What Is the Future Development Trend of RFID

Nowadays, with the rapid development of Internet of things technology, RFID technology has gradually become an important part of the perception layer of Internet of things, and has also been highly valued all over the world. In recent years, China has successively issued policies to support the development of Internet of things and RFID technology, and the development trend of RFID industry will be better and better.

As a sub industry of the Internet of things, RFID is located in the perception layer. It is not only the basis of the development of the Internet of things, but also the premise of realizing the Internet of things. The development of the application layer of the Internet of things must be supported by the perception layer. Therefore, in order to develop the Internet of things, the perception layer is a priority industry in the Internet of things industry. The development of the Internet of things makes the demand of the application layer diversified and complex. The application scenarios continue to expand and release the demand for new technologies, which drives the innovation and upgrading of related technologies in the perception layer. Compared with other sensing technologies (two-dimensional code, bar code, etc.), RFID technology has the advantages of no contact, no visualization and full automatic identification. It has relatively low restrictions on applicable environment, reading distance, reading efficiency and readability. When the application scope of the Internet of things continues to expand, RFID will become the key development and mainstream perception layer technology, and the gradual decline of future cost makes it expected to further replace the market share of QR code and bar code in a highly intelligent society, and there is a need for renewal in the industry, and technological innovation drives the sustainable and healthy development of the industry.

In the era of intelligence, the transformation of traditional industries has accelerated, and the demand for RFID has increased. The emergence of a new generation of intelligent technologies such as artificial intelligence, cloud computing, big data and quantum computing means that the prelude to the fourth industrial revolution has quietly opened, and the engine of technological social development is gradually turning from the Internet to intelligent technology. Human society has ushered in the era of intelligence. The application of intelligent technology has begun to empower all walks of life. The acceleration of industry intelligence has led to the increase of RFID demand.

In recent years, with the continuous progress of sensing technology and network transmission technology, the hardware cost of RFID chip has been declining. The integrated application solutions based on Internet and Internet of things have been maturing. RFID technology has been more widely used in many fields such as intelligent management. Taking the retail industry as an example, in the past two years, the application of UHF Passive RFID tag has exploded in the clothing retail industry. Because this technology can solve the core pain points of the shoe and clothing retail industry, such as high inventory, untimely replenishment, poor data, low logistics efficiency and long inventory time, retail giants such as fast fashion clothing chain brand ur Zara adopts RFID tags and RFID application solutions to realize the whole chain dynamics of tracing goods from factory to retail, so as to improve operation efficiency. In addition, the rise of unmanned retail also increases the demand for RFID and ushers in new development opportunities for the industry.

UHF RFID will become the focus of industry development. In the Chinese market, the application of high frequency RFID technology is still the mainstream trend of industry development, and UHF is the future development trend. In China, RFID has formed a mature application mode in the fields of electronic ticket, access control and mobile payment. Most of the applications in these fields are concentrated in the low and high frequency band. In terms of high-frequency applications, the chip design, manufacturing, ticket manufacturing process and packaging technology of domestic manufacturers have gradually highlighted their strong competitive strength and advantages. After several years of rapid development, the domestic RFID high-frequency industry chain has been continuously improved, and can match the international level and become the backbone of this market.

One belt, one road policy will be adopted in the future with the continuous breakthrough of China's RFID high frequency technology. More and more RFID enterprises will go out to sea and compete with overseas giants to seize market share. In the field of UHF RFID, China's current market share is only at a low level. However, with the continuous popularization and development of UHF RFID in many fields such as new retail of shoes and clothing, unmanned convenience stores, library management, medical health, aviation, logistics and transportation, UHF RFID will become a key breakthrough in the development of the industry in the future.

The development of the Internet of things makes the demand of the application layer diversified and complex. Intelligent technology can transform the traditional industry, resulting in a significant increase in RFID demand, which has become a new opportunity for the development of the industry and drive the sustainable development of China's RFID industry.

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RFID Technology Is a Contactless Automatic Identification Technology
RFID Technology Is a Contactless Automatic Identification Technology
RFID systemRadio frequency identification (RFID) technology is a contactless automatic identification technology. Its basic principle is to realize the automatic machine identification of stationary or moving objects to be identified by using RF signal and its spatial coupling and transmission characteristics.RFID system generally consists of two parts: electronic tag and reader. The spatial (contactless) coupling of RF signals is realized between the electronic tag and the reader through the coupling element. In the coupling channel, energy transmission and data exchange are realized according to the timing relationship. There are two types of coupling of RF signals between readers and electronic tags:(1) Inductive coupling is realized through space high-frequency alternating magnetic field, which is based on the law of electromagnetic induction.