David Hotte

A Concept of Pressure Sensor Based on Slotted Waveguide Antenna Array for Passive MMID Sensor Networks

The concept presented in this paper proposes to exploit the structure of a 3-D slotted waveguide antenna array (SWAA) to turn it into a completely passive millimeter-wave identification (MMID) pressure sensor. The pressure sensor is realized by ending the SWAA with a metallic membrane, where the variation of pressure causes a variation in the radar cross section (RCS). The concept is studied across the RCS measurement of the SWAA ended by a sliding short circuit to emulate the membrane deflection. Experimental results show that a sensitivity of 22.46 mm2/mm of short-circuit displacement is reached at 57.8 GHz. An estimated read range of 1.1 m is considered with an MMID reader compliant with the ETSI European power emission regulation.

A Method to Characterize the Frequency-Dependent Structural Coefficient of Antennas: Application to Millimeter Wave Identification

The passive UHF RFID technology, well known for the logistics and security applications, is more and more considered for sensor networks and Internet of Things (IoT). Recent works have demonstrated the possibility to exploit the main advantages of RFID in the millimeter-wave domain, giving rise to the millimeter wave identification (MMID) technology. This new technology uses the large available ISM band from 57 to 66 GHz in Europe. In backscatter communications, such as RFID or MMID, the radar cross section (RCS) is a fundamental parameter. The antenna RCS is defined as a function of its load and its structural coefficient. The structural coefficient that depends on the antenna geometry is often approximated to unity in RFID because tag antennas are usually thin dipoles compared to the wavelength. However, in MMID this approximation is no longer suitable due to the use of high directive antennas. This letter aims to propose a method to determine the structural coefficient of any types of antenna. The proposed approach is illustrated through the study of a horn antenna and a slotted waveguide antenna array in WR15 waveguide (from 50 to 75 GHz). Theoretical, simulation, and measurement results are compared and demonstrate the interest of the method.

A humidity sensor based on V-band slotted waveguide antenna array

The paper presents the design of a new type of humidity sensor-tag operating in V-band. The proposed design combines the humidity sensitive properties of Kapton and a slotted waveguide antenna array. Design methodology is high-lighted. Simulation and experimental results are reported which validate the design procedure and show promising perspectives.

A new concept of UHF RFID tag for metallic object tracking with embedded cavity

This paper presents a new solution for labeling metallic items like boxes and cavities. The proposed tag is based on the use of electromagnetic properties of cavities and the passive loop AKTAG RFID tag. Moreover the design avoids the physical connection between the RFID chip and the antenna. Simulation and measurement results are in good agreement. The feasibility of performing hidden tag using existing metallic cavity embedded in the object structure is demonstrated. When the tag is inside the cavity, a read-range of 5.5 m was measured in anechoic chamber, and a read-range of 7.7 m is reached when the loop tag is directly coupled to the slot.