High-efficiency Antenna Research Articles

Compact Ultra-Wideband MIMO Antenna for 5G Communication Systems

Ultra-wideband (UWB) technology is highly respected in modern communication systems because it can enable high-speed, high-data-rate communication over short distances. It is still difficult to achieve optimal multiple-input multiple-output (MIMO) performance in real-world multipath settings, even with breakthroughs in traditional antenna designs. UWB-MIMO antenna solutions have been created and simulated in order to address this problem and fulfill present demands. Nevertheless, maintaining high antenna efficiency and the requirement for antenna designs tailored to a particular bandwidth are two of the difficulties UWB systems must overcome. Recently, a variety of optimization strategies have been employed to obtain high gain and UWB performance by fine-tuning antenna characteristics. The major obstacles are resolved by the optimization process, including the time and computational resource requirements. The difficulty is further compounded by the intricacy of accurately modifying antenna settings to maximize gain. A multi-objective advancement for the design and improvement of the reduced UWB-MIMO test radio wire for 5G was offered as a solution to these problems. In order to attain the UWB feature, we first aim to use a single elliptical-square form antenna that operates from 3.4 to 70 GHz with isolation larger than 29.54 dB. Furthermore, we optimize the impedance bandwidth by tuning the parameters of the structural dimensions using the improved proportional topology optimization (IPTO) technique. Additionally, we present the orthogonal correction using the binarized convolutional neural network (BCNN).

High radiation efficiency and tunable resonance planar double-turn spiral antenna for manipulation of nitrogen-vacancy centers.

Nitrogen-vacancy (NV) centers in diamond are promising quantum sensors, where microwave antennas play a crucial role in manipulating the spin states accurately. Conventional microwave antennas often struggle to balance radiation efficiency and bandwidth. To address this challenge, we design a planar double-turn spiral antenna (PDTSA), based on the ring microstrip antenna (RMA). PDTSA demonstrates an ∼4.5-fold increase in radiation efficiency compared to RMA. In addition, the PDTSA allows linear tunability of the resonance frequency up to 500MHz by adjusting the spiral input length. This feature addresses the limitations of a narrow working frequency range, which are typically caused by the narrowband in high-radiation-efficiency antennas. The experimental results show that at an absolute input power of 1W, the PDTSA increases the Rabi frequency from 1.72 to 8.06MHz compared to the RMA. This enhancement accelerates quantum state manipulation and reduces phase accumulation errors. These characteristics make PDTSA suitable for applications in quantum sensing and precision measurements using NV centers.

Light Emission and Conductance Fluctuations in Electrically Driven and Plasmonically Enhanced Molecular Junctions.

Electrically connected and plasmonically enhanced molecular junctions combine the optical functionalities of high field confinement and enhancement (cavity function), and of high radiative efficiency (antenna function) with the electrical functionalities of molecular transport. Such combined optical and electrical probes have proven useful for the fundamental understanding of metal-molecule contacts and contribute to the development of nanoscale optoelectronic devices including ultrafast electronics and nanosensors. Here, we employ a self-assembled metal-molecule-metal junction with a nanoparticle bridge to investigate correlated fluctuations in conductance and tunneling-induced light emission at room temperature. Despite the presence of hundreds of molecules in the junction, the electrical conductance and light emission are both highly sensitive to atomic-scale fluctuations-a phenomenology reminiscent of picocavities observed in Raman scattering and of luminescence blinking from photoexcited plasmonic junctions. Discrete steps in conductance associated with fluctuating emission intensities through the multiple plasmonic modes of the junction are consistent with a finite number of randomly localized, point-like sources dominating the optoelectronic response. Contrasting with these microscopic fluctuations, the overall plasmonic and electronic functionalities of our devices feature long-term survival at room temperature and under an electrical bias of a few volts, allowing for measurements over several months.

A Compact and High-Efficiency Antenna Design for Tire Pressure Monitoring System Applications

A Compact and High-Efficiency Antenna Design for Tire Pressure Monitoring System Applications

A High-Q Electric-Mechano-Magnetic Coupled Resonator for ELF/SLF Cross-Medium Magnetic Communication.

