RFID Radio Frequency Indentification

[Altruistic69]

1) What's the difference between omnidirectional antenna and the normal UHF antenna? What I know is there are 2types of antenna in RFID implementation; linear polarized and circular polarized. Does omnidirectional refers to circular type antenna?

2) Is the calculation for EIRP / ERP the same for linear and circular polarized antenna?

3) Near field vs far field antenna / reader, do they come with linear polarized and circular polarized or does it use a different kind?

4) As for the combination of tag antenna and reader antenna, I heard that if the tag antenna is circularly polarized then it would be best to use a circular polarized antenna for the reader als. Is this true?

 

[Darkcrusher]

1) directionality has nothing to do with polarisation
2) dont know
3) dont know
4) Circulary polarisation is always better than linear in that case, but the main question is how much better and if you are ready to do extra efforts for a little bit more performance (=larger read distance). In my opinion it is sufficient if either the reader or tag uses circular polarisation, that way the tag is always readable under different angles

Hope this helps!

 

[tony_lth]

2) yes
3) near field is relate to polarized, but it's different method from far field.