Comments on: Adding a remote antenna to Parallax’s RFID reader http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/ Random experiments, circuits, code, rapid prototyping, sometimes things to buy, and the odd tune by Tod E. Kurt. Thu, 11 Mar 2010 14:51:51 +0000 http://wordpress.org/?v=2.9.2 hourly 1 By: Clark http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/comment-page-2/#comment-56983 Clark Sat, 17 Oct 2009 04:00:50 +0000 http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/#comment-56983 Sorry a 3' by 2' area. Thanks Sorry a 3′ by 2′ area.
Thanks

]]> By: Clark http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/comment-page-2/#comment-56982 Clark Sat, 17 Oct 2009 03:59:52 +0000 http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/#comment-56982 Looking for a reader that I can extend the antenna to read a 3" by 2" area. Any suggestions? Looking for a reader that I can extend the antenna to read a 3″ by 2″ area. Any suggestions?

]]> By: todbot http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/comment-page-2/#comment-54596 todbot Tue, 25 Aug 2009 20:55:11 +0000 http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/#comment-54596 Hi Gush, My understanding is that at 13.56MHz it's best to make using a PCB, where the traces on the PCB form one or more inductors and a couple of capacitors are placed next to the traces to form the resonant LC circuit needed. It's a lot more complex than the rather simple single loop + single capacitor of the 125kHz antenna, but there are many application notes on how to design the PCBs. Also, an L/C meter just measures either an isolated inductance (L) or capacitance (C), and doesn't really have a frequency component. It cannot produce meaningful measurements on a resonant circuit like the complex antennas used on 13.56MHz RFID readers. The L/C meter I use is this one: http://www.aade.com/lcmeter.htm Hi Gush,
My understanding is that at 13.56MHz it’s best to make using a PCB, where the traces on the PCB form one or more inductors and a couple of capacitors are placed next to the traces to form the resonant LC circuit needed. It’s a lot more complex than the rather simple single loop + single capacitor of the 125kHz antenna, but there are many application notes on how to design the PCBs.

Also, an L/C meter just measures either an isolated inductance (L) or capacitance (C), and doesn’t really have a frequency component. It cannot produce meaningful measurements on a resonant circuit like the complex antennas used on 13.56MHz RFID readers. The L/C meter I use is this one:
http://www.aade.com/lcmeter.htm

]]> By: gush http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/comment-page-2/#comment-54594 gush Tue, 25 Aug 2009 20:40:08 +0000 http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/#comment-54594 Hi Tod, Would home-brewing a remote 13.56MHz antenna for something like the Skyetek readers require a LC meter that could sample at 13.56MHz? Also, were you just matching the inductance of the antenna on the PCB, or did you calculate what you were going for? Any detuning because of the leads to the remote loop? Thanks! Hi Tod,

Would home-brewing a remote 13.56MHz antenna for something like the Skyetek readers require a LC meter that could sample at 13.56MHz? Also, were you just matching the inductance of the antenna on the PCB, or did you calculate what you were going for? Any detuning because of the leads to the remote loop?

Thanks!

]]> By: todbot http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/comment-page-1/#comment-51531 todbot Tue, 19 May 2009 22:06:41 +0000 http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/#comment-51531 ioan, that's pretty hard. The antenna is embedded in the PCB the reader circuit is on. It would be pretty easy to slip with the cutting tool and destroy the circuit. ioan, that’s pretty hard. The antenna is embedded in the PCB the reader circuit is on. It would be pretty easy to slip with the cutting tool and destroy the circuit.

]]> By: ioan http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/comment-page-1/#comment-51529 ioan Tue, 19 May 2009 21:37:27 +0000 http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/#comment-51529 What about cutting off the old antenna and use the old antenna (that you just cut off) as a remote antenna? What about cutting off the old antenna and use the old antenna (that you just cut off) as a remote antenna?

]]> By: Sha http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/comment-page-1/#comment-50349 Sha Wed, 21 Jan 2009 02:33:31 +0000 http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/#comment-50349 So did the hack of ASPX RW210, 13.56 ever happen? If so any details would be appreciated. Thanks! So did the hack of ASPX RW210, 13.56 ever happen? If so any details would be appreciated. Thanks!

]]> By: todbot http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/comment-page-1/#comment-50240 todbot Tue, 16 Dec 2008 03:22:22 +0000 http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/#comment-50240 Hi Alain, Unfortunately, no. The Parallax RFID reader (like most low-frequency readers) are designed for a specific frequency and protocol. In the Parallax reader's case, it's designed for the EM410x protocol which is at 125kHz. Hi Alain,
Unfortunately, no. The Parallax RFID reader (like most low-frequency readers) are designed for a specific frequency and protocol. In the Parallax reader’s case, it’s designed for the EM410x protocol which is at 125kHz.

