Radiation Characteristics Of Antenna Research Articles

A novel multi-resonant and wideband fractal antenna for telecommunication applications

<span>This letter presents the design, simulation, and measurement of a novel multiband fractal circular antenna for wireless applications. In the antenna design, we used a circular antenna where we took a ring. Then, in the first iteration, we added a new ring divided into two of the same size. For the second iteration, we added a ring of the same size after dividing it into two halves. In the third iteration, we added the third ring of the same size after dividing it into four. Due to the resonator defection, we were able to reduce the size of the starting antenna from 60×70×2 mm<sup>3</sup> to 50×50×1.6 mm<sup>3</sup>, to get the frequency of 2.48 GHz, and we generated new bandwidths with a high gain that reaches 5.02 dB. The proposed antenna radiation characteristics, such as the impedance matching, the gain, the radiation pattern, and the surface current distribution are presented and discussed. We find that the simulated and measured results are in acceptable agreement and affirm the good performance of the proposed antenna. The results obtained affirm that the proposed fractal antenna is a better candidate for integration into wireless communication circuits.</span>

Performance Analysis of Wearable Dual-Band Patch Antenna Based on EBG and SRR Surfaces.

This paper presents the performance comparison of a dual-band conventional antenna with a split-ring resonator (SRR)- and electromagnetic bandgap (EBG)-based dual-band design operating at 2.4 GHz and 5.4 GHz. The compactness and dual-frequency operation in the legacy Wi-Fi range of this design make it highly favorable for wearable sensor network-based Internet of Things (IoT) applications. Considering the current need for wearable antennas, wash cotton (with a relative permittivity of 1.51) is used as a substrate material for both conventional and metamaterial-based antennas. The radiation characteristics of the conventional antenna are compared with the EBG and SRR ground planes-based antennas in terms of return loss, gain, and efficiency. It is found that the SRR-based antenna is more efficient in terms of gain and surface wave suppression as well as more compact in comparison with its two counterparts. The compared results are found to be based on two distinct frequency ranges, namely, 2.4 GHz and 5.4 GHz. The suggested SRR-based antenna exhibits improved performance at 5.4 GHz, with gains of 7.39 dbi, bandwidths of 374 MHz, total efficiencies of 64.7%, and HPBWs of 43.2 degrees. The measurements made in bent condition are 6.22 db, 313 MHz, 52.45%, and 22.3 degrees, respectively. The three considered antennas (conventional, EBG-based, and SRR-based) are designed with a compact size to be well-suited for biomedical sensors, and specific absorption rate (SAR) analysis is performed to ensure user safety. In addition, the performance of the proposed antenna under bending conditions is also considered to present a realistic approach for a practical antenna design.

Effect of Buildings on the Radiation Characteristics of MF Broadcast Antennas

This study aims to investigate the impact of the presence of buildings on the radiation characteristics of MF broadcast antennas. Two different antennas are considered: a monopole operating at 1494 kHz and a two-element linear array radiating at 1008 kHz. The buildings were modeled as wire-grids and the total electric field intensity was calculated as the sum of the scattered field by the wire-grid and the field radiated from the antenna in free space. The radiation pattern of the antennas, when one or two buildings were situated in their vicinity, were the end result of the analysis, and they were compared to the corresponding patterns in free space. The results demonstrate that the radiation characteristics of antennas are mostly affected by the heights of buildings. If these heights are less than a critical value, the buildings do not significantly obstruct the operation of the antenna, despite the value of other parameters, such as the length and the width of the buildings, as well as their distance from the antenna.

A Double-Layer Patch Antenna for 5-6 GHz Wireless Communication.

