Antenna Gain Research Articles

A compact wideband self-isolated uniplanar quad MIMO antenna for C-band applications

The paper presents the development of a compact uniplanar MIMO antenna system for C-band applications. A quad-element MIMO system with uniplanar design arrangements for a compact 40 mm × 40 mm mainframe is analyzed. Four similar P-shaped radiators with a common ground form a self-isolating MIMO arrangement. After conducting a thorough parametric analysis, slots are added to the antennas to reduce their size and area. The overall area of the miniaturized radiator element is 16 mm2. The orthogonal mode MIMO covers an operating bandwidth of 5 GHz frequency range from 4 GHz to 9 GHz with the isolation of less than 15.5 dB and an overall gain of 4.6 dBi so it is fabricated and tested. The suggested antenna can cover the entire C-band frequencies (4 GHz-8 GHz) and a partial X-band frequency. The antenna provides a good radiation efficiency of 96%. The suggested antenna’s diversity characteristics, such as ECC (<0.13), TARC (< −10 dB), MEG, and CCL ensure good diversity performances. The SAR value of the MIMO is assessed, and the results are within bounds. The suggested MIMO system exhibits good efficiency, adequate isolation between individual antennas without the need for any decoupling mechanisms, increased antenna gain, and improved ECC while keeping a lower antenna size. The suggested compact quad MIMO system is appropriate for C-band applications.

Broadband packaging solution in embedded wafer level ball grid array technology for D-band PMCW radar

Abstract A system-in-package for a wideband digital radar, in D-band, requires broadband, high-gain antennas combined with broadband chip-to-package and package-to-printed circuit board (PCB) interconnects. This paper demonstrates a wideband, low-loss quasi-coaxial signal transition, and a novel electric split ring resonator (eSRR)-based antenna-in-package (AiP) with a modified reflector concept, for improved gain, in embedded wafer level ball grid array (eWLB) technology. A complete chip-to-package-to-PCB interconnect is also demonstrated by combining the quasi-coaxial transition with a chip-to-package interconnect. The quasi-coaxial signal transition has the largest impedance bandwidth among ball grid array-based quasi-coaxial signal transitions. For the modified reflector concept, a horn-shaped cavity is micromachined in the PCB substrate and remetallized with aerosol-jet printing, placing the reflector 0.25λ from the antenna. The antenna gain is improved with up to 5.3 dB. The AiP with the horn-shaped reflector is the single element with the highest gain, in eWLB technology, above 100 GHz.

Design circular polarized antenna at ISM band for WBAN using parasitic elements

This work represents a single layer wide band circular polarized (CP) antenna with broadside high gain. The antenna configuration comprises an elliptical patch serving as the main radiating element, accompanied by eight parasitic components positioned on the same plane as the patch. This setup demonstrates an enhancement in the antenna's bandwidth and gain in the broadside direction compared to conventional antennas. A detailed analysis of the significant modes, using the characteristic mode analysis (CMA) approach, has been employed to optimize the antenna. This optimization has resulted in a notable increase in the 3-dB axial ratio (AR) bandwidth and radiation gain in the broadside direction, attributed to the presence of extra harmonics and the improved aperture efficiency of the parasitic elements. The significant modes are excited via a full-wave electromagnetic (EM) simulation, utilizing a 50 Ω coaxial feed line in the primary antenna. Furthermore, the proposed antenna's functionality is examined through an analysis based on an equivalent circuit model (ECM). To demonstrate the feasibility of the design approach, an antenna prototype is fabricated on a low-cost FR4 material, occupying an overall volume of 0.58λo×0.58λo×0.030λo (λo is the center operating. frequency). The measured results demonstrate that the suggested antenna operates within a frequency band ranging from 5485 to 6130 MHz for |S11| −10 dB, and the 3-dB axial ratio ranges from 5680 to 5900 MHz. Moreover, the fabricated antenna demonstrates a high gain radiation of 7–7.05 dBi cover the ISM band for biomedical applications.

