Intro To RFID – Radio Frequency Identification Basics – Part I

RFID Antenna and Chip

RFID Antenna and Chip


What is RFID?

RFID stands for Radio Frequency IDentification. RFID is a way to read data from a small chip using RF. The most common type of RFID is passive RFID. Passive means that the chip itself does not require a battery, and uses the small amounts of energy present from a RFID reader’s signal to transmit. Passive RFID is inexpensive and the most common type of RFID.

Another type of RFID is active RFID. Active means that the RFID chip has an active power source and can do much more than passive RFID can. Active RFID might be used in an application where the RFID chip needs to transmit signals by itself, or use encryption. Active RFID costs much more than passive RFID, so for this intro, our focus will be only on passive RFID.

What frequencies does RFID run on?

Most RFID uses one of several frequencies. The two most common frequencies for RFID are the 125kHz frequency, and the 13.56MHz frequency. It is important to know which frequency your tags or readers are. In general, most tags only work for one frequency, and most readers only support one frequency.

What are the differences between using the 125kHz and 13.56 MHz frequencies?

The different frequencies have their advantages and disadvantages. The 125kHz frequency tags are often less durable, but also generally provides better coverage when a reader is not in line of site, such as if there is thin door between the reader and the tag. 125kHz requires that the tag have an antenna made of a thicker copper. These thicker antenna are less durable than the antenna needed to transmit with 13.56 MHz tags.

The antenna required to transmit a 13.56MHz signal needs not the thick copper that the 125kHz antenna does. This allows the 13.56 MHz tags to be more flexible, rugged, and less breakable. The downside to the 13.56Mhz frequency is that this frequency is much more susceptible to interference. While all RFID does poorly with interference, the 13.56MHz tags have a much higher frequency than 125kHz tags and have much more trouble with signal interference than the 125kHz tags do. You must weigh the relative strengths and differences of the tag frequencies and choose for yourself which is best for your design.

Part II of this post discusses setting up an ID-20 RFID reader using an Arduino microcontroller. In this coming post I will explain exactly how to setup your own RFID Reader and read the chip’s data over a serial connection. This series culminates in a RFID based servo door unlocking system! Stay Tuned!

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