{"id":1818,"date":"2017-10-25T08:00:33","date_gmt":"2017-10-25T15:00:33","guid":{"rendered":"http:\/\/www.autodesk.com\/products\/eagle\/blog\/?p=1818"},"modified":"2023-07-18T15:37:45","modified_gmt":"2023-07-18T22:37:45","slug":"rfid-works-antenna-design","status":"publish","type":"post","link":"https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/rfid-works-antenna-design\/","title":{"rendered":"Tags and Readers: How RFID Works, and How to Design Your First RFID Tag Antenna"},"content":{"rendered":"\n<p><span style=\"font-weight: 400;\">Radio-Frequency Identification (RFID) has been around for over 50 years, and in the last decade is finally cheap enough to mass-produce and place in everyday objects. This presents some new opportunities for electronics designers wanting to learn about RF and antenna design. <\/span><a href=\"https:\/\/www.autodesk.com\/products\/eagle\/blog\/amazon-go-rfid-automation-dilemma\/\"><span style=\"font-weight: 400;\">While RFID accomplishes the same functionality of a barcode or magnetic strip on a credit card<\/span><\/a><span style=\"font-weight: 400;\">, it has some unique use cases that make it worth learning about and designing. In this blog, we\u2019ll be covering how RFID works and how you can create your very own RFID tag antenna circuit. <\/span><\/p>\n\n\n<h2 class=\"wp-block-heading\" id=\"how-rfid-works\">How RFID Works<\/h2>\n\n\n<p><span style=\"font-weight: 400;\">An RFID system consists of three parts: a scanning antenna, an RFID tag which includes all of the information about a product, and a reader which decodes and interprets data on a tag. These three pieces fit into a process where:<\/span><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><span style=\"font-weight: 400;\">Data is first stored in an RFID tag in either a read-only or read-write format. The tag is either battery powered or passive.<\/span><\/li>\n\n\n\n<li><span style=\"font-weight: 400;\">When the tag comes within range of a scanning antenna, electromagnetic (EM) energy triggers the tag to start sending data in the form of radio waves. <\/span><\/li>\n\n\n\n<li><span style=\"font-weight: 400;\">These radio waves are picked up by the antenna and send to the reader which decodes the waves as digital information.<\/span><\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full wp-image-1131\"><img loading=\"lazy\" decoding=\"async\" width=\"345\" height=\"292\" src=\"https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/overview.jpg\" alt=\"a complete rfid system\" class=\"wp-image-59940\" srcset=\"https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/overview.jpg 345w, https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/overview-300x254.jpg 300w\" sizes=\"auto, (max-width: 345px) 100vw, 345px\" \/><figcaption class=\"wp-element-caption\"><em>Tags communicate with readers to share data. (<a href=\"https:\/\/www.autodesk.com\/products\/eagle\/blog\/amazon-go-rfid-automation-dilemma\/\">Image source<\/a>)<\/em><\/figcaption><\/figure>\n\n\n\n<p><span style=\"font-weight: 400;\">RFID tags are broken down into one of two types, Active and Passive:<\/span><\/p>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full wp-image-1820\"><img loading=\"lazy\" decoding=\"async\" width=\"277\" height=\"186\" src=\"https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/tag.jpg\" alt=\"rfid antenna\" class=\"wp-image-59945\"\/><figcaption class=\"wp-element-caption\"><em>Tags will typically contain an antenna and microchip. (<a href=\"https:\/\/www.barcodesinc.com\/info\/buying-guides\/rfid.htm\">Image source<\/a>)<\/em><\/figcaption><\/figure>\n\n\n<h3 class=\"wp-block-heading\" id=\"active-rfid-tags\">Active RFID Tags<\/h3>\n\n\n<p><span style=\"font-weight: 400;\">Active RFID tags use an internal battery source to power their circuitry and send radio signals. Because of their battery power, active tags can broadcast at higher frequencies from 805 to 950 MHz. This allows them to be scanned from up to 100 feet away.