Extremely/super low frequency (ELF/SLF) electromagnetic wave can effectively propagate in the harsh cross-medium environment where a high-frequency electromagnetic wave cannot pass due to the fast decay. For efficiently transmitting a strong ELF/SLF radiation signal, the traditional electromagnetic antenna requires a super-large loop (>10km). To address this issue, in this work, a piezoelectric ceramic/ferromagnetic heterogeneous structured, cantilever beam-type electric-mechano-magnetic coupled resonator at only centimeter scale for ELF/SLF cross-medium magnetic communication is reported. Through designing hard-soft hybrid step-stiffness elastic beam, the resonator exhibits a much higher quality factor Q (≈240) for ELF/SLF magnetic field transmitting, which is one to five orders of magnitude higher than those of previously reported mechanical antennas and loop coil antennas. Moreover, the resonator exhibits a 5000 times higher magnetic field emitting efficiency compared to a conventional loop coil antenna in ELF/SLF band. It also demonstrates a 200% increase in magnetic field emitting capacity compared to existing piezoelectric-driven antennas. In addition, an ASK+PSK modulation method is proposed for suppressing relaxation time of the resonator, and a reduction in the relaxation time by 80% is observed. Furthermore, an air-seawater cross-medium magnetic field communication is successful demonstrated, indicating its potential as portable, high-efficient antenna for underwater and underground communications.

A W-Band, Low-Cost and High-Efficiency Antenna Array Using Multilayer SIW-to-SIW Transition With Leakage-Suppressing Scheme

A W-Band, Low-Cost and High-Efficiency Antenna Array Using Multilayer SIW-to-SIW Transition With Leakage-Suppressing Scheme

A Novel Low-frequency Radio Astronomical Observation Array (1 ∼ 90 MHz) and its First Light

The extremely low frequency (f < 40 MHz) is a very important frequency band for modern radio astronomy observations. It is also a key frequency band for solar radio bursts, planetary radio bursts, fast radio bursts detected in the lunar space electromagnetic environment, and the Earth’s middle and upper atmosphere with low dispersion values. In this frequency band, the solar stellar activity, the early state of the universe, and the radiation characteristics of the planetary magnetosphere and plasma layer can be explored. Since there are few observations with effective spatial resolution in the extremely low frequency, it is highly possible to discover unknown astronomical phenomena on such a band in the future. In conjunction with low frequency radio observation on the far side of the Moon, we initially set up a novel low-frequency radio array in the Qitai station of Xinjiang Astronomical Observatory deep in Tianshan Mountains, Xinjiang, China on 2021 August 23. The array covers an operating frequency range of 1 ∼ 90 MHz with a sensitivity of −78 dBm/125kHz, a dynamic range of 72 dB, and a typical gain value of 6 dBi, which can realize unattended all-weather observations. The two antennas due south of the Qitai Low-Frequency Radio Array were put into trial observations on 2021 May 28, and the very quiet electromagnetic environment of the station has been confirmed. So far, many solar radio bursts and other foreign signals have been detected. The results show that this novel low frequency radio array has the advantages of good performance, strong direction, and high antenna efficiency. It can play a unique role in Solar Cycle 25, and has a potential value in prospective collaborative observation between the Earth and space for extremely low frequency radio astronomy.

A double-layer Huygens’ metasurface with complete phase coverage and its dual-polarized meta-lens antenna application

A novel double-layer Huygens’ unit with dual-polarized response and complete phase coverage has been proposed for highly efficient meta-lens antenna application. The designed unit is a symmetric structure in which the double-layer metallic patterns not only act as the electric dipoles but also induce the magnetic dipoles. The balance between the initial electric dipole and the induced magnetic dipole makes the impedance of the metasurface match with that of free space, thus allowing efficient transmission of electromagnetic waves. Moreover, full transmission phase shift and near-unit transmission amplitude can be achieved simultaneously by change the structural parameters of the unit. Utilizing such electromagnetic properties, a dual-polarized meta-lens consisting of 35 × 35 units with size of 161 × 161 mm2 is designed, fabricated and measured. The results exhibit its good radiation performance. The maximum gain at a frequency of 28 GHz reaches 30.8 dBi, with an aperture efficiency of 42.3%. The 3-dB gain bandwidth reaches 12.5%, covering the frequency range of 26.7–30.2 GHz. The simple structure of the designed dual-polarized metasurface, high gain and high antenna efficiency make it an important antenna engineering role.

