This paper presents an original passive microwave substrate integrated cavity resonator [substrate integrated waveguides (SIWs)] as an environment sensor for humidity detection. The proposed structures are based on a high quality factor (Q ~ 300) substrate integrated cavity resonator operating at 3.6 and 4.15 GHz. The detection principle is based on a frequency shift due to the permittivity variation of the humid air. This variation can be detected and used as the sensor indication. The frequency shift has been estimated analytically using the dielectric perturbation method for the resonator prototypes. The structure of the presented SIW resonators has been tested in the presence of humidity and shows sensitive characteristics in the range of 0%-80% relative humidity in accordance with the proposed model. A comparison of sensitivity performance between the new structure and other reported microwave components for environmental sensing is also presented. Measurements of repeatability and reliability for the proposed structure are discussed as well. As a new microwave component type, the proposed substrate integrated environmental sensor has the advantage of providing a new fabrication solution for radio frequency environmental sensing and greatly simplifies the sensor's manufacturing processes and cost.

The aim of this paper is to develop a framework of a chipless wireless system for sensing in compliance with the standard international regulations. The proposed approach offers a solution to solve the main difficulty met for the deployment of chipless systems that require specific readers (based on non-standardized large frequency bands and specific signal waveforms). The possibility of interrogating chipless sensors in the regulated bands is demonstrated. The concept is introduced from several chipless sensor solutions, including specific sensors (here sensors for detecting temperature then motion), and the associated reader architecture built as a prototyping platform based on universal software radio peripheral (USRP).

This letter presents a novel tag structure for microwave identification. The new tag is based on a high quality factor ( Q =366) substrate integrated cavity resonator in which data are encoded by introducing a variation in the effective permittivity which gives a unique and identifiable frequency spectral signature. The proposed tag design operates in the frequency range of 10.5-11 GHz. The substrate integrated tag presented has the advantages of being low cost, zero power consumption, compact and can be also transferred to different types of substrates, making it suitable for many mass production applications.

RFID sensors are increasingly recognized as the way for achieving smart environment monitoring. Real world industrial applications such as multi-objects orientation detection, motion sensing as well as monitoring in harsh environment require real-time operation and fast responses for control decisions. This paper examines timing analysis of UHF networked RFID sensors tag system and the factors influencing time latency. Time constrains in RFID communication channel such as the minimum detection time of the reader in the vicinity of the RFID tag and the effect of protocol requirements are examined experimentally for commercial tags in compliance with European ETSI regulations. This assessment has the objective to analyze the RFID tag for instance as a motion sensor. In order to illustrate the interest of the presented delay analysis, a method to measure the response time due to rotation speed is introduced. A case study using two commercial RFID tags under rotation is presented and analyzed in terms of delays.