Antenna Efficiency Research Articles

Superdirective Wideband Array of Circular Monopoles with Loaded Patches for Wireless Communications.

A wideband superdirective array, composed of a two-element circular monopole configuration, is introduced. The monopoles are placed in close proximity, facing each other on a metal ground. To ensure good matching at high frequencies, two pairs of elliptical patches are added to the sides of the monopoles, enhancing the surface current of the circular patch for wideband performance. To achieve equal amplitude excitation and the desired phase difference, a wideband power divider with a phase shifter is designed to feed the antenna array. Simulation and measurement results demonstrate that the proposed wideband antenna array, operating within the frequency range of 2.94-7.93 GHz, exhibits a maximum directivity of 8.36-10 dBi, with an antenna efficiency ranging from 47.86 to 83.18% across the bandwidth. The proposed array has the advantages of miniaturization, high directivity and wideband operation and can be widely used in various portable wireless communication systems, including WLAN (5.05-5.9 GHz), ISM (5.725-5.875 GHz), 5G communication (3.3-3.8 GHz), etc.

A low-profile flower-shaped MIMO antenna for wireless applications

ABSTRACT A low-profile, compact and efficient antenna is especially desirable for wireless applications, as it can reduce the size and weight of the system and improve its performance. In recent years, flower-shaped antennas have gained popularity due to their low profile, broad bandwidth and good radiation characteristics. In this work, a high-isolated dual-element UWB-MIMO antenna is experimentally verified having size of 32 × 39 × 0.8 mm3. The main radiating element of MIMO setup comprises a Half-Cut Flower-Shaped (HCFS) resonator. A tree-shaped decoupling structure is use to enhance the isolation. The simulated operating band of the proposed 2-port UWB-MIMO antenna ranges from 2.3 to 2.68 GHz and 3.15 to 12.87 GHz which covers Bluetooth, Wi-Fi/WLAN, Wi-MAX and UWB) with inter-element isolation of more than 15 dB and 20 dB, respectively. The measured results are found in close agreement with simulated ones. Furthermore, the diversity parameters such as Envelope Correlation Coefficient (ECC), Channel Capacity Loss (CCL), Mean Effective Gain (MEG), Effective Diversity Gain (EDG) and Total Active Reflection Coefficient (TARC) have also been analysed to ensure its legitimacy for wireless applications. Moreover, the simulation S-parameters characteristic of the proposed 8-element antenna for wireless access point applications has also been showcased.

A wideband substrate integrated waveguide (SIW) antenna using shorted vias for 5G communications

Antennas that have a higher gain and greater efficiency across a broader frequency range are more advantageous and effective. Achieving these characteristics at higher frequency ranges while maintaining a small footprint adds complexity to antenna design. This study investigates and designs a slotted patch antenna (SPA) for the 5G n257 (28 GHz) and n258 (26 GHz) frequency bands, which are supported by a substrate-integrated waveguide (SIW) cavity. This antenna features excellent gain and efficiency coupled with a broader bandwidth. The developed antenna has a wide frequency bandwidth of 3.9 GHz, approximately 14.4% of the central frequency and a peak gain of 7.5 dB. Slots having L type shape are etched into the ground plane, and two shorting vias are placed below each L slot to improve the impedance bandwidth. The dielectric substrate material RT/Duroid 5880 with εr = 2.2 and a thickness of 0.787 mm are employed. The discussed antenna operates between 25.1 GHz and 29 GHz. The antenna is excited by a 50 Ω microstrip transmission line to SIW transition modified taper for optimal electrical performance. The developed antenna displays dual resonant characteristics, one at 26.1 GHz and another at 28.5 GHz. The overall physical dimension of the antenna is only 14 × 18 × 0.787 mm3. The electrical dimensions are 1.26 λu × 1.62 λu × 0.0708 λu, where λu is the wavelength at the centre frequency in a vacuum. The antenna's performance can be comprehended using the reflection coefficient (S11), radiation patterns and electric field distribution. The research described herein compares the simulated antenna's performance and analysis with the experimental prototype. The suggested antenna has high gain, small size and broad spectral coverage—all of which make it ideal for 5G applications.