<\/span><\/p>\n\n\n<?xml encoding=\"utf-8\" ?><figure class=\"wp-block-table MuiTableContainer-root\"><table class=\" MuiTable-root DhigTable--verticalAlignment--top\"><tbody><tr class=\" MuiTableRow-root\"><td class=\" MuiTableCell-root\"><b>Advantages<\/b><\/td><td class=\" MuiTableCell-root\"><b>Disadvantages<\/b><\/td><\/tr><tr class=\" MuiTableRow-root\"><td rowspan=\"4\" class=\" MuiTableCell-root\">\n<ul>\n<li><span style=\"font-weight: 400;\">Can be read at long distances<\/span><\/li>\n<li><span style=\"font-weight: 400;\">Typically includes additional sensors<\/span><\/li>\n<li><span style=\"font-weight: 400;\">Higher bandwidth capabilities<\/span><\/li>\n<li><span style=\"font-weight: 400;\">Autonomous networking capabilities<\/span><\/li>\n<li><span style=\"font-weight: 400;\">Can perform self-diagnostics<\/span><\/li>\n<\/ul>\n<\/td><td rowspan=\"4\" class=\" MuiTableCell-root\">\n<ul>\n<li><span style=\"font-weight: 400;\">Limited lifetime due to battery<\/span><\/li>\n<li><span style=\"font-weight: 400;\">More expensive to manufacture<\/span><\/li>\n<li><span style=\"font-weight: 400;\">Larger footprint<\/span><\/li>\n<li><span style=\"font-weight: 400;\">Higher maintenance costs<\/span><\/li>\n<li><span style=\"font-weight: 400;\">Battery outage can lead to misreading data<\/span><\/li>\n<\/ul>\n<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n<h3 class=\"wp-block-heading\" id=\"passive-rfid-tags\">Passive RFID Tags<\/h3>\n\n\n<p><span style=\"font-weight: 400;\">Passive RFID tags have no battery source and rely on the electromagnetic coupling of an antenna for their power. This leaves them with a shorter reading distance of up to 20 feet. However, because they have fewer components in their circuitry they\u2019re also cheaper to produce and disposable. This is the kind of tag you\u2019ll find in consumer-level products.<\/span><\/p>\n\n\n<?xml encoding=\"utf-8\" ?><figure class=\"wp-block-table MuiTableContainer-root\"><table class=\" MuiTable-root DhigTable--verticalAlignment--top\"><tbody><tr class=\" MuiTableRow-root\"><td class=\" MuiTableCell-root\"><b>Advantages<\/b><\/td><td class=\" MuiTableCell-root\"><b>Disadvantages<\/b><\/td><\/tr><tr class=\" MuiTableRow-root\"><td rowspan=\"4\" class=\" MuiTableCell-root\">\n<ul>\n<li><span style=\"font-weight: 400;\">Long lifespan, 20+ years<\/span><\/li>\n<li><span style=\"font-weight: 400;\">Less expensive to manufacture<\/span><\/li>\n<li><span style=\"font-weight: 400;\">Smaller footprint<\/span><\/li>\n<\/ul>\n<\/td><td rowspan=\"4\" class=\" MuiTableCell-root\">\n<ul>\n<li><span style=\"font-weight: 400;\">Can only be read at short distances<\/span><\/li>\n<li><span style=\"font-weight: 400;\">Basic functionality, no added sensors<\/span><\/li>\n<li><span style=\"font-weight: 400;\">Tags remain readable by any RFID reader<\/span><\/li>\n<\/ul>\n<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p><span style=\"font-weight: 400;\">All RFID tags are classified by their Generation and Class. Current <\/span><a href=\"https:\/\/www.gs1.org\/epcrfid\/epc-rfid-uhf-air-interface-protocol\/2-0-1\"><span style=\"font-weight: 400;\">Gen-2 RFID<\/span><\/a><span style=\"font-weight: 400;\"> tags were adopted in December 2004 and offer several advantages over Gen-1, including:<\/span><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><span style=\"font-weight: 400;\">Interoperability with all RFID systems, the first global standard<\/span><\/li>\n\n\n\n<li><span style=\"font-weight: 400;\">Faster read speeds than Gen-1<\/span><\/li>\n\n\n\n<li><span style=\"font-weight: 400;\">Precise performance with advanced anti-collision protocols<\/span><\/li>\n\n\n\n<li><span style=\"font-weight: 400;\">Improved security and privacy<\/span><\/li>\n\n\n\n<li><span style=\"font-weight: 400;\">Easier physical deployment of multiple readers<\/span><\/li>\n<\/ul>\n\n\n\n<p><span style=\"font-weight: 400;\">RFID tag classes range from Class 0 through Class 5 and define available functionality. Class details include:<\/span><\/p>\n\n\n<?xml encoding=\"utf-8\" ?