how far are RFID tags scanning distance?

[Nick]

hi,guys

Do you guys know if there is a place, link ,or whatever, shows how
far(the scanning distance) different tags support?
I know basically, passive tags, the distance only might be 10mm - less
than 1meter, active tags might support 10 meter far, not sure. And
recently, we need to buy some this kind of products, so we need to do
some reasearch on that.
The scanning distance we need would be around 3 meters. Do you guys
have any suggestion about the tags, and tag readers?

Any help would be appreciated!

Thanks.

 

[Jim Thompson]

hi,guys

Do you guys know if there is a place, link ,or whatever, shows how
far(the scanning distance) different tags support?
I know basically, passive tags, the distance only might be 10mm - less
than 1meter, active tags might support 10 meter far, not sure. And
recently, we need to buy some this kind of products, so we need to do
some reasearch on that.
The scanning distance we need would be around 3 meters. Do you guys
have any suggestion about the tags, and tag readers?

Any help would be appreciated!

Thanks.

SAVI Technologies, Sunnyvale.

...Jim Thompson

 

[Rene Tschaggelar]

hi,guys

Do you guys know if there is a place, link ,or whatever, shows how
far(the scanning distance) different tags support?
I know basically, passive tags, the distance only might be 10mm - less
than 1meter, active tags might support 10 meter far, not sure. And
recently, we need to buy some this kind of products, so we need to do
some reasearch on that.
The scanning distance we need would be around 3 meters. Do you guys
have any suggestion about the tags, and tag readers?

Any help would be appreciated!

Why not ask the manufacturers as part of
your requirements ?

Rene

 

[Sander]

The scanning distance we need would be around 3 meters. Do you guys
have any suggestion about the tags, and tag readers?

Depending on circumstances 3 meters might be feasible with passive UHF
tags. A lot depends on your exact application and requirements though.


http://www.intermec.com/eprise/main/Intermec/content/Products/Products_ListFamily?Category=RFID

Sander

 

[Jim Thompson]

Depending on circumstances 3 meters might be feasible with passive UHF
tags. A lot depends on your exact application and requirements though.


http://www.intermec.com/eprise/main/Intermec/content/Products/Products_ListFamily?Category=RFID

Sander

Yep. It's alright to buy from Intermec. Please support my clients
and say "Hi" to Harley Heinrich for me ;-)

...Jim Thompson

 

[Mike Harrison]

You'd need a BIG antenna on the tag, and/or a LOT of transmit power though.. possibly enough to
raise health concerns if users were exposed continuously to it.

 

[Jim Thompson]

You'd need a BIG antenna on the tag, and/or a LOT of transmit power though.. possibly enough to
raise health concerns if users were exposed continuously to it.

For range, the TAG's of choice are battery-powered, but utilize
sleep-mostly, wake-up-occasionally technologies to maximum battery
life.

Transmit TO the TAG is usually a low frequency (say 132KHz) to
optimize the receiver in the TAG.

Transmit FROM the TAG is usually UHF or up.

...Jim Thompson

 

[Nick]

Thanks guys.
We bought a type of socket RFID reader from socketcom for our PDA
products and it supports 13.56MHz tag that conforms to ISO 15693. But
the range is only 2.0 inchs. This is too short. So we are seeking a
solution that supports at least 1 meter reading range. Do you guys have
any suggestion?

 

[Andy]

Andy writes:

If you use an illumination of 1 watt with a 30 degree beamwidth
from the illuminator antenna, and the passive TAG has an RCS
difference
of 200 sq centimeters during modulation, and the receiver antenna has a
30
degree beamwidth , and the receiver has a -110 dbm tangential
sensitivity and
is a homodyne with I and Q outputs, you can easily read from 5 meters
and
usually from 15 meters, assuming no reflections. With reflections,
all bets
are off.. You will have a static pattern of nodes and nulls depending
on the
antenna angle with the ground.

You see, you did not give enough information about your system to
get a
valid answer that is specific to your needs..

The above description is based on the TIRIS passifve RFID tag which
meets
the CALTRAN Title 11 specifications for California........

Andy Sharpe , retired, (Inventor of the TIRIS RFID tag for Texas
Instruments)

 

[Ian Bell]

Andy writes:

If you use an illumination of 1 watt with a 30 degree beamwidth
from the illuminator antenna,

Which is a bit of a bugger at a mere 13MHz.

Ian

 

[Andy]

Andy replies:

Yeah. Especially for a modulated reflector tag......
I suspect that at 13 Mhz , active tags would be used, tho I haven't
worked RFID at that frequency.

I think that four dipoles , in line, phased, might give you the
30 degrees at 13 Mhz. That array would be about 200 feet wide. Not
too
practical for toll lane purposes (grin).. At 915 Mhz, the four
dipole array is around 8 feet wide.

CALTRAN Title 21 specifies 915 Mhz as the frequency band. But that
is used for toll lane recording and automotive applications.

Andy

 

[Jim Yanik]

Andy replies:

Yeah. Especially for a modulated reflector tag......
I suspect that at 13 Mhz , active tags would be used, tho I haven't
worked RFID at that frequency.

I think that four dipoles , in line, phased, might give you the
30 degrees at 13 Mhz. That array would be about 200 feet wide. Not
too
practical for toll lane purposes (grin).. At 915 Mhz, the four
dipole array is around 8 feet wide.

CALTRAN Title 21 specifies 915 Mhz as the frequency band. But that
is used for toll lane recording and automotive applications.

Andy

The toll road antennas I've seen in the Orlando area are rectangular flat
panels mounted in pairs,size I guesstimate at maybe 18 inches long,perhaps
8 inches wide,maybe two inches thick.
(SunPass/E-Pass)

They are mounted over the lane maybe 10-12 ft above ground(AGL).
I've also seen them at busy local intersections,mounted on a pole next to
the road,or on an arm over the road at about 12-15 ft AGL.
Like SR17-92 and SR436 in Casselberry.

 

[Andy]

Andy writes:
Yes. The antennae used by Amtech are similar.

Obviously, the beamwidths are much wider for these antennae.

The TIRIS antennae are used to provide a much narrower beam so that
lane discrimination can be done without using buried loops, lasers,
etc.

To do this, they required a much narrower beamwidth, so that only one
lane can be illuminated at a time. See CALTRAN Title 21 -- you can
probably call it up with google, if you are interested in the
requirements.

SunPass is a much simpler system. It probably works very well , as
there are several other items which work in conjunction with it to
determine presence of vehicle, multiple cars, multiple lanes, etc.

The TIRIS system that I built had to do all this stuff without the
auxiliary stuff, so different specification were required.....
If memory serves me correctly, TIRIS had to read with 99.9%
accuracy in bumper to bumper cars at about 150 mph , in
multiple lanes without
any lane dividers or other separators. While that condition will
never happen, that what the spec was........

It was tested at a race track somewhere in southwest Texas
using race drivers and cars and did what it was supposed to......
That was back around 1991......... the good old days.....

A damn fun project....

Andy W4OAH