Terahertz radar with all-dielectric leaky-wave antenna

Terahertz radars based on leaky-wave antennas are promising for the realization of radar systems with high resolution over short ranges. This type of radar relies on spatial frequency mapping to realize a wide field of view without mechanical actuation or electrical beam steering. Previously, integrated leaky-wave antennas based on metallic wave confinement have been implemented, but the high ohmic losses limit the realized antenna gain, which is essential for extending the range of such a system when limited power is available. Here, we demonstrate an all-dielectric leaky-wave antenna fabricated monolithically from silicon and then apply leaky-wave radar techniques to realize a terahertz radar system capable of real-time data acquisition. Through this all-dielectric approach, we can avoid metallic losses, achieving an experimentally measured maximum realized gain of 25 dBi and a 34.3° 3-dB field-of-view while utilizing established and scalable fabrication techniques essential for the wide-spread adoption of terahertz technologies. We foresee this technique being applied to a variety of real-time radar applications, and here we demonstrate two potential use-cases: multi-object tracking and differentiation of liquids.

A Low-Profile Circularly Polarized Millimeter-Wave Broadband Antenna Analyzed with a Link Budget for IoT Applications in an Indoor Scenario.

Broadband antennas with a low-profile generating circular polarization are always in demand for handheld/ portable devices as CP antennas counter multipath and misalignment issues. Therefore, a compact millimeter-wave antenna is proposed in this article. The proposed antenna structure comprises two circular rings and a circular patch at the center. This structure is further embedded with four equilateral triangles at a 90° orientation. The current entering the radiator is divided into left and right circular directions. The equilateral triangles provide the return path for current at the differential phase of ±90°, generating circular polarization. Structural development and analysis were initially performed through the characteristic mode theory. It showed that Modes 1 to 4 generated good impedance matching from 20 to 30 GHz and Modes 1 to 5, from 30 to 40 GHz. It also demonstrated the summation of orthogonal modes leading to circular polarization. The antenna-measured reflection coefficient |S11| > 10 dB was 19 GHz (23-42 GHz), and the axial ratio at -3 dB was 4.2 GHz (36-40.2 GHz). The antenna gain ranged from 4 to 6.2 dBi. The proposed antenna was tested for link margin estimation for IoT indoor conditions with line-of-sight (LOS) and non-line-of-sight (NLOS) conditions. The communication reliability with co- and cross-polarization was also studied under these conditions, and the results proved to be satisfactory.

Electromagnetic radiation estimation at the ground plane near fifth‐generation base stations in China by using machine learning method

AbstractA novel method based on machine learning is proposed to estimate the electromagnetic radiation level at the ground plane near fifth‐generation (5G) base stations. The machine learning model was trained using data from various 5G base stations, enabling it to estimate the electric field intensity at any arbitrary radiation point when the base station provides service to different numbers of 5G terminals which are in different service modes. The inputs required for the model include the transmit power of the antenna, the antenna gain, the distance between the 5G base station and 5G terminals, terminal service modes, the number of 5G terminals and the environmental complexity around the 5G base station. Experimental results demonstrate the feasibility and effectiveness of the estimation method, with the mean absolute percentage error of the machine learning model being approximately 5.98%. This level of accuracy showcases the reliability of the approach. Moreover, the proposed method offers low costs when compared with on‐site measurements. The estimated results can be utilised to reduce test costs and provide valuable guidance for optimal site selection, thereby facilitating radio wave coverage or electromagnetic radiation regulation of 5G base stations.