This paper proposes a compact double-layer microstrip patch antenna with a wide bandwidth of 4.83–6.1 GHz and a gain reaching 4.7 dBi. By folding its mirror image through the electric field symmetry principle of the microstrip antenna, its electrical properties are maintained, and the physical size is halved to the compact size of only 25 × 40 mm2. The proposed antenna has the radiation characteristics of a planar inverted-F antenna (PIFA), which can generate the first resonant frequency and realize omnidirectional radiation characteristics. By coupling and feeding the upper patch, the second resonant frequency of the proposed antenna is produced and the directional radiation characteristics of the microstrip patch antenna can be achieved. The consistency of the results between the simulation and test indicates that the proposed antenna design is an ideal potential choice for home wireless local area network (WLAN) communication.

Radiation pattern in a tunable plasma window antenna

The work aims to theoretically and experimentally investigate the radiation characteristics of the plasma window antenna for beam-steering applications. The antenna system consists of a wire antenna in the center, surrounded by a circular array of 22 cylindrical plasma columns. The research reveals that the radiation pattern of the antenna system can be simply controlled by exploiting the variable parameters, such as working frequency, driving current, and plasma configurations. It implies that the beam narrows as the plasma antenna aperture decreases, implying a greater directivity. By electrically tuning the plasma, a maximum directivity of 9.09 dBi and a minimum half-power beam width of 35.86∘ emerged for a specific configuration. The results show that higher currents prevent radiation from escaping from the plasma shell, while higher frequency microwaves are more likely to penetrate the plasma blanket.

Triple Band Mime Antenna for Modern Commercial Applications

The article presents the analysis and design of MIMO monopoly Antenna along with split ring resonator to get frequency notch characteristic in the wide band. Frequency notch characteristics are achieved by keeping the split ring resonators on one side of the substrate and on the back of the substrate at deficient ground structure a complementary split Ring resonator with respect to microstrip feeding. Between 2.5-9.5GHz and 12.548-20GHz the dual notch band characteristics are acquired. The inspected conformal characteristics of the antenna hold eminent unceasing reflection coefficient characteristics at different angles in the overall band. Analyzed the unit cell of the SRR and also examined the antenna impedance and radiation characteristics of the model.

Flexible CP diversity antenna for 5G cellular Vehicle-to-Everything applications

A flexible circularly polarized (CP) MIMO antenna is evaluated for Sub-6 GHz 5G and cellular-vehicle-to-everything (C-V2X) applications. The design radiates CP waves with an L-shaped feed line and a modified ground plane embedded in the slot antenna. The MIMO design resonates in the band of frequencies 3.23–6.26 GHz and radiates CP waves in the 2.95 – 6.02 GHz frequency band. This antenna model is suitable for LTE-V2X/ 5G (3.3 to 4.2 GHz), WLAN 5.2 GHz, WiMAX 5.5 GHz, and IEEE 802.11p (5.85–5.925 GHz) vehicular application bands. Here both planar and antenna conformed on foam material and a car wing mirror are investigated. Improved lowest isolation of 18.2 dB is achieved in the entire working band using the orthogonal CP arrangement of elements. The diversity functionality is tested in terms of ECC, MEG, CCL, etc. Further, the antenna radiation characteristics are tested by positioning it on the vehicle roof-top and side mirror using the Ansys savant tool.

An ultrawideband miniaturized MIMO antenna with split ring Yagi like structures for S and X frequency multiband applications

A miniaturized three split ring-like Multiple-Input Multiple-Output (MIMO) antenna is presented for the S and X frequency band applications. The proposed antenna has been numerically investigated at operating frequency 1-15 gigahertz (GHz). The MIMO antenna is analyzed, and its prototype is measured in five types of structure to identify the effect of the split ring and other physical conditions. This antenna is fabricated on the FR- 4 substrates with a dimension of 25 mm × 40 mm which will provide the miniaturization factor of λ/2. The high gain of 6.61 dBi and an ultrawideband of 3.25 GHz is achieved by using split-ring resonators (SRRs) in the proposed miniaturized MIMO antenna structure. We have also analyzed the effect of the split rings on the overall radiation band and return loss on the S and X frequency band. Furthermore, the prototype measurement confirms the suggested antenna radiation characteristics.

