A U‐shaped antenna is printed on polytetrafluoroethylene film, deposited on a copper base having air cavity inside, using thin film micro‐strip technology. This antenna is as compact as the ...rectangular patch and covers the 51.5–62 GHz band. Unlike the silicon substrate, its metallic support yields better radiation patterns.
In this study, a metamaterial-based LTCC compressed Luneburg lens was designed, manufactured and measured. The lens was designed at 60 GHz to utilize the unlicensed mm-wave spectrum available for ...short-range high-capacity wireless communication networks. The transformation optics method was applied to ensure the compression of the Luneburg lens antenna and thus maintain a low-profile structure. The two different types of unit cells for low and high permittivity regions were considered. The parametric study of the effect of compression on lens performance was presented. The antenna is implemented with a standard high-permittivity LTCC process, and details of the manufacturing process for the metamaterial lens are discussed. The low-profile lens is thinner than 2 mm and measures 19 mm in diameter. A size reduction of 63.6% in comparison with a spherical lens was achieved. The near-field to far-field mm-wave measurement technique is presented, and the measurement results show a peak antenna gain of 16 dBi at 60 GHz and a beam-scanning capacity with 1 dB scan loss within a 50° field of view.
•Description of the sensing principles of chloride ingress monitoring by a radiofrequency dielectric probe.•Decoupling the influence of water and chloride ingress is possible with the proposed ...method.•Ability of the method to monitor diffusion of chloride in concrete at different depths.
The origin of rebars corrosion in concrete infrastructures is frequently associated with the ingress of chloride ions present in water. This is particularly the case of infrastructures located in marine environments or exposed to deicing salts. The present study aims at developing a radio-frequency dielectric sensor dedicated to free chloride ingress monitoring in a well-defined volume of the material. A resonant method operating in a wide frequency range is selected to separate the effects associated with the variation of the real part of the dielectric permittivity and tangent loss. As it will be shown, the method provides useful information on the presence of free chloride in concrete and can be used for the monitoring of chloride diffusion. For this purpose, considering the variation of the transmission parameter S12 value presents clearly some advantages with respect to the frequency shifts of resonances. This allows to decouple water and chloride content.
Wireless and fully energetically passive corrosion sensors inspired from the chipless Radio-Frequency IDentification (RFID) technology are presented for the monitoring of degradation of ...infrastructures located in coastal zones and underwater environments. The device consists of a reader and a remote passive sensor. This study presents two radio-frequency (RF) corrosion-sensitive resonators that can be integrated in such a device. The first is sensitive to a loss of metal due to its degradation, and the second is sensitive to the corrosion potential of metals, with respect to a reference electrode. The RF characterization of these two resonators demonstrates unambiguously the sensitivity of the method to corrosion of metal, passivation of steel as well as degradation of organic coatings. Then, their integration in a demonstrator including antennas is considered. The main parameters that influence the RF wave propagation and thus the reading distance are discussed. Following the presented results, the proposed method is considered as a reliable and versatile tool which should be able to be deployed in immersed, tidal, and splash zones, for example, for offshore facilities monitoring.
The creation of hole, cavity or channel structures in low-temperature cofired ceramics (LTCCs), using different sacrificial volume materials (SVMs) was tested. The main functionality of the SVMs ...should be: easy application into the holes; protection of holes during lamination; uninhibited lamination between layers; and, during firing should burn out before the pores of the LTCCs close, to leave the empty holes clear of any residue. Five different materials were tested—hydroxyethyl cellulose (HEC) 2 wt%, HEC 5 wt%, agar-agar, gelatin, and commercial carbon paste—and compared to a reference sample where no SVMs were used. In all cases, lamination parameters were minimised in order to preserve the tested hole structures. Matrixes with holes ranging from 158 to 268 µm, with pitches of 573 µm in a green state, were tested. The agar-agar caused ceramic deformation as a result of thermal burst during firing and the lamination between the layers was compromised. The carbon paste was difficult to handle, requiring extra equipment for hole filling and incomplete filling of the larger holes. Traces of carbon paste were left as a landing pad on top of the holes, inhibiting lamination at these areas. The gelatin and the 2 wt% and 5 wt% hydroxyethylcellulose (HEC 2 wt% and HEC 5 wt%) filled all holes completely, and also worked as adhesive-assisted lamination (AAL) materials with excellent lamination between layers. Excellent lamination was also observed in the no-SVM case. Thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) analyses established that, for all SVMs tested, the remaining residue is negligible after firing. As a result, the HEC 2 wt% material was considered ideal for use as an SVM.
