Digital Fabrication of UHF Electromagnetic Structures

无线射频识别（RFID）技术使用无线电波在壁挂式或手持阅读设备和不显眼的小标签之间进行通信。与常用的条形码相比，RFID具有更大的潜力，并且越来越多地用于跟踪日常物品的位置，例如工厂或超市。显然，如果它们要与条形码竞争，它们必须非常便宜，并以这样或那样的方式印刷。非常薄的标签设计必须在不同的对象上充分工作。制造技术需要不断发展，以使RFID集成电路连接成本低、容易。虽然RFID已被用于说明印刷标签的概念，但设想皮肤传输天线也可以设计为用外科石膏连接的终端。长期的可能性包括将高阻抗表面直接放在皮肤上，以管理身体周围的无线电频道，甚至可以促进个人隐身，在军事场景中，一个人的可见性可以改变，以避免被雷达发现。这项技术也可以应用于医学传感和植入设备的拾取。由于人体具有高导电性，因此对RFID来说，人体是一个特别具有挑战性的平台。人体标签，在身体外部，通常是基于手腕带或身份徽章，可以取下并给其他人。该提案中概述的设计概念是一种薄的，平台不敏感的UHF RFID标签，可以以传输贴片的形式直接安装在皮肤表面上，就像可以应用临时纹身一样。这项工作还处于早期阶段，需要研究如何将标签图案有效地喷墨打印到转移材料上，以及标签集成电路的可靠安装。未来十年，主流印刷RFID标签的市场份额将快速增长。根据“印刷和无芯片RFID，预测，技术和玩家2011-2021”（IdtechEX），全球销售数量将从2011年的1200万增加到2021年的2090亿。按价值计算，无芯片版本将从2011年的不到138万美元增长到2021年的16.5亿美元，约占2021年RFID标签总收入的五分之一，因为大部分渗透率的增长将来自价格优势。频率选择表面（FSS）：无线电频谱是一种有限的资源，就像石油、天然气和其他燃料供应的情况一样，不断扩大的经济正在增加对它的使用。但是，对于石油和天然气来说，可用的总量是不确定的，随着新油田的不断发现，无线电频谱的范围是有限的。现在几乎每个人都有一部手机和一台无线电脑，无论是在家里还是在办公室。它们都使用无线电波相互通信，因此都有相互干扰的可能。在建筑物中，墙壁和办公家具阻碍了有效的通信，但同时往往不足以阻止不必要的窃听。FSS是扁平的薄材料，有点像印有图案的墙纸。如果画得正确，这些图案有可能增强或严重减少无线电波在建筑物中从一个地方到另一个地方的传播。换句话说，它们会影响建筑物的电磁结构。通过仔细的配置，这意味着如果需要的话，可以在不相互影响的情况下在建筑物中安装更多的计算机，同时可以减少来自其他计算机或其他手机的不必要干扰，从而提高宽带供应的速度并避免电话丢失。喷墨导电油墨工艺将使这些技术变得廉价和广泛。

Radio Frequency Identification (RFID) technology uses radio waves to communicate between wall-mounted or handheld reading devices and small unobtrusive labels. RFID has greater potential than commonly used barcodes and is increasingly used to track the whereabouts of everyday items as they move through, eg, a factory or supermarket. Obviously, if they are to compete with barcodes, they must be very cheap and printed in one way or another. Very thin tag designs must work sufficiently on different objects. Fabrication technologies need to be evolved to make the RFID integrated circuit connection cheaply and easily. Although RFID has been used to illustrate the concept of printed tags, it is envisaged that skin transfer antennas could also be designed with the terminals connected by surgical plaster. Longer term possibilities involve putting high impedance surfaces directly onto the skin to manage the radio channels around the body, and even facilitate personal stealth where the visibility of a person to radar could be altered to avoid detection in a military scenario. The technology could also be applicable for medical sensing and as a pick up for implanted devices. The human body is an especially challenging platform for RFID owing to its high conductivity. Human tagging, external to the body, is usually based on wrist bands or ID badges which can be removed and given to other people. A design concept outlined in this proposal is a thin, platform insensitive UHF RFID tag that can be mounted directly onto the skin surface in the form of a transfer patch in much the same way that a temporary tattoo could be applied. This work is at an early stage and requires research into effective inkjet printing of the tag pattern onto the transfer material and reliable mounting of the tag Integrated Circuit. The next ten years will see a rapid gain in market share of mainstream printed RFID tags. According to 'Printed and Chipless RFID, Forecasts, Technologies & Players 2011-2021' (by IdtechEX), the numbers sold globally will rise from 12 million in 2011 to 209 billion in 2021. By value, chipless versions will rise from less than $1.38 million in 2011 to $1.65 billion in 2021, about one fifth of all income from RFID tags in 2021 because most of the increase in penetration will be by price advantage'.Frequency Selective Surfaces (FSS): The radio spectrum is a finite resource and just as is the case with oil and gas and other fuel supplies, the expanding economies are making ever increase use of it. But whereas with oil and gas the total amount that might be available is uncertain, with new fields discovered from time to time, the extent of the radio spectrum is limited. Almost everyone now has a mobile phone and a wireless computer, whether at home or in the office. They all use radiowaves to communicate with each other and so all have the potential to interfere with each other. In buildings, the walls and office furniture hinder efficient communications but at the same time are often insufficiently hindering to prevent unwanted evesdropping. FSS are flat pieces of thin material somewhat like wall paper with printed patterns. These patterns if drawn correctly have the potential to either enhance or seriously reduce the travel of radiowaves from place to place in the building. In other words they influence the electromagnetic architecture of the buildings. By careful configuration this means that more computers can be installed in a building without interacting with each other if that is required, while at the same time unwanted interference from other computers or other cell phones can be reduced improving the speed of broadband provision and avoiding lost phone calls.Inkjet conducting ink processes will make these technologies inexpensive and widespread.