Visualization of 5G antenna radiation characteristics using 3D printed models – focusing on busting the myths and finding out the truth about 5G health issues

The developments of mobile communication technology accompanied by increase in the number of high frequency bands and antennas, gave the public a negative perception that 5G is harmful to human health. Recently, rumors circulated on social media that 5G spreads COVID-19 and the pandemic. Leaving this situation untouched will hinder the successful landing of 5G and the development of 6G technology. Hence, the misunderstanding and groundless belief in 5G need to be corrected. We believe that misunderstanding and myths about 5G communications stem from fears of invisible electromagnetic waves. We visualize and compare the 5G and 4G antennas’ radiation properties by creating models with 3D printing technology to offer an intuitive impression of antenna characteristics and dispel the invisible fear. The radiation characteristics of the antennas used in 5G and 4G base stations and smartphones and their impacts on the human body are analyzed by using the electromagnetic simulator, HFSS.

Far-Field Radiation Characteristics of Folded Monopole Antennas over a Conducting Ground Plane

Folded monopole structures have been used for many applications, including low-frequency electromagnetic wave transmission and reception. However, the literature on these antenna types is quite limited. Folded monopole antennas are mathematically complex compared to conventional monopole or dipole antennas since every fold introduces a new set of design parameters. This work studied the far-field radiation characteristics of multi-folded monopole antennas operating at 75 MHz in terms of their radiated power concerning the frequency, the far-field directivity of the electric field, and the effect of each design parameter on the far-field radiation power. According to the results, folding a monopole antenna multiple times increases its effective length, making this antenna a suitable candidate for applications where the antenna height is restricted. Additionally, the ground-to-wire separation has the biggest effect on radiated power. In both single-fold and two-fold cases, doubling the ground-to-wire separation increased the radiated power by 0.2 W compared to the other models with the same number of folds. As for the challenges, the impedance mismatch between the source and antenna causes a significant amount of power reflection; hence, suitable impedance matching is required to reduce reflected power.

Phaseless Spherical Near-Field to Far-Field Transformation Algorithm via Sparsity of Spherical Mode Coefficients

In order to overcome the difficulty in obtaining accurate phase information in antenna near-field measurement, this study proposes a phase recovery algorithm that can be applied to phaseless spherical near-field sampling data. Based on the sparsity of spherical mode coefficients (SMCs), under the condition of unknown sparsity level and low oversampling rate, the proposed algorithm can accurately recover SMC to obtain high-precision antenna radiation characteristics. To improve the recovery performance of the algorithm, a spherical sampling strategy matching with the algorithm is also presented. By calculating the correlation of the measurement matrix and comparing the accuracy of the reconstructed far field, a set of optimal parameter settings including the number of spheres, the distribution of the measurement points, radius difference, and polarization mode is determined. On the basis of the obtained measurement data, the performance advantage of the presented algorithm in recovering SMC is demonstrated.

A Vivaldi Antenna with Improved Bandwidth and Gain

In this paper, the radiation characteristics of the conventional Vivaldi antenna are improved by proposing a novel design of a Vivaldi antenna. This proposed Vivaldi antenna is excited through three slots by using the L-probe microstrip feeder. The novel design can provide higher gain and wider bandwidth compared to that of the conventional Vivaldi antenna of the same size. The CST MWS software is used to simulate the proposed Vivaldi antenna. The measured and the simulated S-parameters were compared so that the feasibility of the proposed Vivaldi antenna was validated. The measured S-parameters show that the impedance bandwidth of the proposed Vivaldi antenna was from 1.976 to 7.728 GHz, while the measured maximum gain is 4.9 dBi at the operating frequency of 3 GHz.

