Hi, all,
I am new to RF, but (un)fortunately i am handling a transferred
project on RFID. Some of the rf concepts i am not not so sure, and
seek for assitance here.
Let me give a bit more on the original designs first. They are tags
that talk to each other unlike the passive tag. This design is already
working with a quarter wave-length antenna. My task is to modify it
to a smaller (shorter) one.
The design is like :
antenna----matching circuit----transceiver----mcu

Now comes the questions:
1. when we talk about the load impedance, where should it start
counting? From transceiver down left or from the matching circuit down
left?
2. the original matching circuit is working for the quarter wave
length antenna. Do i need to adjust the value (C and L) if i replace
them with other forms of antennas(e.g chip antenna, loop antenna)?
3. How am i going to measure the load impedance? What equipment is
needed?

thanks. Any advice is favorable.
Sigma