CN208155250U - A kind of chipless RFID range-measurement system based on principle of interference - Google Patents

Abstract

The utility model discloses a chipless RFID ranging system based on the principle of interference, which is characterized in that it includes a reference plane, a target to be measured, a reader and a reader antenna, the target to be measured is a chipless RFID tag, the The target to be measured and the reference plane are on the same side of the reader, the reader antenna adopts a vivaldi antenna, the reference plane is set on the maximum radiation direction of the vivaldi antenna, and the normal direction of the reference plane is parallel to the maximum radiation direction of the vivaldi antenna . The utility model has high precision and good stability, and reduces the steps of calibrating the delay caused by the structure of the antenna and the structure of the reader. Less dependence on the excitation signal waveform.

Description

A Chipless RFID Ranging System Based on Interference Principle

technical field

The utility model is designed in the field of the Internet of Things, and in particular relates to a chipless RFID ranging system based on the principle of interference.

Background technique

Radio Frequency Identification (RFID) is a wireless communication technology that detects and identifies RFID tags attached to objects through electromagnetic wave signals. The advantage of RFID is that it can realize functions such as non-line-of-sight (Non-Line-of-Sight) reading, automatic identification, and object positioning. Traditional tags are composed of antenna and integrated circuit IC (Integrated Circuit). Due to the relatively high cost of integrated circuits, traditional RFID tags still cannot replace optical barcodes. In order to reduce the cost of RFID tags, it is feasible to use chipless RFID tags (Chipless RFID Tag) instead of traditional RFID. Chipless RFID tags can be divided into tags based on frequency domain coding and time domain coding. The chipless RFID tags mentioned in this article refer to chipless RFID tags based on frequency domain coding. Chipless RFID tags can also be used for positioning, but chipless RFID tags do not have battery power. Therefore, most traditional RFID ranging and positioning systems are not suitable for chipless RFID ranging and positioning, so it is necessary to specially design ranging, positioning method. Since there is no battery power supply, the distance is generally measured by measuring the time interval of the electromagnetic echo signal. Using multiple node readers to measure the distance of the chipless RFID tag, the two-dimensional and three-dimensional information of the tag can be determined. A good ranging system plays a vital role in chipless RFID tag location.

At present, there are mainly the following types of chipless RFID tag positioning systems. 1. RTOF (Round Trip Time of Flight), calculates the distance from the tag to the antenna by measuring the time it takes for the pulse radiated by the antenna to reach the chipless RFID tag and then return to the antenna. The disadvantage is that a stable pulse shape is required, the precise start time of the pulse needs to be known, and an antenna with relatively uniform gain of each frequency in the reading area is required. 2. NFMPM (Narrow-Frequency Matrix Pencil Method), which is a further improvement of the RTOF method, can more accurately confirm the arrival time of the pulse, and does not require an antenna with a relatively uniform gain in the reading area for each frequency, but this method is useful for The phase requirements of the pulse are relatively high. 3. RSS (Received Signal Strength), by measuring the strength of the received signal, determine the distance of the tag. The disadvantage is that as the distance increases, the accuracy will become lower and lower, and when the tag rotates at a certain angle, it will have a greater impact on the strength of the backscattered signal.

Utility model content

In order to overcome the shortcomings and deficiencies of the prior art, the utility model provides a chipless RFID ranging system based on the principle of interference.

The utility model adopts the following technical solutions:

A chipless RFID ranging system based on the principle of interference, including a reference plane, a target to be measured, a reader and a reader antenna, the target to be measured is a chipless RFID tag, and the target to be measured and the reference plane are placed on the reader On the same side as above, the reader antenna adopts a vivaldi antenna, the reference plane is set on the maximum radiation direction of the vivaldi antenna, and the normal direction of the reference plane is parallel to the maximum radiation direction of the vivaldi antenna.

The maximum reading distance between the reader and the reader antenna is Rmax, and the reference plane is set at the position of Rmax/2.

The size of the reference plane is consistent with the size of the target to be measured, and the conductive material used is consistent with the chipless RFID tag.

The beneficial effects of the utility model:

The present invention pre-establishes a reference plane as a reference position, uses the interference principle to measure the distance difference between the object to be measured and the reference object to the antenna, and then obtains the distance from the object to be measured to the antenna. Reduced steps to calibrate delays due to antenna structure and reader structure. Less dependence on the excitation signal waveform.

The system has high ranging accuracy and good stability.

Description of drawings

Fig. 1 is the structural representation of the utility model.

Detailed ways

The utility model will be described in further detail below in conjunction with the embodiments and accompanying drawings, but the implementation of the utility model is not limited thereto.

Example

As shown in Figure 1, a kind of chipless RFID ranging system based on interference principle, comprises reference plane 1, target to be measured 2, reader and reader antenna 3, described target to be measured is chipless RFID label, described The reference plane is a plane formed by the conductive material used in the chipless RFID tag or a conductive material with similar properties.

The reader antenna is a broadband antenna, specifically a vivaldi antenna, and the reader is a reader capable of generating ultra-wideband pulse signals, receiving ultra-wideband signals, and having a certain signal processing capability.

The reference plane is set on the maximum radiation direction of the vivaldi antenna, and the normal direction of the reference plane is parallel to the maximum radiation direction of the vivaldi antenna.

In this embodiment, the reference plane is a good conductor with a size of 40mm×40mm. Without loss of generality, for the sake of simplicity, the chipless RFID tag is replaced by a good conductor of 40mm×40mm.

Working process of the present utility model:

The reader generates ultra-wideband pulses, which are radiated into space through the ultra-wideband antenna. The electromagnetic wave meets the reference plane and the tag to be tested in space to generate reflected waves. The reflected frequency domain signal of the tag to be tested includes structural mode signals and antenna mode signals. The tag The antenna mode signal is similar to the signal reflected by the reference plane, so the antenna mode signal of the tag to be tested and the signal reflected by the reference plane are used for ranging.

In this embodiment, when the distance from the reference plane to the antenna is greater than the distance from the tag to the antenna, set the actual distance L1=442.5mm, L2=216.9mm, and calculate the distance to 214.5; when the distance from the reference plane to the antenna is less than the distance from the tag to the antenna , set the actual distance L1 = 442.5mm, L2 = 578.2mm, and calculate the distance to 575.5mm.

The above-mentioned embodiment is a preferred implementation mode of the present utility model, but the implementation mode of the present utility model is not limited by the described embodiment, and any other changes, modifications, modifications, Substitution, combination, and simplification should all be equivalent replacement methods, and are all included in the protection scope of the present utility model.

Claims (3)

1. A chipless RFID distance measuring system based on the principle of interference, characterized in that it comprises a reference plane, a target to be measured, a reader and a reader antenna, the target to be measured is a chipless RFID tag, and the target to be measured And reference plane is on the same side of reader, and described reader antenna adopts vivaldi antenna, and described reference plane is arranged on the maximum radiation direction of vivaldi antenna, and the normal direction of reference plane is parallel with the maximum radiation direction of vivaldi antenna. 2. The chipless RFID ranging system according to claim 1, characterized in that, the maximum reading distance Rmax between the reader and the reader antenna, and the reference plane is set at the position of Rmax/2. 3. The chipless RFID ranging system according to claim 1, wherein the size of the reference plane is consistent with the size of the object to be measured.