><figure class=\"wp-block-table MuiTableContainer-root\"><table class=\" MuiTable-root DhigTable--verticalAlignment--top\"><tbody><tr class=\" MuiTableRow-root\"><td class=\" MuiTableCell-root\"><b>Class&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<\/b><\/td><td class=\" MuiTableCell-root\"><b>Functionality<\/b><\/td><\/tr><tr class=\" MuiTableRow-root\"><td class=\" MuiTableCell-root\"><span style=\"font-weight: 400;\">Class 0<\/span><\/td><td class=\" MuiTableCell-root\"><span style=\"font-weight: 400;\">UHFI read-only, preprogrammed passive tag<\/span><\/td><\/tr><tr class=\" MuiTableRow-root\"><td class=\" MuiTableCell-root\"><span style=\"font-weight: 400;\">Class 1<\/span><\/td><td class=\" MuiTableCell-root\"><span style=\"font-weight: 400;\">UHF or HF, can be written once, read many times (WORM)<\/span><\/td><\/tr><tr class=\" MuiTableRow-root\"><td class=\" MuiTableCell-root\"><span style=\"font-weight: 400;\">Class 2<\/span><\/td><td class=\" MuiTableCell-root\"><span style=\"font-weight: 400;\">Passive read-write tags that can be written at any time<\/span><\/td><\/tr><tr class=\" MuiTableRow-root\"><td class=\" MuiTableCell-root\"><span style=\"font-weight: 400;\">Class 3<\/span><\/td><td class=\" MuiTableCell-root\"><span style=\"font-weight: 400;\">Passive or active read-write tags with added sensors for recording temperature, pressure, and motion.<\/span><\/td><\/tr><tr class=\" MuiTableRow-root\"><td class=\" MuiTableCell-root\"><span style=\"font-weight: 400;\">Class 4<\/span><\/td><td class=\" MuiTableCell-root\"><span style=\"font-weight: 400;\">Active read-write tags with integrated transmitters that can communicate with other tags and readers. <\/span><\/td><\/tr><tr class=\" MuiTableRow-root\"><td class=\" MuiTableCell-root\"><span style=\"font-weight: 400;\">Class 5<\/span><\/td><td class=\" MuiTableCell-root\"><span style=\"font-weight: 400;\">Active read-write tags that can power other tags and communicate with external devices other than readers. <\/span><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n<h2 class=\"wp-block-heading\" id=\"advantages-and-disadvantages-of-rfid\">Advantages and Disadvantages of RFID<\/h2>\n\n\n<p><span style=\"font-weight: 400;\">RFID wireless technology has provided enormous benefits to logistics, inventory control, and retail industries, but that doesn\u2019t make it a perfect technology. However, when compared with barcodes and other manual scanning systems, RFID has some noticeable advantages, including:<\/span><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><b>Scanning multiple items simultaneously<\/b><span style=\"font-weight: 400;\">. RFID systems can scan all incoming items at once, compared with an optical scanner which can only handle one item at a time. <\/span><\/li>\n\n\n\n<li><b>Reduced costs<\/b><span style=\"font-weight: 400;\">. Costs have fallen dramatically to manufacture active and passive RFID tags, which makes them available for use in disposable consumer products. <\/span><\/li>\n\n\n\n<li><b>Read and write capabilities<\/b><span style=\"font-weight: 400;\">. Barcodes can only be written with data once, but RFID tags can be updated as many times as needed for Class 2 tags and above. <\/span><\/li>\n\n\n\n<li><b>No line of sight issues<\/b><span style=\"font-weight: 400;\">. Unlike optical scanners, there are no line of sight requirements when scanning items. This makes RFID ideal for high efficiency industrial environments. <\/span><\/li>\n<\/ul>\n\n\n\n<p><span style=\"font-weight: 400;\">The disadvantages for RFID fall into two categories, technical issues related to RFID implementation and security\/privacy uses.