Faraday Enclosures and Signal Blockers

Faraday Enclosures and Signal Blockers

Protecting devices and spaces from wireless signals, tracking, and remote access.

Overview

Faraday enclosures—also known as Faraday cages, bags, or boxes—are containers that block electromagnetic fields. Signal blockers are similar in purpose, preventing wireless signals (cellular, Wi-Fi, GPS, Bluetooth, RFID) from reaching or leaving a device.

For activists, journalists, and anyone facing potential surveillance or confiscation of electronics, Faraday enclosures provide a crucial layer of protection against remote access, tracking, and data leaks.

How It Works

A Faraday enclosure is made of conductive material (like metal mesh or foil) that distributes and cancels external electric fields. When a device is sealed inside, it is shielded from incoming and outgoing radio frequency signals.

Signal blocking depends on:

• Material conductivity
• Continuity (no gaps or holes)
• Type and strength of signals
• Proper sealing (Velcro, folding, or gasket)

Types of Enclosures

• Faraday Bags:
  • Portable, fabric-based pouches with conductive layers.
  • Common for phones, tablets, key fobs.

• Faraday Boxes:
  • Rigid containers (metal tins, ammo boxes) lined with insulating and conductive materials.
  • Can be DIY-built from household items.

• Faraday Tents or Rooms:
  • Large-scale mesh rooms or enclosures used during sensitive meetings.
  • Used in high-risk spaces to prevent signal leakage.

• Signal Blockers / Jammers:
  • Actively disrupt wireless signals. Often illegal without special authorization.
  • Not covered here beyond conceptual awareness due to legal restrictions.

DIY Builds

• Wrap a phone in aluminum foil as an emergency Faraday shield (single layers may not be reliable).
• Modify a metal cookie tin with foam and copper mesh for a cheap signal-blocking box.
• Use conductive fabric and Velcro to sew custom bags for gear.

Test effectiveness by placing a phone inside and calling it. If it doesn’t ring or receive messages, it's likely working. Some phones may cache messages until reconnected.

Use Cases in Activism

• Preventing location tracking during sensitive travel or protests.
• Protecting data from remote wiping during a raid or arrest.
• Securing backup drives or USB sticks with sensitive documents.
• Hosting device-free, radio-silent meetings to prevent eavesdropping.

Legal and Ethical Considerations

• Legality:
  • Faraday enclosures are legal in most countries.
  • Active jamming devices are usually illegal—avoid.

• Ethics:
  • Use signal blocking to enhance privacy and consent.
  • Avoid blocking emergency communications unless absolutely necessary.

Limitations and Best Practices

• Faraday bags degrade over time—test them regularly.
• Some may block cell signals but not Wi-Fi or GPS.
• Always shut off devices before sealing to reduce battery drain and interference.
• Label or color-code bags to avoid mix-ups in a group.

Recommended Tools and Materials

• Conductive fabric (nickel-copper, silver mesh)
• Steel boxes or aluminum-lined cases
• Mission Darkness or Silent Pocket (commercial bags)
• Multimeter or RF meter to test signal resistance

References and Further Reading

• DIY Faraday cage guides on Instructables and YouTube
• EFF Surveillance Self-Defense materials
• Field reports from journalists and researchers on using Faraday gear

Legal Disclaimer

This page is for educational purposes only. Faraday enclosures are generally legal to own and use. Do not construct or use signal jamming devices unless specifically authorized. Always follow local laws and regulations.