I am currently in the process of building an RFID access system for my house + car. I've worked out the software side (I am using an arduino) but am having difficulty with the hardware side. I bought one of these for the transmitter but the read range is terrible - the access dongle has to be touching it for it to register.
I'm thinking about cutting the traces on the card and building a new antenna to amplify the read range. Unfortunately I don't know how to do this. I've read through the antenna cookbook and the antenna design notes from TI, but I'm a hobbyist and a lot of it seemed very general and went over my head - it would be great if I could get a more prescriptive answer.
I would like to have the antenna read from 5-10cm in most orientations if possible.
How important is material choice (wire/tape/tube)? Do I need an additional power supply on the antenna end or is the 5V from arduino enough? Can I build a square antenna into the flashing around the card window or will the metal create too much interference?