A 3D Printed Nearly Isotropic Luneburg Lens Antenna for Millimeter-Wave Vehicular Networks

A three-dimensional (3D) printed Luneburg lens with nearly isotropic properties is presented. The cubical-lattice-type and the rod-type gradient-index materials are employed together to construct the novel printable spherical lens geometry, whose nearly isotropic properties improve the antenna radiation characteristics significantly. The dual-polarized radiation beam generated by the lens antenna can steer in a wide angular range with stable performance throughout a wide operating band. A prototype with an equivalent radius of 16.8 mm is printed and measured in the Ka-band. An impedance bandwidth of more than 40% for |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> | of less than −17.5 dB, a gain of up to 21.3 dBi, and promising radiation patterns with the dual polarization scanning in an angular range of ±60° are obtained experimentally. With the advantages of satisfying operating performance and ease of realization, the lens investigated in this paper would be an attractive candidate for the wireless applications in millimeter-wave vehicular networks.

Performance Improvement of Aperture Coupled MSA through Si Micromachining

In recent times rectangular patch antenna design has become the most innovative and popular subject due to its advantages, such as being lightweight, conformal, ease to fabricate, low cost and small size. In this paper design of aperture coupled microstrip patch antenna (MSA) on high index semiconductor material coupled with micromachining technique for performance enhancement is discussed. The performance in terms of return loss bandwidth, gain, cross-polarization and antenna efficiency is compared with standard aperture coupled antenna. Micromachining underneath of the patch helps in to reduce the effective dielectric constant, which is desirable for the radiation characteristics of the patch antenna. Improvement 36 percent and 18 percent in return loss bandwidth and gain respectively achieved using micromachined aperture coupled feed patch, which is due to the reduction in losses, suppression of surface waves and substrate modes. In this article along with design, fabrication aspects on Si substrate using MEMS process also discussed. Presented antenna design is proposed antenna can be useful in smart antenna arrays suitable in satellite, radar communication applications. Two topologies at X-band are fabricated and comparison between aperture coupled and micromachined aperture coupled are presented. Index Terms—Microstrip Patch Antenna, Aperture Coupled, Micromachining, High Resistivity Silicon

A loop antenna with quasi‐two sources for circular polarisation

A novel method of exciting a circularly polarised (CP) loop antenna is proposed using the moment method. A horizontal square loop above the ground plane has two corners connected to a vertical, branched feedline with one source. First, the authors show the radiation characteristics of a reference antenna whose corners are excited with two sources having the same amplitudes and a phase difference of 90°. Next, we excite the loop corners with one source using the branched feedline. It is found that when the branch location along the feedline is selected, the antenna radiates a CP wave. The frequency responses of the antenna show that the 3 dB axial-ratio bandwidth is 12%, where the gain is more than 7.3 dBi. The simulated results are verified with experimental ones.

A Compact Self-Isolated MIMO Antenna System for 5G Mobile Terminals

A compact self-isolated Multi Input Multi Output (MIMO) antenna array is presented for 5G mobile phone devices. The proposed antenna system is operating at the 3.5 GHz band (3400–3600 MHz) and consists of eight antenna elements placed along two side edges of a mobile device, which meets the current trend requirements of full-screen smartphone devices. Each antenna element is divided into two parts, a front part and back part. The front part consists of an I-shaped feeding line and a modified Hilbert fractal monopole antenna, whereas the back part is an L-shaped element shorted to the system ground by a 0.5 mm short stub. A desirable compactness can be obtained by utilizing the Hilbert space-filling property where the antenna element’s overall planar size printed on the side-edge frame is just (9.57 mm × 5.99 mm). The proposed MIMO antenna system has been simulated, analyzed, fabricated and tested. Based on the self-isolated property, good isolation (better than 15 dB) is attained without employing additional decoupling elements and/or isolation techniques, which increases system complexity and reduces the antenna efficiency. The scattering parameters, antenna efficiencies, antenna gains, and antenna radiation characteristics are investigated to assess the proposed antenna performance. For evaluating the proposed antenna array system performance, the Envelope Correlation Coefficients (ECCs), Mean Effective Gains (MEGs) and channel capacity are calculated. Desirable antenna and MIMO performances are evaluated to confirm the suitability of the proposed MIMO antenna system for 5G mobile terminals.

