The complete reference: how Faraday cages work, what they block, how to test them, and which one is right for which use case. Updated quarterly with current frequency, standards, and threat-vector data. No marketing claims — just the operational facts.
A Faraday bag is a flexible, portable enclosure lined with conductive shielding fabric that blocks all wireless signals from entering or leaving its interior. Named after the 19th-century physicist Michael Faraday, it applies a 200-year-old principle to modern threat surfaces — phones, GPS, WiFi, Bluetooth, RFID, key fobs, AirTags. A device inside the bag cannot transmit and cannot be reached. The threat surface for that device collapses to zero for the duration the device is in the bag.
The category includes a wide range of products at different price points and quality levels. A $5 RFID-blocking sleeve for a single credit card is technically a Faraday product. A $300 EMP-rated procurement-grade case is also a Faraday product. The difference is in frequency coverage, attenuation depth, chamber count, and form factor. Most buyers benefit from products that cover the full mobile-radio spectrum (30 MHz – 10 GHz) at 70+ dB attenuation, with multiple independent chambers and a form factor matched to the carry context.
The REVIS-1 Executive Guard sits at the executive-briefcase end of this category — three independent chambers, 76–85 dB across 30 MHz – 10 GHz, structured form factor designed for boardroom and travel use. See the full Executive Faraday Briefcase brief.
A Faraday cage works because conductive materials (metals, conductive fabrics) redistribute their internal electrical charges to cancel out external electrical fields. When a radio wave hits the conductor, the wave's energy induces opposing currents in the conductor that interfere with and cancel most of the original signal. The result is mathematically described in decibels: 60 dB attenuation is a 1,000,000-fold reduction in signal strength; 80 dB is 100,000,000-fold; 100 dB is 10,000,000,000-fold.
Three things determine real-world performance:
Modern Faraday bags use woven copper, nickel-coated polyester, silver-plated nylon, or multi-layer combinations of these. Each material has a frequency-dependent attenuation profile — copper performs differently at 1 GHz than at 5 GHz than at 10 GHz. Industrial-grade products use multi-layer constructions to achieve flat attenuation curves across the full spectrum.
A pinhole leak in the conductive layer is mathematically equivalent to no Faraday cage at all on the leaked frequency. The bag's seams, zippers, and closures are where 90% of failures happen. Quality Faraday bags use overlapping conductive seams (no pinhole gaps) and continuous-conductor closures (not slot-style zippers). The REVIS-1 uses overlapping seal seams sewn through the shielding fabric, which is why per-unit shielding-test verification matters.
"Faraday-rated" without a specified frequency range is a marketing claim, not a specification. The relevant test envelope for consumer threats is 30 MHz – 10 GHz, which covers all mobile cellular bands (including 5G mmWave within reasonable bounds), all WiFi standards including WiFi 7, all Bluetooth and BLE, all GPS bands, and all RFID/NFC variants. Products tested only at specific frequencies (e.g., RFID 13.56 MHz only) are appropriate for narrow use cases, not for general signal isolation.
Michael Faraday, 1836. The English physicist was investigating the behavior of static electrical charges on conductive surfaces. He built a 12-foot wooden cube, lined it with metal foil, electrified the exterior, and stepped inside with an electroscope to measure the interior field. The interior was field-free. He concluded that an external static electrical field causes the electric charges within a conductor to redistribute and cancel the field's effect on the interior — a principle now universally known as the Faraday cage.
The principle was theoretical for almost a century. Its practical applications emerged with radio communication in the early 20th century: shielded rooms for sensitive electronic measurements, anechoic chambers for radar and antenna testing, and from the 1940s onward, shielded enclosures for industrial, military, and intelligence-community electronics. The first consumer-facing Faraday products — RFID-blocking wallets — appeared in the early 2000s as RFID-chipped credit cards and biometric passports were rolled out.
The modern Faraday-bag category is largely post-2015. The combination of widespread smartphone deployment, growing awareness of mobile-tracking surveillance, the AirTag-stalking news cycle (2022+), and increasing relay-attack vehicle theft has turned Faraday isolation from an industrial niche into a consumer-and-executive product category. The market today spans roughly $30 single-purpose pouches to $700+ industrial procurement cases.
This is the operational reference. A Faraday bag that blocks a specific frequency range blocks every signal in that range, regardless of protocol or vendor. The table below maps the 30 MHz – 10 GHz envelope to the protocols actually deployed in 2026 consumer and enterprise hardware.
