BLOCKING READER: DESIGN AND IMPLEMENTATION OF A ...
BLOCKING READER: DESIGN AND IMPLEMENTATION OF A ...
BLOCKING READER: DESIGN AND IMPLEMENTATION OF A ...
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good knowledge of this device which has a very important role in the performance<br />
of a system. An RFID system is a wireless system, with power less that 1W for<br />
passive systems, it is very important for any design engineer to have knowledge of<br />
basic antenna operational parameters including input impedance, efficiency, radiation<br />
pattern, directivity, gain and noise temperature. In this section we will very briefly<br />
discuss about different types of antennas used in RFID systems and its gain.The<br />
reader antennas must be very directional and sensitive. And tag antennas must be<br />
wide-band, in some cases low cost compact design. In RFID system there are two<br />
sets of antennae used, one is with the reader and other in the tag.<br />
2.6.1 Reader Antenna<br />
Reader antennas should be directional and sensitive as mentioned earlier. Most<br />
of the time multiple antennas are connected to the Reader. The reader antenna<br />
is mostly a smart antenna where the gain, sensitivity, protocol parameters can be<br />
changed. There are readers like Voyantic reader which can be used to do tag analysis,<br />
environment analysis by changing these parameters. An EPC-compliant antenna<br />
costs up to $500 [11]. Some of the reader antennas are mentioned below.<br />
• Coil Antennas<br />
• Patch Antennas<br />
• Etched Antennas<br />
• Monopole Antennas<br />
• Lens Antennas<br />
• Fractal Antennas<br />
Figure 2.3 shows a Alien linear antenna with 5.90dbi gain and operates at 902-<br />
928MHz. A Patch antenna is designed in FEKO and simulated for 915 Mhz and the<br />
radiation patterns are as shown below.<br />
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