The roll-to-roll electronic label production line is a device that meets the RFID market's massive demand for electronic labels. Many factors in production can affect the performance of electronic tags, especially the sensitivity of electronic tags. The consistency of electronic tag sensitivity reflects the reliability of reading different electronic tags in the same environment. It directly affects or represents the reliability of RFID system operation. Since the global retail giant Walmart introduced RFID technology in the retail industry, Walmart's demand for RFID electronic tags has attracted the attention of electronic tag suppliers. In particular, Walmart's acceptance of the RFID electronic label acceptance criteria provided by suppliers (including the requirement for consistency in the sensitivity of electronic labels) has attracted the attention of electronic label manufacturers. Therefore, electronic label manufacturers must pay attention to various factors affecting the consistency of the sensitivity of electronic labels, and control them in production to meet the acceptance of electronic labels through Walmart. There are many factors that may affect the consistency of the sensitivity of electronic tags. Finding the main factors affecting the consistency of the sensitivity of electronic tags is of practical significance in guiding the production of electronic tags.
Because the sensitivity of RFID UHF RFID tags has a great influence on system operation, only the sensitivity of UHF RFID tags is studied in this paper.
2 experimental test
2.1 Various Factors Grouping and Test Equipment and Test Environment
Factors that may affect the consistency of the sensitivity of electronic tags include: parameters such as temperature, pressure, and time of the packaging line of unpackaged packages; uncoated and coated films; surface cleanliness of antennas; different metal antennas; wide gaps between antenna feed points and Narrow gaps and so on. Combine different factors into electronic tags, take 30 electronic tags for each combination to test their sensitivity, and use Minitab software to analyze product process capabilities. The test equipment mainly includes Tagformance UHF electronic tag tester and computer from Voyantic, Finland; the test environment is in the microwave darkroom.
2.2 Test results
2.2.1 Analysis of sensitivity curve of electronic tag tester
Examples of results obtained after testing a large number of electronic tags by an electronic tag tester are as follows:
(1) The sensitivity gain of the unlabeled chip electronic tag at 900MHz frequency point is generally between -18dBm~-12dBm, and the dispersion is large, as shown in Figure 1.
(2) The sensitivity gain of the electronic label of the coated chip at 900 MHz is generally between -15 dBm and -12 dBm, and the consistency is good, as shown in Figure 2.
(3) The electronic tag combined with the uncoated and wide slot antennas has slightly better sensitivity than the electronic tag combined with the narrow slot antenna.
(4) The cleanliness of the antenna surface; parameters such as temperature, pressure, and time when the package is dropped; different metal antennas and other factors have no obvious effect on the consistency of the sensitivity of the electronic tag.