About the Competition

The Tinfoil Hat Competition is a unique event that tests the signal attenuation properties of contestant-made tinfoil hats. Using professional RF testing equipment, we measure how effectively your hat blocks various radio frequencies.

How It Works

1. Create Your Hat

Design and build your tinfoil hat using any materials you choose. Be creative and innovative in your approach to RF shielding!

2. Test the Hat

You place your hat on our handy test dummy, and the hat will be tested using a HackRF One device, measuring signal attenuation from 1 MHz to 6 GHz.

3. Results & Scoring

We compare signal strength with and without the hat, calculating average attenuation in decibels (dB). The highest attenuation score in each category wins!

Competition Details

Categories

Classic

Pure tinfoil hats that showcase the traditional art of RF shielding. No additional materials allowed.

Hybrid

Innovative designs that combine tinfoil with other materials to create unique and effective shielding solutions.

Style

Show off your creativity with unique designs that catch the eye while maintaining functionality. Style is judged by the TFH staff based on the overall appearance of the hat.

Testing Equipment

We use the HackRF One as our SDR of choice, selected for its exceptional frequency range from 1 MHz to 6 GHz. This wide range allows us to test your hat's effectiveness across various radio frequencies.

Our testing environment is standardized using the official Tinfoil Hat Competition software, ensuring fair and consistent measurements for all participants.

Competition Rules

Categories

Build a hat out of purely tinfoil to compete in the classic category, or combine tinfoil with other materials for the hybrid category. You can also win on style!

Supplies

We will provide a limited amount of tinfoil, but you are welcome to bring your own supplies.

Basic Rules

The wearer must be able to see, and you can test as many times as you want. You are not allowed to interfere with or manipulate the test equipment. Please be courteous of the other participants.

Testing Process

  1. TFH staff will run a baseline with nothing on the mannequin
  2. You will be asked to place your hat on the mannequin
  3. The scoring test will be performed on your hat
  4. Your best score will be used for the competition results

About RF Attenuation

Understanding RF Shielding

Radio Frequency (RF) shielding is the practice of reducing electromagnetic field penetration by blocking it with conductive or magnetic materials. In our competition, we focus on measuring how effectively your tinfoil hat can block various radio frequencies, from common FM radio (88.5 MHz) up to 6 GHz, which includes most modern wireless communications.

The Science Behind It

When an electromagnetic wave hits a conductive material like aluminum foil, it induces an electric current in the material. This current creates its own electromagnetic field that opposes the incoming wave, effectively canceling it out. The effectiveness of this shielding depends on several factors:

  • Conductivity of the material
  • Thickness of the shielding
  • Frequency of the incoming wave
  • Presence of gaps or holes in the shield

Attenuation Properties of Aluminum Foil

100 dB 75 dB 50 dB 25 dB 1 MHz >100 dB 10 MHz >100 dB 100 MHz 90 dB 500 MHz 70 dB 1 GHz 60 dB 2 GHz 50 dB 3 GHz 45 dB 4 GHz 40 dB 6 GHz 30 dB

* Attenuation values are approximate for a single layer of heavy-duty aluminum foil (0.024mm thick). Higher frequencies are more difficult to shield effectively.

Measurement Process

We measure RF attenuation using a HackRF One software-defined radio (SDR) device. The process involves:

  1. Establishing a baseline by measuring signal strength without any shielding
  2. Measuring signal strength with your hat in place
  3. Calculating the difference in decibels (dB) between these measurements

A higher dB value indicates better shielding. For example, 20 dB means the signal is reduced to 1/100th of its original strength.

Faraday Cage Principles

A Faraday cage is an enclosure formed by conductive material that blocks external electric fields. For optimal shielding:

  • The material must be conductive (like aluminum foil)
  • The enclosure should be continuous with no gaps
  • Ideally, the shield should be grounded
  • Any openings should be smaller than 1/10th of the wavelength of the highest frequency you want to block

Common Challenges

Building an effective RF shield presents several challenges:

  • Ventilation needs vs. shielding effectiveness
  • Visibility requirements vs. complete coverage
  • Comfort vs. material thickness
  • Style vs. functionality

Design Tips

To maximize your hat's shielding effectiveness:

  • Use multiple layers of foil for better shielding
  • Ensure good contact between layers
  • Minimize gaps and seams
  • Consider the wavelength of the frequencies you want to block
  • Use conductive tape to seal seams

Frequency Considerations

Different frequencies require different shielding approaches:

  • FM Radio (88.5 MHz): Wavelength ≈ 3.4 meters
  • WiFi (2.4 GHz): Wavelength ≈ 12.5 cm
  • 5G (6 GHz): Wavelength ≈ 5 cm

This means that gaps or holes that might not affect FM radio shielding could significantly impact WiFi or 5G shielding.

Signal Leakage

Hole Size Signal Leakage Example Applications Shielding Effectiveness
λ/10 Minimal Ventilation Holes Excellent
λ/5 Low Mesh Screens Good
λ/2 Moderate Large Vents Fair
λ Significant Openings Poor

λ (lambda) represents the wavelength of the frequency being blocked