(2) Electromagnetic backscatter coupling: radar principle model. The electromagnetic wave emitted is reflected when it meets the target and carries back the target information at the same time, which is based on the spatial propagation law of electromagnetic wave.Inductive coupling mode is generally suitable for short-range RFID system working at medium and low frequency. Typical operating frequencies are 125kHz, 225khz and 13.56MHz. The identification action distance is less than 1m, and the typical action distance is 10cm 20cm. The coupling mode of electromagnetic backscatter is generally suitable for long-distance RFID system working at high frequency and microwave. Typical operating frequencies are 433MHz, 868mhz, 915MHz, 2.45GHz and 5.8GHz. The identification action distance is greater than 1m, and the typical action distance is 3M l0m.Electronic tag is also called radio frequency tag, transponder and data carrier. Electronic tag attached to the object to be identified is the real data carrier of radio frequency identification system. Generally, electronic tags are composed of tag antenna and tag special chip.According to the different power supply modes of electronic tags, they can be divided into active tags and passive tags. Active tags contain batteries, while passive tags do not contain batteries.The reader is also called readout device. The reader can be a read / write or read-only device, which is used to automatically take out the agreed identification information in the electronic tag in a contactless manner when the article to be identified attached with the electronic tag passes through its readout range, so as to realize the function of automatically identifying the article or automatically collecting the article identification information.Saw device technologySurface acoustic wave (SAW) is a mechanical wave propagating on the surface of piezoelectric crystal. Its sound velocity is only one thousandth of that of electromagnetic wave, and the propagation attenuation is very small. SAW devices use microelectronic technology to make interdigital electroacoustic transducers and reflector couplers on piezoelectric substrates. Using the piezoelectric effect of substrate materials, the electrical signals are converted into acoustic signals by inputting interdigital transducers (IDT) and limited to the surface of the substrate. The output IDT restores the acoustic signals into electrical signals to realize the process of electrical acoustic electrical conversion, Complete the electrical signal processing process to obtain electronic devices for various purposes. Surface acoustic wave devices manufactured by advanced microelectronic processing technology have the advantages of small volume, light weight, high reliability, good consistency, multi-function and flexible design. They have been widely used in communication, television, remote control and alarm systems. Hundreds of millions of mobile phones and televisions have applied multiple surface acoustic wave filters. With the rapid development of processing technology, the working frequency of SAW devices has covered 10MHz 2.5GHz. It is an indispensable key component in modern information industry.Working principle of saw passive electronic tagSaw passive electronic tag adopts reflection modulation to complete the transmission of electronic tag information to the reader.Saw tag is composed of interdigital transducer and several reflectors. The two buses of the transducer are connected with the antenna of the electronic tag. The antenna of the reader periodically sends high-frequency interrogation pulses. Within the receiving range of the electronic tag antenna, the received high-frequency pulses are transformed into surface acoustic waves through the interdigital transducer and propagate on the crystal surface. The reflector group partially reflects the incident surface wave and returns to the interdigital transducer, which converts the reflected acoustic pulse train into high-frequency electrical pulse train. If the reflector group is designed according to a specific law so that its reflected signal represents the specified coding information, the reflected high-frequency electric pulse train received by the reader will have the specific coding of the article. Through demodulation and processing, the purpose of automatic recognition is achieved.Due to the low propagation speed of saw, the effective reflection pulse train returns to the reader after a delay time of several microseconds. During this delay, the interference reflection from around the reader has been attenuated and will not interfere with the effective signal of saw electronic tag.Saw passive electronic tag applicationElectronic tags using SAW technology began in the late 1980s. In recent years, the research of saw tags has become a hot spot. Surface acoustic wave electronic tag is a new achievement in the application of modern electronics, acoustics, semiconductor planar technology, radar and signal processing technology. It is another new non-contact automatic identification technology different from IC chip identification.Because the saw device itself works in the RF band, passive and strong anti electromagnetic interference ability, the electronic tag realized by SAW technology has certain unique advantages and is a supplement to the integrated circuit technology. Its main features are:1. The reading range is large and reliable, up to several meters;2. It can be used on metal and liquid products;3. Simple matching between tag chip and antenna and low manufacturing cost;4. It can recognize not only stationary objects, but also high-speed moving objects with a speed of 300 km / h;5. It can be used in harsh environments such as high temperature difference (- 100 ℃ 300 ℃) and strong electromagnetic interference.Electronic label technology has a wide range of applications, including logistics management, road and bridge charging, public transportation, access control, anti-counterfeiting, health and safety monitoring and identification of farms, supermarket anti-theft and charging, air baggage sorting, parcel tracking, factory assembly line control and tracking, equipment and asset management, sports competitions, etc.Saw label is also applicable to the measurement of parameter changes such as pressure, stress, distortion, acceleration and temperature, such as hot shaft positioning of railway infrared axle temperature detection system, track scale, overload and eccentric load detection system, automobile tire pressure, etc.Ois-w surface acoustic wave label produced by Baumer ident GmbH of Germany and SOFIS surface acoustic wave system of Siemens have been successfully used in automatic toll collection system for automobile bridge crossing in Oslo, Norway and train arrival positioning system in Munich, Germany. In the United States, identtronix, i-ray, rf-saw and other companies also produce commercial saw electronic labels.Related linksSaw R & DThe 55th Research Institute of China Electronics Technology Corporation (hereinafter referred to as the 55th Institute) is a national key military research institute, which has decades of mature experience in high-frequency microwave components.In recent years, we have invested a lot of money to carry out the industrialization of high-frequency SAW devices: introducing foreign advanced equipment, completing the transplantation of microelectronic technology, developing international general batch production technology, standardizing enterprise management, implementing ISO9001-2000 quality management system and large-scale production of SAW devices for modern wireless communication, It has won the science and technology progress award of Jiangsu Province twice.At present, 55 institutes have developed into a leading R & D and production base of high-frequency SAW devices recognized internationally, with a manufacturing capacity of 0.5 μ M (2GHz) high frequency saw device capability. The product specifications of batch production of Nd series high-frequency SAW devices are equivalent to those of similar foreign products, with good economic operation and an annual growth rate of more than 30%.434MHz and 915MHz are civil unregulated radio bands, which are generally used by civil remote control equipment. ISO also recommends opening them for RFID. Therefore, we have started the product technology development and sample prototype trial production of the project since the beginning of 2003. Now we have trial developed several application device samples and prototypes to achieve the expected results.Key to developing saw electronic tag1. Optimization of label coding capacity and action distance;2. Cooperation between coding and reader;3. Small electronic tag antenna with low cost and suitable for the object to be identified;4. Mass production of different code label chips;5. Anti collision and readable / writable labels.
