RFID is an automatic contactless identification method based on radio frequency (RF). The reading process depends of the power of electromagnetic signal received by a tag. Thus an accurate characterization of RFID tags is crucial for early adopter in aerospace industry. The present study shows the preliminary approach to characterize the reading distance for UHF RFID passive tag from the low-cost application test deployment.
KEYWORDS:
RFID; Application test; Aerospace industry
| Parameter | Specification |
|---|---|
| Ambient Temperature | 25 ºC ± 5 ºC |
| Ambient Humidity | Above 75% ± 1% |
| Step | Calculations | Comments |
|---|---|---|
| 1. For the desired frequency range, verify the calculated loss (Eq. 1) | ~ 30.63 dB | FSL is the free space loss calculated for a distance of 0.90 m (from the center of antenna up to the center of reference point) at 902 MHz initially |
| 2. Calculated power (Prt) in the direct linkthat theoretically reaches the reference point at 0.90 meter | EIRP = (30 + 6) - 3 = 33.00 dBm Replacing in: Prt = 33 + 0 - 30.62898 = 2.37102 dBm |
Prt = EIRP + Gtag - FSLwhere: EIRP = (Pt + Gt) - Pclwhereas: EIRP = isotropic power effectively radiated (dBm); Pt = reader maximum power (dBm). (e.g., 30.00 dBm);Gt = antenna gain (dBi) (e.g., 6.00 dBi); Pcl - estimated loss for cable/connector (dB) (e.g., 3.00 dB); Gtag = tag antenna gain (dBi) (in this case it is 0); FSL = free space propagation loss (dB) |
| 3. Theoretical Maximum Power at the Reference Point (Prt) | 2.37 dBm | 2.37 dBm refers to theoretical maximum power at the reference point, for 902 MHz, without the utilization of any equipment for verification, as per EPC policy |
| Frequency (MHz) | Theoretical Maximum Power (Prt) at the Reference Point (dBm) |
|---|---|
| 902 | 2.37 |
| 915 | 2.25 |
| 928 | 2.13 |
| Freq. (MHz) | (A) Reader Maximum Power (dBm) | (B) Maximum Power calculated (Prt) at the Ref. Point (dBm) | (B - A) Power Correction Factor Calculated (dB) |
|---|---|---|---|
| 902.00 | 30.00 | 2.37 | -27.63 |
| 915.00 | 30.00 | 2.25 | -27.75 |
| 928.00 | 30.00 | 2.13 | -27.87 |
| Step | Calculation | Comments |
|---|---|---|
| 1. Start with the interrogator power setting where the tag turned on (detection rate = 50%) | 24 dB (A) | In this example the interrogator was set first at 902 Mhz - 30 dBm. Adjust transmit attenuation (1 dBm per cycle on reader) and repeat the read trial until the tag detection rate falls to 50% |
| 2. Subtract the transmit attenuation level (Theoretical Offset Calculus) | 2 dB (B) | In this example is used the Theoretical Offset Calculus |
| 3. Add Theoretical Power Correction Factor | -27.63 dBm (C) | In this example see Table 4 |
| 4.Tag Turn on Power Calculus (PturnOn) | (A - B) + C = PturnOn(24 - 2) + (-27.63) = -5.63 dBm | This is the final result for the unit under test |
| Freq. (MHz) | (A) Measured |
(B) Theoretical |
(C) Calculated |
(A - B) + C |
|---|---|---|---|---|
| 902.00 | 24.00 | 2.00 | -27.63 | -5.63 |
| 915.00 | To be defined | 2.00 | -27.75 | To be defined |
| 928.00 | To be defined | 2.00 | -27.87 | To be defined |
| Xerafy DASH-IN XS (Tag Turn on) | Simplified Static Test (Tag Turn on) |
|---|---|
| Uninformed | 0.75 dBm (915MHz) -3.23 dBm (927MHz) 4.87 dBm (902MHZ) |
| Xerafy DASH-IN XS (Tag Turn on) (Xerafy 2015Xerafy (2015) Dash-in XS; [accessed 2016 April 10] http://www.xerafy.com/en/catalogue/product/dash-in-xs/2
http://www.xerafy.com/en/catalogue/produ... ) |
Simplified Static Test (Max Reading Distance) |
|---|---|
| 1.50 m (on metal) | 1.43 m (915MHz) 2.26 m (927MHz) 0.90 m (902MHz) 1.53 m (average frequency) |