Exploring the geometry of miniaturized Archimedean SPIRAL Antennas for small and portable multitask devices

The focus of miniaturization is the production of small and portable devices that can be carried in the pocket anywhere and anytime. Small and portable devices that perform multitask such the smartphone requires a portable and efficient antenna that operates in many frequency bands. A single planar miniaturized Archimedean spiral antenna, which operates in a frequency range that is determined by its inner and outer radii of its arc, has been adjourned to be a better candidate for these multiple tasks. This study examined the geometry of a miniaturized Archimedean spiral antenna of varying turns. An inner radius of 4.90 mm and a thickness of 0.0356 mm suitable for the printed antenna were previously chosen for the study. The length of the arc and the outer radius were determined for spiral turns ranging from 0.5 to 100 with an incremental step of 0.5. Results revealed the radial distance generating the spiral, the length of its arc, the outer radius, and the surface area were 4.97 mm, 2 15.51 mm, 4.97 mm and 77.16 mm for 0.5 spiral turns, and 19.12 mm, 7,546.80 mm, 2,849.33 mm and 1,148.64 2 mm for 100 spiral turns. Based on the outer radii, the frequency range of operation will be between 16.76 MHz and 9.60 GHz. The mathematical functions formulated through curve fitting described the relationship between the outer radius and arc length with a power function and the number of turns and frequency with an exponential function, while arc length and radial distance, area and number of turns, and area and pitch angle are described by polynomial functions. It is recommended that further analysis on the geometry of the minimized Archimedean spiral antenna be conducted.

A 28/32/38 GHz Circularly Polarized DRA Micro-strip Antenna for 5G mm-Wave Applications

In modern communication system, mobile communication spectrum, below 3 GHz bands, faces more shortage and is not able to serve people with more efficient device connectivity and required data speed. Upon this background, 5G wireless communication – the 5th generation mobile technology standards are able to deliver high data rates, low latency communications, and massive device connectivity. For the efficient deployment of the 5G systems, and in order to support higher bandwidth, there is a dire need to design a compact and efficient antenna at mm wave frequencies (26/28 and 38). The resulting antenna, as the outcome, has been established to possess a compact size of 10 × 12 × 0.254 mm3 that covers three bands from the frequency spectra. The lower band resonant frequency is located at 26.74 GHz, the range between 25.44 GHz and 28.37 GHz, the middle band resonant frequency is located at 32 GHz, the range between of 31.08 GHz and 32.48 GHz, and the higher resonant frequency is located at 38.76 GHz, the range between 36.04 GHz and 40.34 GHz. In this article a modified novel structure of partial ground plane and DRA are used to get the better radiation enhancement and circular polarization. In this, the circularly polarized bands consist of the axial ratios <3 dB which are 27.95 GHz to 28.37 GHz, 31.08 GHz to 31.67 GHz, and 36.04 GHz to 38.73 GHz. The gain achieved is greater than 6.5 dBi and the efficiency is greater than 96% over the three bands. Ultimately, it is proved to the right option for 5G mm wave applications.

Wideband high-isolation antenna pair for 5G smartphones using multiple characteristic modes

A wideband and high-isolation mobile phone antenna pair with low envelope correlation coefficient (ECC) for fifth-generation (5G) smartphone applications based on four orthogonal modes is proposed in this communication. According to the characteristic mode analysis, except for the original two resonant modes, the other two resonant modes are introduced by arranging a metallic strip at the top of the vertical bezel. With the help of dual-mode excitation and orthogonal property, wideband and high-isolation merits are achieved for the shared radiator antenna pair. Finally, four antenna modules are deployed along the long edge of the system circuit board to form an 8 × 8 multiple-input multiple-output (MIMO) system. The measured results prove that the impedance matching bandwidth of the fabricated prototype ranges from 3.3 to 5 GHz while the isolation level is higher than 17.5 dB. The antenna efficiencies are higher than 45% and 48% for the two different antenna elements. Guaranteed by the orthogonal relationship between different characteristic modes, the extremely low ECC (<0.04) is achieved.

