Application Note

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Introduction
A wave of development by the very large and well-established players in antenna design and manufacture has led to tremendous technical advances in the performance of reader antennas for RFID. These antenna designers typically have either specialty antenna design experience or strong telecom antenna backgrounds (base station antennas), and they have fought the material cost vs. system performance vs. reliability battle for years. As a result of their entry into the RFID reader antenna market, there has been a transition from using FR-4 and simple metal antennas to using a more highly engineered approach. Names typically associated with the telecom sector such as Kathrein (Scala Division), EMS Technologies (LXE Inc.), and Andrew Corporation (Omnix Asset Management) have made public efforts in the RFID reader antenna market.

First-generation (Gen 1) RFID efforts focused on using the lowest cost materials for proof of concept. This simplistic approach fulfilled the minimalist requirements and system complexities developed during beta and pilot programs. However, these antennas left much to be desired in complex multi-antenna sites that require low side lobes, low passive intermodulation (PIM), and high-speed readability and rewriteability environments. Little attention was paid to the antennas for readers, with most of the technical resources being used to develop tags, determine where to place RFID chips on tags, and create software for the reader to provide accurate information.

Second-generation (Gen 2) RFID development efforts have focused on higher read accuracy and satisfying actual field difficulties, such as high-speed reading of tags that are in the presence of metal or liquids that create backscatter (in containers of soda, paint, soup, or water, for example). There are also advanced efforts in developing higher performing and more sophisticated reader antennas. The telecom antenna manufacturers and specialty antenna design houses have found that their expertise in developing higher performing antennas in a commercially aggressive market is their core competency. These designers are well suited to making the trade-offs between materials and performance.

A few well-established specialty RFID providers who manufactured systems for high-value products (train cars, trailers, high-value assets, cargo containers, etc.) have experience with low-loss materials and have created high-performance antennas by utilizing these materials in creative, intelligent designs. Handheld scanning companies also recognize the need to reduce antenna size through the use of higher dielectric constant materials that are not subject to shattering during shock testing. Package engineers working in the cell phone market sometimes call this the "Nokia Drop Test."

Arlon has a variety of materials that are being used or considered for specialty, high-performance RFID reader antenna designs by the RFID reader OEMs and antenna design companies. This paper provides a summary of these materials and the value they provide to RFID designers. It also provides an argument against using FR-4 in RFID antenna designs.

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•Application Note: High Performance Laminate Materials For RFID Antennas