2.1 RFID Tag Group Performance Measurement
43
Fig. 2.8 The reading distance when the number of multiple tags changes
distance. Combined with tag put schematic diagram and the data can be seen, tabbed
position number changes, the tag of the read distance along with the reduction in
the number of tags gradually become smaller, the tag clouds performance gradually
along with the reduction in the number of tags, but the tag group of sensitivity
value is always less than the value of the sensitivity of key tag, so when the tag
number is greater than or equal to two, tag, tag quantity is less, tag clouds the worse
performance.
Equation (2.8) was used to calculate the sensitivity of tag group of five placement
modes. r
is 3.418 m, 3.144 m, 2.994 m, 2.626 m, and 4.208 m, respectively. The
wavelength of electromagnetic wave in free space is 0.33 m. The transmission power
of the RFID reader is 24 dBm, the calculated input value is 251, the gain of the RFID
reader antenna is 2 dBi, the calculated input value is 1.58, the gain of the RFID tag
antenna is 9dBi, the calculated input value is 7.94, and the antenna coefficient is
1. The sensitivity of the five groups was calculated as –7.305 dBm, –6.579 dBm,
–6.154 dBm, –5.015 dBm, and –9.111 dBm, respectively. According to the preobtained environmental error value of 1.891 dBm, the final values of tag group
sensitivity were –9.196 dBm, –8.470 dBm, –8.045 dBm, –6.906 dBm, and –11.002
dBm, respectively.
(4) Influence of tag number on tag group sensitivity
Can be seen from the three test results: tag number unchanged structure changes, the
location of the key tags have certain influence the performance of tag clouds, namely
when key tags in the group of edge, the tag of the value of the minimum sensitivity,
key tags most affected by the performance of tag clouds, on the contrary, when the
key tag, in the middle, tag clouds tag group of the value of the maximum sensitivity,
key tags to group of minimal performance impact; When the number of multiple tags
is unchanged and the order is changed, the position of key tags is unchanged, while
other tag changes have little impact on the performance of tag group. Tabbed position
unchanged number changes, tag clouds sensitivity value decreased gradually with
43
Fig. 2.8 The reading distance when the number of multiple tags changes
distance. Combined with tag put schematic diagram and the data can be seen, tabbed
position number changes, the tag of the read distance along with the reduction in
the number of tags gradually become smaller, the tag clouds performance gradually
along with the reduction in the number of tags, but the tag group of sensitivity
value is always less than the value of the sensitivity of key tag, so when the tag
number is greater than or equal to two, tag, tag quantity is less, tag clouds the worse
performance.
Equation (2.8) was used to calculate the sensitivity of tag group of five placement
modes. r
is 3.418 m, 3.144 m, 2.994 m, 2.626 m, and 4.208 m, respectively. The
wavelength of electromagnetic wave in free space is 0.33 m. The transmission power
of the RFID reader is 24 dBm, the calculated input value is 251, the gain of the RFID
reader antenna is 2 dBi, the calculated input value is 1.58, the gain of the RFID tag
antenna is 9dBi, the calculated input value is 7.94, and the antenna coefficient is
1. The sensitivity of the five groups was calculated as –7.305 dBm, –6.579 dBm,
–6.154 dBm, –5.015 dBm, and –9.111 dBm, respectively. According to the preobtained environmental error value of 1.891 dBm, the final values of tag group
sensitivity were –9.196 dBm, –8.470 dBm, –8.045 dBm, –6.906 dBm, and –11.002
dBm, respectively.
(4) Influence of tag number on tag group sensitivity
Can be seen from the three test results: tag number unchanged structure changes, the
location of the key tags have certain influence the performance of tag clouds, namely
when key tags in the group of edge, the tag of the value of the minimum sensitivity,
key tags most affected by the performance of tag clouds, on the contrary, when the
key tag, in the middle, tag clouds tag group of the value of the maximum sensitivity,
key tags to group of minimal performance impact; When the number of multiple tags
is unchanged and the order is changed, the position of key tags is unchanged, while
other tag changes have little impact on the performance of tag group. Tabbed position
unchanged number changes, tag clouds sensitivity value decreased gradually with