiation performance of large array antennas at small calculation cost. Finally, using a large transmitting array as an example, the proposed method is verified by comparing the results of subarray extrapolation, commercial software of entire array, and the experimental measurement to validate the correctness and advancement.

A High-Gain Wideband Microstrip Patch Antenna With Folded Ground Walls

This letter proposes an approach to improve the gain of a microstrip patch antenna on a suspended substrate without compromising its bandwidth. The ground plane of the antenna is folded upward to form sidewalls parallel to the nonradiating edges. The distance from the patch edges and the height of the sidewalls are determined to maximize the radiation performance of the resultant antenna. This approach results in a peak gain better than 12 dBi and impedance bandwidth of around 45 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> . Simulation studies indicate that sidewalls parallel to radiating edges degrade the antenna performance.

DESIGN OF A COMPACT BROADBAND ANTENNA USING CHARACTERISTIC MODE ANALYSIS FOR MICROWAVE APPLICATIONS

A compact broadband antenna of dimensions 27 mm x 28 mm x 1.6 mm and with good impedance matching is designed for high-bandwidth radio systems with a short range. To improve the impedance matching, two rectangular slots are created on the radiating element, and the ground plane size is reduced to extend the ultra-wideband frequency band. The antenna bandwidth and radiation performance are analysed using characteristic mode theory (TCM). The performance is compared to the desired specifications, and the shape and size are modified to produce efficient radiation and dominant radiation patterns. The findings clearly demonstrate that the six modes are resonant with (λn = 0). This implies that the eigenvalues of the six modes contribute strongly to dominant electromagnetic radiation and have high modal significance values around 1 at their respective frequencies. Furthermore, the characteristic angle indicates that the antenna resonates at 180°, since the six modes intersect the axis line at 180° at their respective frequencies. Experimental results show a bandwidth of 109.7% between 5.64 and 19.34 GHz, a maximum gain of 6.3 dB, and a maximum efficiency of approximately 86.5%. These results make this antenna a versatile and effective choice for a wide variety of communications and electronics applications and easy to install in narrow spaces due to its easy design characteristics, small size, and light weight.

AMC-Based Low-Profile Dual-Band Slotted Patch Antenna for IoT Devices in the Healthcare System

An artificial magnetic conductor (AMC)-based patch antenna with a low profile is developed for wireless devices in IoT-based healthcare systems. The proposed antenna comprises two pairs of circular-shaped patches with circular-shaped slots and a dual-band 4 × 4 array of AMC reflectors with two zero-degree reflection responses to enhance the antenna's radiation performance. For the 2.45 GHz ISM and 5.4 GHz WLAN bands, the patch antenna has dimensions of 0.44λ0 × 0.52λ0 × 0.013λ0, with partial ground structures to improve radiation characteristics. Following that, a unique dual-band symmetrical AMC unit cell with dimensions of 22 × 22 × 1.6 mm3 is developed. There is a gap of 15 mm between the antenna and the AMC surface. The antenna is supported by a 4 × 4 AMC array that has a total dimension of 0.72λ0 × 0.72λ0 × 0.15λ0. The reflection coefficient values of less than − 10 dB in the 1.7–2.5 and 5.1–5.6 GHz bands, with a bandwidth percentage of 38 and 9.3%, respectively. The antenna's gains were 7.2 and 4 dBi inside the bands. Furthermore, the Specific Absorption Rate (SAR) value did not match the WHO's safety and health guidelines. The issue was solved by including an AMC surface in the proposed antenna. At 2.45 and 5.4 GHz, SAR values of 0.58 and 1.04 W/Kg were measured. Vector network analyser and anechoic chamber were used to test the performance of antenna and AMC surface prototypes. There is a substantial agreement among measured and simulated parameters of an antenna. Consequently, the developed antenna combination with the AMC structure is suited for wireless devices in ISM and WLAN bands, often used in IoT-based healthcare systems.

Radiation Performance of Different Triangular Microstrip Patch Antenna Configuration Shapes Operating at 28 GHz

The radiation performance of different triangular microstrip patch antenna (TMPA) shapes such as right triangle (RTMPA), isosceles triangle (ITMPA), obtuse triangle (OTMPA), and equilateral triangle (ETMPA) operating at (28 GHz) are computed and compared using inset-fed techniques and Rogers-RT5880 substrate material of permittivity and (h=0.15 mm) height. The directivity, gain, efficiency, bandwidth, VSWR, S11 and 2D-radiation pattern for each mentioned triangular patch shapes are computed utilizing CST and HFSS method. The computed results reveal generally that the ETMPA provide better radiation performance whereas the OTMPA displays lower antenna radiation parameter values compared to the other considered ones. In addition, the antenna parameters of ETMPA with the use of coaxial probe fed are also simulated and the results are compared to those previously achieved experimentally and theoretically by other researchers. Generally, a good agreement between mentioned antenna parameter results is displayed and reliability of those achieved by CST with inset fed techniques is clearly observed. Moreover, the overall antenna parameter obtained, respectively, with CST and HFSS techniques for inset fed ETMPA are S11 (-28.68, -20.64), VSWR (1.076,1.20), gain (5.82, 6.29) dB, directivity (6.85, 7.09) dB, bandwidth (0.452, 0.369) GHz, efficiency (78.9%, 83.2%) and with a small antenna size of about (3.88 mm3) which is most reliable for 5G technology application systems.