What Are the Four Main Characteristics of RFID
What Are the Four Main Characteristics of RFID
RFID is radio frequency identification, commonly known as electronic tag. It is a non-contact automatic identification technology. It automatically identifies the target object and obtains relevant data through RF signal. The identification work does not need manual intervention and can work in various harsh environments. RFID technology can identify high-speed moving objects and multiple tags at the same time, which is fast and convenient to operate.Compared with other automatic identification technologies, what are the main characteristics of RFID?The history of radio frequency technology can be traced back to the 1930s. The physical principle of RFID technology is the same as that of radio broadcasting invented in the 19th century. In the 1930s, the U.S. Army and Navy were faced with the problem of identifying targets on the ground, at sea and in the air. The US Naval Research Laboratory (NRL) developed the identification friend or foe (IFF) system in 1937, which can identify friendly and enemy aircraft. This technology became the basis of the world's air traffic control system in the late 1950s. However, due to the high cost and large volume of equipment, it is generally only used in military or laboratories and large commercial enterprises. After the emergence of smaller and lower cost technologies, such as integrated circuits, programmable memory chips, microprocessors and modern software applications and programming language technology, RFID has gradually become the mainstream of commercial applications.Compared with other automatic identification technologies, what are the main characteristics of RFID?By the end of the 20th century, many RFID application systems began to expand all over the world, including access control system, flight baggage identification, car anti-theft, electronic payment and so on.In the 21st century, RFID has the characteristics of long-distance and one to many reading, lightness and miniaturization, signal penetration and anti pollution, reusable and high storage capacity, which makes this technology increasingly attract attention in the application field of automatic management.For logistics and retailers, they expect to strengthen the automatic management process of goods through this technology and improve the overall efficiency of supply chain operation. Wal Mart, the world's leading department store retailer, requires its top 100 suppliers to adopt RFID system, which makes this small chip a hot star in an instant. According to Wal Mart's full use of RFID tags, it will save $8.4 billion a year, reduce the company's inventory by 5% and reduce the personnel cost of managing the warehouse by 7%.Compared with other automatic identification technologies, what are the main characteristics of RFID?Compared with other automatic identification technologies, the main characteristics of RFID include the following four aspects.(1) Data readwrite function. As long as you use the rfidreader, you can directly read the message into the database without contact, process multiple tags at a time, and write the processing status into the tags for reading judgment in the next stage of data processing.(2) Miniaturized and diversified shapes. RFID is not limited by size and shape in reading, and does not need to match the fixed size and printing quality of paper for reading accuracy. In addition, RFID tags can also be miniaturized and diversified to be applied to different products.Compared with other automatic identification technologies, what are the main characteristics of RFID?(3) Environmental resistance. Once the paper is dirty, it will not be seen, but RFID has strong anti fouling properties to substances such as water, oil and drugs. RFID can also read data in dark or dirty environment.(4) Reusable. Since RFID data is electronic data and can be overwritten repeatedly, it can be recycled and reused. For example, passive RFID can be used without battery, and there is no need for maintenance.
Design of Access Control System Based on MCU and RFID Technology
Radio frequency identification technology is mainly a non-contact automatic identification technology. In the process of its application, it is necessary to use radio frequency signal to obtain the information of the target object on the basis of electromagnetic principle. Due to its wide application, it can be applied in different areas, so it is widely used in various environmental operations. In the RFID system, the output data of the RF card reader shall strictly comply with the provisions made in the wieggand format, that is, it shall be transmitted by using two data lines with transmission of 0 and 1 respectively.The access control system based on MCU and RFID technology is a RFID lock system based on MCU STC89C52 and IC RF card. It can be used in laboratories, machine rooms, office buildings, archives, finance rooms and other places with high security requirements1. System design schemeThe access control system consists of a client installed on the door and an authorization terminal for writing the new card. The client consists of a power module, a single chip microcomputer minimum system, a serial communication module, a card swiping module, a buzzer module and an electromagnetic lock module, as shown in Figure 1. At the client, when the user needs to open the door, the IC RF card needs to be placed in the sensing area of the card reader to read the information in the card. When the read information is verified successfully, the door lock will be opened while the buzzer "beeps", and the door will be locked again after a delay of one second; If the information verification fails, the buzzer will send out four continuous and short beeps. The authorization end is used to write the authorization information of each IC card. The whole system can work with a single card reader and is easy to operate.Figure 1   Hardware system module block diagram2. System hardware design2.1 circuit design of power moduleThe function of the power module is to supply power to the whole system. In the system, the card swiping module needs to use a power supply voltage of 3.3V, the electromagnetic lock module needs to use a voltage of 12V, and the smallest system part of the single chip microcomputer needs to use a voltage of 5V. Therefore, the types of power supply that the power module needs to provide are 12V 5V and 3.3V. The module realizes the conversion from 12V to 5V and from 5V to 3.3V respectively through lm7805 and ams1117 chips. As shown in Figure 2, the circuit design of the system power moduleFigure 2   Power module circuit2.2 circuit design of card swiping moduleRadio frequency read-write chip mfrc522 is a low-power, small package and highly integrated contactless (13.56MHz) read-write card chip launched by NXP. It uses the principle of modulation and demodulation, It fully integrates all types of passive contactless communication methods and protocols at 13.56MHz. It supports multi-layer applications of iso14443a. Its internal transmitter part can drive the reader antenna to communicate with iso14443a / Mifare card and transponder without other circuits. The receiver part provides a solid and effective demodulation and decoding circuit, It is used to process iso14443a compatible transponder signals. The digital circuit part processes iso14443a frames and error detection (parity & CRC). In addition, it also supports fast crypto1 encryption algorithm for verifying Mifare series products. Mfrc522 supports higher speed contactless communication of Mifare series, The two-way data transmission rate is up to 424kbit / s. The communication between it and the host adopts serial communication with fewer connections, and one of SPI, I2C or Serial uart (similar to RS232) modes can be selected according to the different needs of users, which is conducive to reducing circuit connection, reducing the volume of circuit board and reducing production cost. The application circuit of mfrc522 in card swiping module is shown in Figure 3Figure 3   Card swiping module circuit2.3 circuit design of buzzer moduleWhen the user swipes the card, if the information verification is successful, the p2.0 pin of the MCU is given a low level (software setting), the triode Q2 (PNP type) is turned on, and the buzzer gives a beep. When the information verification is unsuccessful, the buzzer gives four continuous and short beeps. The circuit design of the module is shown in Figure 4Figure 4   Buzzer module circuit2.4 circuit design of electromagnetic lock moduleWhen the user swipes the card, if the information is verified successfully, the system gives a low level to the p2.5 