Specific Antenna Design Research Articles

GPS-Free Wireless Precise Positioning System for Automatic Flying and Landing Application of Shipborne Unmanned Aerial Vehicle.

This research is dedicated to developing an automatic landing system for shipborne unmanned aerial vehicles (UAVs) based on wireless precise positioning technology. The application scenario is practical for specific challenging and complex environmental conditions, such as the Global Positioning System (GPS) being disabled during wartime. The primary objective is to establish a precise and real-time dynamic wireless positioning system, ensuring that the UAV can autonomously land on the shipborne platform without relying on GPS. This work addresses several key aspects, including the implementation of an ultra-wideband (UWB) circuit module with a specific antenna design and RF front-end chip to enhance wireless signal reception. These modules play a crucial role in achieving accurate positioning, mitigating the limitations caused by GPS inaccuracy, thereby enhancing the overall performance and reception range of the system. Additionally, the study develops a wireless positioning algorithm to validate the effectiveness of automatic landing on the shipborne platform. The platform's wave vibration is considered to provide a realistic landing system for shipborne UAVs. The UWB modules are practically installed on the shipborne platform, and the UAV and the autonomous three-body vessel are tested simultaneously in the outdoor open water space to verify the functionality, precision, and adaptability of the proposed UAV landing system. Results demonstrate that the UAV can autonomously fly from 200 m, approach, and automatically land on the moving shipborne platform without relying on GPS.

The origin of distorted intensity pattern sensed by a lens and antenna coupled AlGaN/GaN-HEMT terahertz detector**Project supported by the National Key Research and Development Program of China (Grant No. 2016YFF0100501), the National Natural Science Foundation of China (Grant Nos. 61771466, 61775231, and 61611530708), the Six Talent Peaks Project of Jiangsu Province, China (Grant No. XXRJ-079), the Youth Innovation Promotion Association

Antenna-coupled field-effect-transistors (FETs) offer high sensitivity for terahertz detection. Both the magnitude and the polarity of the response signal are sensitive to the localized terahertz field under the gate. The ability of accurate sensing the intensity pattern is required for terahertz imaging systems. Here, we report artefacts in the intensity pattern of a focused terahertz beam around 1 THz by scanning a silicon-lens and antenna coupled AlGaN/GaN high-electron-mobility-transistor (HEMT) detector. The origin of the image distortion is found to be connected with one of the antenna blocks by probing the localized photocurrents as a function of the beam location and the frequency. Although the exact distortion is found with our specific antenna design, we believe similar artefacts could be commonplace in antenna-coupled FET terahertz detectors when the beam spot becomes comparable with the antenna size. To eliminate such artefacts, new antenna designs are welcomed to achieve strong asymmetry in the terahertz field distribution under the gate while maintaining a more symmetric radiation pattern for the whole antenna.

A Multiband Biconical Log-periodic Antenna for Swarm Communications

In this paper, we present a specific multiband antenna design that addresses the problem of communication with unmanned aerial vehicles (UAVs). We consider a scenario where multiband single-antenna UAV communicates with the rest of the swarm members that are equipped with similar antennas. The key point in the design is that the communication does not require high or low elevation angles in most of the cases. The suggested design has a sufficient degree of freedom to select the desired features for the field pattern while keeping other features such as antenna impedance and gain relatively stable or at least in the acceptable operation region.

Optimized Planar Elliptical Dipole Antenna for UWB EMC Applications

This paper presents a novel method for optimizing a planar elliptical dipole antenna with elliptical slots, for ultrawideband electromagnetic compatibility applications. The antenna is required to achieve minimum return loss and boresight realized gain with an adequate gain flatness across the frequency range of 1–5 GHz. Such an antenna is a powerful tool for electromagnetic measurements, due to its very compact size and its wide operating bandwidth. The main optimization method used in this paper is the invasive weed optimization (IWO), which is a nature-inspired metaheuristic evolutionary algorithm. The conventional and a modified version of IWO are compared to other prior-art evolutionary algorithms, such as the particle swarm optimization and differential evolution. The comparison is performed by applying all the methods on a set of mathematical test functions and also on the specific antenna design problem presented in this paper. The comparative results demonstrate the superiority of the modified IWO over the other optimization methods.

Optimization of wearable microwave antenna with simplified electromagnetic model of the human body

Abstract In this paper the problem of optimization design of a microwave wearable antenna is investigated. Reference is made to a specific antenna design that is a wideband Vee antenna the geometry of which is characterized by 6 parameters. These parameters were automatically adjusted with an evolution strategy based algorithm EStra to obtain the impedance matching of the antenna located in the proximity of the human body. The antenna was designed to operate in the ISM (industrial, scientific, medical) band which covers the frequency range of 2.4 GHz up to 2.5 GHz. The optimization procedure used the finite-difference time-domain method based full-wave simulator with a simplified human body model. In the optimization procedure small movements of antenna towards or away of the human body that are likely to happen during real use were considered. The stability of the antenna parameters irrespective of the movements of the user’s body is an important factor in wearable antenna design. The optimization procedure allowed obtaining good impedance matching for a given range of antenna distances with respect to the human body.

