scholarly journals Interdigital Capacitor-Based Passive LC Resonant Sensor for Improved Moisture Sensing

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6306
Author(s):  
Kristian Chavdarov Dimitrov ◽  
Sanghun Song ◽  
Hyungjun Chang ◽  
Taejun Lim ◽  
Yongshik Lee ◽  
...  
Keyword(s):  
Radio Frequency Identification ◽  
Frequency Offset ◽  
Detection Distance ◽  
Moisture Sensor ◽  
Interdigital Capacitor ◽  
Enhanced Sensitivity ◽  
Low Profile ◽  
Frequency Identification ◽  
Fringing Capacitance ◽  
Moisture Sensing

Herein, a passive low-profile moisture sensor design based on radio frequency identification (RFID) technology is proposed. The sensor consists of an LC resonant loop, and the sensing mechanism is based on the fringing electric field generated by the capacitor in the circuit. A standard planar inductor and a two-layer interdigital capacitor (IDC) with a significantly higher fringing capacitance compared to that of a conventional parallel plate capacitor (PPC) are used, resulting in improved frequency offset and sensitivity of the sensor. Furthermore, a sensor tag was designed to operate at an 8.2 MHz electronic article surveillance (EAS) frequency range and the corresponding simulation results were experimentally verified. The IDC- and PPC-based capacitor designs were comprehensively compared. The proposed IDC sensor exhibits enhanced sensitivity of 10% in terms of frequency offset that is maintained over time, increased detection distance of 5%, and more than 20% increase in the quality factor compared to sensors based on PPC. The sensor’s performance as a urine detector was experimentally qualified. Additionally, it was shown experimentally that the proposed sensor shows a faster response to moisture. Both simulation and experimental data are presented and elucidated herein.

A low-profile FSS-based high capacity chipless RFID tag for sensing and encoding applications

2021 ◽  
pp. 1-9
Author(s):  
Shahid Habib ◽  
Amjad Ali ◽  
Ghaffer Iqbal Kiani ◽  
Wagma Ayub ◽  
Syed Muzahir Abbas ◽  
...  
Keyword(s):  
Radio Frequency Identification ◽  
High Capacity ◽  
Frequency Selective Surface ◽  
Rfid Tag ◽  
Sensing Applications ◽  
Low Profile ◽  
Simple Geometry ◽  
Chipless Rfid ◽  
Frequency Identification ◽  
Good Agreement

Abstract This paper presents a polarization-independent 11-bit chipless RFID tag based on frequency-selective surface which has been designed for encoding and relative humidity (RH) sensing applications. The 10 exterior U-shaped resonators are used for item encoding whereas Kapton has been incorporated with the interior resonator for RH sensing. This radio-frequency identification (RFID) tag operates in S- and C-frequency bands. The proposed design offers enhanced fractional bandwidth up to 88% with the density of 4.46 bits/cm2. Both single- and dual-layer tags have been investigated. The simulated results are in good agreement with measured results and a comparison with existing literature is presented to show the performance. Simple geometry, high code density, large frequency signature bandwidth, high magnitude bit, high radar cross-section, and angular stability for more than 75° are the unique outcomes of the proposed design. In addition, RH sensing has been achieved by integrating the Kapton on the same RFID tag.

The Design of Intelligent Water-Saving Irrigation System for Greenhouse

2011 ◽  
Vol 121-126 ◽  
pp. 4826-4831
Author(s):  
Fu Gang Wang ◽  
Li Jia Xu ◽  
Chun Long Du ◽  
Yang Yang ◽  
Ye Sen Li
Keyword(s):  
Water Consumption ◽  
Radio Frequency Identification ◽  
Precision Agriculture ◽  
Irrigation System ◽  
Water Saving ◽  
High Yield ◽  
Moisture Sensor ◽  
Soil Moisture Sensor ◽  
Control Interface ◽  
Frequency Identification

In the premise of ensuring the high yield of the crops in greenhouse, how to save water has became a research focus in precision agriculture. An intelligent water-saving irrigation system based on fuzzy control is designed in the paper. By the proposed system, the best water consumption can be calculated to meet the goal of high yield but low water-using. In the system, the soil moisture sensor TDR-3 is used to measuring the soil humidity data, whiles the radio frequency identification (RFID) modules, i.e., nRF905, is applied to transmit the data wirelessly. The control interface based on LABVIEW on PC is designed as well. Thus the goal of saving water consumption and querying historical data can be accomplished.