pin of the single chip microcomputer. At this time, the triode Q1 (PNP type) is turned on, and the relay is powered on to generate magnetic attraction armature, making the dynamic and static contacts contact, so that the high-voltage working circuit is connected and the electromagnetic lock is opened; In case of power failure, the electromagnet of the relay loses magnetism and loses attraction to the armature, so that the dynamic and static contacts are separated, the working circuit is disconnected and locked again. The circuit of the module is shown in Figure 5. The diode D2 plays the role of freewheelingFigure 5 electromagnetic lock module circuit3. System software design3.1 client software designFirstly, the system initializes the mfrc522 RF card reader, delays for a certain time, waits for the antenna to stabilize, and then carries out card search, anti-collision, card selection, card reading and authorization information verification. If the authorization information verification is successful, the door lock will be opened and locked again after a delay of one second; If the authorization information verification fails, an alarm will be given. Figure 6 is the flow chart of the client softwareFigure 6   Client software flow chart3.2. Design of authorization end softwareThe system uses the authorization terminal to write the authorization information of the new card. The workflow is system initialization, sending system initialization information, system startup prompt, opening serial port to receive, waiting for permission writing status flag, permission writing initialization setting, authorization information writing, and alarm prompt if writing fails, as shown in Figure 7Figure 7 mfrc522 authorization information writing process4. Experiment and result analysisDuring the system test, three electromagnetic locks are set, representing the company gate, sales department and finance department respectively. The authorization end authorizes three IC cards respectively. One card authorizes three doors, one card authorizes two doors of the company gate and sales department, and one card authorizes two doors of the company gate and Finance Department. The experimental verification shows that the system is easy to operate, Stable and practical. The system test is shown in Figure 8Figure 8   System test diagram5. ConclusionIn view of the shortcomings of traditional mechanical, fixed keyboard password lock, contact card swiping and other access control systems, an access control system based on single chip microcomputer and RFID technology is designed and implemented. The system adopts modular design, takes STC89C52 single chip microcomputer as the control core, and the periphery is composed of card reading module, display module It is composed of electromagnetic lock module and buzzer module. It uses non-contact IC card to swipe the card into the door, and has the functions of identity recognition, automatic opening and closing door and alarm prompt
Application of RFID System and Tag in Production Line
Easier said than done, radio frequency identification (RFID) systems and tags are still quite expensive. Considering that almost all goods have to be labeled, and the labels are difficult to reuse, the high cost can be imagined. Therefore, when Wal Mart informed its 100 largest suppliers in June 2003 that all RFID tags must be used, and the relevant equipment should be in place in the delivery center before January 2005, many suppliers were busy trying to improve the return on investment (ROI) and reduce costs.One of the 100 largest suppliers is wells' dairy, which provides Wal mart with Blue Bunny ice cream and various small commodities. Wells' report points out that it is the largest family owned dairy company in the United States and operates the world's largest ice cream factory, which is located in lemars, Iowa and works 160 hours a week.In order to comply with the new RFID regulations, many suppliers label before shipment, but wells' approach is different. It adopts RFID system early in the manufacturing process, so as to save costs and realize other advantages. Brad Galles, process control manager of wells' started a pilot project with Rockwell Automation, an automation supplier of dairy companies, in mid-2004. Its internally developed solution uses Allen Bradley 1756 eweb module for ControlLogix to process data from alien technology's RFID reader and 915 MHz, 96 bit squiggly tag.The antenna reader writes on the RFID tag, which is pasted on the outer packaging of two barrels of products, and 30 outer packaging boxes can be pasted every minute. During quick freezing, read the label on the outer packing box again. At this time, the speed can be up to four times that of the previous one. Finally, the product is shipped. RFID system transmits information back to wells' control system to realize information sharing in the company's enterprise network. Gales explained that if the usual label pasting and then shipping system is adopted, wells' must introduce manual repacking, which will increase labor costs."From the beginning, we believed that RFID technology could promote process transformation and improve performance. Once we collected data, we could use it to improve catalog tracking, automate most quality control and catalog work, and simplify data collection." wells' report also showed that its RFID system liberated employees from heavy work, Reduce shipping errors and reduce manual repair as much as possible.The dairy company and Rockwell realized efficiency improvement through RFID system and made full use of the data processing function of the tag. For example, each RFID tag of a dairy company is connected to the database with the production parameters of ice cream in the packaging box, including production time, batch identification information, product line, etc. This enables the operators of wells' company to accurately understand when each label is pasted and which batch of batch shipment belongs to.In a word, the advanced characteristics of RFID tag identification data help to strengthen the physical state and environmental data of user database, ensure the effective change or test of process, and support relevant decision-making and implementation, so as to further improve product quality.Gales pointed out: "The role of RFID is that it can enhance the visibility of factory production, because we can use RFID to collect information. The way of information collection is matched with the existing equipment, which creates more value for us. In order to achieve the highest return on investment, we should continue to use the ControlLogix platform used in the existing process to design the RFID system."RFID BasicsRFID tags do not need to monitor the production line and can process more data. Although bar codes are ubiquitous and relatively cheap, RFID tags are more robust and should replace bar codes. In addition, RFID is cheaper than traditional radio transmitters and other wireless technologies.However, in terms of current applications, RFID is mainly used for identification, material processing and other types of document work, which can meet the needs of Wal Mart and the U.S. Department of Defense (DoD) With regard to the requirements for installing RFID system, people have great expectations for the development of this technology, but it is also reported that there are still obstacles to its realization and doubts about the return on investment, so the implementation of RFID should not be carried out in a hurry.In view of this, generally speaking, the development trend of applications depends on users. Users should clarify their own needs, understand the functions and costs of RFID, and then decide whether RFID will help improve work efficiency, promote decision-making, strengthen quality control and promote production. If it is not suitable, users will still choose bar codes, radio transmitters or wired networks Technology.Bill Arnold of OMRON electronics LLC states: "If the data acquisition system uses its' eyes' to see the bar code, it can also hear the information of the RFID tag through the 'ears' of the system, and can also talk to it through the' language 'of the system. In this way, RFID technology is obviously a better way to achieve control and visibility in the supply chain. The bar code is only 14 to 16 bits, and each RFID tag is different There are 96 to 256 bits. As a unique technology, it can be used to clarify various parameters of the product, including production shifts, machine tools used and operators. "RFID tags can be read-only, write once read many (worm), read-write, passively read with an antenna / reader, or actively transmit signals (usually assisted by batteries).
