Hi all,
Hope someone can help/point me in the right direction, I've been working on a rfid reader for some time now based on iso 11784/85, the reader needs to read both hdx and fdx-b transponders. My prototype works and will read both but the range on the fdx-b is poor. (fdx is when the the transponder loads the activating field, but you probably knew that!) I've spent some time playing around with different values for the coil (I want to keep the same dia so it fits in a bit of plastic 35mm pipe) the tranponders are the 3mm dia glass type so have a very small coil. I'm using the atmell u2270b front end ic (the data sheet should be attached) with diode feedback. Changing the value of L from 700uH up to 2.2mH (which is where I started) seems to make little difference to range, peak to peak voltage goes up as L goes down but I guess the current the chip can supply is the limiting factor? Would making a antenna with a ferrite core help? Or should I add a H bridge or similar to drive the coil at a higher voltage and current.
Thanks Geoff
Hope someone can help/point me in the right direction, I've been working on a rfid reader for some time now based on iso 11784/85, the reader needs to read both hdx and fdx-b transponders. My prototype works and will read both but the range on the fdx-b is poor. (fdx is when the the transponder loads the activating field, but you probably knew that!) I've spent some time playing around with different values for the coil (I want to keep the same dia so it fits in a bit of plastic 35mm pipe) the tranponders are the 3mm dia glass type so have a very small coil. I'm using the atmell u2270b front end ic (the data sheet should be attached) with diode feedback. Changing the value of L from 700uH up to 2.2mH (which is where I started) seems to make little difference to range, peak to peak voltage goes up as L goes down but I guess the current the chip can supply is the limiting factor? Would making a antenna with a ferrite core help? Or should I add a H bridge or similar to drive the coil at a higher voltage and current.
Thanks Geoff
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