Design of the high field side antenna of the new reflectometric system for plasma position estimate in RFXmod2

A reflectometric system will be installed in the RFX-mod2 experiment, consisting of 4 couples of transmitting/receiving antennas working in the range 16–26.5 GHz in X-mode wave propagation for tokamak discharges. They will be placed within dedicated plasma accesses in the same poloidal section at 4 equispaced poloidal positions, two on the equatorial plane, High Field Side (HFS)/Low Field Side (LFS), and two at the vertical top/bottom ports. This configuration was conceived to perform plasma position control experiments without using the magnetic measurement signals. While the accesses in LFS, top and bottom positions will accommodate pyramidal antennas, the strict room constraints in the HFS position required a special routing of the feeding waveguide and the design of a different type of antenna, described in the paper. The horn reflector (also named hoghorn) type was preferred which allows radiating (and receiving) a beam at a 90° direction with respect to the horn axis, which will be perpendicular to the equatorial plane. After fixing a reference working frequency f = 21 GHz (wavelength λ = 14.3 mm), an antenna fitting the available room was designed by means of the COMSOL Multiphysics Radio Frequency module. Four different versions were developed by introducing some modifications of the aperture shape to study their effect on the antenna performance. FEM analyses were run for frequencies in the 17–26 GHz interval to characterize the frequency response in terms of radiative patterns of the total and far electric field. The directivity of the antennae was also evaluated. The 4 versions exhibited comparable responses and the observed beam directional properties at the expected plasma distance were considered acceptable for the development of this application. A prototype of the antenna has been realized by additive manufacturing process.

Effects of the Feedline Position on Microstrip Patch Antenna Performance

In this study, it is aimed to demonstrate the effects of the feed line position on the operating frequency, return loss and bandwidth of the rectangular patch microstrip antenna. For this purpose, a compact-sized antenna that can operate at 2.4-2.45 GHz frequencies is designed in High Frequency Structure Simulator (HFSS) program. Then, the position of the feedline is changed horizontally and vertically, and its effects are observed. The results obtained after the modificaions are given and discussed. It is stated that the feed line position is a very important parameter that affects the basic characteristics of the antenna.

Optimization Environment Definition for Beam Steering Reflectarray Antenna Design

Reflectarray antennas are low-profile high-gain systems widely applied in the aerospace industry. The increase in their application is leading to the problem of getting more advanced performance while keeping the system as simple as possible. In these cases, their design cannot be conducted via analytical methods, thus evolutionary optimization algorithms are often implemented. Indeed, the design is characterized by the presence of many local minima, by high number of design variables, and by the high computational burden required to evaluate the antenna performance. The purpose of this paper is to develop, implement, and test a complete Optimization Environment that can be applied to achieve high scanning capabilities with a reflectarray. The design of the optimization environment has been selected to be flexible enough to be applied also with other different algorithms.

RECONFIGURABLE MONOPOLE ANTENNA DESIGN BASED ON FRACTAL STRUCTURE FOR 5G APPLICATIONS

a reconfigurable antenna design for 5G applications is presented. It is based on monopole antenna and fractal structure. The design structure is consisted of (monopole) feedline, ground plane, L-shape reflector, fractal structure and PIN diodes. The antenna is printed on (25×29×1.6 mm3) FR-4 substrate of εr=4.3 and tanδ =0.001. The antenna shows a resonant frequency at 4.1 GHz with S11=-11.4 dB and Omni-direction pattern of 1.21 dB gain. The L-shaped reflector is used to maintain the radiation pattern in a specific direction. Moreover, the proposed fractal structure is found to operate as a circuit to give another resonant frequency and enhance the antenna performance. Where it is used to give more manipulation in the antenna performance including: frequency resonance and radiation patterns. The PIN-diodes are used to give many cases for more current manipulation. moreover, the authors used RF (50 SMA port) between monopole antenna and right side of ground plane to optimize directing radiation pattern and to eliminate the problems of interference between AC and DC current that produced from using PIN diode. This manipulation leads to change the resonant frequency and radiation pattern to the desired direction.So all parts are printed on a single side of FR4 substrate

Wearable Metamaterial Dual-Polarized High Isolation UWB MIMO Vivaldi Antenna for 5G and Satellite Communications