How Can the Directivity of Coupler in RFID System Be Improved
0 IntroductionRFID system has been more and more widely used in the world. It is known as a new technology that will develop rapidly in the 21st century. RFID system can be applied to multiple frequency bands. Different frequency bands have different characteristics. RFID system in UHF frequency band has fast reading speed and long recognition distance. It has developed rapidly in recent years. This paper will focus on the improvement of microstrip directional coupler design in RFID system in UHF band.In many RFID systems, some microwave multi port devices are placed between the reader antenna and the signal processing module to separate the output reader signal and the tag scattered signal, such as circulator, directional coupler and so on. The toroidal coupler has a large volume and needs ferrite material, so the manufacturing cost is high. However, the microstrip directional coupler is usually small and easy to process, so it has been widely used in these systems. Microstrip coupler is generally composed of a 1 / 4 wavelength microstrip coupling line, and two ports are added at both ends of two parallel conduction bands to form a four port network of directional coupler.However, because the transmission mode of microstrip line is not strict TEM wave and has a small amount of longitudinal field components, the phase velocity imbalance of odd and even mode transmission is caused, which directly leads to the reduction of the directivity of microstrip coupler. As shown in formula (1):In this formula, I = e, O. It can be seen from the above formula that the phase velocity of odd and even modes is different, which will not only affect the coupling performance and orientation performance of microstrip coupler, but also narrow the frequency band. At this point, the strip line is better than the microstrip line, because the filling medium around the strip coupling line is uniform, the phase velocity of odd and even modes is the same, and the transmission of TEM wave itself has advantages over the microstrip line, but the processing is more troublesome, and other errors will be introduced in the bonding.For the above reasons, the isolation of directional couplers on the market is only about - 30dB, and the directivity usually does not exceed 20dB. A new improved scheme introduced in this paper is to add a high impedance line at the coupling end, so that the coupling end does not match and there is a certain amount of reflection. The reflected energy is transmitted to the isolation end through the microstrip line, so as to offset part of the leakage energy at the isolation end, which greatly improves the directivity. In the following experiments, it can be seen that at the specified frequency point, the isolation can reach below - 50dB and the directivity can reach - 30dB.Theoretical analysis and Simulation of coupler modelThe model of microstrip directional coupler in ads is shown in Figure 1. It is a four port device with a coupling line in the middle. The four ports are respectively connected to the external 50 Ω port. From point 5 to point 7 is the high impedance line, and the 7 ends are grounded. This length is a variable. The microstrip line connecting each port (except 3 ports) is 2.25mm wide and 14.4mm long, and the microstrip line connecting 3 ports is 1.4mm wide and 5mm long. The length of the coupling line is 57.7mm, the width of the conduction band is 2.1mm, and the spacing of the conduction band is o.45mm. This paper mainly discusses the function of high impedance line, so first set the length of high impedance line to zero. The PCB is made of PTFE with a dielectric constant of 2.5 and a thickness of 0.5cm.Firstly, the directional coupler is analyzed by theoretical analysis method. Using the line calculation tool in ads, the characteristic impedance and electrical length of each line can be obtained. The characteristic impedance of the microstrip line connecting ports 1, 2 and 4 is 36.24 Ω and the electrical length is 22.6 °. The characteristic impedance of the microstrip line connecting ports 3 is 50 Ω and the electrical length is 8.2 °. The characteristic impedance of the coupling line is 37.5 Ω, the odd mode impedance is 33.72 Ω, the even mode impedance is 41.73 Ω, the coupling degree is -19.48db, and the electrical length is 92.4 °. Theoretically, if the length of the coupling line is 90 °, the maximum coupling energy and the maximum coupling terminal voltage can be seen from formula (2). In ads, the simulation results of such a directional coupler are shown in Figure 2.Where: C is the coupling degree; V3 is the output voltage of the coupling end; V0 is the input voltage of the coupler. Obviously, when the length is 90 °, Tan θ= 0, V3 = CV0, maximum signal at coupling end. The length of the coupler is 92.4 °, which basically conforms to the basic theory of the coupler, and the value of this coupling degree should be close to that of S31. It can be seen from the following analysis that this value is basically consistent with the results calculated by the method of moments. Another important parameter is S41, which is 0 in the ideal coupler theory, but it is obviously not 0 in practice. Because of the imbalance of odd and even modes, its performance may become worse or even very poor. In addition, the input S11 parameters are analyzed by the transmission line equivalent theory analysis method, but this method can only be a rough analysis, because the phase velocity of odd and even modes transmitted by microstrip lines is unbalanced, and the odd and even mode components are difficult to calculate. However, because the coupling degree is relatively low, it can be calculated by assuming that the coupling line from port 1 to port 2 is an independent lossless transmission line. The impedance of Ports 1 and 2 is 50 Ω. According to formula (3), zin1 = 44.25-j10.24 Ω, zin2 = 30.7 j7.71 Ω, zin3 = 37.12 j10.65 Ω. Here 1, 2 and 3 refer to the points marked on the graph. It can be calculated by formula (4) Γ= 0.13 j0.138, S11 = -14.4db. From this data, the impedance matching is not very good. The present theoretical analysis results are compared with the later calculation results of the moment method.Figure 2 (a) is a diagram of S31 and S41. At 900MHz, S31 is -19.116db and S41 is -25.589db. Fig. 2 (b) is a diagram of S11. Between 800MHz and 1GHz, S11 is between - 12dB and - 20dB. As can be seen from Figure 2, the performance of this coupler is not good. Firstly, S11 is only -15.39db at 900MHz. The directional coupler is a straight through device. Generally speaking, S11 must be below - 30dB, otherwise the insertion loss is too large, which will damage the system. In addition, the directivity is too low. At 900MHz, the isolation is -25.589db, the coupling is -19.116db, the directivity is only about 6dB, and the directivity does not exceed 8dB in the whole frequency band. This result is obviously in line with the results calculated above. S11 = -15.39db is close to -14.42db above, while S31 = -19.116db is also close to the theoretical value of maximum coupling power -19.48db.Such performance obviously does not meet the requirements. Because the power difference between the signal scattered by tag tag and the signal transmitted by reader is more than 40 50 dB. The directivity of the coupler is only 8dB, so it is difficult to separate tag signal and reader signal. At the output of tag signal, the amplitude of reader signal is much larger than that of tag signal. Especially at the output of the amplifier, the tag is superimposed on the continuous wave signal of the reader. It is likely that the amplifier is saturated before the tag signal is amplified enough to be detected, which is very harmful. Next, the size of the high impedance line of the directional coupler will be adjusted to make the coupler reach a better index.2 improvement method and effect of couplerIn this section, we mainly describe an improved scheme of coupler, that is, adding high impedance line method. As shown in Figure 1, the terminal grounding of high impedance line belongs to short route, and most of the energy will be reflected back. Theoretically, the reflected energy is used to offset the energy of the coupler at the isolation end (port4) to improve its isolation. In addition to the poor isolation of the coupler itself, the energy leaked by the 4 port also includes the coupling of the signal reflected from the 2 port on the 4 port in practical application. This reflected signal is mainly caused by the mismatch of the antenna. Here, only 2 