Electromagnetic shielding often requires the integration of thick shielding structures in the form of metal casings, walls, or via arrays. These shields typically isolate the entire package from external or internal noise sources. In some cases, they also isolate components within the package. However, integration of shielding structures with the required performance creates miniaturization and fabrication constraints, and results in longer product development cycle times. To address these limitations, a novel approach is presented for component- and package-level shielding. This approach is based on electromagnetic interference (EMI) shield integration through a microassembly of prefabricated shields inside microslots in packages and printed circuit boards (PCBs). This approach eliminates many of the design and process constraints during the shield integration within packages. Various design options were considered to mitigate capacitive and inductive coupling between representative microstrip lines that act as aggressors and victims. Three types of EMI shielding architectures, U-shaped, inverted-L-shaped, and T-shaped, were investigated with 17.5 μm copper. The fabricated EMI shields were studied for their shield performance, both as a compartmental shield between specific components and as a conformal shield from external and internal noises. The role of the ground termination was also investigated to further optimize the shielding performance.
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Novel Metamaterial Design for Electromagnetic Interference Mitigation between Transmission Lines
Electromagnetic compatibility (EMC) is a key requirement for electronic system design. Meeting the EMC regulations becomes more challenging as the component density increases and operation frequencies spread to multiple bands. Coupling between transmission lines is a common manifestation of electromagnetic interference (EMI). In this work, we present a novel method to suppress the noise between two transmission lines by using a metamaterial (MTM) structure. This MTM design helps to mitigate the coupling between the two transmission lines where one acts as an aggressor and the other as the victim. This approach helps miniaturize the solutions such as shielding or filtering to mitigate the noise. MTM provides good protection in terms of EMI isolation, is inexpensive, and has a smaller footprint compared to traditional EMC solutions. The second part of this article studies the impact of the relative permittivity (ε r ) of the MTM structure. Changing the ε r modifies the transmission and absorption bands. Thus, that can help in modulating the operation of the MTM through appropriate designs. The MTM designs used in this work enhanced the isolation between the victim and aggressor by 1–13.5 dB across 1–5 GHz.
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- Award ID(s):
- 2029007
- NSF-PAR ID:
- 10513127
- Publisher / Repository:
- IEEE
- Date Published:
- ISBN:
- 979-8-3503-1554-7
- Page Range / eLocation ID:
- 1 to 5
- Subject(s) / Keyword(s):
- Couplings, Power transmission lines, Electromagnetic interference, Electromagnetic compatibility, Metamaterials, Permittivity, System analysis and design
- Format(s):
- Medium: X
- Location:
- Miami, FL, USA
- Sponsoring Org:
- National Science Foundation
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Abstract Simulation and experimental studies are carried out on single‐layer and double‐layer embedded metal meshes (SLEMM and DLEMM) to assess their performance as transparent electromagnetic interference (EMI) shielding. The structures consist of silver meshes embedded in polyethylene terephthalate (PET). As a transparent electrode, SLEMMs exhibit a transparency of 82.7% and a sheet resistance of 0.61 Ωsq−1as well as 91.0% and 1.49 Ωsq−1. This performance corresponds to figures of merit of 3101 and 2620, respectively. The SLEMMs achieve 48.0 dB EMI shielding efficiency (SE) in the frequency range of 8–18 GHz (X‐ and Ku‐bands) with 91% visible transmission and 56.2 dB EMI SE with 82.7% visible transmission. Samples exhibit stable performance after 1000 bending cycles with a radius of curvature of 4 mm and 60 tape test cycles. DLEMMs consist of fabricating SLEMM on opposite sides of the substrate where the distance can be varied using a spacer. Simulations are performed to investigate how varying spacer distance between two layers of metal meshes influences the EMI SE. DLEMMs are fabricated and achieved an EMI SE of 77.7 dB with 81.7% visible transmission. SLEMMs and DLEMMs may have a wide variety of applications in aerospace, medical, and military applications.
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Abstract Recent advancement in digital coding metasurfaces incorporating spatial and temporal modulation has enabled simultaneous control of electromagnetic (EM) waves in both space and frequency domains by manipulating incident EM waves in a transmissive or reflective fashion, resulting in time-reversal asymmetry. Here we show in theory and experiment that a digitally space-time-coded metamaterial (MTM) antenna with spatiotemporal modulation at its unit cell level can be regarded as a radiating counterpart of such digital metasurface, which will enable nonreciprocal EM wave transmission and reception via surface-to-leaky-wave transformation and harmonic frequency generation. Operating in the fast wave (radiation) region, the space-time-coded MTM antenna is tailored in a way such that the propagation constant of each programmable unit cell embedded with varactor diodes can toggle between positive and negative phases, which is done through providing digital sequences by using a field-programmable gate array (FPGA). Owing to the time-varying coding sequence, harmonic frequencies are generated with different main beam directions. Furthermore, the space time modulation of the digitally coded MTM antenna allows for nonreciprocal transmission and reception of EM waves by breaking the time-reversal symmetry, which may enable many applications, such as simultaneous transmitting and receiving, unidirectional transmission, radar sensing, and multiple-input and multiple-output (MIMO) beamformer.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/DMC58182.2023.10412596