Photosensitization of TiO2 microspheres by novel Quinazoline-derivative as visible-light-harvesting antenna for enhanced Rhodamine B photodegradation

Water pollution is one of the global threats severely affecting our planet and human health. Organic textile dyes are one of the common organic water pollutants that are presentient to degradation by traditional physical methods. Semiconductor-assisted photocatalysis is considered a green, efficient, and sustainable technology for wastewater treatment. To maximize the efficient utilization of solar radiation, it is of pivotal significance to explore novel organic molecules to be employed as efficient dye sensitizers for wide-bandgap semiconductors to extend their performance to the Visible-light region. Hence, in this work, we are proposing the design and synthesis of novel structures of QAD molecule as a dye photosensitizer with extended visible light absorptivity due to the extended π–π/n–π conjugations, to promote the performance of TiO2 nanoparticles to the visible-light region and enhance the charge separation. The physicochemical characterizations confirmed the successful synthesis of QAD, TiO2, and QAD/TiO2 samples with the proposed structures. The anchoring of QAD molecules on the surface of TiO2 caused a substantial improvement in the optical characteristics of TiO2 as well as overcoming its common drawbacks by decreasing its bandgap energy to 2.6 eV, a remarkable reduction of PL intensity indicating reducing the e–h recombination and enhancing the charge separation, and creation of efficient visible light-harvesting antenna in the range of 400–600 nm. Besides, the QAD/TiO2 sample achieved a 3-fold enhancement in the observed rate constant of the photodegradation of Rhodamine B dye compared to the bare TiO2. The parameters affecting the photodegradation process were optimized and the sample displayed outstanding stability after 4 consecutive cycles. Finally, the effect of the scavengers was investigated and {mathrm{O}}_{2}^{cdot -} was proposed to be the most reactive species and the mechanism of the enhancement was suggested based on the electron injection from the QAD’s HOMO level to the TiO2’s CB. Finally, this work opens the door for various studies for the investigation of the proposed structures or similar structures in various photocatalytic/biomedical applications.

Synthesis, crystal structure, luminescent properties, and magnetic properties of lanthanide(III) complexes containing the chiral (S,S/R,R)-N,N'-bis(3,5-dinitrosalicylidene)-1,2-cyclohexanediamine ligand

In this work, we report novel enantiopure mononuclear complexes (teaH)[Ln((S,S)-dnsalcd)2] and (teaH)[Ln((R,R)-dnsalcd)2] (Ln = Eu3+ for 1 and 4, Tb3+ for 2 and 5, and Sm3+ for 3 and 6), where teaH = triethylammonium and (S,S/R,R)-H2dnsalcd = (S,S/R,R)-N,N'-bis(3,5-dinitrosalicylidene)-1,2-cyclohexanediamine. Their unique structural features have been studied by single crystal diffraction and chiral and magnetic properties have been investigated by circular dichroism and susceptibility, respectively. Notably, 1 and 3 were found to be isomorphous and exhibited a single intramolecular π-π interaction between two (S,S)-dnsalcd2- ligands. In contrast, 2 and 5 were found to be isomorphous and displayed two intramolecular π-π interactions between two (S,S/R,R)-dnsalcd2- ligands. Interestingly, strong Eu3+/Sm3+-based emissions in the solid and solution states were observed by efficient antenna effects due to the π-π interaction modes of the coordinated ligands. Furthermore, density functional theory calculations indicated that 1 contained a single localized benzene group in the highest occupied molecular orbital (HOMO), whereas 2 exhibited full delocalization via π-π interactions in the HOMO.

