Abstract

Passive RFID has come to dominate all facets of modern life and thereby making auto-identification a daily occurrence in our daily activities. From the complex application of nuclear waste tracking to supply chain management, RFID passive tags have come under various form factors ranging from paper to plastic tags. What determines what form factor to be used and best angle between the tag and the reader is analyzed in this paper. The objective of this paper is to determine the effects of reader transmitted power, form factors and as well as cross and linear polarization on  ultra high frequency (UHF) passive tags in a free and metallic environment as seen in real life environment not a controlled environment. The settings of this experiment were based on real life environment where RFID tags are deployed. Rotor which has the capacity to change every 45° was used to position the tag in different angles to enable readings to be taken in the ranges of 0, 45, and 90, 135, 180 clockwise and same angles in anticlockwise. Results have shown “paper” tags tend to be affected less in all these factors than the plastic tags and also, it was discovered that at lower power of -2 dB, the tags read more than the maximum power of 0 dB. The maximum distance of paper tag was also noticed to read more close to 100 cm in metallic environment while in free environment, the read distance of paper tags are limited to 80 cm. In this paper, it has been able to prove the existence of read range deterioration in RFID tags when they are in direct contact with metals whereas, it increases in the presence of metals. Also, the existence of polarization loss factor (PLF) has been proved beyond any reasonable doubt.

Key words: Radiation pattern, E and H fields, cross polarization, polarization loss factor.