ports are considered as the ideal matching load. In an ideal coupler, the signal leaked at the isolation end is 90 ° later than the signal at the coupling end, and the offset signal should be exactly 180 ° different from the signal at the isolation end. Since the offset signal is mainly reflected by the terminal of the high impedance line, in Figure 1, the electrical length from point 4 to point 7 should be about 90 °. In this way, when the reflected signal is transmitted to point 4, it will be reversed, and then transmitted to point 6, and the signal at the isolation end is exactly reversed. Adjusting the width of the high impedance line can control the power of the reflected signal; By adjusting its length, the phase of the reflected signal can be controlled. After adjustment, the length of the high impedance line is 53.7mm and the width is 0.4mm. This length plus the 5mm short microstrip line connecting three ports, the electrical length is close to 90 ° (91.2 °). The simulation results of S11, S31 and S41 are shown in Figure 3.It is obvious from Figure 3 that S11 has only a small change because the energy of the coupling line coupled to ports 3 and 4 is relatively small and has little impact on the input reflection coefficient. In the improved model, the parameters other than the high impedance line are not changed. Both S31 and S41 change, especially S41 changes obviously from - 25dB to - 51dB, while S31 also changes from - 19dB to - 21db. The change of S31 is mainly due to the addition of high impedance lines, the matching condition of 3 ports changes, and the reflection increases. Therefore, the energy of 3 ports decreases slightly. S41 decreased significantly to nearly - 51dB, resulting in directivity of more than 30dB, which is due to reflection cancellation of high impedance line. This directivity has been very high, exceeding the index of most directional couplers in the market. Such directional couplers are very useful in the application of RFID system. It is worth noting that although such a high-performance coupler is applied, the reader signal is still much larger than the tag signal, but the system resolution is increased, and the tag scattering signal with smaller power can be recognized. If the amplitude difference between the two signals is not very large, the tag scattering signal can be obtained under the condition of unsaturated amplifier.However, it can also be seen from Figure 3 that the disadvantage of the coupler is that the bandwidth of high directivity is very narrow, and 20dB is only about 20MHz, because the performance of the coupler itself is poor. If it is a coupler with good performance and adjusted by high impedance line, a satisfactory frequency characteristic can be obtained. The lowest 903mhz in the middle can show such high directivity, obviously because at this frequency, the leakage signal at the isolation end is just opposite to the reflection cancellation signal.3 conclusionIn RFID system, multi port networks such as coupler and circulator are very important components, which are mainly used to separate reader and tag signals. However, the general directional coupler in the market can only reach the directivity of 20dB at most, which is very limited. When applied to RFID system, the ability of separating tag signal is relatively weak, or it can be separated from the channel only when the tag signal is relatively strong. Therefore, its structure needs to be improved.Theoretically, the signal strength of the directional coupler at the isolation end is 0, but in practice, due to the imbalance of the phase velocity of odd and even modes, the components of odd and even modes often change in the process of transmission, and the signal at the isolation end is not 0, or even very large. In the model proposed in this paper, the signal strength leaked at the isolation end is very large, only about 6dB less than that at the coupling end. In order to improve the directivity, the method of adding high impedance line is proposed. This method uses the reflected signal at the terminal of high impedance line to offset the leakage signal at the isolation terminal.An important conclusion of the high impedance line is that the electrical length from the end to the coupling end is about 90 °. According to the microstrip coupler theory, in order to achieve the best coupling effect, the length of the coupling end and the isolation end is about 90 °, and the signal phase difference is 90 °. The reflected signal shall be 180 ° different from the signal at the isolation end. The signal reflected back to the coupling end at the high impedance line terminal must be reversed from the original signal at the coupling end, so that it can be isolated after 90 ° transmission
What Are Some Ways to Keep My Hair Really Healthy?
What Are Some Ways to Keep My Hair Really Healthy?
Use professional shampoo & conditioner. I know it may seem like a rip-off, however all the shampoos like Pantene, Garnier, etc. have a high alcohol content....since the normal pH of your hair is 4.5-5.5, things containing high amounts of alcohol throw your hair all out of whack and cause breakage, split-ends, fly-aways, etc. The reason these shampoos make your hair feel soft is because they contain high amounts of humectants, which are just a cover for how damaging they really are! Another tip is ALWAYS use a thermal protector while applying heat. Heat appliances cause tons of damage to your hair. Usually this is a cream/clear gel you apply before blow drying. Never use a flat iron on hair that is not completely dry!1. Split End Help. ( 10 Points) !!!!!!!!!!!!!!!!!!!!!!?For sure you should get a trim and maybe even cut your hair as short as you are comfortable doing it. You should for no reason straighten or dye your hair. Look for some Garnier Fructis or Pantene shampoos and conditioner for curly hair so that it extra moisturizes it and helps the split ends repair themselves. I say from experience that ppl with curly hair have really bad split ends, which is why we have special stuff in our hair products. The split ends wont magically go away in like a month or a few weeks, but you will see improvement after a while. Oh, and for sure DO NOT PICK THEM OFF!! It will just make it worse. Every two months until your hair is healthy get a trim. just maybe half an inch or an inch will be just fine. Eventually your hair will go back to normal. Good luck with that!.2. Whats the best shampoo conditioner for cheap?clever or V05 are solid inexpensive ($a million) shampoos, yet whilst it is composed of conditioner i could bypass Tresemme ($6) it does an somewhat solid interest. i take advantage of salon shampoo because of the fact i am form of a hair snob, yet I nonetheless use the cheap conditioner. Pantene is undesirable on your hair (too plenty protein and reasons alot of greater build up on the hair) so i does not bypass there. desire this permits! My hair is oily, superb, and colour-taken care of if that helps you any!3. How can I get my curly hair to be nice like Taylor Swift?Haha i have the same hair long and curly..but not pretty curly! im completely obsessed with taylor and her hair so i did so playing with it and what you really NEED to get is the conair hot sticks!! they are these little flexible curlers and they are not very expensive and i would look like a frizz ball without them!! you can like get them at walmart. anyways what i do when iwear my hair curly is like i get up and get in the shower and wash it and condition it and this may sound weird but dont use a whole lot of conditioner just enough to get it done cause it will help your hair hold the curl the just get out and towel dry your hair till it is just damp and then put a curling mouse in it and frizz serum then finish blow drying it straight! and you know have the curlers on like when your gettin in the shower and then just make sure the little light is on meaning that they are hot enough and then seperate your hair into pretty small peices (if you have really thick hair then you might need to buy two sets cause they only have 14 in them and you use small sections) and then start from the botom of your hair and role it through your hair and pin it together youll see the instructions on how to pin them together and make sure you wrap it all the way to the top of your head and leave them for like 15 or 20 minutes while your finishin gettin ready and then use like a light hairspray about 5 minutes before you take them out then your done. i know this thing was really long but its not that hard lol!!!! hope i helped good luck!!!!!!!!
