2.1 RFID Tag Group Performance Measurement
41
P
r =
λ
2 P
t G
t G
r τ
(4π) 2
×
1
r 2
(2.8)
Equation (2.8) was used to calculate the sensitivity of tag group of five placement
modes. r
is 2.401 m, 3.091 m, 3.418 m, 3.089 m, and 2.425 m, respectively. The
wavelength of electromagnetic wave in free space is 0.33 m. The transmission power
of the RFID reader is 24dBm, the calculated input value is 251, the gain of the RFID
reader antenna is 2dBi, 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 –4.237 dBm, –6.431 dBm,
–7.305 dBm, –6.426 dBm, and –4.324 dBm, respectively. According to the preobtained environmental error value of 1.891 dBm, the final values of tag group
sensitivity were –6.128dBm, –8.322 dBm, –9.196 dBm, –8.817 dBm, and –6.215
dBm, respectively.
Without changing the experimental environment and experimental Settings, when
the number of tags and key tag positions remain unchanged, the schematic diagram
and measurement results of tags when the order of other tags changes are shown in
Table 2.4. The schematic diagram of the first group of tags is the same as that of the
first group in Table 2.3, so the test results in Table 2.3 are directly used.
Equation (2.8) was used to calculate the sensitivity of tag group of five placement
modes. r
is 2.401 m, 2.384 m, 2.394 m, 2.393 m, and 2.396 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 2dBi, the calculated input value is 1.58, the gain of the RFID tag
antenna is 9 dBi, the calculated input value is 7.94, and the antenna coefficient is
1. The sensitivity of the five groups was calculated as –4.237 dBm, –4.176 dBm,
–4.212 dBm, –4.208 dBm, and –4.219 dBm, respectively. According to the preobtained environmental error value of 1.891 dBm, the final values of tag group
sensitivity were –6.128 dBm, –6.067 dBm, –6.103 dBm, –6.099 dBm, and –6.110
dBm, respectively.
Table 2.4 The reading distance of tag group when the seed tag is unchanged
Distance/m
1
2.413
2.376
2.369
2.403
2.416
2
2.382
2.407
2.425
2.399
2.379
3
2.416
2.367
2.390
2.376
2.399
4
2.396
2.374
2.376
2.373
2.412
5
2.427
2.396
2.410
2.414
2.373
Average
2.401
2.384
2.394
2.393
2.396
41
P
r =
λ
2 P
t G
t G
r τ
(4π) 2
×
1
r 2
(2.8)
Equation (2.8) was used to calculate the sensitivity of tag group of five placement
modes. r
is 2.401 m, 3.091 m, 3.418 m, 3.089 m, and 2.425 m, respectively. The
wavelength of electromagnetic wave in free space is 0.33 m. The transmission power
of the RFID reader is 24dBm, the calculated input value is 251, the gain of the RFID
reader antenna is 2dBi, 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 –4.237 dBm, –6.431 dBm,
–7.305 dBm, –6.426 dBm, and –4.324 dBm, respectively. According to the preobtained environmental error value of 1.891 dBm, the final values of tag group
sensitivity were –6.128dBm, –8.322 dBm, –9.196 dBm, –8.817 dBm, and –6.215
dBm, respectively.
Without changing the experimental environment and experimental Settings, when
the number of tags and key tag positions remain unchanged, the schematic diagram
and measurement results of tags when the order of other tags changes are shown in
Table 2.4. The schematic diagram of the first group of tags is the same as that of the
first group in Table 2.3, so the test results in Table 2.3 are directly used.
Equation (2.8) was used to calculate the sensitivity of tag group of five placement
modes. r
is 2.401 m, 2.384 m, 2.394 m, 2.393 m, and 2.396 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 2dBi, the calculated input value is 1.58, the gain of the RFID tag
antenna is 9 dBi, the calculated input value is 7.94, and the antenna coefficient is
1. The sensitivity of the five groups was calculated as –4.237 dBm, –4.176 dBm,
–4.212 dBm, –4.208 dBm, and –4.219 dBm, respectively. According to the preobtained environmental error value of 1.891 dBm, the final values of tag group
sensitivity were –6.128 dBm, –6.067 dBm, –6.103 dBm, –6.099 dBm, and –6.110
dBm, respectively.
Table 2.4 The reading distance of tag group when the seed tag is unchanged
Distance/m
1
2.413
2.376
2.369
2.403
2.416
2
2.382
2.407
2.425
2.399
2.379
3
2.416
2.367
2.390
2.376
2.399
4
2.396
2.374
2.376
2.373
2.412
5
2.427
2.396
2.410
2.414
2.373
Average
2.401
2.384
2.394
2.393
2.396