The **MH28TAG-R** is a specific type of passive Radio Frequency Identification (RFID) tag, commonly used in automotive security systems, specifically as a transponder for immobilizer systems. Below is an overview of its electronic characteristics and technical specifications. --- ### 1. Technical Specifications The MH28TAG-R typically operates on low-frequency bands and relies on electromagnetic induction for power and data transmission. | Feature | Description | | :--- | :--- | | **Component Type** | Transponder Chip / RFID Tag | | **Operating Frequency** | 125 kHz (Low Frequency) | | **Memory Type** | Read/Write (usually contains a unique ID and encrypted area) | | **Power Source** | Passive (Powered by the reader's magnetic field) | | **Common Application** | Suzuki / Mitsubishi / Honda Immobilizer Keys | | **Chip Equivalent** | Often associated with PCF7936 (ID46) or similar logic | --- ### 2. Electronic Components & Internal Logic Internally, the tag consists of three primary electronic sections: 1. **Antenna Coil (Inductor):** A micro-coil of copper wire that picks up the 125 kHz magnetic field generated by the car's ignition barrel. 2. **Capacitor:** Forms a resonant LC circuit with the antenna to tune the tag to the specific frequency of the reader. 3. **Integrated Circuit (IC):** The "brain" of the tag. It contains the EEPROM for data storage and the modulator used to "backscatter" data to the reader. --- ### 3. Functional Mechanism The MH28TAG-R functions through a process called **Inductive Coupling**: * **Energy Transfer:** The vehicle's immobilizer antenna generates an electromagnetic field. When the MH28TAG-R is placed within this field, the internal coil converts the magnetic energy into electrical energy to power the IC. * **Authentication:** The car sends a "challenge" signal. The chip processes this using its internal algorithm and sends back a "response" (the security code). * **Security:** These tags often use **Mutual Authentication**, meaning the car must prove it is the correct vehicle and the key must prove it is the correct key before the engine is allowed to start. --- ### 4. Comparison with Standard RFID While it shares the same physics as a standard key card, the MH28TAG-R is specialized for high-security environments: | Feature | Standard RFID | MH28TAG-R (Immobilizer) | | :--- | :--- | :--- | | **Security Level** | Low (UID only) | High (Crypto-coding) | | **Durability** | Plastic Card | Ceramic or Glass Encapsulation | | **Distance** | Up to 10cm | Near-field (1-3cm) | ---