An improved gain and directivity design of an antipodal Vivaldi antenna for ultra‐wideband detection

AbstractA novel antipodal Vivaldi antenna (AVA) is proposed to achieve improved gain and directivity. To enhance the bandwidth of the antenna, a series of equal‐sized slots are etched onto the patch surface. Additionally, a dielectric lens with a fan‐shaped structure is integrated along the patch openings to boost gain. The length of the lens which will affect the radiation characteristics of the antenna in the end‐fire direction will be discussed. Furthermore, three arrays of directors are added to enhance the directivity. The fabricated antenna is then measured using a vector network analyzer in a microwave chamber to assess its performance. The results indicate that the antenna's minimum operating frequency is reduced by 0.5 GHz after etching the slots. Besides, the average gain is improved by 1 dBi after installing the fan‐shaped expansion structure. By introducing the directors, the sidelobe levels decrease and the 3 dB Half‐Power Beamwidth becomes sharper. Finally, an ultra‐wideband (UWB) detection experiment is designed to analyze the detection capability of the fabricated antennas. The results demonstrate that the antenna is well‐suited for UWB applications.

Unknown PD distinction in HVAC/HVDC by antenna-sensor with pulse sequence analysis

Ultra-high frequency (UHF) antenna-sensors are becoming popular for non-invasive detection of unwanted electric discharge i.e., partial discharge (PD) in high-voltage (HV) systems. Early PD signals are weak for detection and classification by UHF antenna-sensors. Early PD detection and distinction are crucial to prevent equipment failure. Typically, PD signals are distinguished in HVAC by phase resolved PD (PRPD) patterns. Whereas in HVDC, some unconventional methods are applied. However, a blind distinction of PDs under unknown HVAC/HVDC conditions still remains a challenge. In this article, we address this issue by using a lotus-shaped UHF antenna-sensor for early PD detection. Unlike cut-and-try technique-based conventionally designed bio-inspired antennas, our sensor is designed by a precisely derived equivalent circuit model to systematically optimize antenna gain over size to detect early PDs. The fabricated sensor has a size of 18×11 cm2, an average realized gain of 3.05 dBi in 740–1600 MHz frequencies, and a sensitivity index of 154.04 dBi/m2. The sensor prototype is applied to wirelessly distinguish PD signals from unknown sources under HVAC and HVDC by pulse sequence analysis. Early detection, characterization, and distinction of unknown PD signals are ensured by the proposed sensor and interpretation technique. This work offers a distinctive PD sensing method for HVAC/HVDC converter stations.

Reconfigurable graphene antenna for a network cognitive radio: A novel solution for X-band satellite communications

This study introduces a graphene-based antenna tailored for X-band satellite communication within a cognitive radio network. Leveraging graphene's distinctive traits high conductivity and mechanical flexibility, the antenna design achieves reconfigurability in frequency, polarization, and radiation pattern. This adaptability enables dynamic adjustments to environmental shifts, bolstering the efficiency and dependability of satellite communication. Operating on software-defined radio technology, the cognitive radio system monitors and allocates the available frequency spectrum, allowing real-time adjustments to antenna parameters. Given the widespread usage of the X-band in satellite communications, this antenna proposal stands as an appealing solution for such systems. Its potential applications encompass providing broadband access in remote regions, supporting emergency communication networks, facilitating maritime and aeronautical communications, and enabling self-sustaining wireless networks. The approach involves a novel graphene antenna with slots to facilitate frequency reconfigurability. At 9 GHz, the graphene antenna achieves a gain of 6 dBi, surpassing the 4.3 dBi gain of a copper antenna. By varying the chemical potential of graphene from 0 to 4 eV, we achieved a high gain of 6.4 dBi at 9 GHz and an excellent reflection coefficient of −42 dB at 11.63 GHz. The graphene antenna's improved gain and tuning capabilities surpass traditional materials, showcasing adaptability across diverse frequencies, promising versatility for varied communication needs, and enhancing overall system reliability and effectiveness.

