Working on a RFID project that would involve a PN5180 and an external, off pcb, antenna connected with some twisted pair cable (distance is around 1m). Power is not a problem : the system isn't on battery, and the more range the better. I'm using a differential antenna topology and i'm trying to use the "matching antennas.xls" tool provided by NXP. That brings me to the following picture :
Let's say the twisted pair has a characteristic impedance of 50 Ohms and the antenna already has its own matching circuit on the antenna pcb to accomodate for that.
Now, how should i use the excel tool ? Because it seems to adress only the case of antenna next-to the transceiver. How do i need to understand the following sentences taken from the documentation on the PN5180 :
"the antenna impedance is tuned to Z ≈ 20Ω"
"Note: The antenna impedance tuning and measurement must be done with R = 10Ω
between ANT1 and ANT2."
(both from AN11744 - page 9/45).
Would there be an advantage to redesign the antenna pcb to change its matching circuit and the type of cable to accomodate for what the PN5180 needs ?
Thank you in advance
Thanks for contacting us and say sorry for the late to response.
For your questions, it's recommended that you follow this application notes AN11740 - PN5180 antenna design, which will give you the answers what you want. Please check the attachment.
Please feel free to contact us if any questions.