A 2.45 GHz microstrip patch antenna design, simulation, and anlaysis for wireless applications

This paper designs, simulates, and analyzes the S-band microstrip patch antenna (MPA) for wireless applications. FR-4 (lossy) and Rogger RT/duroid, whose dielectric permittivity is 4.3 and 2.2, respectively, have been used as substrate materials. Simulation is done by computer simulation technology (CST) suite studio 2019 software. Simulations with FR-4 material showed that the return loss was -20.405 dB, the gain was 2.592 dB, the directivity was 7.47 dBi, the voltage standing wave ratio (VSWR) was 1.221, the bandwidth (BW) was 0.0746 GHz, and the efficiency was 34.69%. Also, Rogers RT/duroid material gives results of a return loss of -12.542 dB, a bandwidth (BW) of 0.0349 GHz, a gain of 8.092 dB, a directivity of 8.587 dBi, and an efficiency of 94.24%. The main goal of this antenna is to have a low return loss while getting as close as possible to a VSWR of 1. This will improve the antenna's gain, directivity, and efficiency compared to other antennas. Copper was used to make the patch and the ground, which were 0.35 mm and 0.0077 mm thick, respectively. The results obtained from the proposed antenna were better than those previously published in various in modern scientific journal and conference papers.

A 2.45 GHz microstrip patch antenna design, simulation, and anlaysis for wireless applications

This paper designs, simulates, and analyzes the S-band microstrip patch antenna (MPA) for wireless applications. FR-4 (lossy) and Rogger RT/duroid, whose dielectric permittivity is 4.3 and 2.2, respectively, have been used as substrate materials. Simulation is done by computer simulation technology (CST) suite studio 2019 software. Simulations with FR-4 material showed that the return loss was -20.405 dB, the gain was 2.592 dB, the directivity was 7.47 dBi, the voltage standing wave ratio (VSWR) was 1.221, the bandwidth (BW) was 0.0746 GHz, and the efficiency was 34.69%. Also, Rogers RT/duroid material gives results of a return loss of -12.542 dB, a bandwidth (BW) of 0.0349 GHz, a gain of 8.092 dB, a directivity of 8.587 dBi, and an efficiency of 94.24%. The main goal of this antenna is to have a low return loss while getting as close as possible to a VSWR of 1. This will improve the antenna's gain, directivity, and efficiency compared to other antennas. Copper was used to make the patch and the ground, which were 0.35 mm and 0.0077 mm thick, respectively. The results obtained from the proposed antenna were better than those previously published in various in modern scientific journal and conference papers.

Low‐profile broadband circularly polarized short‐circuited dipole antenna with backed cavity

AbstractA broadband circularly polarized (CP) dipole antenna with a backed cavity is presented in this letter. The proposed antenna consists of a pair of rotational symmetric short‐circuited branches and a Γ‐shaped feed structure. Each branch is designed to be axe‐shaped so that the antenna can achieve a broad 3‐dB axial ratio (AR) bandwidth. The coupled feeding method assures the antenna is wideband, and the shorting‐to‐the‐ground technique miniaturizes the lateral dimensions of the antenna. The profile of the proposed antenna is around 0.16λL (λL denotes the wavelength of the lower bound frequency). The introduction of a back cavity effectively enhances the boresight gain and improves the isolation level if the antenna is used to form an array. Finally, the design is prototyped, and the measurement results agree well with the simulation. The fractal voltage standing wave ratio (VSWR)&lt;2 bandwidth and 3‐dB AR bandwidths are 61.15% (2.725–5.125 GHz) and 45.9% (3.15–5.03 GHz), respectively. The antenna's efficiency exceeds 91.5% over the target frequency band.

Ultrawideband Dual Circularly Polarized Waveguide Array Antenna for K- and Ka-Bands Satellite Communications

In the letter, a wideband dual circularly polarized (CP) waveguide antenna array is designed for K and Ka dual-band satellite communications. A multi-stage square waveguide structure is exploited into the radiating part to facilitate the excitation of a dual polarization response. A ridge waveguide polarizer is integrated to form the left-hand circular polarization (LHCP) and the right-hand circular polarization (RHCP). For a better arrangement of the feeding network, a transition structure with E-plane waveguides to double-ridge waveguides reduces the cross-sectional area of the feeding network. An 8 x 8 array antenna prototype was designed, fabricated and measured for demonstration purposes. The axial ratio (AR) and impedance bandwidth of the array antenna are more than 45%, according to simulation and measurement results. Input reflection coefficient and isolation lower than -15 dB for the dual CP from 19 to 30 GHz, the total antenna efficiency for the entire operating band exceeded 72%. For both polarizations, the peak gain ranges between 24.6 and 28.8 dBi from 19 to 30 GHz.

