High Gain Characteristics Research Articles

A Design of Hign Gain Wideband Circular Polarization Antenna Based on All-Metal Vivaldi Antenna

This paper designs a broadband circularly polarized antenna covering the 25 GHz to 31 GHz band. The Vivaldi antenna is used as the basic structure to generate broadband electromagnetic waves; circular polarization is achieved by feeding through a circularly polarized bridge; a metal choke ring is used at the bottom to ensure the low side lobes of the antenna. The antenna consists of four basic Vivaldi antennas, a metal choke ring, a grounded substrate, and a feed network. The results show that the antenna covers the entire frequency band when the axial ratio is lower than 3 dB, and the impedance matching is better. The use of a choke ring structure ensures that the antenna electromagnetic waves are radiated upward, resulting in higher gain and lower side lobes. The highest gain in the included frequency band is 11.4 dB, and the simulation result is good. The antenna has high gain and low sidelobe characteristics.

Crystal surface and reflector optimization for the SiPM-based dual-ended readout TOF-DOI PET detector

Silicon photomultipliers (SiPMs) are now widely used for positron emission tomography (PET) applications because of their high gain and low noise characteristics. The PET image quality has been improved with the advancement of time-of-flight (TOF) and depth-of-interaction (DOI) measurement techniques. For brain-dedicated PET systems, both TOF and DOI information are beneficial for enhancing the reconstructed PET image quality. In a previous study, we proposed SiPM-based dual-ended readout PET detectors that used a mean time method to achieve coincidence timing resolution (CTR) of 349 ps and DOI resolution of 2.9 mm. However, the coincidence timing resolution (CTR) was worse than 300 ps since the crystal surface and the reflector type were not optimized. This study aimed at investigating the optimal crystal surface treatment and the reflector material to achieve a sub-200 ps CTR and sub-3 mm DOI resolution with a dual-ended readout PET detector using an LYSO crystal (2.9 × 2.9 × 20 mm3). The scintillation light inside the LYSO crystal was read out by two SiPMs using the dual-ended readout method. The CTR and DOI resolution were measured with two different crystal surfaces (polished and saw-cut) and three different reflector material scenarios of ESR without grease (i.e., air coupling), ESR with optical grease and Teflon. We digitized the timing and energy signals by using a V775N TDC module (35 ps bit−1) and V965 QDC module, respectively. The combination of the saw-cut LYSO crystal and the ESR with air coupling resulted in the best CTR (188 ± 32 ps) and DOI resolution (2.9 ± 0.2 mm) with the dual-ended readout configuration. We concluded the dual-ended readout method in combination with the saw-cut crystal and the ESR reflector with air coupling can provide a sub-200 ps CTR and sub-3.0 mm DOI resolution simultaneously.

Vivaldi antennas: a historical review and current state of art

AbstractThe progressions in the field of wireless technology can be highly attributed to the development of antennas, which can access high data rates, provide significant gain and uniform radiation characteristics. One such antenna called the Vivaldi antenna has attracted the utmost attention of the researchers owing to its high gain, wide bandwidth, low cross-polarization, and stable radiation characteristics. Over the years, different procedures have been proposed by several researchers to improve the performance of the Vivaldi antennas. Some of these different approaches are feeding mechanisms, integration of slots, dielectric substrate selection, and radiator shape. Correspondingly, the performance of a Vivaldi antenna can be increased by including dielectric lens, parasitic patch in between two radiators, corrugations, as well as metamaterials. This paper gives a systematic identification, location, and analysis of a large number of performance enhancement methods of Vivaldi antenna design depicting their concepts, advantages, drawbacks, and applications. The principal emphasis of this article is to offer an outline of the developments in the design of Vivaldi antennas over the last few years, where the most important offerings, mostly from IEEE publications, have been emphasized. This review work aims to reveal a promising path to antenna researchers for its advancement using Vivaldi antennas.

