CN208297413U - A kind of chipless RFID humidity sensor - Google Patents

Abstract

The utility model discloses a kind of chipless RFID humidity sensors, including humidity sensitive material layer, label chip unit, metal floor and medium substrate, the humidity sensitive material layer is covered on label chip unit surface, the label chip unit is located at the upper surface of the medium substrate, and the metal floor is located at the lower surface of the medium substrate.The utility model has many advantages, such as at low cost, strong antijamming capability and has biggish code capacity compared with same kind chipless humidity sensor.

Description

A kind of chipless RFID humidity sensor

Technical field

The utility model relates to chipless RFID fields, and in particular to a kind of chipless RFID humidity sensor.

Background technique

Radio frequency identification (Radio Frequency Identification, RFID) is detected as a kind of by electromagnetic signal Specific objective and related data is read, without establishing the wireless identification of mechanical or optical contact between system and specific objective Technology.Nowadays, Radio Frequency Identification Technology has been widely used in various industries, can all create the income of over ten billion every year.It is typical Radio-frequency recognition system include application system, reader and label three parts, wherein label plays key player.

Traditional has chip tag due to including integrated circuit (IC) chip in structure, increases manufacturing cost, Wu Faman The requirement of sufficient large-scale serial production and application.Chipless RFID label eliminates IC chip, has chip with traditional RFID tag is compared, and chipless RFID label has the advantage of low cost.

Conventional RFID tag can be unable to Direct Recognition physical message with coded address information.Chipless RFID label The combination of label and sensor can be subjected to Address Recognition, positioning, tracking to object using radio frequency identification, while can also examine The physical features of accompanying object are measured, such as: temperature, humidity, gas, displacement.

Therefore, chipless RFID sensor can be used as the sensing network of passive sensor node composition, be widely used in agriculture The fields such as industry, logistics, smart city, environmental monitoring just become the hot spot of current research.

Utility model content

In order to overcome shortcoming and deficiency of the existing technology, the utility model provides a kind of chipless RFID humidity sensor Device.

The utility model adopts the following technical solution:

A kind of chipless RFID humidity sensor, including humidity sensitive material layer, label chip unit, metal floor and Jie Matter substrate, the humidity sensitive material layer are covered on label chip unit surface, and the label chip unit is located at the medium The upper surface of substrate, the metal floor are located at the lower surface of the medium substrate.

The label chip unit is made of three coaxial square loop nestings, and the perimeter of square loop is according to from outside to inside Nesting order successively successively decrease.

Described three coaxial square loops are provided with corner cut structure and hatch frame, and the corner cut structure is located at three coaxially On the leading diagonal of square loop, and about medium substrate central symmetry；The hatch frame is located at three coaxial square loops Counter-diagonal on, and about medium substrate central symmetry.

The humidity sensitive material layer is polyvinyl alcohol film.

The width of described three coaxial square loops is 0.3mm, is divided into 0.7mm between adjacent square ring.

The corner cut structure, which is square, subtracts equilateral triangle composition.

The humidity sensitive material layer is covered on the square loop surface of innermost layer.

Label chip unit realizes polarization function, when vertically polarized wave is incident on the label chip unit surface, Resonance peak is detected on the horizontal direction component of echo-signal.

The utility model has the beneficial effects that

(1) the utility model provides one kind and works in ultra wide band (Ultra-Wide Band, UWB) frequency range (3.1GHz- It 10.6GHz) can be used for the chipless RFID label of humidity sensor.UWB is a kind of carrierfree suitable for short-distance wireless communication The communication technology has many advantages, such as that power system capacity is big, transmission rate is high, small power consumption.When reader emits a linear polarization to label When wave is as request signal, various sizes of label chip unit can generate resonance in different Frequency points, and intersect Radar cross section (Radar Cross-Section, RCS) in polarization direction at corresponding frequency point generates resonance peak.

