Digital Fabrication of UHF Electromagnetic Structures

射频识别(RFID)技术使用无线电波在壁挂式或手持阅读设备与小型不显眼的标签之间进行通信。与通常使用的条形码相比，RFID具有更大的潜力，越来越多地被用于跟踪日常物品在工厂或超市中移动时的去向。显然，如果它们要与条形码竞争，它们必须非常便宜，并以某种方式打印。非常薄的标签设计必须在不同的对象上充分发挥作用。需要发展制造技术，以使RFID集成电路连接更便宜、更容易。虽然RFID已经被用来说明打印标签的概念，但可以设想，皮肤转移天线也可以设计成与终端通过外科石膏连接。更长期的可能性包括将高阻抗表面直接放置在皮肤上，以管理身体周围的无线电频道，甚至促进个人隐形，在军事场景中，可以改变人对雷达的可见度，以避免被发现。这项技术还可以应用于医学传感，并作为植入式设备的拾取器。由于人体的高导电性，对于RFID来说，人体是一个特别具有挑战性的平台。人体外部的标记通常是基于腕带或ID徽章，这些徽章可以被取下并交给其他人。该提案中概述的设计概念是一种薄的、对平台不敏感的UHF RFID标签，它可以以转移贴片的形式直接安装在皮肤表面上，其方式与应用临时纹身的方式大致相同。这项工作还处于早期阶段，需要研究标签图案在转移材料上的有效喷墨打印和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IDTechEx的《2011-2021年打印和无芯片RFID、预测、技术和玩家》，全球销售的RFID数量将从2011年的1200万台增加到2021年的2090亿台。按价值计算，无芯片版本将从2011年的不到138万美元增加到2021年的16.5亿美元，约占2021年来自RFID标签的所有收入的五分之一，因为渗透率的大部分增长将来自价格优势。频率选择性表面(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一样，不断扩大的经济体正在不断增加对它的使用。但是，由于不时发现新的油田，石油和天然气的可利用总量尚不确定，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，因此都有可能相互干扰。在建筑物中，墙壁和办公家具阻碍了有效的通信，但同时往往不足以防止不必要的窃听。FSS是一块扁平的薄料，有点像印有图案的墙纸。如果绘制正确，这些图案可能会增强或严重减少无线电波在建筑物内各个地方的传播。换句话说，它们会影响建筑物的电磁建筑。通过仔细的配置，这意味着如果需要的话，可以在一栋建筑中安装更多的计算机，而不需要相互作用，同时可以减少来自其他计算机或其他手机的有害干扰，提高宽带供应的速度，避免丢失电话。进行墨水处理的喷墨打印机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.