Study of A designed and experimental multi-beam antennas based on Spoof Surface Plasmon Polaritors structure

The new type of artificial electromagnetic two-dimensional surface consists of an array of subwavelength unit structures arranged according to the periodicity of the dispersion curve. It has a significant role in regulating electromagnetic waves, and it has become one of the hot topics in the field of information. In this paper, the Spoof Surface Plasmon Polaritons (SSPPs) are regulated and applied to the wireless millimeter-wave base station communication. It has the characteristics of low profile, low cost, high isolation, broadband, and high gain. As a proof of concept, the antenna array is designed, simulated, processed and measured. The dual-beam adaptive antenna based on SSPPs at 10 GHz. The experimental results are in good agreement with numerical simulations. The proposed antenna has promising applications on planar wireless communication devices, such as multi-beam antennas, beam-scanning antennas, and wave controllers.

An integrated isolated inverter fed bldc motor for photovoltaic agric pumping systems

This research article proposes an isolated converter integrated with Pulse Width Modulated (PWM)Inverter fed Brushless DC motor (BLDC) for Photovoltaic agric pumping applications. The drift free Optimum Power Point Tracking (OPPT) algorithm is utilized to get maximum power from the Photo Voltaic (PV) Module.The proposed inverter has the features of high voltage gain, galvanic isolation, and better performance even in partially shaded conditions. Photovoltaic Agric Pumping System (PMPS) is aimed to support the rural development and reduce the maximum demand and burden on the distribution system. The proposed one is simulated with Matlab/Simulink software and prototype model alsobuilt with Field Programmable Gate Array (FPGA) controller.The developed systemresults demonstrate that its capability of better solar power utilization for water pumping applications.

A multi frequency point broadband compound antenna for partial discharge detection in gas insulated switchgear

In order to meet the requirements of the miniaturized and wide-band antennas for ultra-high frequency (UHF) detection method, a multi frequency point broadband compound antenna for detecting partial discharges (PD) of gas insulated substations (GIS) was designed. Firstly, through the analysis of the principle of miniaturization and broadbandization of the compound antenna, the meander technology was used to realize the miniaturization of the antenna, the multiple radiation unit technology was used to broaden the detection frequency band of the antenna, and the HFSS simulation software was used to simulate the design of the compound antenna. Then we made the antenna object according to the optimized simulation results, and the voltage standing wave ratio (VSWR) of this antenna was tested by vector network analyzer. Finally, the GIS PD test system was built in the laboratory to conduct the actual measurement research on the antenna. The test results show that: The compound antenna has the characteristics of miniaturization, high gain and multi-band. In the frequency range of 1.0 GHz to 3.0 GHz, its VSWR is less than 2, has a wide frequency range, can record most of the PD information. With the increase of frequency, the compound antenna gain is gradually increasing, and the maximum gain of the antenna can reach 6.5 dB, which can effectively receive weak UHF signals. The proposed antenna is quite promising for PD on-line detection applications.

Design of a wideband substrate integrated waveguide antenna with high‐gain employing two bow‐tie‐shaped slots

In this work, a compact antenna employing the substrate integrated waveguide (SIW) technology is investigated to achieve the characteristics of wideband and high gain. A pair of novel elliptical patches, which operate as an electric dipole, are loaded on the upper surface of the antenna. Two bow-tie-shaped slots are etched in parallel on the upper surface of SIW to obtain the features of magneto dipole and wideband. Combined with the low profile character of the SIW, the low cost of printed circuit board technology and the broadband characteristic of magneto-electric (ME) dipole, a 1 × 8 SIW ME-dipole antenna array is proposed and fabricated. The experimental result of the proposed prototype shows that the 10 dB impedance bandwidth is 42.3% from 19.4 to 29.8 GHz, which is basically consistent with the simulated result. Moreover, the antenna gain up to 14.6 dBi and the radiation efficiency higher than 82.6% are also obtained during the experiment. In the whole resonance band, excellent directional radiation, cross-polarisation level <−25 dB and gain fluctuation <2.7 dB all suggest that the array can be applied to a fifth-generation wireless network.

