METAG - 限制超高頻電子標籤讀取距離之因素(二): RFID_讀取器輸出功率 & 天線增益＿測試_FCC Part 15_FCC Part 90_30W_Transmitted Power_UHF Reader_Interrogator_ Receiver Sensitivity _Interferences _線性極化_天線極化

日期: 2011/08/30

限制超高頻電子標籤讀取距離之因素(二): 讀取器輸出功率 & 天線增益
The limiting factors for the read range of UHF RFID tag: Reader Transmitted Power & Antenna Gain

在不考量外在環境干擾 Interferences 及多重路徑效應 Multipath Effect 條件下，UHF RFID 電子標籤的讀取距離是和讀取器Reader or Interrogator 的輸出功率 Transmitted Power 與天線增益 Antenna Gain 成正向關係，本測試之目的是要驗證電子標籤在不同總輸出功率下(Reader Transmitted Power + Antenna Gain)和其讀距之關係。

  ■ 量測工具: Tagformance lite + Tag Designer Suite             ■ 量測項目: Backscatter
  ■ 待測標籤: UPM DogBone Monza 4                                    ■ 量測頻率:  925 MHz
  ■ 量測環境: 建儒實業辦公室                                                      　         ■ 天線極化: 線性極化

	0.5W EIRP (Reader Transmitted Power: 22 dBm, Antenna Gain: 5 dBi) Read Range: 2.8M 1W EIRP (Reader Transmitted Power: 25 dBm, Antenna Gain: 5 dBi) Read Range: 4M 2W EIRP (Reader Transmitted Power: 27 dBm, Antenna Gain: 6 dBi) Read Range: 5.7M 4W EIRP (Reader Transmitted Power: 30 dBm, Antenna Gain: 6 dBi) Read Range: 8M 8W EIRP (Reader Transmitted Power: 30 dBm, Antenna Gain: 9 dBi) Read Range: 11M 16W EIRP (Reader Transmitted Power: 30 dBm, Antenna Gain: 12 dBi) Read Range: 16M 30W EIRP (Reader Transmitted Power: 30 dBm, Antenna Gain: 14.7 dBi) Read Range: 22M

結論：
1. 總輸出功率(Reader Transmitted Power + Antenna Gain)增加 6dB，電子標籤讀距將增加 1 倍。
2. 美國 FCC Part 15 Unlicensed Radio Frequency Devices 規範最大總輸出功率是4W EIRP(902~928MHz)。
3. 台灣容許最大(室內)總輸出功率是4W EIRP (922~928MHz)和2W EIRP(室外)。請參閱附件
4. 美國 FCC Part 90 Private Land Mobile Radio Service 規範最大總輸出功率是30W EIRP。
*上述測試未將傳輸線損耗 Cable Loss 納入考量，讀取器接收靈敏度 Receiver Sensitivity 為-70dBm。