B
Ben
Guest
Hi all,
I am going to use some RFID (radio frequency identification) tags to
track some birds as they move around our aviary. If you don't know how
these work, basically the idea is that you have a coil antenna which
creates a field which is somehow modulated in a unique manner by any tag
which might come into its range, in a way which allows the antenna
driver circuitry to identify the tag.
You can only put small tags onto birds, which means read range can be a
problem. Most easily available antenna are loop shaped, and the area
where the tag can be read is mostly inside the loop. This works well
with animals if you can get the animal to pass inside the loop, but I
would like to try something different and I wonder if anyone can offer
me some advice. I want to build a perch antenna, but I'm not certain how
to go about it. Even if you don't know much about how RFID works, but
you know the shape of a coil determines its field you might be able to
help me because I know nothing!
Assume a perch would be a cylinder around 10cm long and 4cm diameter. I
have two ideas. One would be to just wind the coil around the cylinder
with each turn going around the cylinder like a solenoid or something.
But I have no idea if that will produce much field outside the coil? My
other idea is to wind it with each turn going around the whole perch
from end to end, to produce a coil shaped like a very flattened
rectangle. Would either of these ideas work? By the way I do know how to
use a formula to tell me how many turns I need to tune the antenna to
the right frequency. I need 1600 LuH so for the first idea around 366
turns.
Thanks very much for any advice.
Cheers,
Ben Kenward
I am going to use some RFID (radio frequency identification) tags to
track some birds as they move around our aviary. If you don't know how
these work, basically the idea is that you have a coil antenna which
creates a field which is somehow modulated in a unique manner by any tag
which might come into its range, in a way which allows the antenna
driver circuitry to identify the tag.
You can only put small tags onto birds, which means read range can be a
problem. Most easily available antenna are loop shaped, and the area
where the tag can be read is mostly inside the loop. This works well
with animals if you can get the animal to pass inside the loop, but I
would like to try something different and I wonder if anyone can offer
me some advice. I want to build a perch antenna, but I'm not certain how
to go about it. Even if you don't know much about how RFID works, but
you know the shape of a coil determines its field you might be able to
help me because I know nothing!
Assume a perch would be a cylinder around 10cm long and 4cm diameter. I
have two ideas. One would be to just wind the coil around the cylinder
with each turn going around the cylinder like a solenoid or something.
But I have no idea if that will produce much field outside the coil? My
other idea is to wind it with each turn going around the whole perch
from end to end, to produce a coil shaped like a very flattened
rectangle. Would either of these ideas work? By the way I do know how to
use a formula to tell me how many turns I need to tune the antenna to
the right frequency. I need 1600 LuH so for the first idea around 366
turns.
Thanks very much for any advice.
Cheers,
Ben Kenward