I would really like to here more about a 100 meter RFID. What is it's intended use, how large is it, is it implantable, does the device gather it's operating power from the incoming scanner signal, &c, &c?
I can see how a dual scanner setup could generate location information (LORAN comes to mind) but such operation would require two transmit and two receive frequencies would it not? Also, would not the scanners need to be spatially separated along a baseline to provide a timing difference between the two return signals?
Regards,
GtG
PS I'll grant you the foil idea may not work but given the microscopic power of the signal involved it might bear looking into... how much of a pulse would serve to destroy an RFID? Care to speculate?
PPS I expect bird hunters would love such technology to locate their retrievers when "on point" and out of sight.
http://www.gaorfid.com/index.php?main_page=product_info&cPath=130&products_id=642
It may seem rather large but there is barely anything in
the package but a flex strip antenna and a 2mm x 2mm
ic.
“I can see how a dual scanner setup could generate location information (LORAN comes to mind) but such operation would require two transmit and two receive frequencies would it not?”
No simply alternate the reads between transponders.
“Also, would not the scanners need to be spatially separated along a baseline to provide a timing difference between the two return signals?”
Yes. by triangulation the distance to the tag is not
needed only the 2 directional angles from the transponders.
“PS I'll grant you the foil idea may not work but given the microscopic power of the signal involved it might bear looking into... “
Unless you could completely enclose the RFID tag, any slot, edge or hole will radiate the signal to and from the tag.
Make any slot, hole or edge in you foil 1 to 1/4 of the transponders wavelength and you now have added an external antenna to
the RFID tag.
“how much of a pulse would serve to destroy an RFID? Care to speculate?”
That depends on two factors.
1. The maxim voltage of the analogue front end.
It could be anywhere from 7 to 100 volts. some
ruggedized devices have thick oxide and can withstand
higher working voltages.
2. The Silicon I.C.’s process level.
Most Rfid i.c’s are 1 to 0.1 um.
Max ESD input clamping may be from .010 to .020 Amps
By these calculations it would take 140 mW to 2 watts
(on ruggedized devices)of power at the RFID's operational frequency to damage the front ends.
Here is a data sheet on a typical RFID I.C. chip.
http://www.atmel.com/dyn/resources/prod_documents/doc9167s.pdf
"PPS I expect bird hunters would love such technology to locate their retrievers when "on point" and out of sight."
A bit expensive but many cattle ranches are already using these systems to track and locate cattle.