I am a software engineer and I know nothing about hardware
design....

Recently I am asked to collect some information about the components
of
RFID reader that can read ISO-18000-6 (Type A) tag. The tag works in
the UHF
band (860-930 MHz). I have some question but I don't have any friend
that
have RFID experience. I would really appreciate if you could kindly
answer
the questions below.....

1) The operational principle of this kind of tag is "backscatter
coupling". However, I am not sure how the reader distinguish the
forward
signal and the backscattered signal, which of the same frequency. I
read
some information from internet and someone mentioned about the
"directional
coupler". Is directional coupler really used in a typical UHF RFID
reader?
If so, could you kindly recommend a brand and the model number of
directional coupler that can be used in RFID reader?

2) The reader is supposed to be used in a cashier of shop. The range
of
distance of the reader to the tag is about 30cm. Do you have some
typical
power values that the reader need to send and the power of the
backscattered
signal? I need this kind of figure because I was ask to choose the
transceiver IC and I wonder if the power is enough. Do you have any
recommendation of transceiver IC?

3) About the antenna. I found some paper mention about 4 phased
array, which is good for sending RF signal in one direction. Have
anyone used it before? If yes, where can I found it? Any brand name or
model number recommend?

4) Do you have any reference design / paper on the design of RFID
reader?

Thanks in advance.

NOSPAM