# Dual-Frequency Key Fobs — One Credential, LF + HF

URL: https://proudtek.com/products/rfid-keyfobs/dual-frequency-key-fob/
Source URL: https://proudtek.com/products/rfid-keyfobs/dual-frequency-key-fob/
Generated: 2026-03-16T01:42:30.697Z
Kind: product
Publisher: Proud Tek Co., Limited
Author: Proud Tek Co., Limited
Credentials: ISO 9001:2015, ISO 14001:2015, RoHS Compliant, CE Marking, REACH Compliant
Image: https://proudtek.com/landing-images/dual-frequency-key-fob.png
Image Alt: Dual-frequency RFID key fob with LF and HF chips

## Description
Dual-frequency key fobs embed two electromagnetically-isolated RFID chip-antenna systems — a 125 kHz LF transponder (EM4100 / T5577 / HID Prox...

## Procurement Snapshot
- Best fit: Best for access control, parking, elevator, and membership credential projects.
- Key options: Form Factor: Compact keyfob form factor for handheld access credentials.
- Customization: Confirm artwork, encoding, material, chip, and finish requirements before quoting.
- Quote checklist: Reference Dual-Frequency Key Fobs — One Credential, LF + HF in your inquiry so the matching product page stays attached to the quote. Compact keyfob form factor for handheld access credentials. Share target chip or protocol, quantity,...

## Key Specs
- Form Factor: Compact keyfob form factor for handheld access credentials.

## FAQ
- Q: Is the fob bigger than a standard single-frequency fob?
  A: Only slightly. Our dual-frequency fob is 40×32×6 mm — about 1 mm thicker than a standard single-frequency fob. The size difference is imperceptible on a keychain. The dual antenna design fits within the standard fob form factor through careful coil positioning.
- Q: Can you match our existing fobs?
  A: Yes. Send us samples of both your LF and HF fobs (or tell us the reader models) and we produce a single dual-frequency fob that matches both. We provide a UID correlation table linking the LF and HF chip IDs for each fob.
- Q: How do I program both chips?
  A: Each chip is programmed independently using its respective frequency reader/writer. We can pre-encode both chips at our factory. Provide your LF credentials (facility code, card number) and HF credentials (sector keys, access data) and we program everything before shipment. A UID mapping file is included with each order.
- Q: Does the LF chip interfere with the HF chip during a dual-frequency scan?
  A: No. The two antennas are tuned to very different frequencies (125 kHz and 13.56 MHz — two orders of magnitude apart) and the coil geometries are designed for electromagnetic isolation. Each chip only responds to its own band; a 125 kHz reader energises only the LF coil and a 13.56 MHz reader energises only the HF coil. ProudTek verifies isolation per unit during production by running both chips against a test reader of each frequency and rejecting any unit where cross-coupling affects sensitivity by more than 1 dB.
- Q: What's the typical migration timeline with dual-frequency fobs?
  A: A typical enterprise LF-to-HF migration runs 12-18 months. Phase 1: issue dual-frequency fobs to all users in a single re-issuance event (zero access disruption because both chips work). Phase 2: roll out new HF readers building by building over 6-12 months. Phase 3: firmware-cut-over to disable LF mode on the dual-frequency credential (or simply retire the LF reader fleet) and operate HF-only. Because users carry the same fob throughout, there is no second issuance event and no mid-migration access interruption — this is the pattern ProudTek's logistics-operator and corporate-campus references ran through.

## Machine Routes
- JSON: https://proudtek.com/machine/products/rfid-keyfobs/dual-frequency-key-fob.json
- Text: https://proudtek.com/machine/products/rfid-keyfobs/dual-frequency-key-fob.txt