Design, characterization, fabrication, and performance evaluation of ferroelectric dielectric resonator antenna for high-speed wireless communication applications

The research comprehensively analyzes the structural, electrical, and electrodynamic characteristics of Ba0.7Sr0.3TiO3 nanoparticles synthesized using a sol-gel approach. The formation of a tetragonal perovskite phase and the nano-crystalline nature have been confirmed using X-ray diffraction (XRD) analysis. Fourier transform infrared (FTIR) spectroscopy has been employed to identify characteristic absorption bands correlated with the crystal lattice vibrations of Ba0.7Sr0.3TiO3. The sample’s morphology has been examined using scanning electron microscopy (SEM), revealing a relatively dense and homogeneous composition composed of small spherical particles. The electrical properties of Ba0.7Sr0.3TiO3 nanoparticles have also been investigated using a ferroelectric measurement technique. The soft electric hysteresis loop with a small coercive field value makes the sample suitable for photovoltaic applications. Finally, a compact dielectric resonator antenna (DRA) based on Ba0.7Sr0.3TiO3 nanoparticles has been designed and characterized. The designed DRA demonstrates good impedance matching, broadside radiation pattern, and high antenna gain and efficiency at the frequency band of 5.6–6.15 GHz, making it suitable for sub-6 GHz (5 G) applications.

Polarization-Resolved THz Imaging With Orthogonal Heterostructure Backward Diode Detectors

A fully integrated lens-coupled dual-polarization detector for imaging was designed, fabricated, and characterized in the terahertz (THz) region. Two zero-bias heterostructure backward diodes (HBDs) were monolithically integrated into a planar dual-polarization annular-slot antenna. An impedance matching network consisting of an interdigitated DC block and shorted stubs was implemented for maximum power transfer. The fabricated chip was then mounted on an extended hemispherical silicon lens for high antenna efficiency. The performance of the integrated detector has been characterized at 200 GHz. The detector module can simultaneously measure the two orthogonal linear polarized components of the incident THz waves, and hence obtain the polarization direction. On the basis of this polarimetric detection, polarization-resolved imaging of a Gaussian beam, as well as birefringent samples, was performed using the integrated detectors. The angular resolution of the polarization detection has been demonstrated to be as small as 3°. The single-pixel detector demonstrated here is amenable to array applications for THz focal-plane arrays that will have a significant impact on a wide range of remote sensing, though-barrier imaging, and detection/identification applications.

Millimeter-wave Wideband High-isolation Antenna Array Based on End-fire Magnetoelectric Dipole Antenna for 5G Applications

In this paper, a millimeter-wave (mmW) wideband high-isolation wide-angle scanning antenna is presented. The end-fire magnetoelectric (ME) dipole with wideband impedance characteristic and wide beamwidth is selected. Based on the ME dipole, a 1×4 subarray with a stripline feed network is constructed to get higher antenna efficiency. Then, four 1×4 subarrays are adopted to form a 4×4 array to realize the wide-angle scanning performance. Furthermore, to get better isolation between the subarrays, the beam is tilted on the non-scanning plane; in addition, the resonant split rings are added on the background of the subarrays. With these two measures, the isolation between the subarrays can be effectively reduced, with more than 20 dB over the entire bandwidth. Owing to the wide beamwidth of ME dipole and high isolation between the subarrays, the 4×4 array can obtain the wide-angle scanning characteristic. The final antenna covers an operating bandwidth of 19.5% (24.25-29.5 GHz) with return loss more than 10 dB, which can meet the band in the 5G standard. The beam can scan approximately ±55∘ with a realized gain reduction under 3 dB within the wide operating bandwidth. Also, the simulated radiation efficiency of the array is more than 77% over almost the entire band. The antenna will be a potential candidate to be applied in 5G applications.

Design of Low-SAR Terminal Antenna Using Characteristic Mode Manipulation

A novel specific absorption rate (SAR) reduction method based on the characteristic mode theory (CMT) is proposed for mobile terminal. The CMT is introduced to establish the relationship between the characteristic electric field and the induced electric field in human tissues. The design process and mechanism of a low-SAR antenna are demonstrated. To verify the effectiveness of the proposed SAR reduction method, a low-SAR loop antenna is designed. The measurement results show that the 10 g average SAR peak value of the proposed antenna is reduced by 26.1%. The measured −10 dB bandwidth of the low-SAR antenna is 320 MHz, which is increased by 60% compared with the reference antenna (200 MHz). The measured efficiency of the reference antenna and low-SAR antenna are better than 64% and 73% in the entire operating frequency band. With the advantages of bandwidth enhancement, significant SAR reduction and high antenna efficiency, the proposed SAR reduction method is a good choice for the low-SAR terminal antenna design.