<\/span><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><b>RFID can be disrupted<\/b><span style=\"font-weight: 400;\">. Someone using the right frequency on the electromagnetic spectrum can potentially jam an RFID system. You can also continually read a battery-powered RFID tag until it powers down. <\/span><\/li>\n\n\n\n<li><b>Reader collision issues<\/b><span style=\"font-weight: 400;\">. Systems need to be carefully set up to avoid any collision issues where multiple signals overlap. This has been improved with Gen-2\u2019s improved anti-collision protocols. <\/span><\/li>\n\n\n\n<li><b>Can be read at longer distances<\/b><span style=\"font-weight: 400;\">. Most RFID systems are designed to work at small distances. However, with a high-gain antenna, you can read tags from over a hundred feet away without anyone knowing.<\/span><\/li>\n\n\n\n<li><b>Can be read without permission<\/b>. As we begin to embed RFID in everyday items like clothing and consumer products, we\u2019re also at the mercy of stores scanning every item we\u2019re carrying to prevent theft. Is this an issue of privacy, or just the cost of convenience?<\/li>\n<\/ul>\n\n\n<h2 class=\"wp-block-heading\" id=\"use-cases-for-rfid\">Use Cases for RFID<\/h2>\n\n\n<p><span style=\"font-weight: 400;\">With its lower manufacturing costs, the uses for RFID are spreading across a variety of industries and settings. Some of the most common applications we see today include:<\/span><\/p>\n\n\n<h3 class=\"wp-block-heading\" id=\"retail-and-inventory-control\">Retail and Inventory Control<\/h3>\n\n\n<p><span style=\"font-weight: 400;\">RFID tags are attached to clothing and other consumer goods in retail stores. This allows employees to scan items and track inventory levels without dealing with barcodes.<\/span><\/p>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full wp-image-1821\"><img loading=\"lazy\" decoding=\"async\" width=\"728\" height=\"546\" src=\"https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/rfid-powerpoint-presentation-8-728.jpg\" alt=\"rfid in retail supply chain\" class=\"wp-image-59950\" srcset=\"https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/rfid-powerpoint-presentation-8-728.jpg 728w, https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/rfid-powerpoint-presentation-8-728-300x225.jpg 300w\" sizes=\"auto, (max-width: 728px) 100vw, 728px\" \/><figcaption class=\"wp-element-caption\"><em>Retail giants like Walmart are integrating RFID into their retail supply chain. (<a href=\"https:\/\/www.slideshare.net\/PeterSam67\/rfid-powerpoint-presentation\">Image source<\/a>)<\/em><\/figcaption><\/figure>\n\n\n<h3 class=\"wp-block-heading\" id=\"subway-passes-and-toll-booths\">Subway passes and toll booths.<\/h3>\n\n\n<p><span style=\"font-weight: 400;\">RFID tags are commonly added to toll booths, and subway passes. This allows commuters to swipe a card and automatically deduct the cost of the fare.<\/span><\/p>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full wp-image-1822\"><img loading=\"lazy\" decoding=\"async\" width=\"492\" height=\"326\" src=\"https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/Electronic-Toll-Booth.jpg\" alt=\"rfid electronic toll booth\" class=\"wp-image-59955\" srcset=\"https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/Electronic-Toll-Booth.jpg 492w, https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/Electronic-Toll-Booth-300x199.jpg 300w\" sizes=\"auto, (max-width: 492px) 100vw, 492px\" \/><figcaption class=\"wp-element-caption\"><em>Many toll booths are now implementing RFID technology. (<a href=\"https:\/\/www.trakaid.com\/rfid-solution-toll-collection\/\">Image source<\/a>)<\/em><\/figcaption><\/figure>\n\n\n<h3 class=\"wp-block-heading\" id=\"theft-prevention\">Theft Prevention<\/h3>\n\n\n<p><span style=\"font-weight: 400;\">High priced, luxury items like custom-built guitars are now having RFID tags embedded inside them. This inventory is then shared with local law enforcement, dealers, and repair shops to help prevent