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graph TB
RFID["RFID TAG TYPES"]
RFID --> Passive
RFID --> SemiPassive
RFID --> Active
subgraph PassiveDetails["PASSIVE TAG"]
P1["Power Source:<br/>Reader's RF field"]
P2["Components:<br/>Antenna + Chip"]
P3["Range:<br/>cm–meters<br/>(band dependent)"]
P4["Cost:<br/>Low"]
P5["Use Cases:<br/>Retail, Inventory,<br/>Access Cards"]
end
subgraph SemiPassiveDetails["SEMI-PASSIVE TAG"]
SP1["Power Source:<br/>Battery (sensors)<br/>RF (communication)"]
SP2["Components:<br/>Antenna + Chip<br/>+ Battery + Sensors"]
SP3["Range:<br/>Similar to passive<br/>(design dependent)"]
SP4["Cost:<br/>Medium"]
SP5["Use Cases:<br/>Cold Chain,<br/>Temperature Monitoring"]
end
subgraph ActiveDetails["ACTIVE TAG"]
A1["Power Source:<br/>Internal Battery"]
A2["Components:<br/>Antenna + Chip<br/>+ Battery + TX"]
A3["Range:<br/>Longer (tens–100+ m)<br/>(deployment dependent)"]
A4["Cost:<br/>High"]
A5["Use Cases:<br/>Vehicle Tracking,<br/>Asset Management"]
end
Passive -.-> PassiveDetails
SemiPassive -.-> SemiPassiveDetails
Active -.-> ActiveDetails
style RFID fill:#2C3E50,stroke:#16A085,stroke-width:4px,color:#fff
style PassiveDetails fill:#E8F4F8,stroke:#16A085,stroke-width:3px
style SemiPassiveDetails fill:#FFF5E6,stroke:#E67E22,stroke-width:3px
style ActiveDetails fill:#F8E8E8,stroke:#2C3E50,stroke-width:3px
864 RFID System Components
864.1 RFID System Components
864.1.2 RFID Readers (Interrogators)
Readers emit RF signals and decode tag responses:
Types:
- Fixed readers: Mounted at entry points (warehouses, toll booths)
- Handheld readers: Portable devices for inventory
- USB readers: Desktop accessories for PC access control
- Embedded modules: Integrated into IoT devices (ESP32, Arduino)
Components:
- Antenna(s)
- RF transceiver
- Control unit / microprocessor
- Communication interface (USB, Ethernet, Wi-Fi, Bluetooth)
TipUnderstanding Check: Marathon Race Timing System Requirements
Scenario: You’re designing an RFID timing system for a marathon tracking 5,000 runners. The system must read timing chips attached to shoes as runners pass checkpoints at 3m distance while running at speed. Up to 50 runners may pass simultaneously per second. Timing chips must be reusable for 100+ races to justify the investment.
Think about: 1. What read speed (tags/second) is required to handle 50 simultaneous runners? 2. Why does passive vs active tag selection affect multi-race reusability? 3. How do different frequency bands affect the ability to read runners in motion at 3m distance?
Key Insight: This high-throughput, high-reliability scenario demands UHF passive RFID with anti-collision:
UHF Passive with Anti-Collision (recommended): - Designed for high multi-tag throughput at checkpoints (anti-collision + engineered read zone) - Mat/portal antennas can create a controlled read zone as runners pass through - No battery (lower maintenance); durability and reusability depend on packaging and how tags are attached
Why alternatives fail:
LF 125 kHz: Very short range makes it hard to read reliably at speed unless tags pass extremely close to the antenna
HF 13.56 MHz: Short range often makes checkpoint reads challenging at a distance unless the read zone is tightly constrained
Active tags + GPS: Adds battery logistics and cost without clear benefit if you only need checkpoint timestamps (not continuous tracking)
Verify Your Understanding: - Why is anti-collision algorithm critical when 50 runners pass simultaneously? - How does mat antenna placement enable 3m read range for shoe-mounted tags? - What are the lifecycle trade-offs (reusability, maintenance, infrastructure) between passive and active approaches?