Gain and bandwidth enhancements of sequential‐fed circularly polarized patch antenna array using multiple parasitic elements

This paper presents a circularly polarized (CP) antenna array with wideband operation and high gain characteristics. The single array element is composed of a slotted CP patch and parasitic elements. It has been found that besides improving the operating bandwidth (BW), properly choosing a number of parasitic elements can also contribute to a significant increase in the antenna gain over the entire operating band. For further boost in the performance, multiple array elements are arranged in 2 × 2 configuration and fed by a sequential-phase feeding network. In comparison with the related works in the literature, the proposed design shows approximately 3-dB higher gain. The design concept has been validated by experiments. The fabricated array has a measured operating BW of 28% (4.6-6.1 GHz) and a peak broadside gain of 15.8 dBic.

A dual‐polarized antenna with low cross polarization, high gain, and isolation for the fifth‐generation array/multiple‐input multiple‐output communications

A dual-polarized antenna for the fifth-generation (5G) array/massive multiple-input multiple-output (MIMO) communications is proposed in this paper. Through combining dual-polarized differentially feeding structure and complementary magneto-electric (ME) dipole antenna, low cross polarization (X-pol), high gain, and isolation characteristics can be achieved by the antenna element. To take advantage of these characteristics in the array, a modified 1-to-16-way H-shaped differentially feeding network is designed to feed the 16-element antenna array. Here, vertical cross-shaped patches with dotted slots are arranged between adjacent ME-dipole antenna elements to further improve the array isolation. By removing the H-shaped differentially feeding network and the substrate at the bottom, a high-capacity MIMO antenna system can be achieved. Measured results show that low X-pol level of −35.7 dB and high gain of larger than 8.1 dBi can be attained by the antenna elements across the 5G frequency bands (3.3-5.1 GHz). In addition, the antenna array has exhibited high gain of 17.3 dBi and the MIMO antenna has realized very low envelope correlation coefficient of 0.004.

Thermal Remote Sensing for Water Outflows Detection and Determination of the Role of Lineaments in Underground Hydrodynamics of Evia Island, Central Greece

The coastal karst system of Evia Island is developed due to the extended presence of carbonate formations, discharges into the sea either at the coastal zone or via submarine springs, having a direct relation to the tectonic system of the area. Thermal infrared remote sensing has been proved its capability in monitoring thermal differentiations of coastal water plumes. This work aims to locate the freshwater outflows through remote sensing and specific with the use of Landsat’s 8 thermal images and to reveal how the lineaments of the area control this karstification process. L8 contains two thermal bands (Band 10, high gain and Band 11, low gain) with resolution 30m which record the scattering of infrared radiation from the sea surface. Spectral Band 10 was selected due to the high gain characteristics which provide more suitable radiometric resolution (sensitivity). Finally, combing thermal images with geological maps, sea surface temperature (SST) maps have been created.

A Family of Single-Stage, Buck-Boost Inverters for Photovoltaic Applications

This paper introduces a family of single-stage buck-boost DC/AC inverters for photovoltaic (PV) applications. The high-gain feature was attained by applying a multi-winding tapped inductor, and thus, the proposed topologies can generate a grid-level AC output voltage without using additional high step-up stages. The proposed topologies had a low component count and consisted of a single magnetic device and three or four power switches. Moreover, the switches were assembled in a push-pull or half/full-bridge arrangement, which allowed using commercial low-cost driver-integrated circuits. In this paper, the operation principle and comparison of the proposed topologies are presented. The feasibility of the proposed topologies was verified by simulations and experimental tests.

A Compact Single-Layer Wideband Microstrip Antenna With Filtering Performance

A compact single-layer filtering microstrip antenna with diverse characteristics of low profile, high gain, wide band, and high selectivity is proposed in this letter. Simple structure as it is, the presented antenna mainly consists of a rectangle driven patch, four parasitic strips, a pair of symbiotic strips, and a set of shorting pins. By attaching four parasitic strips to the original rectangular patch antenna, an additional resonance can be excited while the high-band edge selectivity is greatly improved due to the formation of a radiation null outside. Then, two symbiotic strips are embedded on both sides of the driven patch, which in turn creates an extra resonance mode and a lower-band radiation null. The set of shorting pins are applied to further improve operating and filtering response. Finally, the use of two parasitic patches can effectively improve the level of impedance bandwidth (IBW) and upper-band suppression. To verify this design, the corresponding antenna is fabricated and tested. The measured and simulated results are highly consistent, which reveals that it owns a wide IBW of 20.1% (2.19-2.68 GHz) with three resonance points, a higher average gain larger than 9.5 dBi, and a flat radiation efficiency above 88% in-band. The suppression level of the out-of-band gain on both sides can reach 14.5 dB.