Radial Line Planar Phased Array Using Electromechanically Rotated Helical Antennas

In this paper, we propose a novel radial line planar phased array in which helical antenna elements are individually rotated by their respective connected micromotors to realize dynamic beam-scanning. To our knowledge, this is the first radial line planar array (RLPA) that has antenna elements electromechanically rotated by their individual micromotors. To facilitate its fabrication, helix and its probe are directly metallized on a plastic shaft using molded interconnect device technology, and a motor shaft is press-fitted into the plastic shaft. We also present a new design methodology for RLPA, which combines the equivalent circuit theory and electromagnetic simulations of the unit cell element. The proposed procedure is practical to design an RLPA of antenna elements with arbitrary probe shape without large-scale full-wave analysis of the whole structure of the RLPA. We design, fabricate, and evaluate a 7-circle array with 168 helical antenna elements fabricated using molded interconnect device technology. The prototype antenna exhibits dynamic and accurate beam-scanning performance. Furthermore, the prototype antenna exhibits a low reflection coefficient (less than -17dB) and high antenna efficiency (above 77%), which validates the proposed design methodology.

THE INFLUENCE OF MISMATCHES ON THE RESULTS OF MEASURING THE NOISE TEMPERATURE AND THE EFFECTIVE APERTURE OF ANTENNAS BY RADIO ASTRONOMY METHODS

The radio astronomy methods for measuring antenna properties allow to measure noise temperature and effective antennas aperture with high accuracy when the antenna and the standard load are ideally matched in the input of the radiometer. Due to appear-ance of high-efficiency antennas, the requirements to high-precision measurements of noise temperature and the effective aperture of antennas have increased. The earth meth-ods for measuring those antenna parameters turns out to be insufficient and, in some cas-es, impossible. In practice, antenna parameters measuring and radioastronomy research with high efficiency convincingly proved that the difficulties in measuring by earth meth-ods are relatively easy to overcome. As high efficiency antennas and low noise receivers have appeared the require-ments to measuring antenna properties with high accuracy have increased. For measuring the parameters of large antennas more than 10 cosmic standard sources are chosen. Among them standard sources Cassiopeia - A, Cygnus - A, Taurus - A, and Virgo – A meet the requirements, that have an aperture of up to 80 m of mirrors. In real systems antenna – radiometer, standard load – radiometer always exist a whole reason leading to power re-reflection. At that, the measure and values are characterized by errors (mismatch errors). The goal of the work is consideration of errors which are conditioned by mismatch and giving methods to decrease them, which allows to eliminate the influence of mis-matches in the measurement results. The influence of mismatch are studied when we measure noise temperature and effective antenna aperture in a system which consists of a noisy signal source plus radiometer. Methods which decrease and fully eliminate the influ-ence of those mismatches in measurement results are proposed.

Compact Dual-Band High-Efficiency Antennas Based on Spoof Surface Plasmon Polaritons

A compact dual-band high-efficiency antenna based on spoof surface plasmon polaritons (SSPPs) is proposed by well exciting both the TM10 mode and the LC resonant mode. Each mode can be tuned separately without affecting the other mode. The whole SSPP slab is utilized as the radiator of the TM10 mode, while the air ring gap, the shorting pin, and a minor part of SSPP slab work as the radiator of the LC resonant mode. The compact size and the high radiation efficiency of the proposed antenna are due to the high field confinement and high effective refractive index of SSPPs. A reliable circuit model is first proposed for an SSPP antenna and applied to design it for dual-band operation. A prototype was fabricated using PCB technology and measured. The proposed antenna achieves a compact electrical size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.18\lambda _{\mathbf {0}} \times 0.18\lambda _{\mathbf {0}} \times 0.07\lambda _{\mathbf {0}}$ </tex-math></inline-formula> , which is significantly smaller than its counterparts ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{\mathbf {0}}$ </tex-math></inline-formula> is the wavelength at lower resonant frequency). Our proposed antenna possesses higher relative bandwidth per wavelength square area in comparison with other dual-band antennas. Both the simulated and measured results verified the high total efficiencies of the proposed dual-band antenna. The proposed antenna will have potential applications in wireless communication systems.

Enhancing the power level harvested by rectenna systems based on focusing metasurfaces for ambient environments

Electromagnetic (EM) RF (radio frequency) energy harvesting in dynamic ambient environments is a challenge for conventional energy harvesting systems such as rectennas. The main challenges are the low efficiency of the collector and low ambient power levels, which makes it hard to consider in industrial applications. Several research works have focused on the design of high-efficiency antennas to achieve an efficient and maximum possible level of RF EM energy harvesting. Their main objective is to improve the EM energy harvesting system by overcoming the low efficiency of the collector, which is the main part of the rectenna system. In this work, we propose and investigate a methodology in terms of EM energy harvesting based on the concentration and focusing of EM energy in a small zone where it can be easily collected and transferred indirectly to the rectenna system. It consists of a focusing device and a methodology to associate the latter with existing RF energy harvesting systems. We demonstrate a focusing metasurface design implemented alongside an off-the-shelf rectenna device at 900 MHz, where an enhanced energy harvested power level up to a linear gain of 8 is achieved compared to the case when only the rectenna is used. Numerical results as well as measurements results in an anechoic chamber are shown. Experimental power received levels are given both in the focusing plane and in time for the validation of the concept.