Influence of static strong magnetic field on antenna radiation in hypersonic vehicle

To enhance the radiation performance of the Beidou antenna in the near-space hypersonic vehicle, the static strong magnetic field is used to weaken the electron density in plasma surrounding the antenna. In order to demonstrate the effect of this program, a time-domain multi-physical method is proposed. In the proposed method, what is first analyzed is the reduction of electron concentration in plasma sheath by static strong magnetic field with the spectral element time domain (SETD) method, which has spectral accuracy. Then, the electron density after mitigation is extracted to replace the original electron concentration around the antenna. Hence, the distribution of the manipulated plasma sheath can be obtained. Finally, the radiation characteristics of BeiDou antenna installed in the vehicle are analyzed by the conformal finite difference time domain (CFDTD) method. The simulation results exhibit radiation patterns under different conditions. With the plasma sheath, the radiated electromagnetic waves are greatly attenuated, which will significantly affect the transmission of communication signals. Importantly, the radiation patterns are effectively improved with the external static magnetic field, confirming that it provides an effective tool to mitigate the influence of plasma sheath on the radiation performance of antenna in hypersonic vehicle.

Ultra-Wideband Coplanar Vivaldi Antenna Array With Dielectric Patch Antenna for Grating Lobes Suppression

This paper details a new approach for enhancing the radiation characteristics of a coplanar Vivaldi antenna (CVA) array. First, the inter–element mutual coupling is reduced by introducing slots in the conventional CVA array. Then, a low-profile dielectric patch antenna (DPA) is situated between the CVA flares when it acts as a travelling wave radiator at the higher frequency band. The DPA is excited by the loop current at the radiation part of the CVA and a set of TE modes with omnidirectional radiation patterns are excited. This combination enhances the directivity in the broadside direction of the CVA by suppressing the grating lobes by as much as 10 dB. The 4×1 linear array covers the frequency range of 2.77-13.6 GHz, with 132% fractional bandwidth. Then, four of the proposed linear arrays are connected to constitute an 8×2 planar array to achieve a gain of 15.2-24.6 dBi. The proposed arrays are fabricated, tested and mounted on a small (Unmanned Aerial System) sUAS for radar measurements. The real-life field radar results with the proposed arrays are presented in this paper including the echogram of the scanned area.

Reconfigurable Filtenna using Varactor Diode for Wireless Applications

This paper presents a compact and planar reconfigurable filtenna for application in Wireless systems. The filtenna is composed of a UWB circular antenna and a filter with two trapezoidal resonators. The filter is integrated on the antenna feed line and has a band-pass frequency response. The filtenna frequency response reconfiguration is achieved by changing the capacitance of a varactor diode, placed between filter resonators; the capacitance varies continuously from 1.32 pF to 4.09 pF according to an applied bias voltage. The varactor capacitance analog variation defines the filtenna frequency of operation, which can be varied from 2.2 GHz to 3.4 GHz with an average bandwidth of 200 MHz, while maintaining the radiation characteristics of the UWB antenna. Simulated and measured filtenna results are shown according to varactor diode bias, demonstrating multiband operation using a compact planar design.

A Novel Perforated Rectangular Dielectric Resonator Antenna with Semi Elliptical Conformal Feed for C-Band Applications

ABSTRACT In this article, a compact perforated rectangular dielectric resonator antenna (RDRA) for wideband applications is proposed. The basic RDRA is perforated to increase the bandwidth while lowering the quality factor. The resonator is fed by a semi-elliptical conformal microstrip line. A rectangular slot is etched at the center of the ground plane to optimize the radiation characteristics of the DR antenna. This topology offers 90.6% (4.08 –8.15 GHz) simulated bandwidth, and 97.2% (3.99 –8.23 GHz) measured bandwidth for dB with a gain of 3.5–7.8 dB tested over the operating bandwidth with more than 94% efficiency. mode at 4.5 GHz and mode at 6.4 GHz is excited by choosing optimized dimensions of the RDRA. The proposed antenna is best suitable for the entire C-band applications.