An EIRP Measurement Method of High-Power Microwave Systems Based on Near-Field Testing

The equivalent isotropic radiated power (EIRP) of high-power microwave (HPM) systems is a core-evaluating indicator. In practical testing, locating a suitable test site for the far-field method becomes challenging due to the requisite antenna separation. The conventional near-field method necessitates the extraction of the antenna’s near-field distribution, resulting in a testing system of intricate complexity and diminished efficiency. Therefore, the traditional near-field method cannot be directly applied in HPM systems. In the present study, a new EIRP measurement method for HPM systems based on near-field testing was proposed. First, a monitoring antenna of a considerable scale is positioned within the near-field vicinity of the HPM antenna to capture radiation power, thereby deriving its equivalent input power. Subsequently, according to the EIRP definition and the measured gain of the HPM antenna, the EIRP of the HPM system can be acquired. Theoretical research on this measurement method was conducted, the electromagnetic simulation model was constructed, and a comprehensive analysis through simulation was undertaken. A measurement system was developed and verified experimentally. The results demonstrate the precision of this approach in determining the EIRP of the HPM system, thereby serving as a valuable tool for assessing the power-handling capability of the HPM antenna. The test error is ±0.5 dB.

Novel Meta-Fractal Wearable Sensors and Antennas for Medical, Communication, 5G, and IoT Applications

Future communication, 5G, medical, and IoT systems need compact, green, efficient wideband sensors, and antennas. Novel linear and dual-polarized antennas for 5G, 6G, medical devices, Internet of Things (IoT) systems, and healthcare monitoring sensors are presented in this paper. One of the major goals in the evaluation of medical, 5G, and smart wireless communication devices is the development of efficient, compact, low-cost antennas and sensors. Moreover, passive and active sensors may be self-powered by connecting an energy-harvesting unit to the antenna to collect electromagnetic radiation and charge the wearable sensor battery. Wearable sensors and antennas can be employed in smart grid applications that provide communication between neighbors, localized management, bidirectional power transfer, and effective demand response. A low-cost wearable antenna may be developed by etching the printed feed and matching the network on the same substrate in the printed antenna. Active modules may be placed on the same dielectric board. The antenna design parameters and a comparison between the computation and measured electrical performance of the antennas are presented in this paper. The electrical characteristics of the new compact antennas in the vicinity of the patient’s body were simulated by using electromagnetic simulation techniques. Fractal and metamaterial efficient antennas and sensors were evaluated to maximize the electrical characteristics of smart communication and medical devices. The dual- and circularly polarized antennas developed in this paper are crucial to the evaluation of wideband and multiband compact 5G, 6G, and IoT advanced systems. The new efficient sensors and antennas maximize the system’s dynamic range and electrical characteristics. The new efficient wearable antennas and sensors are compact, wideband, and low-cost. The operating resonant frequency of the metamaterial antennas with circular split-ring resonators (CSRRs) may be 5% to 9% lower than the resonant frequency of the sensor without CSRRs. The directivity and gain of the metamaterial fractal antennas with CSRRs may be up to 3 dB higher than the antennas without CSRRs. The directivity and gain of the metamaterial fractal passive sensors with CSRRs may be up to 8.5 dBi. This study presents new wideband active meta-fractal antennas and sensors. The bandwidth of the new sensors is around 9% to 20%. At 2.83 GHz, the receiving active sensor gain is 13.5 dB and drops to 8 dB at 3.2 GHz. The receiving module noise figure with TAV541 LNA is around 1dB.

A Metamaterial Surface Avoiding Loss from the Radome for a Millimeter-Wave Signal-Sensing Array Antenna