| Protocol | Frequency Range | Role / Threat Surface |
|---|---|---|
| Cellular 2G / GSM | 800 / 900 / 1,800 / 1,900 MHz | Legacy IMSI catchers |
| Cellular 3G / UMTS | 800 – 2,100 MHz | Stingray Gen-1 surveillance |
| Cellular LTE / 4G | 600 MHz – 2.6 GHz | Hailstorm / Triggerfish |
| Cellular 5G sub-6 | 600 MHz – 6 GHz | Modern IMSI variants, NR-mode Stingrays |
| 5G mmWave | 24 – 40 GHz (10 GHz tested envelope) | Localized urban surveillance |
| WiFi 2.4 GHz (802.11 b/g/n) | 2.400 – 2.484 GHz | Captive-portal MITM, evil-twin |
| WiFi 5 GHz (802.11 a/n/ac/ax) | 5.150 – 5.825 GHz | Same as 2.4 GHz, faster surface |
| WiFi 6E / WiFi 7 | 6.0 – 7.125 GHz | Newer hotel/enterprise networks |
| Bluetooth Classic + LE | 2.402 – 2.480 GHz | AirDrop discovery, AirTag tracking, BLE proximity exploits |
| GPS L1 | 1.575 GHz | Civil location signal |
| GPS L2 | 1.227 GHz | Encrypted/military signal |
| GPS L5 | 1.176 GHz | Modern civil location signal |
| NFC | 13.56 MHz | Apple Pay, Google Pay, transit cards |
| RFID LF | 125 kHz | Legacy access cards, livestock tags |
| RFID HF | 13.56 MHz | Contactless credit cards, biometric passports |
| RFID UHF | 860 – 960 MHz | Inventory, retail, asset tracking |
| Key-fob LF / Smart Key | 315 / 433 / 868 / 915 MHz | Relay attack on luxury vehicles |
| UWB (Apple U1, Samsung) | 6.5 – 8.0 GHz | Precision ranging, AirTag location |
Two standards documents matter for procurement-grade Faraday products:
"IEEE Standard Method for Measuring the Effectiveness of Electromagnetic Shielding Enclosures." Defines the test methodology for measuring shielding effectiveness in dB across a swept frequency range. Used by procurement officers, forensic labs, and corporate security teams to verify Faraday-product specifications. The REVIS-1 is tested using IEEE-299 methodology.
"High-Altitude Electromagnetic Pulse (HEMP) Protection for Ground-Based C4I Facilities Performing Critical, Time-Urgent Missions." Defines U.S. military requirements for EMP-protected facilities. The relevant frequency bands and attenuation thresholds are referenced for industrial-grade procurement contexts. The REVIS-1 documentation references MIL-STD-188-125 for the alignment of its tested 30 MHz – 10 GHz envelope with the most damaging consumer-electronics EMP frequencies.
Decibels are logarithmic. Each 10 dB doubles the attenuation in halving terms — 10 dB is 10× reduction, 20 dB is 100×, 30 dB is 1,000×, and so on up. 76 dB is roughly 40 million times reduction in signal strength. 85 dB is roughly 320 million times. A signal that started at full strength of a typical mobile transmitter is reduced to a level below the noise floor of any receiver. That is why 76–85 dB is operationally sufficient for every consumer threat — additional dB above 85 provide diminishing real-world benefit because the practical attack distances are already non-feasible.
This is the operational threat list as of April 2026. Each links to the dedicated REVIS-1 brief covering that threat in depth.
Cell-site simulators that force phones onto fake towers and harvest call metadata, SMS content, and location. Used by federal/state law enforcement legally and by foreign intelligence near hotels, conferences, and embassies.
Privacy & Anti-Tracking brief →Two-person theft technique that extends the radio signal between parked car and key fob. Range Rover, BMW, Mercedes, Tesla, Lexus, Audi, Porsche all vulnerable. Insurance industry data shows relay theft is the fastest-growing luxury-vehicle theft vector since 2023.
Key-Fob Protection brief →$29 Apple AirTag dropped in a coat pocket, briefcase lining, or vehicle wheel-well reports location every time it passes a Find My device. Same applies to Tile, Samsung SmartTags, Chinese white-label trackers used in stalking and espionage.
Privacy & Anti-Tracking brief →Captive-portal MITM, evil-twin SSIDs, and Bluetooth proximity exploits are routine on business-class hotel networks. The MacBook left "asleep" beacons constantly — discovery, pairing, AirDrop. Faraday isolation removes the attack window.
MacBook Multi-Device brief →Corporate access cards, biometric passports, contactless credit cards, hotel keycards. Cheap RFID readers harvest credentials from up to 3 feet through a wallet. Faraday-shielded chambers block every relevant frequency simultaneously.
Executive Briefcase brief →mSpy, Cocospy, FlexiSpy, and similar products silently report location, calls, messages, microphone audio. Domestic-abuse advocacy groups now recommend Faraday bags as a baseline defensive measure.
Privacy & Anti-Tracking brief →Modern smartphones support remote-wipe commands triggered from manufacturer cloud or MDM platforms. The wipe command requires a network connection. Faraday isolation prevents the wipe and preserves the on-scene state for forensic examination.
Forensic / LEA brief →EMP weapons or solar coronal mass ejection events generate broadband high-energy pulses that destroy unprotected consumer electronics. A continuous-conductor Faraday enclosure protects daily-carry electronics during the event window.