(2) label uses the nested structure of three square loops, and humidity sensitive material layer is covered on innermost square Ring surface, when label local environment humidity changes, the label chip unit of covering humidity sensitive material layer can generate phase The frequency shift (FS) answered, to realize humidity sensor.It can be with by the minor matters length that hatch frame changes two square loops in outside Resonance peak position is adjusted, to realize frequency shif coding.This mode can while realizing humidity sensor encoded digital information.

(3) label provided by the utility model realizes polarization-agile technology, if there is the line polarization wave of a vertical direction to enter It is mapped to the label surface, specific coding can be identified by the RCS component in detection level direction, not only can be simplified Calibration process when detection, and the isolation of reader transmitting and receiving antenna can be increased, improve anti-interference ability.

Detailed description of the invention

Fig. 1 is the top view of the utility model structure；

Fig. 2 is the side view of the utility model structure；

Fig. 3 is the parameter mark figure of the utility model structure；

Fig. 4 (a) is RCS map of magnitudes of the utility model on cross polarization direction；

Fig. 4 (b) is the RCS width that the utility model realizes 6-bit coding " 001000 ", " 010000 " and " 011001 " respectively Degree figure；

Fig. 5 is the utility model as humidity increases, dielectric constant increase so that RCS width from resonance frequency to low frequency offset Degree figure.

Specific embodiment

Below with reference to examples and drawings, the utility model is described in further detail, but the reality of the utility model It is without being limited thereto to apply mode.

Embodiment

As shown in Figures 1 and 2, a kind of chipless RFID humidity sensor works in UWB frequency range (3.1GHz- 10.6GHz), including humidity sensitive material layer 5, label chip unit, metal floor 6 and medium substrate 1, the medium substrate are Single layer, the humidity sensitive material layer are covered on label chip unit surface, and the label chip unit is located at single layer Jie The upper surface of matter substrate, the metal floor are located at the lower surface of the single-layer medium substrate.

The label chip unit is made of three coaxial 2,3,4 nestings of square loop, the week of three coaxial square loops Length is successively successively decreased according to nesting order from outside to inside.Described three coaxial square loops are provided with corner cut structure and opening knot Structure, the corner cut structure are located on the both ends of three coaxial square loop leading diagonals, and about single-layer medium substrate center pair Claim；The hatch frame is located on the both ends of the counter-diagonal of three coaxial square loops, and about single-layer medium substrate center Symmetrically, a corner cut square loop is a coding unit, and leading diagonal and X-axis angle are obtuse angle, and counter-diagonal and X-axis are pressed from both sides Angle is acute angle.

Each square loop can generate second harmonic in high frequency treatment, limit the working frequency range of label, three ring structures Frequency spectrum can relatively be made full use of and realize frequency shif coding.If ring setting is excessive, it can generate and intercouple, lead to label Back-scattered signal is difficult to tell resonance point.

The humidity sensitive material layer is polyvinyl alcohol film (PVA), is particularly located at the square loop 4 for being nested in innermost layer Upper surface, the dielectric constant of PVA material can be increased as ambient humidity increases, so that covering the mark of humidity sensitive material layer It signs chip unit and generates corresponding frequency shift (FS), to realize humidity sensor.

Polarization function may be implemented in the label chip unit, i.e., when vertically polarized wave is incident on the label patch list When first surface, resonance peak can be detected on the horizontal direction component of echo-signal, change the branch of ring by hatch frame The adjustable resonance peak position of length is saved, to realize frequency shif coding.

As shown in figure 3, being located at outermost 2 length L1 of square loop is 11.6mm, intermediate in the label chip unit The length L2 of the square loop 3 of layer is 9.6mm, and the length L3 of the square loop 4 of innermost layer is 7mm.Three openings corner cut The width W of square loop is 0.3mm, and the interval d2 of ring is 0.7mm, and the interval d1 of label chip unit and medium substrate is 1mm.The corner cut structure is located on the leading diagonal of square loop, and about square patch central symmetry.Corner cut structure is The equilateral triangle that side length S is 1mm is subtracted with square to constitute.