SiP Technology for Wireless Module Miniaturization

SiP (System in package) module provide a integrate functions, smaller and thinner package solution on electronic portable devices. For the wireless application, the advanced AoP (Antenna on package) and compartment shielding has been proposed and developed by Advanced Semiconductor Engineering (ASE), Inc. to be the next request for complex application and miniaturization solution. For AoP package, more focus on near field/wireless connection to have specific metal antenna design and attached on package surface to achieve SiP module miniaturization and perform required antenna efficiency on low frequency application. Advanced compartment shielding provide the simple method on function isolation area to prevent the electromagnetic noise interference (EMI) and high level of total radiated EMI from system product due to more complex package performance. The major benefit of novel AoP package is transfer the antenna designed on PCB to directly attached on package to reduce the PCB X/Y dimension but still keep antenna efficiency performance. The fabrication of AoP consists of following factors: 1) special substrate design to have antenna connection pads; 2) specific 3D metal frame design for antenna; 3) antenna frame attachment and over mold for package. Following these processes, AoP provide a simple process on package assembly and smaller dimension of package. For compartment shielding development in ASE, previously we design a metal can on module package to reduce EMI but induce a thickness increase. The novel compartment shielding more focus on shielding frame design inside the package to achieve simple process flow and good shielding performance, their fabrication consists the following factors: 1) specific tooth-type frame design to have shielding function for different zone in package and provide suitable slot width/pitch ratio for mold flow; 2) adhesion material for metal frame attached on substrate ; 3) over mold and laser trenching; 4) conductive material sputtering on package surface. This novel compartment shielding solution provides a simplified shielding and more reliable process on SiP module package. Wireless module was designed RF/power/Switch/Bluetooth function inside the package, the high density of electrical function is usually designed in the portable devices with small/thinner size. Advanced AoP or compartment shielding technology provides more competitive solution on SiP module miniaturization. In the paper, we will present the design for AoP and compartment shielding, process characterization and measurement of antenna and shielding performance of module to present the advantage of SiP modules with this technology application.

Polyurethane membranes for flexible centimeter-wave patch antennas

In this paper, we present the original use of a recyclable and low cost soft polymer, polyurethane (PU) (εr ≈ 3.5 at 10 GHz), as part of a dielectric substrate of a microstrip patch antenna. The combination of simple membrane manufacturing process and the low Young’s modulus of PU (EPU ≈ 30 MPa) are employed in an X-band antenna application in this study. The PU dielectric characterizations indicate the high loss tangent value (tan δ ≈ 0.1 at 10 GHz). Membrane supported technology is used to reduce the influence of this high loss and increase the antenna efficiency. The measurement of antenna performances such as efficiency (η ≈ 31.7%) confirms the viability of the technological process and the specific patch antenna design developed in this work. Besides, the potential of the PU-based soft patch antenna for frequency agility (3.88%) via mechanical reconfiguration is also shown.

Highly resonant and directional optical nanoantennas

Plasmonic nanoantennas permit many functional components for future generations of nanoscale optical devices. They have been intensively studied and means were devised to engineer their optical response. However, as a metal-based resonator, the low quality factor of a plasmonic antenna hinders its further applications. Here, we propose a novel design to improve the quality factor of a dipolar nanoantenna by combining it with plasmonic Bragg gratings. This specific antenna design can support extraordinary sharp resonances and highly directional emissivity. Therefore, it promises to achieve many novel applications, e.g., in the field of cavity quantum electrodynamics where the strong coupling regime for light and matter comes in reach.

Progress in Antenna Coupled Kinetic Inductance Detectors

This paper describes the combined Dutch efforts toward the development of large wideband focal plane array receivers based on kinetic inductance detectors (KIDs). Taking into account strict electromagnetic and detector sensitivity requirements for future ground and space based observatories, this work has led to the identification of well-suited coupling strategies based on the use of lens antenna and the demonstration of their feasibility. Moreover, some specific antenna design difficulties that characterize KIDs-based designs have been investigated, and innovative feeds for the focal plane array which could allow the receivers to be sensitive over a decade of Bandwidth have been proposed.

RF transmit power limit for the barewire loopless catheter antenna.

The safety of the barewire loopless catheter antenna in transmit mode is addressed with respect to radiofrequency (RF) heating. Analytical expressions for electric field and specific absorption rate (SAR) distributions surrounding the antenna are postulated and experimentally verified. Limiting RF transmit power to 40-70 mW time-averaged power, depending on the specific antenna design, will ensure that the current regulatory guideline of SAR of 8 W/kg in any gram of tissue is not exceeded. These limits can act as guidelines for the design of RF pulses for use with this device. Further study is required to examine the safety of the antenna in receive mode.

RF Transmit Power Limit for the Barewire Loopless Catheter Antenna

The safety of the barewire loopless catheter antenna in transmit mode is addressed with respect to radiofrequency (RF) heating. Analytical expressions for electric field and specific absorption rate (SAR) distributions surrounding the antenna are postulated and experimentally verified. Limiting RF transmit power to 40-70 mW time-averaged power, depending on the specific antenna design, will ensure that the current regulatory guideline of SAR of 8 W/kg in any gram of tissue is not exceeded. These limits can act as guidelines for the design of RF pulses for use with this device. Further study is required to examine the safety of the antenna in receive mode.