Radar systems are a type of sensor that detects radio signals reflected from objects located a long distance from transmitters. For covering a longer range and a higher resolution in the operation of a radar, a high-frequency band and an array antenna are measures to take. Given a limited size to the antenna aperture in the front end of the radar, the choice of a millimeter-wave band leads to a denser layout for the array antenna and a higher antenna gain. Millimeter-wave signals tend to become attenuated faster by a larger loss of the covering material like the radome, implying this disadvantage offsets the advantage of high antenna directivity, compared to the C-band and X-band ones. As the radome is essential to the radar system to protect the array antenna from rain and dust, a metamaterial surface in the layer is suggested to meet multiple objectives. Firstly, the proposed electromagnetic structure is the protection layer for the source of radiation. Secondly, the metasurface does not disturb the millimeter-wave signal and makes its way through the cover layer to the air. This electromagnetically transparent surface transforms the phase distribution of the incident wave into the equal phase in the transmitted wave, resulting in an increased antenna gain. This is fabricated and assembled with the array antenna held in a 3D-printed jig with harnessing accessories. It is examined in view of S21 as the transfer coefficient between two ports of the VNA, having the antenna alone and with the metasurface. Additionally, the far-field test comes next to check the validity of the suggested structure and design. The bench test shows around a 7 dB increase in the transfer coefficient, and the anechoic chamber field test gives about a 5 dB improvement in antenna gain for a 24-band GHz array antenna.

Gain-enhanced and Mechanical Reconfigurable Slot Antenna with Metasurface

A novel wideband slot antenna with metasurface is presented. In order to achieve broadband, high-gain, and mechanical reconfigurable performance, a metasurface is adopted and combined with a new-type planar slot antenna The antenna and metasurface are designed on F4B substrate, and the overall dimension of the antenna is 1.48λ0×1.48λ0×0.2λ0 (λ0 is the free space wavelength at center frequency). Different from the traditional square metasurface, a structure with different properties in the x and y directions is utilized in the proposed antenna, which can be reconstructed by adjusting the relative position between the slot antenna and the metasurface. By introducing the metasurface, the maximum gain of the whole antenna is improved. The antenna works in two states with respect to the two locations of the metasurface. The impedance bandwidth of the proposed antenna in state A is from 5.49 to 9.40 GHz (52.5%), and the impedance bandwidth of the proposed antenna in state B is from 5.83 to 6.01 GHz (3%) and 7.05 to 9.62 GHz (30.8%). The gain of the whole antenna in both states is higher than that of the original slot antenna (without metasurface), and the maximum gain is 9.1 dBi.

Ultrawide-band Wearable Antenna with Uniplanar Compact Electromagnetic Band Gap

Ultrawide-band technology, commonly known as UWB, sends data over a wide frequency range for many applications. WBAN applications use wearable antennas because they have flexible materials and are suitable for telemedicine technology and have many advantages such as small size, lightweight, able to work at a wide enough frequency, easy fabrications, and affordable costs. In this research, the hexagonal patch ultrawide-band monopole planar wearable antenna was designed using Cordura Delinova 2000 textile material for the substrate and copper tape for the groundplane and patch. The Uniplanar Compact Electromagnetic Band Gap (UC-EBG) as a metamaterial was added to the design of the monopole planar antenna in this final project which aims to improve antenna parameters, increase efficiency, and reduce the effects of radiation on the body. From the measurement results on the antenna with the addition of the UC-EBG structure at the bottom of the patch, it produces a 6% fractional bandwidth increase and able to work in the frequency range of 3-10 GHz off-body conditions and 2-11 GHz on-body conditions. In the SAR test at 45 mm, it was found that the value decreased from previously 1.535 W/Kg to 1.31 W/Kg at a frequency of 3.5 GHz and previously from 1.421 to 1.267 W/Kg at a frequency of 5 GHz on a wrist phantom object which is a good value for SAR. The resulting increase in antenna gain after the addition of the UC-EBG structure. The radiation pattern on the antenna is bidirectional.

Front‐to‐back ratio improvement of a compact base‐station antenna for 5G NR applications

AbstractThe front‐to‐back ratio (FBR) of a compact dual‐polarized antenna is improved for 5G new radio (NR) base‐station applications. A rim made of partially reflective surfaces is introduced to improve the FBR. A meta‐surface and a parasitic element are employed to lower the antenna height. The dual‐polarized base‐station antenna with improved FBR features a compact size of , where is the wavelength in free space at the lowest operating frequency. The FBR achieved over the 5G NR n28/n82/n83 bands (0.69–0.96 GHz) for return loss &gt;15 dB is higher than 26 dB. The antenna gain is higher than 7 dBi and the isolation is higher than 30 dB.