Guest Editorial for the special issue on devices and circuits for millimeter‐wave and THz applications

Guest Editorial for the special issue on devices and circuits for millimeter‐wave and THz applications

High gain and low excess noise InGaAs/InP avalanche photodiode with lateral impact ionization.

In this paper, modeling for a lateral impact ionization InGaAs/InP avalanche photodiode (APD) has been performed based on a device simulator, i.e., Silvaco ATLAS. Compared with traditional APDs, the lateral impact ionized APD has much higher gains as well as lower excess noise. The internal gain for our newly proposed lateral APD is over 1000-near the breakthrough voltage. In addition, the excess noise characteristic of this device is also discussed with three-dimensional dead space multiplication theory, and the calculated effective $k$k value is obviously lower than traditional InGaAs/InP APDs. Because of the high gain and low excess noise characteristics, the proposed APD can be widely applied for optical detection with high sensitivity.

Design and implementation of an improved sinusoidal controller for a two-phase enhanced impedance source boost inverter

This study presents a novel Sinusoidal Pulse Width Modulation (SPWM) model for a two-phase Impedance Source-based Inverter (ZSI) with a hardware prototype implementation. The high-gain feature is investigated based on an innovative mathematical model that involves fewer components and presents efficient performances. The presented topology can be applied broadly in Photo Voltaic systems, Wind Power, Fuel Cell, and Uninterrupted Power Supply topologies due to the ability of wide-range load regulation with higher duty cycles. Through Shoot (TS) and higher Total Harmonic Distortion (THD) problems can be solved by a carefully designed gate-drive circuit and proper switching frequency for the appropriate resistance against the Electromagnetic Interfaces (EMIs). One of the essential specifications of the proposed controller is working with intermediate values of duty cycles for power MOSFETs that can decrease the losses for the inverter. A set of numerical simulation and hardware results are presented for ensuring the proposed claims.

A wide‐scanning ellipsoid lens antenna fed by phased array antenna

Luneburg lens antennas have been widely applied to many communication systems for their multibeam scanning and high gain characteristics. However, the large profiles of conventional Luneburg lens antennas restrict their applications. To solve these issues, an ellipsoid lens antenna fed by phased array antenna (PAA) operating at Ka-band is proposed in this article. The profile of the ellipsoid lens is reduced by half compared to the conventional Luneburg lens, based on the transformation optics theory. The wide-angle scanning property is obtained by optimizing the amplitude and phase distributions of the PAA, combined with the element pattern superposition principle. The proposed five-layer ellipsoid lens antenna is able to scan up to ±45° with less than 3 dB scanning loss at 28 GHz. Finally, the lens was easily fabricated through three dimensional printing technology and computer numerical control. Experimental results are in good agreement with the numerical results, thus validating the proposed design.

Metasurface-Based Single-Layer Wideband Circularly Polarized MIMO Antenna for 5G Millimeter-Wave Systems