A low-profile Multiple Input Multiple Output (MIMO) antenna showing dual polarization, low mutual coupling, and acceptable diversity gain is presented by this paper. The antenna introduces the requirements of fifth generation (5G) and the satellite communications. A horizontally (4.8–31 GHz) and vertically polarized (7.6–37 GHz) modified antipodal Vivaldi antennas are simulated, fabricated, and integrated, and then their characteristics are examined. An ultra-wideband (UWB) at working bandwidths of 3.7–3.85 GHz and 5–40 GHz are achieved. Low mutual coupling of less than −22 dB is achieved after loading the antenna with cross-curves, staircase meander line, and integration of the metamaterial elements. The antennas are designed on a denim textile substrate with = 1.4 and h= 0.5 mm. A conductive textile called ShieldIt is utilized as conductor with conductivity of 1.8 × 104. After optimizing the proposed UWB-MIMO antenna’s characteristics, it is increased to four elements positioned at the four corners of a denim textile substrate to be employed as a UWB-MIMO antenna for handset communications, 5G, Ka and Ku band, and satellite communications (X-band). The proposed eight port UWB-MIMO antenna has a maximum gain of 10.7 dBi, 98% radiation efficiency, less than 0.01 ECC, and acceptable diversity gain. Afterwards, the eight-ports antenna performance is examined on a simulated real voxel hand and chest. Then, it is evaluated and compared on physical hand and chest of body. Evidently, the simulated and measured results show good agreement between them. The proposed UWB-MIMO antenna offers a compact and flexible design, which is suitably wearable for 5G and satellite communications applications.

Design of a dual-band antenna for energy harvesting application

This report presents an investigation on how to improve the current dual-band antenna to enhance the better result of the antenna parameters for energy harvesting application. Besides that, to develop a new design and validate the antenna frequencies that will operate at 2.4 GHz and 5.4 GHz. At 5.4 GHz, more data can be transmitted compare to 2.4 GHz. However, 2.4 GHz has long distance of radiation, so it can be used when far away from the antenna module compare to 5 GHz that has short distance in radiation. The development of this project includes the scope of designing and testing of antenna using computer simulation technology (CST) 2018 software and vector network analyzer (VNA) equipment. In the process of designing, fundamental parameters of antenna are being measured and validated, in purpose to identify the better antenna performance.

Design of Compact MIMO Multiband Antenna for Wireless Radio Communication Application

Slot and patch modification for the design of a compact multiband antenna with Multi-Input-Multi-Output (MIMO) functionality is proposed in this paper. At various frequency bands, the antenna performance is obtained by modification and addition of slot and patch shapes in the design of the compact MIMO multiband antenna. Addition of slots or patches is done separately in the already existing multiband antenna designs. Whereas in this work, the addition of slot and patch are combined. Arlon Diclad 880 with a dielectric constant of 2.17 - 2.2 (εr) and height 0.75mm is used for the antenna design. The MIMO multiband antenna with the dimension of 12.5 mm × 7.5 mm is designed. On various millimeter-wave frequency bands ranging from 20 GHz to 40 GHz, the MIMO antenna can function as observed in the results of simulation and evaluation. This work shows that microstrip antennas can be added with slots and patches during their design and development, thereby enabling the antenna to operate under multiple frequency bands.

Stainless-Steel Antenna on Conductive Substrate for an SHM Sensor System with High Power Demand

This paper presents the novel concept of structuring a planar coil antenna structured into the outermost stainless-steel layer of a fiber metal laminate (FML) and investigating its performance. Furthermore, the antenna is modified to sufficiently work on inhomogeneous conductive substrates such as carbon-fiber-reinforced polymers (CFRP) independent from their application-dependent layer configuration, since the influence on antenna performance was expected to be configuration-dependent. The effects of different stack-ups on antenna characteristics and strategies to cope with these influences are investigated. The purpose was to create a wireless self-sustained sensor node for an embedded structural health monitoring (SHM) system inside the monitored material itself. The requirements of such a system are investigated, and measurements on the amount of wireless power that can be harvested are conducted. Mechanical investigations are performed to identify the antenna shape that produces the least wound to the material, and electrical investigations are executed to prove the on-conductor optimization concept. Furthermore, a suitable process to fabricate such antennas is introduced. First measurements fulfilled the expectations: the measured antenna structure prototype could provide up to 11 mW to a sensor node inside the FML component.