Enhancing the Scanning Gain of Phased Array Antenna Using a Holographic Metasurface

Enhancing the Scanning Gain of Phased Array Antenna Using a Holographic Metasurface

Wideband miniaturized circularly polarized magnetoelectric dipole antenna array for millimeter‐wave applications

AbstractA wideband and miniaturized circularly polarized (CP) magnetoelectric (ME) dipole antenna is proposed. Two pairs of rotationally symmetric patch structures replace the rectangular structure of the original linearly polarized ME dipole, generating a rotating electric field that results in CP‐radiated waves. And the magnetic dipole is modified to broaden the impedance bandwidth (IBW) and the axial ratio bandwidth (ARBW). Meanwhile，the simple l‐shaped feed structure makes the antenna more compact. To improve the antenna gain, a 2 × 2 CP ME‐dipole antenna array was designed, completed, and measured. The measured results show that the IBW of the antenna array is 41.5% (from 29.2 to 44.5 GHz), and 3 dB ARBW of 26.7% (from 34.7 to 45.4 GHz) has a peak gain of 13.7 dBic.

A wideband X‐band circularly polarized printed monopole antenna backed by AMC reflector for 5G/IoT CubeSat applications

AbstractThis letter presents a coplanar waveguide‐fed printed monopole antenna backed by an artificial magnetic conductor (AMC) reflector. The proposed monopole antenna achieves circular polarization by loading the monopole with a printed coil and using an asymmetric ground plane. In addition, the AMC increases the antenna gain while maintaining a wide axial ratio (AR) bandwidth. The unit cell of the AMC is based on a Minkowski‐like prefractal geometry. The antenna is fabricated and measured with a total size of 1.07 λ0 × 1.07 λ0 × 0.25 λ0 at the operating frequency of 8.5 GHz. The measured results show a wide −10 dB impedance bandwidth of 26.9% (7.12–9.38 GHz), a wide 3 dB AR bandwidth of 22.23% (8–9.89 GHz) as well as a peak gain of 8.3 dBi at 8.5 GHz. This is significantly better than comparable antennas in addition to this design being the smallest in size.

Diplexer Antenna for 5G Full-duplex Application

This work proposes a spiral filter-based diplexer antenna for dual-band full-duplex 5G application in C-band. The shared radiator is formed by a cross-shape Yagi-Uda antenna. The dual-band full-duplex characteristic is obtained by applying a diplexer with two different band-stop filters (BSFs) based on a high-order rectangular spiral-shaped open-stub filter. The proposed diplexer antenna is suitable for modern 5G full-duplex communication system applications with a small frequency ratio and high isolation between two ports by applying a Wilkinson power divider. The diplexer antenna is designed, fabricated, and measured, showing good performance of channel isolations of 27 dB/23 dB and the antenna gain of 4.7 dBi/4.2 dBi at two operation bands from 3.56 GHz to 3.68 GHz and from 3.72 GHz to 3.83 GHz covering the required 100 MHz maximum bandwidth in C-band while its frequency ratio is only 1.04.

Compact Archimedean spiral antenna with high gain for electrostatic discharge detection

AbstractA compact Archimedean spiral antenna with high gain for electrostatic discharge (ESD) detection is investigated. A frustum‐shaped cavity proposed in this work is formed to optimise the maximum antenna gain. Additionally, a helix arm is loaded to enhance antenna gain in lower band. The measured results demonstrate that the proposed antenna, which employs a unidirectional radiation mode, exhibits a maximum antenna gain ranging from −0.74 dBi to 9.46 dBi and a voltage standing wave ratio less than 3 across a frequency range of 0.65–5 GHz. A test system consisted of proposed antenna and a commercial ESD detection antenna is established. The verified results indicate that the proposed antenna has a performance close to the commercial antenna, so that proposed antenna with compact size is preferred to be utilised for ESD detection.