A Half-Mode Groove Gap Waveguide for Single-Layer Antennas in the Millimeter-Wave Band

This letter presents an alternative to significantly reduce the time and difficulty in designing and fabricating antennas in gap waveguide (GW) technology by using a novel half-mode groove GW. GW is often criticized within the subtractive manufacturing field for the high fabrication time required to mill many pins with the waveguides in the same piece. To demonstrate the possibilities of this new approach, two different antennas have been designed, fabricated, and measured. Both antennas, formed by only two pieces with no contact, operate from 29 to 31 GHz and present reflection coefficients below <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> 10 dB and high antenna efficiency above 90 <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> . In addition, both prototypes can reuse the bed of nails, which favors shorter manufacturing times and lower costs in the development phase.

Design of Ultra High Aperture Efficiency Surface Wave Antenna Array Based on the Three-Dimensional Aperture Principle

To overcome the conflict between limited space and the requirement for high gain antennas, a novel high aperture efficiency antenna array consisting of surface wave end-fire antennas is proposed based on the three-dimensional aperture principle. By introducing longitudinal dimension into the calculation of the regular aperture antenna gain, the two-dimensional aperture principle is expanded into the three-dimensional aperture principle. Meanwhile, the directivity and gain of the array could increase without increasing the aperture area. The aperture efficiency of the array could be more than 100% in this situation. The gain of the surface wave end-fire element antenna is 9.5 dBi. The proposed 3 × 3 square antenna array with the size of 1.5λ × 1.5λ × 2.24λ obtains a gain of 15.3 dBi and its aperture efficiency reaches 120%.

Extremely Low-Profile Periodic 2-D Leaky-Wave Antenna: An Optimal Solution for Antenna-Frontend Integration

We investigate and present a very low-profile, high-efficiency, and high-gain 2-D leaky-wave antenna (2DLWA) implemented on a high permittivity substrate operating in the millimeter-wave range, paving the way for the seamless integration of a high-gain and high-efficiency antenna with a frontend. In contrast to the typical air-filled 2DLWA, where a perturbation of the first higher-order mode (TE1/TM1) results in highly directed broadside radiation, in the proposed antenna, the propagation and leakage of a quasi-TEM (Q-TEM) mode results in an extremely low-profile ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.065\lambda _{0}$ </tex-math></inline-formula> ), high-gain (~15 dBi) antenna. In this scenario, the transverse resonance condition for a Q-TEM mode is established by employing a capacitive partially reflective surface (PRS) in a thin ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.065\lambda _{0}$ </tex-math></inline-formula> ) substrate with a relative permittivity of 10.2. The proposed periodic 2DLWA, unlike the conventional uniform/quasi-uniform air-filled counterparts, radiates based on the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathbf {n}=-\mathbf {1}$ </tex-math></inline-formula> space harmonic operation. Due to a strong mutual interaction between the PRS and ground plane, conventional design and analysis approaches are no longer relevant in this low-profile architecture. Instead, we employ the Floquet modal expansion theory to create an equivalent circuit model (ECM) for the PRS that takes into account the contributions and mutual interactions of the Floquet harmonics as well as the ground plane effect. By employing reflecting boundaries realized with edge truncation (air trenches) in a high permittivity substrate, we show that the aperture efficiency is enhanced by 15% compared to conventional counterpart.

High-Isolation wideband MIMO antenna with offset T-Shaped slots for 5G/WLAN applications

A broadband multiple-input multiple-output (MIMO) antenna with high isolation operating in 3.14–5.42 GHz (2.28 GHz, 53.3%) is proposed for 5G smartphones. An offset T-shaped slot with dual functions is employed to improve the bandwidth of one antenna element and enhance the isolation. Then, the double L-shaped stubs are loaded to improve the impedance matching of the other antenna in the MIMO antenna. Finally, the 2 × 2 MIMO antenna is constructed by four T-shaped monopole antennas, two double L-shaped stubs, and two offset T-shaped slots. The proposed MIMO antenna is first simulated and then experimentally tested with a good agreement. High isolation of greater than 15 dB, high antenna efficiency of more than 54%, and low envelope correlation coefficient (ECC) of smaller than 0.08 are realized within 3.14–5.42 GHz. These good performances indicate that the proposed antenna can be applied for MIMO applications in smartphones.