How Was the First Sale of Vivo X60 Series?
How Was the First Sale of Vivo X60 Series?
Zeiss lens has a history of 175 years. Its biggest advantage is its ultra-clear imaging ability. Generally, only using high-end cameras has become the dream of camera lovers around the world with its unique selling points such as color restoration, high resolution and almost no corner distortion. Why do you talk about dreams here? Because of its ultra-high price, ordinary people can only think but can not become a reality.On December 29, 2020, vivo X60 series, the first product jointly developed by vivo and Zeiss, was officially launched. All the series are equipped with Zeiss optical lenses as standard, which can be owned for a minimum of 3498 yuan. On January 8, vivo X60 series was officially launched. We can see that it won the double champions of JD platform sales sales, tmall platform sales sales, Suning platform sales sales, and also the double champions of online sales and sales. Besides Zeiss blessing, why is vivo X60 series so popular with the market and consumers?Ultra lightweight appearanceThe thickness of vivo X60 does not exceed 8mm, and the weight of vivo X60 does not exceed 180g (excluding the unpublished Super Cup). Among them, the vivo X60 is only 7.36mm thick, making it the lightest 5g mobile phone in the world, 0.04mm thinner than the iPhone 12 series. The slim and fashionable appearance and vivo's strict pursuit of technology and design create the unparalleled hand feel of vivo X60 series. If you don't believe it, you can try it in the offline experience store in person. You can't forget the feeling of holding it in your hand.Top imaging systemThe vivo X60 is equipped with Zeiss optical lens as standard. Whether it is the main camera, ultra wide angle or professional image lens, it is an optical lens jointly developed by both sides. The whole system is equipped with the second generation micro PTZ as standard. With these two hardware blessings and the image system jointly developed by vivo Zeiss, you can take a good picture at any light source and scene. You can learn from the comments of professional photographers on the imaging effect of vivo X60 series.Performance of flagship aircraftVivo X60 is the world's first Samsung Orion 1080 processor. The overall performance of this processor is lower than that of Xiaolong 865. It is much stronger than what MediaTek Tianji 1000 and Xiaolong 765G are used in the same level models. With the blessing of Samsung Orion 1080, vvio X60 is far more competitive than its competitors.
Huami Technology Held a Press Conference on August 27, and Amazfit Smart Sports Watch 3 Officially A
Huami Technology Held a Press Conference on August 27, and Amazfit Smart Sports Watch 3 Officially A
This morning, huami technology officially announced that it would hold the 2019 new product Conference on August 27. Then, Huang Wang, CEO of huami technology, posted the invitation letter for the new product Conference on his microblog. Huami technology distributed amazfit one-way wet guide short sleeved T-shirts and amazfit antelope running shoes to the media as physical invitations. The gift box vacated a watch position, which triggered extensive discussion in the media. Huang Wang also explained that this vacancy was actually reserved for the new amazfit intelligent movement watch 3.(invitation letter from Huang Wang, CEO of huami Technology)The theme of huami technology's 2019 new product launch is "run, amazfit! Run!", which is adapted from the classic line "run, Forrest! Run!" of Forrest Gump. With his pure love for sports, Forrest Gump, the protagonist in the film, runs across the United States. No matter how many difficulties and ridicules he encounters, he also doesn't give up. "Run, Forrest! Run!" is the symbolic line that Forrest Gump's mother encourages him, and Forrest Gump can persevere and succeed step by step. This spirit also inspires many people. According to Huang Wang's microblog, the amazfit smart sports watch 3 not only symbolizes huami technology's understanding and adherence to the sports spirit, but also has a taste of paying tribute to Forrest Gump.(theme poster of huami technology's 2019 new product launch)At present, huami technology has become a leading enterprise in the wearable field. With the power of technology, it promotes everyone in the world to enjoy better sports, health and medical services. Sports is undoubtedly an important part of the mission of huami technology. In the past amazfit smart watch products, we can also see a lot of improvements in sports functions.Taking the amazfit smart watch GTR released last month as an example, it provides 12 sports modes such as outdoor running, walking, outdoor cycling, indoor running, indoor cycling, open water swimming, swimming pool swimming, elliptical machine, mountaineering, cross-country running, skiing and exercise. Turn on the corresponding professional sports mode before sports, you can always understand your sports status and help improve sports efficiency.(huami technology amazfit smart watch GTR)Facing the professional sports market, huami technology has also launched several products of amazfit smart sports watches 1, 2 and 2S. It is worth mentioning that it has been a long time since huami technology last updated the smart sports watch series. With more and more attention to sports and healthy life, huami technology still needs to bring more stimulation to the sports watch market and further implement the mission of huami technology. This may also be an important reason why huami technology updates amazfit smart sports watch 3.In terms of function, at present, amazfit smart sports watch 2 has been equipped with 16 sports modes. According to Xiaobian's guess, amazfit smart sports watch 3 will be richer in sports modes to meet the sports monitoring needs of different users. With more powerful functions, the price of amazfit smart sports watch 3 may reach 2500 yuan, which is also the price level of mainstream sports watches at present. As for whether the new product has more professional sports function improvement, we still need to wait for the official answer on August 27.