In the present embodiment, the medium substrate is that medium substrate uses high frequency plate Taconic TLX-8, opposite dielectric Constant is 2.55, and electrical loss angle tangent value is 0.0019.Square medium substrate length L where label chip unit is 15mm, thickness H are 0.8mm.

As shown in Fig. 4 (a), when the line polarization wave for having a vertical direction is incident on this chipless RFID humidity sensor table When face, radar cross section can be detected on horizontal direction (namely cross polarization direction) component of echo-signal (RCS) resonance peak can be with wherein the square loop 2-4 of label chip unit in three resonance wave crests and Fig. 1 is corresponded Length L1, L2 by adjusting square loop 2 and 3 realizes 6-bit coding.When length L1, L2 of square loop 2 and 3 is respectively When 11.2mm and 9.6mm, label coding is " 001000 "；When L1, L2 are respectively 11mm and 9.6mm, label coding is "010000"；When L1, L2 are respectively 10.8mm and 9.4mm, label coding is " 011001 ".As shown in Fig. 4 (b), when being located at When the length L1 variation of the square loop 2 of outer layer, the resonance frequency generated positioned at the square loop 3 of middle layer is almost without generation Offset, therefore reliable frequency shif coding may be implemented.The working frequency range of this chipless RFID humidity sensor is UWB frequency range (3.1GHz-10.6GHz)。

The dielectric constant of PVA material can be increased as ambient humidity increases, so that the mark of covering humidity sensitive material layer It signs chip unit and generates corresponding frequency shift (FS).As shown in figure 5, in order to simulate when humidity increases, the increased feelings of dielectric constant Condition sets 1.6,5,10 for the permittivity ε of humidity sensitive material layer, and the resonance peak of the RCS finally obtained is inclined to low frequency It moves.

The chipless RFID humidity sensor have at low cost, strong antijamming capability, be easy to detect in the actual environment with And there is biggish code capacity compared with same kind chipless humidity sensor.

Above-described embodiment is the preferable embodiment of the utility model, but the embodiments of the present invention is not by described The limitation of embodiment, it is made under other any spiritual essence and principles without departing from the utility model to change, modify, replacing In generation, simplifies combination, should be equivalent substitute mode, is included within the protection scope of the utility model.

Claims (7)

1. a kind of chipless RFID humidity sensor, which is characterized in that including humidity sensitive material layer, label chip unit, gold Possession plate and medium substrate, the humidity sensitive material layer are covered on label chip unit surface, label chip unit position In the upper surface of the medium substrate, the metal floor is located at the lower surface of the medium substrate.

2. a kind of chipless RFID humidity sensor according to claim 1, which is characterized in that the label chip unit It is made of three coaxial square loop nestings, the perimeter of square loop successively successively decreases according to nesting order from outside to inside.

3. a kind of chipless RFID humidity sensor according to claim 2, which is characterized in that described three coaxial square Shape ring is provided with corner cut structure and hatch frame, and the corner cut structure is located on the leading diagonal of three coaxial square loops, and About medium substrate central symmetry；The hatch frame is located on the counter-diagonal of three coaxial square loops, and about medium Substrate center is symmetrical.

4. a kind of chipless RFID humidity sensor according to claim 1, which is characterized in that the humidity sensitive material Layer is polyvinyl alcohol film.

5. a kind of chipless RFID humidity sensor according to claim 3, which is characterized in that described three coaxial square The width of shape ring is 0.3mm, is divided into 0.7mm between adjacent square ring.

6. a kind of chipless RFID humidity sensor according to claim 3, which is characterized in that the corner cut structure is positive It is rectangular to subtract equilateral triangle composition.

7. a kind of chipless RFID humidity sensor according to claim 2, which is characterized in that the humidity sensitive material Layer is covered on the square loop surface of innermost layer.