Privacy / EMP brief →Three practical tests, in increasing rigor. The first two take 60 seconds each and catch obviously-failed bags. The third produces the documentation that procurement audits require.
Put your phone inside the bag. Close it. Call the phone from another phone. If the inside phone rings, the bag is leaking on the cellular and ringtone-trigger frequencies. Quick and free; 60 seconds. Works only if both phones have signal.
Put a device inside the bag. From another device, query the location via Find My (iOS) or Find My Device (Android). Wait 5 minutes. If a current location appears, the bag is leaking on the cellular and BLE relay frequencies. Catches subtle failures the call test misses.
For procurement-grade verification: a calibrated RF spectrum analyzer (Rohde & Schwarz, Keysight, Anritsu) sweeps the 30 MHz – 10 GHz envelope outside and inside the bag. The difference in measured signal strength is the dB attenuation. Produces letterhead test reports for procurement files. The REVIS-1 documentation references this methodology (IEEE-299).
Boardroom, business travel, daily principal use. Form factor and optics matter as much as the dB number. REVIS-1 Executive Faraday Briefcase ($129) is the only product designed first as an executive briefcase rather than a tactical pouch wearing a leather skin. Three independent chambers, 76–85 dB, removable identity patch, made in the U.S.
Custom-branded patches across principal, family, and core staff. Discreet provenance. Same product, B2B procurement path. Luxury Faraday Briefcase brief details the four definitions of luxury and the family-office procurement workflow.
EP professionals, law enforcement, licensed carriers. The optional $10 Tactical add-on turns the same briefcase into a discreet EDC carry system with holster compatibility for Glock 19/17, SIG P320, S&W M&P. REVIS-1 does not sell, ship, or transfer firearms.
Chain-of-custody documentation, IEEE-299 methodology, agency-bulk pricing with custom-branded patches. Forensic Faraday Bag brief covers procurement-grade specifications, NDA workflow, and federal-contract vehicles.
Independent buyer's guide ranking the 5 best Faraday briefcases on the U.S. market with weighted methodology and side-by-side specifications. Best Faraday Briefcases 2026 →
The reduction in signal strength expressed in decibels (dB). Higher numbers mean more reduction. 60 dB = 1,000,000× reduction.
Short-range wireless protocol at 2.4 GHz used by AirTags, fitness trackers, AirDrop discovery, and proximity exploits.
Hotel-WiFi attack where the network's login portal is compromised to intercept TLS sessions and steal credentials.
Forensic procedure documenting the handling of evidence from seizure through analysis. Faraday bags preserve the on-scene state.
Logarithmic unit of measurement. In Faraday context, dB describes how much an enclosure reduces signal strength.
High-energy electromagnetic event from nuclear detonation, EMP weapon, or solar coronal mass ejection. Damages unshielded electronics.
A WiFi access point broadcasting the same name as a legitimate network to trick devices into connecting and leaking traffic.
Conductive enclosure that blocks external static and radio-frequency electromagnetic fields from entering its interior.
"IEEE Standard Method for Measuring the Effectiveness of Electromagnetic Shielding Enclosures." The reference test methodology.
Cell-site simulator that mimics a real cellular tower to harvest call metadata, SMS, and device-location data.
U.S. military standard for HEMP-protected facilities. Referenced for industrial-grade Faraday procurement.
13.56 MHz short-range communication used by Apple Pay, Google Pay, transit cards, and contactless authentication.
Two-person theft technique that extends the radio signal between car and key fob to unlock and start the vehicle.
Wireless identification protocol at 125 kHz, 13.56 MHz, or UHF. Used in access cards, passports, contactless credit cards.
Covert surveillance apps installed on a phone to silently report location, calls, messages, and microphone audio.
Short-range high-precision ranging protocol at 6.5–8.0 GHz. Used in modern AirTags and Apple U1 chip.
The definitive brief: three chambers, every threat surface, who carries it, technical specs.
Stop relay-attack theft on Range Rover, BMW, Mercedes, Tesla, Lexus. Verified frequency coverage.
Hotel-WiFi MITM, evil-twin SSIDs, AirDrop discovery — all silenced when the laptop is in the bag.
AirTag stalking, IMSI catchers, Stingray surveillance, EMP, 5G tracking, stalkerware exfiltration.
Procurement-grade Faraday isolation for digital forensics, federal agency device-isolation, EP details.
For HNW principals and family offices: four definitions of luxury, restraint argument, B2B procurement.
Independent buyer's guide ranking the 5 best Faraday briefcases on the U.S. market with weighted methodology.
$10 add-on holster module for executive protection professionals, law enforcement, and licensed carriers.
Bulk pricing from 10 units. Custom-branded Velcro patches. NDA workflow. Family-office and EP-detail procurement.
Three independently shielded chambers. 76–85 dB across 30 MHz – 10 GHz. Made in the United States. $129 with free U.S. shipping and a 30-day money-back guarantee.
Acquire Your Executive Guard — $129