This paper presents a procedure to implement the concept of surface impedance boundary condition (SIBC) for lossy dielectrics in time domain. The SIBC formulation, validation, and results are ...obtained with a time domain numerical method, namely the transmission-line matrix (TLM). The formulation of surface impedance in frequency domain is converted to the time domain using a rational approximation followed by a bilinear transform with a canonical representation in the state-space. This surface impedance formulation has been implemented in TLM. Simulations show that the proposed model is valid for interfaces between air and a lossy dielectric, and arbitrary conductivity \sigma. An application that concerns mode propagation in a rectangular tunnel with lossy dielectric walls is shown. A comparison with an approximate method proposed by Marcatilli is presented. It confirms that the propagation in electrically large guided structures, such as tunnels with lossy dielectric walls, can be efficiently modeled by this approach.
This study focuses on the impact of planar near-field measurement parameters, such as plane size, sampling step and the distance between the Antenna Under Test (AUT) and the measurement plane. The ...main objective of this work is to determine the optimal near-field measurement parameters that achieve an assessment of far-field (FF) radiation pattern accuracy versus measurement duration.
mmWave Channel Sounding for Vehicular Communications Attwood, Nicholas; Gallee, Francois; Pajusco, Patrice ...
2024 18th European Conference on Antennas and Propagation (EuCAP),
2024-March-17
Conference Proceeding
Odprti dostop
This paper provides initial findings from a Vehicle-to-Infrastructure radio channel measurement campaign. The channel sounder used is the IMT Atlantique SIMO (Single Input Multiple Output) SDR ...(Software Defined Radio), operating at a frequency of 60 GHz with a bandwidth of 180 MHz. The transmitter (Tx) is mounted on the roof of a moving car, and the receiver (Rx) is positioned like a traffic sign. The measurement scenario is a street with vehicles parked on both sides of the road. For each scenario, the paper presents measurements of the Channel Transfer Function (CTF) gain, the Power Delay Profile (PDP), and the Doppler spread average function.
A new design method for multi-access antennas is presented. This method is based on a modal analysis assuming the microstrip antennas as a resonant cavity. Using this cavity approach, the eigenmodes ...perturbation induced by the cavity deformation (adding slots or short circuits) is studied. As an application, a solution of multi-access antenna with two ports, with operating frequency bands centered approximately on digital cellular system (DCS) and universal mobile telecommunication system (UMTS)/Wi-Fi standards is developed. These two ports are isolated using the previous original design method. In addition to the design method, the innovation of the structure resides on its application in terms of flexibility, reconfigurability, and portability for the future development of a unique system that allows cross services where telephony joined multimedia and online services. The design method and the performances are validated through comparisons between simulations and measurements.
The paper presents a metamaterial based LTCC compressed Luneburg lens antenna for wireless communications. The antenna is designed at 60 GHz to utilize the unlicensed mm-wave spectrum available for ...short-range high-data-rate communications. The gradient index compressed Luneburg lens antenna is designed using the quasi-conformal transformation optics method. The design of the antenna is fully compliant with the standard LTCC process with a high-permittivity host material. The diameter of the antenna is 19 mm and the thickness is less than 2 mm. The peak antenna gain at 60 GHz of 16 dBi is demonstrated. Beam scanning capacity is demonstrated with 1 dB scan loss within ±25 degree field of view.
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