This paper presents a metasurface-based single-layer low-profile circularly polarized (CP) antenna with the wideband operation and its multiple-input multiple-output (MIMO) configuration for fifth-generation (5G) communication systems. The antenna consists of a truncated corner patch and a metasurface (MS) of a 2 × 2 periodic square metallic plates. The distinguishing feature of this design is that all the radiating elements (radiator and MS) are printed on the single-layer of the dielectric substrate, which ensures the low-profile and low-cost features of the antenna while maintaining high gain and wideband characteristics. The wideband CP radiations are realized by exploiting surface-waves along the MS and its radiation mechanism is explained in detail. The single-layer antenna geometry has an overall compact size of 1.0λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 1.0λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.04λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> . Simulated and measured results show that the single-layer metasurface antenna has a wide 10 dB impedance bandwidth of 23.4 % (24.5 - 31 GHz) (23.4 %) and overlapping 3-dB axial ratio bandwidth of 16.8 % (25 - 29.6 GHz). The antenna also offers stable radiation patterns with a high radiation efficiency (>95%) and a flat gain of 11 dBic. Moreover, a 4-port (2 × 2) MIMO antenna is designed using the proposed design by placing each element perpendicular to each other. Without a dedicated decoupling structure, the MIMO antenna shows an excellent diversity performance in terms of isolation between antenna elements, envelope correlation coefficient, and channel capacity loss. Most importantly, the operational bandwidth of the antenna covers the millimeter-wave (mm-wave) band (25 - 29.5 GHz) assigned for 5G communication. These features of the proposed antenna system make it a suitable candidate for 5G smart devices and sensors.

Analysis and design of novel wideband and high efficiency millimeter-wave antenna arrays for 60-GHz applications

A type of millimeter-wave antenna array with flexible design is proposed for a variety of applications at 60 GHz. The antenna array can be adjusted to be linearly or circularly polarized by simply changing the radiation part of the antenna array. High gain, wideband, and high radiation efficiency characteristics can be achieved by adopting a low insertion loss feeding network and broadband antenna elements. For the linearly polarized antenna array, simulation results show that the impedance bandwidth of the 2×2 antenna subarray reaches 21.6%, while the maximum gain achieves 15.1 dBi and has a fluctuation of less than 0.4 dBi within the working bandwidth. Simulation results of the 8×8 linearly polarized antenna array show a bandwidth of 21.6% and a gain of (26.1±1) dBi with an antenna efficiency of more than 80%. For the 8×8 circularly polarized antenna array, simulation results show that an impedance bandwidth of 18.2% and an axial ratio (AR) bandwidth of 13.3% are obtained. Gain and efficiency of up to 27.6 dBi and 80% are achieved, respectively. A prototype of antenna array is fabricated, and results are compared and analyzed.

Vibration Suppression and Over-Quadrant Error Mitigation Methods for a Ball-Screw Driven Servo System With Dual-Position Feedback

For high-precision control in a ball-screw driven servo system, the full-closed loop position control structure with position measurements from both the drive side and the load side are usually required. However, compared with semi-closed loop position control, if only the load side position feedback is being used, then the inherent elastic link is included in the position loop, and the mechanical vibration will be easily induced. For this situation, the stability of the servo system will be affected. Moreover, in the ball-screw driven servo system, the backlash and friction in the mechanical transmission chain will introduce a typical contour error-over-quadrant error, which cannot be eliminated by adopting full-closed loop control. In order to maintain stability and high precision positioning performance, both vibration suppression and over-quadrant error mitigation methods are proposed in this paper. First, the model of full-closed loop position control system is established, on this basis, the reasons that why the full-closed loop control is more easily to induce the position vibration than the semi-closed loop control is analyzed. Then, a dual-position feedback control method, by introducing the drive side position information with a filter to the position loop feedback channel, is proposed, which combines the advantages of semi-closed loop control and full-closed loop, and features high gain margin and high control precision. Furthermore, based on the analysis of the mechanism of over-quadrant error, an adaptive backlash error compensation method which can reduce the over-quadrant error is proposed. Finally, simulation and experimental results in both single axis and dual axis are provided to demonstrate the feasibility and effectiveness of the proposed methods.

High-Efficiency Bidirectional LLC Resonant Converter with Primary Auxiliary Windings

In this paper, high-efficiency bidirectional LLC resonant converters with primary auxiliary windings in transformers of resonant circuits are proposed. Even though resonant capacitors are used on the primary and secondary sides, the proposed converter can operate, regardless of the direction of the power flow, with the high gain characteristics of the LLC resonant converter without the mutual coupling of resonant capacitors. The operation principles and gain characteristics of the proposed bidirectional DC–DC converters are described in detail. A 3.3 kW prototyped bidirectional LLC resonant converter for interfacing 750 VDC buses was built and tested to verify the effectiveness and applicability of this proposed converter.