High frequency 13.56MHz contactless card is with wide application, Identifcation card, public transportation, campus student card, shopping card, hotel key card, etc. Among all these applications, normal IC card reading distance is with 3-6cm reading distance, in some application environment, this reading distance maybe lowerred down by surrounded items, thus, we have to put the card close to the reader or even put the card on the reader to get response.
For How to improve contactless HF reading distance, we have below ways:
Improve card reader's voltage. As per RFID working principle, larger reader voltage would offer more energy to card, thus enable the RFID card to response with longer reading distance.
Using larger antenna for RFID reader.
To use standard size card instead of small size card. The bigger antenner the card has, the longer reading distance the card gives.