theft. <\/span><\/p>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full wp-image-1823\"><img loading=\"lazy\" decoding=\"async\" width=\"547\" height=\"411\" src=\"https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/4124_p54583.jpg\" alt=\"rfid in gibson guitar\" class=\"wp-image-59960\" srcset=\"https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/4124_p54583.jpg 547w, https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/4124_p54583-300x225.jpg 300w\" sizes=\"auto, (max-width: 547px) 100vw, 547px\" \/><figcaption class=\"wp-element-caption\"><em>The little dot under the truss rod on this Gibson guitar is an RFID chip. (<a href=\"http:\/\/www.lespaulforum.com\/forum\/showthread.php?107919-implanting-RFID-tags-in-Gibson-guitars\">Image source<\/a>)<\/em><\/figcaption><\/figure>\n\n\n\n<p><span style=\"font-weight: 400;\">These are just a few of the many uses for RFID. In the future, this technology is proving to be a major disruptor for the retail shopping experience with concepts like <\/span><a href=\"https:\/\/www.autodesk.com\/products\/eagle\/blog\/amazon-go-rfid-automation-dilemma\/\"><span style=\"font-weight: 400;\">Amazon Go<\/span><\/a><span style=\"font-weight: 400;\">. Some other use cases for RFID include:<\/span><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><span style=\"font-weight: 400;\">Person and animal tracking<\/span><\/li>\n\n\n\n<li><span style=\"font-weight: 400;\">Contactless payments with NFC<\/span><\/li>\n\n\n\n<li><span style=\"font-weight: 400;\">Travel documents<\/span><\/li>\n\n\n\n<li><span style=\"font-weight: 400;\">Healthcare data management<\/span><\/li>\n\n\n\n<li><span style=\"font-weight: 400;\">Tracking shipping containers and railroad cars<\/span><\/li>\n<\/ul>\n\n\n<h2 class=\"wp-block-heading\" id=\"designing-your-first-rfid-antenna-tag-circuit\">Designing Your First RFID Antenna Tag Circuit<\/h2>\n\n\n<p><span style=\"font-weight: 400;\">When designing an RFID system, engineers will typically utilize exiting tag microchips like the <\/span><a href=\"http:\/\/www.st.com\/en\/nfc\/st25-nfc-rfid-tags-readers.html\"><span style=\"font-weight: 400;\">STMicroelectronics ST25<\/span><\/a><span style=\"font-weight: 400;\"> in combination with a custom antenna. In this section, we\u2019ll be covering some practical tips on how to approach this antenna design process, along with further details in an application note.<\/span><\/p>\n\n\n<h3 class=\"wp-block-heading\" id=\"know-the-frequency-of-your-application\">Know the Frequency of Your Application<\/h3>\n\n\n<p><span style=\"font-weight: 400;\">Before designing a custom antenna, you need to know the frequency of your application. Nearly all RFID systems operate in two lower-frequency bands, either 13.56 MHz or 125 KHz, both of which are applicable in almost every country. Within the 13.56 MHz band, your application can be categorized as:<\/span><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><b>Long Range (LR)<\/b><span style=\"font-weight: 400;\">. These products are tuned between 13.6 MHz and 13.7 MHz. <\/span><\/li>\n\n\n\n<li><b>Standard Short Range (SR)<\/b><span style=\"font-weight: 400;\">. These products are tuned between 13.6 MHz and 13.9 MHz. <\/span><\/li>\n\n\n\n<li><span style=\"font-weight: 400;\">SR products being used as <\/span><b>transport tickets<\/b><span style=\"font-weight: 400;\"> are turned between 14.5 MHz and 15 MHz. <\/span><\/li>\n<\/ul>\n\n\n\n<p><span style=\"font-weight: 400;\">To determine the frequency of your application you also need to consider the material and environment of your device. For example, an RFID tag with a paper label held together with adhesive will reduce the antenna frequency by about 300 KHz. This reduction makes it necessary to tune the antenna at 13.9 MHz instead of its specified 13.6 MHz.