Design of Normal Mode Helical Antenna for Seawater Application

To overcome the substantial propagation loss in the ocean, a low frequency band should be chosen when contemplating radio wave communication.Then, the antenna used at the portable radio equipment should be very small compare to the wavelength. For the miniaturized antenna, the normal mode helical antenna(NMHA) is suitable because of achieving high efficiency. In this paper, design method of NMHA in the seawater condition (r=81, =4) is explained. The frequency bands of 100MHz and 15MHz are selected. The self-resonant structures are determined based on the theoretical equation. Electrical characteristics such as resonant frequency, input impedance, VWSR and antenna efficiency are obtained through simulation by FEKO simulator. Electromagnetic simulation model is formed by taking into account the practical experimental condition. At 100MHz and 15MHz, resonances are ensured for antenna diameter lengths of 6.83 cm and 12.2 cm respectively. Input resistance of 27.15and 94.14, antenna efficiencies of -14.88dB and -26.27dB are achieved at 100MHz and 15MHz respectively.

Optimized transmit antenna selection and self-attention based convolutional resource allocation model for massive MIMO technology

Massive multiple input and multiple output (MIMO) plays an important role in enhancing the transmission reliability and capacity of the transmitting channel. However, the resource allocation (RA) and transmit antenna selection (TAS) scheme are essential for massive MIMO systems to reduce implementation costs and complex operations. Because the presence of a large antenna consumes enormous resources that must be reduced in order to develop a user-friendly model. Hence, this article introduces a novel TAS and RA scheme in a massive MIMO system that can enhance communication performance efficiently. In this study, an improved sheep flock optimization algorithm (ISFOA) is first emphasized to select the efficient antenna, thus effectively minimizing the cost and the design complexity. Then, a novel deep learning (DL) based self-attention aided deep convolutional neural network (SA-DCNN) model for the stable allocation of resources to all available users is proposed. Thus, the user equipment (UE) can develop a better quality path and reduce the power consumption of the entire system. In the experimental scenario, the performance of the proposed model is compared with an existing technique based on sum rate, spectral efficiency (SE) and energy efficiency (EE) by varying base station (BS) antennas, varying user, signal to noise ratio (SNR), and sub-carriers along with the computational performance. Particularly, when the SNR=10 dB, the proposed model obtains the SE of about 50 bits/s Hz compared to the existing techniques.

Compact Sub 6 GHz Dual Band Twelve-Element MIMO Antenna for 5G Metal-Rimmed Smartphone Applications.

In this paper, a twelve-antenna system is designed for 5G smartphones with metal frames. The system is compact and operates on dual bands within the sub-6 GHz frequency range using multiple-input multiple-output (MIMO) technology. Two sets of six-antenna units are included in the system, arranged in a diagonal mirror-image configuration, and positioned at the center of the circuit board's longer edges. The profile height of each of the six-antenna units is only 3 mm, and the overall array dimensions are 105 × 3 × 3.1 mm3. A single antenna unit is 15 × 3 × 3.1 mm3 (0.173 λ × 0.035 λ × 0.036 λ, where λ equals the free-space wavelength of 3450 MHz). The arrangement of the antennas in the six-antenna units is parallel, with a 3 mm separation between adjacent antennas. The antenna structure comprises of an inverted L-shaped feed branch and two inverted L-shaped short-circuit branches integrated into part of the metal frame. The proposed array can form multiple resonance paths, achieving dual-band operation at 3300-3600 MHz and 4800-5000 MHz. The measured isolation of this twelve-antenna system within the operating frequency band is over 10 dB, and the measured antenna efficiency is greater than 36%. Therefore, the system is suitable for use in smartphones with high screen-to-body ratios and metal frames.

