RFID Frequency 918.4–923 MHz for Fashion: Vietnam Compliance

The RFID frequency 918.4–923 MHz is the only UHF band licensed for RFID applications in Vietnam, according to Circular 08/2021/TT-BTTTT. For the fashion industry, this band directly determines read/write performance on fabric, metal, and liquids — a key factor when deploying supply chain management systems.

Table of Contents

• What is the RFID frequency 918.4–923 MHz and why is it important for fashion?
• What compliance regulations apply to RFID frequencies in Vietnam?
• How does the UHF band affect read/write performance on fabric?
• How do metal and liquids block RFID signals in fashion environments?
• What are the criteria for selecting RFID tags for fashion products?
• Summary table of key RFID frequency terms
• Common mistakes when choosing RFID frequency and tags for fashion
• What should be noted in the RFID deployment process for fashion supply chains?
• Frequently Asked Questions

#What is the RFID frequency 918.4–923 MHz and why is it important for fashion?

This is the UHF (Ultra High Frequency) band from 918.4 MHz to 923 MHz, licensed by the Ministry of Information and Communications for RFID devices in Vietnam. Compared to lower frequencies (LF/HF), the UHF band allows reading at longer distances (3-8 meters), faster read speeds, and supports reading multiple tags simultaneously — suitable for inventory, warehouse inbound/outbound, and merchandise management in fashion supply chains.

In the fashion industry, each SKU (stock keeping unit) often has multiple color and size variants. UHF RFID allows reading an entire clothing rack in 3-5 seconds, instead of scanning each barcode which takes 15-20 minutes. The compliant frequency ensures stable device operation, avoids interference with other telecommunications systems, and is legally recognized.

#What compliance regulations apply to RFID frequencies in Vietnam?

Circular 08/2021/TT-BTTTT of the Ministry of Information and Communications stipulates that the 918.4–923 MHz band is permitted for RFID devices, with a maximum transmit power of 500mW ERP. Imported devices must have a conformity certification before being circulated. VietPOS provides infrastructure and equipment that complies with this regulation — businesses should seek separate legal advice for each case.

Key points of the regulation:

• Permitted frequency band: 918.4 – 923 MHz (UHF band)
• Maximum transmit power: 500mW ERP (Effective Radiated Power)
• Conformity certification required for imported devices
• Must not cause harmful interference to other radio services

International standard RFID equipment (e.g., UHF EPC Gen2 tags) typically operates in the 860–960 MHz range. In Vietnam, devices need to be configured to the 918.4–923 MHz band for optimal performance and legal compliance. Zebra, Impinj readers, and common UHF tags all support configuration for this region.

#How does the UHF band affect read/write performance on fabric?

Cotton, polyester, and linen fabrics have low dielectric constants and absorb little radio wave energy, so UHF RFID tags perform well on regular clothing. Read distances reach 4-7 meters with passive tags, sufficient for warehouse or store inventory. However, fabrics containing metal fibers (technical fabrics, protective clothing) or carbon coatings will cause signal interference.

Fabric moisture also affects performance: damp fabric (after washing, in high-humidity environments) absorbs wave energy, reducing read distance by 20-40%. In real-world operations like industrial laundry or coastal warehouses, tag performance should be tested under actual humidity conditions. For regular garments (dry, no metal coating), the 918.4–923 MHz band achieves good performance.

#How do metal and liquids block RFID signals in fashion environments?

How do metal and liquids block RFID signals in fashion environments?

Metal reflects radio waves, liquids absorb energy — both severely degrade UHF RFID signals. For fashion accessories (metal buckles, watches, jewelry, shoes with metal soles), standard RFID tags can see read distances drop by 80-90%, or even fail to read. The solution is to use specialized on-metal tags with an anti-interference spacer layer.

Common challenging scenarios:

• Clothing with metal zippers: if the tag is placed near the zipper, performance degrades noticeably
• Footwear: rubber/leather soles have little effect, but shoes with metal lining require on-metal tags
• Bags with metal frames: tags should be placed away from the frame
• Liquids (perfume, cosmetics): absorb waves, reducing read distance to 1-2 meters

Practical solution: test tags at multiple positions on the product (seams, labels, inner pockets) before mass printing. For products with significant metal content, use on-metal tags (with ferrite anti-interference layer) or larger tags to maintain sensitivity.

#What are the criteria for selecting RFID tags for fashion products?

Selecting RFID tags for fashion requires considering 4 criteria: surface type (fabric or metal), tag size relative to the product, read distance requirements, and environmental conditions (humidity, temperature, washing). For regular garments, UHF inlay tags sized 70x15mm or 50x50mm work well. For metal accessories, use specialized on-metal tags.

Comparison table of common tag types:

Tag type	Suitable surface	Read distance	Application example
UHF inlay tag (wet/dry)	Fabric, paper, plastic	4-7 meters	Shirts, jeans

#Summary table of key RFID frequency terms

This table summarizes important terms related to RFID frequency, helping businesses understand technical concepts and communicate effectively with suppliers.

Term	Definition
UHF (Ultra High Frequency)	Frequency band from 300 MHz to 3 GHz, used for RFID with long read range
ERP (Effective Radiated Power)	Actual radiated power of the device, used to measure transmit power
EPC Gen2	Global standard for UHF RFID tags, ensuring interoperability between devices
Passive tag	Tag without internal battery, powered by reader signal
On-metal tag	Specialized tag with anti-interference layer, designed for metal surfaces
Read range	Maximum distance at which the reader can read the tag
RSSI (Received Signal Strength Indicator)	Signal strength measurement, used to assess tag performance

#Common mistakes when choosing RFID frequency and tags for fashion

Common mistakes include choosing tags not compliant with Vietnam's frequency band, using standard tags on metal surfaces, ignoring environmental factors, and not testing before mass deployment. These errors lead to poor performance, wasted costs, and project delays.

• Buying tags optimized for other markets: Some tags are optimized for EU (865-868 MHz) or US (902-928 MHz) bands, which may not perform well in Vietnam's 918.4–923 MHz band.
• Using standard tags on metal: Read distance drops sharply, or tags fail completely.
• Ignoring moisture: In humid environments or after washing, performance degrades significantly.
• Not testing before mass printing: Skipping pilot tests leads to costly rework.

#What should be noted in the RFID deployment process for fashion supply chains?

The deployment process includes: assessing needs, selecting tags and readers, pilot testing, system integration, and staff training. Key considerations include ensuring frequency compliance, testing on real products, and planning for scalability.

1. Assess needs: Define inventory frequency, product types, and environmental conditions.
2. Select tags and readers: Choose tags suitable for the surface and readers that support Vietnam's frequency band.
3. Pilot test: Test tags on actual products in real conditions to verify performance.
4. System integration: Connect RFID readers to existing POS or inventory management systems.
5. Staff training: Train staff on using readers and interpreting data.

#Frequently Asked Questions