<\/span><\/p>\n\n\n<h3 class=\"wp-block-heading\" id=\"reference-an-equivalent-circuit-model\">Reference an Equivalent Circuit Model<\/h3>\n\n\n<p><span style=\"font-weight: 400;\">Many antenna design application notes will include an equivalent circuit model that you can follow when designing your own. The schematic below shows how the chip and antenna fit together in a typical circuit:<\/span><\/p>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full wp-image-1824\"><img loading=\"lazy\" decoding=\"async\" width=\"1011\" height=\"373\" src=\"https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/2017-10-24_15-37-19.jpg\" alt=\"equivalent circuit model\" class=\"wp-image-59965\" srcset=\"https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/2017-10-24_15-37-19.jpg 1011w, https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/2017-10-24_15-37-19-300x111.jpg 300w, https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/2017-10-24_15-37-19-768x283.jpg 768w\" sizes=\"auto, (max-width: 1011px) 100vw, 1011px\" \/><figcaption class=\"wp-element-caption\"><em>(<a href=\"http:\/\/www.st.com\/content\/ccc\/resource\/technical\/document\/application_note\/d9\/29\/ad\/cc\/04\/7c\/4c\/1e\/CD00221490.pdf\/files\/CD00221490.pdf\/jcr:content\/translations\/en.CD00221490.pdf\">Image source<\/a>)<\/em><\/figcaption><\/figure>\n\n\n\n<p><span style=\"font-weight: 400;\">The Chip<\/span><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><span style=\"font-weight: 400;\">The chip circuit is referenced by R<\/span><span style=\"font-weight: 400;\">chip<\/span><span style=\"font-weight: 400;\"> and represents current consumption in parallel with capacitor C<\/span><em><span style=\"font-weight: 400;\">tun<\/span><\/em><\/li>\n\n\n\n<li><span style=\"font-weight: 400;\">C<\/span><em><span style=\"font-weight: 400;\">tun<\/span><\/em><span style=\"font-weight: 400;\"> defines the chip\u2019s internal tuning capacitance and internal parasitics. <\/span><\/li>\n<\/ul>\n\n\n\n<p><span style=\"font-weight: 400;\">The Antenna<\/span><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><span style=\"font-weight: 400;\">C<\/span><em><span style=\"font-weight: 400;\">ant<\/span><\/em><span style=\"font-weight: 400;\">. Determines the stray capacitance<\/span><\/li>\n\n\n\n<li><span style=\"font-weight: 400;\">R<\/span><em><span style=\"font-weight: 400;\">ant<\/span><\/em><span style=\"font-weight: 400;\">. Determines the resistance loss<\/span><\/li>\n\n\n\n<li>L<em>ant<\/em>. Determines the self inductance<\/li>\n<\/ul>\n\n\n<h3 class=\"wp-block-heading\" id=\"determine-the-inductance-of-your-antenna-coil\">Determine the Inductance of Your Antenna Coil<\/h3>\n\n\n<p><span style=\"font-weight: 400;\">At 13.56 MHz your antenna design will either be circular, spiral, or square shaped. What shape you use will depend on your design requirements. Below are three formulas you can use to determine the inductance for your specific antenna type quickly:<\/span><\/p>\n\n\n<h4 class=\"wp-block-heading\" id=\"circular-antenna-inductance\">Circular Antenna Inductance<\/h4>\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"323\" height=\"61\" src=\"https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/Formula1.jpg\" alt=\"antenna coil formula 1\" class=\"wp-image-59970\" srcset=\"https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/Formula1.jpg 323w, https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/Formula1-300x57.jpg 300w\" sizes=\"auto, (max-width: 323px) 100vw, 323px\" \/><\/figure>\n\n\n\n<ul class=\"wp-block-list\">\n<li><span style=\"font-weight: 400;\">r is the mean coil radius in millimeters<\/span><\/li>\n\n\n\n<li><span style=\"font-weight: 400;\">R<\/span><span style=\"font-weight: 400;\">0 <\/span><span style=\"font-weight: 400;\">is the wire diameter in millimeters<\/span><\/li>\n\n\n\n<li><span style=\"font-weight: 400;\">N is the number of turns<\/span><\/li>\n\n\n\n<li><span style=\"font-weight: 400;\">0<\/span><span style=\"font-weight: 400;\"> = 4\u03c0 x 10<\/span><span style=\"font-weight: 