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• The NASA 3D printed EMI shield project will serve to determine the viability of conductive 3D printing filaments as RF absorbers.

• NASA spares many line replaceable units on campaigns, adding a significant amount to the overall launch mass.

• Investigating 3D printing materials and their mechanical, thermal and in this case electrical properties could allow NASA to 3D print many of their spared parts, drastically reducing launch mass.

• The focus will be on creating an insertion loss absorber to attenuate the interference, with minimal reflections, to mitigate the amount of interference in the environment.

• The absorber designs will go through simulation scrutiny using an electromagnetic solver software, as well as physical testing. This allows for theoretical and real-world comparisons, as well as alleviating stresses on the project budget.

Project Description Next Semester PlansApproach

1.9 – 3D Printed EMI Shield

Daniel Valle, Isabella Collins, Robert Castorena, Josh De LongChatwin Lansdowne – NASA Johnson Space Center

• Parameter measurements received from Damaskos Inc. will be used to create a material model in our simulation software (as seen in bottom-right graph of Approach section).

• With this information, frequency sweeps can be performed in our simulator to predict how the materials will attenuate/reflect signals over our frequency range of interest.

• Absorption tests will be conducted by placing printed test plates between two waveguides. The measured S-parameters will reveal the plates EMI absorbing abilities.

• Comparisons between simulated and measured results will be made.

Materials• Multi3D LLC’s Electrifi filament (16667 S/m)• Black Magic 3D’s Conductive Graphene

(166.67 S/m) • Proto-Pasta’s Conductive Graphite (6.667

S/m)Simulations• Samples of the materials have been sent to

Damaskos Inc. to obtain the permittivity and permeability of each material.

• Simulations will be made using the information we receive from Damaskos Inc. to create material profiles. Shape and thickness of the materials will be varied in our simulations to determine the optimal absorber design.

Testing• Plates of varying thicknesses and infill

percentages (based off simulations) will be fabricated. If time allows, we will print more complex geometries.

• Prints will be tested by placing them between two waveguides and measuring the S11 and S21

parameters.

EMI absorbers are used to attenuate electromagnetic energy. Insertion loss absorbers attenuate signals traveling from point A to point B[1].

Background

Stretch Goals

Acknowledgements

Horn Antenna template in CST Studio Suite

𝑍𝐿 = 𝑍𝑐 =𝜇∗

휀∗

Performance of EMI absorbers can be treated as a transmission line problem with two major considerations – impedance matching and attenuation in dB/cm.

Performance Parameters

ParameterTest Conditions Min Max Units How Tested

Signal Attenuation

f = 0.8-6GHz 20 dB Power ratio change when receiving antenna is shielded as seen by connected network analyzer

Impedance Matching

f = 0.8-6GHz 377 Ω Input impedance of the absorber will be measured as a function of frequency

Reflected power

f = 0.8-6GHz -10 dB Damaskos Model 8 Thin Sheet Tester can measure reflections going back into waveguide cavity

Polarization f = 0.8-6GHz 0 360 degrees Absorber performance tested at various orientations

References

Dr. Chen Dr. CompeauMr. Chatwin LansdowneMr. Sagar Navle

[1]Forum.nasaspaceflight.com. (2018). Theory and Application of RF/Microwave Absorbers. [online] Available at: http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36313.0;attach=829404 [Accessed 27 Feb. 2018].

Attenuation (dB/cm) =

2𝜋(8.686)

λ0𝜇′𝜀′

2( 1 + 𝑡𝑎𝑛2𝛿𝑒)(1 + 𝑡𝑎𝑛2𝛿𝑚) − 1 − 𝑡𝑎𝑛𝛿𝑒𝑡𝑎𝑛𝛿𝑚 )

휀∗ = 휀′ − 𝑗휀′′ 𝜇∗ = 𝜇′ − 𝑗𝜇′′

𝑡𝑎𝑛𝛿𝑒 =𝜀′′

𝜀′𝑡𝑎𝑛𝛿𝑚 =

𝜇′′

𝜇′

(Left) Damaskos Thin Sheet Tester (Right) Illustration of 3D printing infill percentages

Dielectric/Magnetic dispersion model parameter entries in CST Studio Suite

Gain pattern change when shielded with ECCOSORB MF-117