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I am trying to connect a RFID reader chip to an W3113 antenna on PCB. As said in datasheets, the antenna pin of the reader chip has internal 50 ohm impedance and antenna W3113 also has 50 ohm impedance. I first use 50 ohm microstrip and a L-network matching circuit with capacitors but it does not read RFID tags.

Now I use a 50 ohm microstrip and 0 ohm resistor to connect them together. It works, but the performance of reading RFID tags is not so good. It can only read tags with really short distance. I guess this might still be the problem of impedance mismatching. I am thinking to add some capacitors to the matching circuit, but I do not know what values might be better, because both datasheets only say impedance is 50 ohm. Any advice for this? Thank you!

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    \$\begingroup\$ What RFID reader chip? The datasheet appears to be: datasheet.octopart.com/W3113-Pulse-datasheet-11770657.pdf page 4. That is an ISM-band antenna, 902-928MHz. A quick google of RFID frequencies shows 125kHz, 134kHz, 13.56MHz, 433MHz, and 860-960MHz. I assume this chip is outputting a 902-228MHz carrier frequency? \$\endgroup\$ – rdtsc Jul 25 '18 at 23:16
  • \$\begingroup\$ @rdtsc The chip is RLM060 from Raylinks. Yes, the frequency is 900MHz. \$\endgroup\$ – LFJY Jul 26 '18 at 1:07

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