400;\">-7<\/span><span style=\"font-weight: 400;\"> H\/m<\/span><\/li>\n\n\n\n<li><span style=\"font-weight: 400;\">L is measured in Henry<\/span><\/li>\n<\/ul>\n\n\n<h4 class=\"wp-block-heading\" id=\"spiral-antenna-inductance\">Spiral Antenna Inductance<\/h4>\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"388\" height=\"57\" src=\"https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/Formula2.jpg\" alt=\"antenna coil formula 2\" class=\"wp-image-59975\" srcset=\"https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/Formula2.jpg 388w, https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/Formula2-300x44.jpg 300w\" sizes=\"auto, (max-width: 388px) 100vw, 388px\" \/><\/figure>\n\n\n\n<ul class=\"wp-block-list\">\n<li><span style=\"font-weight: 400;\">d is the mean coil diameter in millimeters<\/span><\/li>\n\n\n\n<li><span style=\"font-weight: 400;\">c is the thickness of the winding in microns<\/span><\/li>\n\n\n\n<li><span style=\"font-weight: 400;\">N is the number of turns<\/span><\/li>\n\n\n\n<li><span style=\"font-weight: 400;\">0<\/span><span style=\"font-weight: 400;\"> = 4\u03c0 x 10<\/span><span style=\"font-weight: 400;\">-7<\/span><span style=\"font-weight: 400;\"> H\/m<\/span><\/li>\n\n\n\n<li><span style=\"font-weight: 400;\">L is measured in Henry<\/span><\/li>\n<\/ul>\n\n\n<h4 class=\"wp-block-heading\" id=\"square-antenna-inductance\">Square Antenna Inductance<\/h4>\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"367\" height=\"59\" src=\"https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/Formula3.jpg\" alt=\"antenna coil formula 3\" class=\"wp-image-59980\" srcset=\"https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/Formula3.jpg 367w, https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/wp-content\/uploads\/2023\/07\/Formula3-300x48.jpg 300w\" sizes=\"auto, (max-width: 367px) 100vw, 367px\" \/><\/figure>\n\n\n\n<ul class=\"wp-block-list\">\n<li><span style=\"font-weight: 400;\">d is the mean coil diameter<\/span><\/li>\n\n\n\n<li><span style=\"font-weight: 400;\">d = (d<\/span><span style=\"font-weight: 400;\">out<\/span><span style=\"font-weight: 400;\"> + d<\/span><span style=\"font-weight: 400;\">in<\/span><span style=\"font-weight: 400;\">) \/ 2 in millimeters, where d<\/span><span style=\"font-weight: 400;\">out <\/span><span style=\"font-weight: 400;\">= outer diameter and d<\/span><span style=\"font-weight: 400;\">in <\/span><span style=\"font-weight: 400;\">= inner diameter<\/span><\/li>\n\n\n\n<li><span style=\"font-weight: 400;\">p = (d<\/span><span style=\"font-weight: 400;\">out<\/span><span style=\"font-weight: 400;\"> &#8211; d<\/span><span style=\"font-weight: 400;\">in<\/span><span style=\"font-weight: 400;\">) \/ (d<\/span><span style=\"font-weight: 400;\">out<\/span><span style=\"font-weight: 400;\"> + d<\/span><span style=\"font-weight: 400;\">in<\/span><span style=\"font-weight: 400;\">) in millimeters<\/span><\/li>\n\n\n\n<li><span style=\"font-weight: 400;\">K1 and K2 depend on your antenna layout, see the table below for values<\/span><\/li>\n<\/ul>\n\n\n<?xml encoding=\"utf-8\" ?><figure class=\"wp-block-table MuiTableContainer-root\"><table class=\" MuiTable-root DhigTable--verticalAlignment--top\"><tbody><tr class=\" MuiTableRow-root\"><td class=\" MuiTableCell-root\"><b>Layout&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<\/b><\/td><td class=\" MuiTableCell-root\"><b>K1&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<\/b><\/td><td class=\" MuiTableCell-root\"><b>K2&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<\/b><\/td><\/tr><tr class=\" MuiTableRow-root\"><td class=\" MuiTableCell-root\"><b>Square<\/b><\/td><td class=\" MuiTableCell-root\"><span style=\"font-weight: 400;\">2.34<\/span><\/td><td class=\" MuiTableCell-root\"><span style=\"font-weight: 400;\">2.75<\/span><\/td><\/tr><tr class=\" MuiTableRow-root\"><td class=\" MuiTableCell-root\"><b>Hexagonal<\/b><\/td><td