Connect to Nonencrypted Wireless Network Using Ubuntu Commands
Connect to Nonencrypted Wireless Network Using Ubuntu Commands
Connect to Nonencrypted Wireless Network Using Ubuntu Commandsthe output from /sbin/iwconfig wlan0 shows you are not associated with any APs.you will need to do /sbin/iwlist wlan0 scan to search for nearby APs, before, and in my experience, sometimes after, you set /sbin/iwconfig wlan0 essid "essid"again, the app wicd is quite nice for managing your wireless, without requiring a lot of extras— — — — — —how to hack into a wireless network?While cracking a wireless security key is somewhat of a grey area legally, using someone elses internet without permission is a crime. But, a google search for WEP cracking might point you in right direction, but no recommended to do so.— — — — — —How to network a house, both wireless and wired.?The best way would be to recreate the wired network, then set up a wireless network. Use a computer to bridge them together— — — — — —Is it possible to extend the range of your wireless network?You have a couple of different options at your disposal. One is getting higher dbi gain antennas for your ROUTER. The second is adding a higher gain dbi antenna to your adapter (optionally, you can do both and really extend the range). Another is getting a range extender. The higher dbi gain antenna plugged into your router and adapter can really extend your network. Without any obstructions, and 15 dbi gain antennas, you can connect at about 2 miles away. The range extender might be a little cheaper. It plugs into an electrical socket and you run an ethernet cable right into it. This is good if you have quite a few walls in between you and router. Not practical if you do not like wires, you would be better off with the antennas. Regards, Brandon— — — — — —Is it a good idea to download something from an unsecured network?If you see that a wireless network says it's "unsecured", this only means that that wireless network does not have a wireless password. Hence, you or anyone can readily connect to it without entering a password. There is minimal risk of you getting a virus just because of connecting to an "unsecured network", except probably if you go to a website or accidentally downloaded an email that has a virus attached to it - things of that sort. Another risk, although very negligible, is that other people who are connected to that same unsecured network may access your computer files given that you have set your computer files to be on SHARED mode. This is HARDLY ever the case, since you will need to grant that person permission via the Windows File Sharing application. So I tell you, it's okay.— — — — — —XBOX 360 WIRELESS NETWORK ADAPTER BYPASS?There are a number of possible solutions here, but they all depend on you having existing hardware that would cost significantly more than the adapter. Firstly, if you have/buy one of the new "slim" xbox 360s, they have wireless built in, so no need for an adapter. Second, if you have a computer connected to the internet near the 360, you can use the laptop as a wireless receiver, then run an ethernet (CAT5) cable from the laptop to your 360. Thirdly, if you have a computer nearby that is connected by a wired connection (cables through the roof etc) then you can use that computer as a router, and plug the xbox into the computer to share connection. If you just have an xbox 360 original in a room that has no wired connection or a computer connected to wireless, your only option is to buy the adapter.— — — — — —Problems with Wireless Network internet connectionWich encryption type do you use? Maybe the router is set to WPA or WPA2 but your PC does only support WEP— — — — — —Setting up a wireless network..?1) Make sure you are on the same Workgroup, ie, both laptop and desktop have same name. 2) Make sure to turn off all software firewalls for setup puroses. 3) Install/enable file/print sharing in Network Connections. 4) Share a folder on each computer, I usually use c:temp, and then map them to each other computer. 5) sometimes you may have to install Netbios/IPX protocol. email/IM me for more help, Good luck!— — — — — —Wireless network card installation problems.?Switch to a USB wireless. Some machines can not handle more than one or two cards, no matter what they can "hold"
Is Time Travel Possible? Can We Travel Back in Time?
Is Time Travel Possible? Can We Travel Back in Time?
There is no actual "correct." Einstein made a "theory," not a fact. If Einstein's theory is correct, we could theoretically travel back in time but the problem is, we would not be able to go into the future1. What's the similarities between time travel and space travel?The faster your motion through space relative to a stationary reference frame, the more your motion is diverted from your motion through time. In other words, in a very specific sense, we move through time at lightspeed. The faster you move through space, the more your movement through time is diverted by your movement through space. At lightspeed, all your motion through time is diverted by your motion through space. A photon does not experience time. All of its motion through time is diverted by its motion through space. According to relativity theory anyway2. How to travel with cats?Some cats do fine being loose in the car. Try taking them for a little ride (5-10 minutes) and see how they react. I had one cat, a wonderful loving tabby, that I took for a car ride. I was not driving, so she crawled into my lap, squalled, and peed all over my lap! Some years later I had 3 Siamese, and drove from Wisconsin to Montana with them loose in the car, without a bit of a problem. I think its great that you are taking your cats along with you!!!3. Is it Cheap to Travel to Trinidad?It all depends on where you are flying from. If you are in the US it might be better for you to go to Miami. For me in the Caribbean, I would definitely go to Trinidad because the fair is cheaper, the prices are not that bad, I know my way around and I would feel safe. I can just go down town and buy a few doubles and just watch the people go buy sitting on the side of the road. You might not want to do that. I might even buy some shark and bake. Generally, I go to Chaguanas and shop but I might just stay in POS. From the time I take to spend that extra money to go to Miami I could stop right here in Trinidad. I have been there many times and I have not have a problem. It is up to you though because my experiences might be different to yours. All you have to do is to stay where there is lots of people and the same precautions you would take in your country take there. Do not walk around with your purse expose because that would be asking for trouble.4. Is it safe to travel to Israel?Of course it's safe. It's safer than the US. all that stuff you hear is media bullS5. Where to travel in Europe?You can visit Norway :)6. How do I learn about mountain bikes?Firstly, size. Also, go and have a look at a few of their bikes, there is an interesting rating system next to the bikes, indicating the type of riding that it is suitable for. Next, using 1 - 10 scale. But this is based upon components, layout and value for money. MBR is a good place to do some research. For general bike buying, it is advisable to stick to some of the bigger brands. Trek, Scott, Giant, Specialized. You might also consider some of the smaller manufacturers like Claude Butler or Dawes. For components use either SRAM or Shimano gears. Cranks, either Shimano or Truvative, although if you want to throw money at this you could easily look at 2 - 300 on Race Face or Hollowtec. However, many manufacturers use their own brand, eg. Bontager = Trek. However, if you stick with the brands listed above, they will use viable kit, it just depends how much money that you want to spend on your bike. Hard tail or full sus? Firstly, do not spend less than 700 on a full sus. Do not buy an all singing, all dancing 200 bike from Walmart, Tesco, Cycleking, etc. Hard tails tend to be lighter. Also, because you are not spending huge amounts on a rear shock, you get better quality components elsewhere. So, spending 700 on a hardtail will get you a nice race machine with good quality components and viable suspension. You will still get a nice full sus for this price, but the overall quality will not be as high. If you are just hitting well maintained gravel tracks and roads, you do not want your front fork to do too much, so 80mm travel is good. This is also good if you want to race, since you lose less forward power to bouncy forks. For general XC, about 100mm fork travel, although an adjustable fork between 80 and 130 mm is OK. Any fork that starts at 120mm travel will tend to fall into the all mountain category. These will have chunkyer tyres than XC and are better for bounlders and logs etc. Downhill will have a lot of travel up front, with a raked back design. Luck
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