A Low Profile Asterick-Shaped Polarization Free Metamaterial-Inspired Absorber for Penta-Band Characteristics

2021 ◽  
Author(s):  
Raghvenda Kumar Singh ◽  
Ashish Gupta ◽  
Akash Yadav ◽  
Nishchay Gupta ◽  
Utkarsh Tyagi
Keyword(s):  
Radio Frequency Identification ◽  
Electromagnetic Compatibility ◽  
Absorption Mechanism ◽  
Stealth Technology ◽  
Low Profile ◽  
Symmetric Geometry ◽  
Frequency Identification ◽  
Polarization Insensitive ◽  
Independent Behavior ◽  
Electrical Thickness

Abstract A penta-band absorber is proposed and developed exhibiting ultra thin and polarization insensitive behavior. It has been designed to be operated in S, C and Ku bands with absorptions peaks at more than 95%. Proposed absorber is processed on a FR4 Glass Epoxy laminate with equivalent electrical thickness of 0.0108 λ0 where λ0 is the wavelength corresponding to the lowest frequency of operation. This confirms the ultra-thin nature of the structure. The absorption pattern of the proposed structure has been characterized under normal and oblique incidence followed by their experimental verification. Presented results demonstrate highly polarization-independent behavior of the proposed absorber due to its symmetric geometry. Also, the electromagnetic field distributions have been studied to acquire better insight of the absorption mechanism corresponding to distinct elements presented in the structure. Then the suggested structure is characterized in terms of its behavior as metamaterial, which ensures the miniaturization. The proposed absorber is suitable to be used in applications like radar cross section reduction, stealth technology, radio frequency identification and electromagnetic compatibility.

scholarly journals A Passive Harmonic Tag for Humidity Sensing

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Antonio Lazaro ◽  
Ramon Villarino ◽  
David Girbau
Keyword(s):  
Schottky Diode ◽  
Radio Frequency Identification ◽  
Humidity Sensor ◽  
Second Harmonic ◽  
Interdigital Capacitor ◽  
Sensor Applications ◽  
Dc Power ◽  
Frequency Identification ◽  
Bias Point ◽  
Harmonic Power

This paper describes a passive harmonic tag for radio frequency identification (RFID) and wireless sensor applications. The tag uses a dual polarized UHF patch antenna as an input antenna. One of the outputs is connected to a frequency doubler, which consists of a Schottky diode with its output connected to a patch tuned at twice the input frequency. The other output of the input antenna feeds a DC power harvested converter that drives an oscillator which modulates its output signal by controlling the bias point of the Schottky diode. The antenna’s output is also used as a humidity sensor. To achieve this, the antenna is loaded with an interdigital capacitor with humidity-dependent capacitance. The antenna is consequently detuned when humidity varies, and therefore the second harmonic power is received. The tag is manufactured using standard fiberglass substrate. The basic theory of harmonic tag operation is described and compared with the standard backscattering approach. Experimental results with a proof of concept using commercial components are presented.

scholarly journals Low-Profile Flexible UHF RFID Tag Design for Wristbands Applications

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Guan-Long Huang ◽  
Chow-Yen-Desmond Sim ◽  
Shu-Yao Liang ◽  
Wei-Sheng Liao ◽  
Tao Yuan
Keyword(s):  
Radio Frequency Identification ◽  
Free Space ◽  
Complex Impedance ◽  
Uhf Rfid ◽  
Healthcare Applications ◽  
Space Condition ◽  
Rfid Tag ◽  
Low Profile ◽  
Frequency Identification ◽  
Slot Cavity

In this study, a low-profile ultrahigh frequency (UHF) radio-frequency identification (RFID) tag antenna designed for wristbands in healthcare applications is proposed. The radiator is based on the open-slot cavity technique that is composed of a slotted patch (double-T slots) loaded onto a flexible open cavity. The proposed slotted design can easily allow the tag’s input impedance to be tuned to the complex impedance of typical UHF RFID chips. The proposed tag antenna has a size of 86 mm × 25 mm × 1.6 mm (0.26λ0×0.07λ0×0.004λ0) at 915 MHz, and it can yield a maximum reading range of 8 m (stand alone in free-space condition), 6.6 m (when placed on the human wrist in free-space condition), and up to 3 m (when placed on the human wrist in a crowded condition).

scholarly journals Unidirectional Dual-Band CPW-Fed Antenna Loaded with an AMC Reflector

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Qun Luo ◽  
Huiping Tian ◽  
Zhitong Huang ◽  
Xudong Wang ◽  
Zheng Guo ◽  
...  
Keyword(s):  
Radio Frequency Identification ◽  
Coplanar Waveguide ◽  
Ground Plane ◽  
Dielectric Substrate ◽  
Dual Band ◽  
Magnetic Conductor ◽  
Suitable Candidate ◽  
Gain Enhancement ◽  
Low Profile ◽  
Frequency Identification

A unidirectional dual-band coplanar waveguide fed antenna (DB-CPWFA) loaded with a reflector is presented in this paper. The reflector is made of an electric ground plane, a dielectric substrate, and artificial magnetic conductor (AMC) which shows an effective dual operational bandwidth. Then, the closely spaced AMC reflector is employed under the DB-DPWFA for performance improvement including unidirectional radiation, low profile, gain enhancement, and higher front-to-back (F/B) ratio. The final antenna design exhibits an 8% and 13% impedance bandwidths for 2.45 GHz and 5.8 GHz frequency regions, respectively. The overall gain enhancement of about 4 dB is achieved. The F/B ratio is approximate to 20 dB with a 16 dB improvement. The measured results are inconsistent with the numerical values. The presented design is a suitable candidate for radio frequency identification (RFID) reader application.

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