class=\" MuiTableCell-root\"><span style=\"font-weight: 400;\">2.33<\/span><\/td><td class=\" MuiTableCell-root\"><span style=\"font-weight: 400;\">3.82<\/span><\/td><\/tr><tr class=\" MuiTableRow-root\"><td class=\" MuiTableCell-root\"><b>Octagonal<\/b><\/td><td class=\" MuiTableCell-root\"><span style=\"font-weight: 400;\">2.25<\/span><\/td><td class=\" MuiTableCell-root\"><span style=\"font-weight: 400;\">3.55<\/span><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n<h3 class=\"wp-block-heading\" id=\"read-the-full-app-note\">Read the Full App Note<\/h3>\n\n\n<p><span style=\"font-weight: 400;\">The details we covered above just scratch the surface of designing a custom RFID tag antenna. Be sure to read the full application note for STMicroelectronics on <\/span><a href=\"http:\/\/www.st.com\/content\/ccc\/resource\/technical\/document\/application_note\/d9\/29\/ad\/cc\/04\/7c\/4c\/1e\/CD00221490.pdf\/files\/CD00221490.pdf\/jcr:content\/translations\/en.CD00221490.pdf\"><span style=\"font-weight: 400;\">How to design a 13.56 MHz antenna for ST25 RFID tags<\/span><\/a><span style=\"font-weight: 400;\">.<\/span><\/p>\n\n\n<h2 class=\"wp-block-heading\" id=\"wireless-magic\">Wireless Magic<\/h2>\n\n\n<p><span style=\"font-weight: 400;\">RFID takes advantage of <\/span><a href=\"https:\/\/www.autodesk.com\/products\/eagle\/blog\/electromagnetic-wireless-electronic-basics\/\"><span style=\"font-weight: 400;\">radio waves<\/span><\/a><span style=\"font-weight: 400;\"> to read and capture information stored on tags that can be attached to a variety of objects. From high-dollar guitars to pets and shipping containers, the uses for RFID are almost limitless. This technology is poised to be a replacement for the standard barcode and magnetic strips in the future, but what will that future look like? If it\u2019s anything like what <\/span><a href=\"https:\/\/www.autodesk.com\/products\/eagle\/blog\/amazon-go-rfid-automation-dilemma\/\"><span style=\"font-weight: 400;\">Amazon Go has envisioned<\/span><\/a><span style=\"font-weight: 400;\">, we\u2019ll soon be enjoying a shopping experience without any of the tedium of lines and checkouts. But what does all of that mean for our personal privacy?<\/span><\/p>\n\n\n\n<p><span style=\"font-weight: 400;\">Ready to design the future of wireless electronics? Get started today with the <\/span><a href=\"http:\/\/www.st.com\/en\/nfc\/st25-nfc-rfid-tags-readers.html\"><span style=\"font-weight: 400;\">ST25 RFID tag microchips from STMicroelectronics<\/span><\/a><span style=\"font-weight: 400;\">. Then design your custom antenna with <\/span><a href=\"https:\/\/www.autodesk.com\/products\/eagle\/free-download\"><span style=\"font-weight: 400;\">Autodesk EAGLE<\/span><\/a><span style=\"font-weight: 400;\">!<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Interested in designing an RFID system? Learn how the technology works and how to design an RFID tag antenna inside. <\/p>\n","protected":false},"author":2425,"featured_media":440,"menu_order":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":""},"categories":[434],"tags":[],"coauthors":[],"class_list":["post-1818","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-eagle","dhig-theme--light"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.3 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>How RFID Works &amp; Antenna Design | EAGLE | Blog<\/title>\n<meta name=\"description\" content=\"Learn how RFID wireless technology works with the use of tags, antennas, and scanners. Then learn how to design your first RFID antenna in EAGLE!\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/rfid-works-antenna-design\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"How RFID Works &amp; Antenna Design | EAGLE | Blog\" \/>\n<meta property=\"og:description\" content=\"Learn how RFID wireless technology works with the use of tags, antennas, and scanners. 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