Effect of PIN Diode Integration on Patch Antennas for Frequency Reconfigurable Antenna Applications

PIN diodes are commonly used to design reconfigurable antennas owing to their sufficient isolation, lower cost, and ease of fabrication. This study aims to explore the effect of biasing conditions of a PIN diode radio frequency (RF) switch on a frequency-reconfigurable antenna. This approach investigates the contribution of the forward diode current and the reversed biased voltage on the shift in the operating band, the impedance matching, and the radiation efficiency of a reconfigurable antenna. The benefits and drawbacks of different approaches to modeling PIN diode RF switches are demonstrated on Ansys electromagnetic switch. The result shows a significant match between simulated and measured operating bands, impedance matching, and radiation efficiency. The proposed RF switch model can be used as a practical simulation model for implementing various reconfigurable microwave components.

A Fast Time-Domain Method of Antenna Efficiency Measurement in a Reverberation Chamber

In this letter, a fast energy-based method of antenna efficiency measurement in a reverberation chamber (RC) in time domain (TD) is proposed. The antenna efficiency is determined by comparing the received energy from the antenna under test with that from the reference antenna. The measurement results are compared with that from the conventional reference antenna method in the frequency domain (FD). The proposed method needs no mechanical stirring or only a few mechanical stirrer positions, which could reduce the measurement time significantly.

A Wideband Full-Metal Sidewall-Loaded Magnetoelectric Dipole Array Based on Combined Ridge and Groove Gap Waveguides in the Q-Band

A wideband full-metal sidewall-loaded magnetoelectric (ME) dipole array antenna fed by combined ridge-groove gap waveguide is proposed. Three promising full-metal aperture-coupled 2×2-element ME-dipole subarrays are investigated and compared in detail. By introducing sidewalls around the metal pillars and increasing their height to 0.36λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> , the bandwidth of the subarray is substantially enhanced to 33% for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> < -15 dB. An eigenmode analysis is performed to explain and validate the broadband property of the proposed subarray with taller pins and sidewalls. The combined ridge gap waveguide and E-plane groove gap waveguide are employed in the feeding layer for a compact array as well as for lower losses and better isolation between the gap waveguides. Wideband ridge-to-groove (RG) and groove-to-ridge (GR) junctions are designed using stepped transformers for bandwidth enhancement. For verification, an 8×8-element sidewall-loaded ME-dipole array is designed and fabricated by computer numerical controlled (CNC) milling technique in the Q-band. The bandwidth for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> < -10 dB is widened to 35.9% from 34.5 to 49.4 GHz. From 34.3 GHz to 34.7 GHz and 35.6 GHz to 48.7 GHz, the antenna efficiency is better than 75%, with a bandwidth of 32.5%. The proposed design is attractive for wideband and higher-frequency wireless applications.

Improved Butterfly Optimization Algorithm for Energy Efficient Antenna Selection Over Wireless Cellular Networks

Improved Butterfly Optimization Algorithm for Energy Efficient Antenna Selection Over Wireless Cellular Networks

Design and Analysis of Multi-Layer Patched Efficient Antenna for 28-GHz Applications

Microstrip antennas possess a compact form factor, exhibit a low profile, and demonstrate a lightweight nature, thereby enabling their suitability for deployment on both planar and non-planar surfaces. When the framework is installed, it requires a comparatively small amount of space. The production of printed circuits has become a facile and inexpensive process owing to advancements in contemporary technology. Antennas with a low profile are often required owing to space, weight, cost, performance, simplicity of installation, and aerodynamic profile in powerful planes, spaceships, satellites, and rocket operations. Many other applications, not only mobile radio and wireless communications, have comparable requirements. Microstrip antennas are a useful tool for accomplishing this goal. A proposal has been put forth to utilize a patch antenna for 5G cellular connectivity at 28 GHz, with the aim of generating robust beams on the azimuthal plane. The antenna proposed in this study exhibits a radiation efficiency of 93.46 percent and a total efficiency of 92.80 percent, as demonstrated through simulations. This study showcases the feasibility of producing millimeter-wave antennas operating at 28 GHz through the utilization of cost-effective additive manufacturing techniques. The simulation of all outcomes is conducted through the utilization of the CST Microwave Studio.