PN5180 Matching circuit and Antenna (coil) connection.

[oferrer]

Hi, I'm designing an esp32+pn5180 reader device. The Main board includes Power supply, micro controller, pn5180, emc filter and matching circuits. The antenna (coil) will be on another board. The boards Will be very close each other but they won't be on the same plane. So, i need a cable to connect them. How long this cable can be? What connectors should I use for each coil end? Any SUGGESTION for this layout. Thanks in advance, Osmany

[EduardoZamora]

Hello @oferrer,

Hope you are doing well.

Some recommendations available for the antenna can be found in the PN5180 Antenna design guide; this document describes the "standard" antenna design and tuning for PN5180. Also, you can follow our NFC Antenna Design training, an online training series that could help you with key aspects for the antenna, in addition to the NFC Antenna Tool.

Also, you can consider using an antenna from the market, such as this NFC antenna with wire.

Regards,
Eduardo.

[oferrer]

Hi @EduardoZamora,

Thanks for your answer.

I´ve checked the list. AN11740, AN11741, AN11744, UM11232. Lant,  Cant and Rant and the rest of the values (filter, matching) were calculated by NXP Antenna Tool.

The case of my device looks like two adjacent plane with 30 degree between them. The reader (and its antenna) had to be into the first plane, but the whole reader didn´t fit. Then I had to move both emc filter and matching circuits to the other board (into the other plane). So, i need to connect the antenna from one plane to the other.

Thats the reason of my question.

Best regards,

Osmany

[EduardoZamora]

Hi,

My apologies, we may not have any documentation for antenna design with coaxial cable. However, I would recommend using a 50 ohm shielded coaxial cable, just be sure to follow our matching circuit tutorial (which can be found in the NFC Antenna Design online training). Also, keep in mind that one matching circuit should be right after the EMC filter and another Matching circuit should be at the other end of the coax cable.

Unfortunately, we cannot provide any other information or support for this configuration. Please, consider implementing a standard antenna design (with no cable), according to the recommendations from PN5180 Antenna design.

Regards,
Eduardo.

[oferrer]

Hi @EduardoZamora,

Thanks for answering me.

I´ve watched the training videos you suggested me. Unfortunately, nothing is said about that connection explicitly. Maybe, i have to measure the antenna impedance as close to emc filter as possible to get real value (as said) in order to observe how that wire connection behaves and then do retuning.

Alternatives for the space problem such as circuitery inside or othogonal track crossing are not recommended because of metal enviroment. The whole circuit (supply+uC+nfcIC+filter+matching) inside de antenna coil migth actually solve my problem.

AN11740 3.2 Layout recommendations say nothing about this connection.

Currently, i´ve got a funtional prototype (printed by JLCPCB) to run well out of case . My problem is strictly mechanical. The whole thing doesn´t fit if circuitery is outside of coil.

What about range extender alternative?

Appreciating your help,

Osmany

[EduardoZamora]

Hi,

An amplifier or extender may deliver more RF power, but it does not provide a better coupling. Therefore, this will not guarantee the communication.

Please, consider using an antenna from the market, as the one previously mentioned. Also you could contact one of our partners listed in the RFID Ecosystem webpage. There you can find the contact for tag and reader manufacturers, solutions providers and system integrators, I am pretty sure that they could help you with a solution that meets your needs.

Regards,
Eduardo.