]]> By: alain http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/comment-page-1/#comment-50239 alain Tue, 16 Dec 2008 02:31:52 +0000 http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/#comment-50239 Hellow i need to use this rfid the parallax to read the glass rfid for animal uses and the frecc is like 134,2khz how i make or is posible to modifi the software or the hardware for read this freccuencie thans A Durot Hellow i need to use this rfid the parallax to read the glass rfid for animal uses and the frecc
is like 134,2khz how i make or is posible to modifi the software or the hardware for read this freccuencie thans
A Durot

]]> By: todbot http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/comment-page-1/#comment-50156 todbot Wed, 19 Nov 2008 23:36:14 +0000 http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/#comment-50156 Hi Koyote, Not a dumb question at all. Unfortunately, the hack as presented effectively replaces the original antenna. You can use the original antenna by sticking a jumper across the two-pin jack that was added. So in theory you could put a relay in that that lets you programmatically switch between one antenna or the other. But having both at the same time I think would be a no-no. Hi Koyote,
Not a dumb question at all. Unfortunately, the hack as presented effectively replaces the original antenna. You can use the original antenna by sticking a jumper across the two-pin jack that was added. So in theory you could put a relay in that that lets you programmatically switch between one antenna or the other. But having both at the same time I think would be a no-no.

]]> By: Koyote http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/comment-page-1/#comment-50155 Koyote Wed, 19 Nov 2008 20:33:53 +0000 http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/#comment-50155 I'm sorry for the stupid question but with this hack(connected the built-in antenna too) both antennas will work? i would like to do this to use my reader on very thick door having the RFID reader on the inside and the external antenna outside. Thanks I’m sorry for the stupid question but with this hack(connected the built-in antenna too) both antennas will work? i would like to do this to use my reader on very thick door having the RFID reader on the inside and the external antenna outside.
Thanks

]]> By: Fabrice http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/comment-page-1/#comment-49821 Fabrice Thu, 07 Aug 2008 09:46:02 +0000 http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/#comment-49821 Hello, I'd like to know what's the formula which relates reading distance, diameter of the coil, and number of turns for 125 kHz RFID systems? Let's say I wanna be able to read a tag placed at 20 cm: what should be the diameter and the number of turns of the antenna? Best regards! Hello,

I’d like to know what’s the formula which relates reading distance, diameter of the coil, and number of turns for 125 kHz RFID systems? Let’s say I wanna be able to read a tag placed at 20 cm: what should be the diameter and the number of turns of the antenna?

Best regards!

]]> By: Jayabaya http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/comment-page-1/#comment-49695 Jayabaya Wed, 23 Jul 2008 18:41:13 +0000 http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/#comment-49695 Increase the reading distance of RFID antenna depend on size of your antenna, reader power. Of course there are physics limitation of how big the antenna will be. Able to properly tune the antenna is another problem you are facing. What is the read distance work for you ? Increase the reading distance of RFID antenna depend on size of your antenna, reader power. Of course there are physics limitation of how big the antenna will be. Able to properly tune the antenna is another problem you are facing. What is the read distance work for you ?

]]> By: todbot http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/comment-page-1/#comment-49674 todbot Sat, 19 Jul 2008 19:18:36 +0000 http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/#comment-49674 Hi Michael, At HF frequencies like your TI RFID, you have to start paying attention to properly tuning the antenna lines so the impedance matches. That's not a simple task. Tuning isn't that critical in the LF frequencies used by the 125kHz RFID of the Parallax reader. Hi Michael,
At HF frequencies like your TI RFID, you have to start paying attention to properly tuning the antenna lines so the impedance matches. That’s not a simple task. Tuning isn’t that critical in the LF frequencies used by the 125kHz RFID of the Parallax reader.

]]> By: Michael Carter http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/comment-page-1/#comment-49672 Michael Carter Sat, 19 Jul 2008 14:18:44 +0000 http://todbot.com/blog/2007/08/09/adding-a-remote-antenna-to-parallaxs-rfid-reader/#comment-49672 Hey, I am working on increasing the range of a 13.56 MHz TI reader and will this set up work for my system? If so, what are all of the parts required? Great how-to on making this, but if you could post all the required components, would greatly appreciate it. Thanks. Hey,

I am working on increasing the range of a 13.56 MHz TI reader and will this set up work for my system? If so, what are all of the parts required? Great how-to on making this, but if you could post all the required components, would greatly appreciate it. Thanks.

]]>