AN OVERBROAD PATENT ON RFID Spacers - This application seeks to patent the idea of... RFID spacers! 10 minutes of your time can help narrow US patent applications before they become patents. Follow @askpatents on twitter to help.

QUESTION - Have you seen anything else that was published before Jan, 2010 that discusses:

us20110234383 (recently issued as 8,576,051, see this answer)appears to be nothing more than a patent for placing a foam spacer on the RFID tag to keep it away from the body of the runner. These have been in use for as long as I can remember since RFID tags do not operate when directly placed in contact with an object that absorbs RF such as the human body or metal.

In particular, this blog post made within days of the application date http://rfidtiming.com/tech-talk-the-great-spacer-debate/ explains the problem and the solution that this patent filer is claiming to have invented. At the time of the blog post, the solution of using a foam spacer (explicitly noted in claim 64) was not new or novel. The post is notable in that it was explaining the problem that was known to anybody skilled in the art and the solution that was by then the accepted practice.

Also note http://www.schreiner-group.com/3/company/press-room/schreiner-logidata/rfid-foam-label/ is a product with a press-release date of Aug-2010, a year before the application date. A simple google search for "rfid tag foam spacer" will return a number of products going back 5+ years before the application date. The problem was well known and the solution well implemented before 2011.

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  • Hi John, AskPatents is an online service in Q&A format where users ask for help finding prior art on US Patent Applications and US Patents and ask questions about the US Patent process. What you are looking for is called a prior-art-request If you would like to create a prior art request for US20110234383 please follow the prior-art-request format. See faq for more information.
    – Micah Siegel
    Jul 17, 2013 at 10:27
  • 2
    I am voting to reopen. This may not be in the preferred Ask Patnets format but has enough information in it for a response. I assume the proper format is for the OP to post the question "Can you help me find prior art for XYZ?" and then post his own answer mentioning the blog and product release.
    – George White
    Jul 18, 2013 at 3:57

4 Answers 4


Loads on this. I'm quite sure I've seen pictures in a 10 year old phd thesis with a foam spaced RFID tag.

Existing EU Patent EP 2206077 B1

In embodiments, the spacer material comprises (consists essentially of or even, consists of) a foam, such as a polymethacrylimide foam.

This white paper from 2009:

One solution used in the past has been to reduce the effects of interference by adding a “spacer” made from high air-content material such as foam. Spacers are typically 5 mm thick or more, and they separate the RFID tag from the interfering material with enough distance to mitigate the disruption of the electromagnetic field.

This Paper (pdf published 2007)

We tested three different ways of improving the performance of RFID.

1) Using a spacer between the transponder and metal

Since all concern is due to the metal being in background of the transponder, its distance from the metal is increased by introducing a 10 mm thick Perspex® spacer between them. It is indeed found that there is a huge improvement in performance of RFID


I'm pretty sure that most if not all of the following "metal mount" RFID tags provide prior art:

"SmartMark Durable RFID Tags and Labels"

For example, see this tag/product (PDF from 2009):

Part Number: WF-SM-22, Size: 4" x 1.375" x .1875"

Many of the claims mention, "...spaced apart distance between a surface of the user body and the mounting substrate of between about 0.125 inches and about 0.5 inches." (it really is quite repetitive to a silly degree)

That product/PDF example appears to be an RFID tag using an adhesive foam backing providing a spacing of 0.1875 inches (which is precisely within the claimed distance). The patent application appears to describe that very product.


We used spacers on front axles of trucks to identify them entering a weighbridge. This was in 1990 onwards. I'll see if I have a photograph. Also contact Hennie Visser at OptoAfrica.co.za.


Astoundingly the patent was granted as 8,576,051 in November 2013. However, during prosecution the independent claims were narrowed to state the width of the spacer to be "greater than or equal to about 1/4 of a wavelength of the predetermined operating frequency." The operating frequency is the UHF band of which a quarter wavelength is ~8.83cm or ~3.4inches. That is much wider than all applications of RFID tags used in timing systems I have seen, including that of the patentees' system. That said, obviously this patent should never have been granted at all.

Note another example of prior art is patent 8,159,349 which states

A key characteristic of the encoder of the present invention is that the encoder encodes tags of many different types, shapes, sizes, and thicknesses; which includes efficiently encoding thick tags, tags that are thicker than a sheet of paper because a foam layer is present.

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