Technical Procurement Authority
In military, government, and intelligence environments, electronic processing equipment generates unintended electromagnetic emissions. These conductive and radiated emissions—known in defense standards as TEMPEST signals—can be intercepted and decoded by hostile entities to reconstruct classified data, voice communications, or cryptographic keys.
Astrodyne TDI designs and manufactures specialized Tempest EMI Filters that construct an impenetrable electromagnetic barrier across AC/DC power lines, control lines, and data interfaces entering or exiting shielded enclosures. By deploying feed-through filter topologies, advanced soft-magnetic core materials, and Hermetically sealed enclosures, our filter assemblies attenuate parasitic noise by up to 100 dB across broad frequency spectrums (from 10 kHz to 10 GHz and beyond).
Whether you are outfitting a NATO SDIP-27 compliant Sensitive Compartmented Information Facility (SCIF), hardening a tactical mobile shelter against HEMP/EMP threats, or securing server racks in defense cloud centers, our engineering teams provide full design, pre-compliance validation, and production support.
Product Recommendations
Explore our portfolio of standard and engineered-to-order Tempest filter configurations. Every unit undergoes rigorous 100% functional testing, dielectric withstand verification, and insertion loss screening prior to deployment.
Engineered for high-security single-phase AC equipment and server enclosures. Delivers 100 dB insertion loss from 10 kHz to 10 GHz with minimal voltage drop and low thermal rise under continuous rated load.
Designed for 3-wire high-power industrial and tactical distributions without neutral. Eliminates common-mode and differential-mode noise coupling across severe military operational spectrums.
Tailored for 4-wire systems with neutral conductors. Incorporates dedicated ultra-high attenuation filtering components on the neutral line to prevent backdoor intelligence leakage.
Dual-rated protection combining high-level Tempest security with high-altitude electromagnetic pulse (HEMP) surge suppressors to shield entire facility power feeds against electronic warfare.
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Compact, ultra-low capacitance feed-through filtering units engineered for copper telemetry lines, intercoms, and peripheral interfaces crossing shielded facility walls without signal degradation.
Integrated power panels combining custom Tempest filters, main breakers, transient surge arrestors, and current monitoring instrumentation inside custom MIL-STD shock-mounted enclosures.
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Engineering Insight — Insertion Loss Mechanics
Standard commercial EMI filters generally focus on conducted emissions from 150 kHz to 30 MHz. In contrast, Tempest EMI Filters must maintain an insertion loss profile exceeding 100 dB from frequencies as low as 10 kHz all the way up to 10 GHz. Achieving this performance requires addressing parasitic resonance, internal capacitive crosstalk, and inductive saturation.
Compliance Engineering
One of the primary engineering trade-offs when specifying high-attenuation Tempest power filters is managing line-to-ground earth leakage current. Large Y-capacitors essential for 100 dB low-frequency attenuation can introduce substantial reactive leakage currents at 50 Hz/60 Hz/400 Hz utility frequencies, posing personnel safety risks and triggering breaker trips on tactical power grids.
Strategic Procurement Insights
As defense electronics transition toward wide-bandgap semiconductors, higher power density, and cloud-connected tactical edge computing, procurement directors must evaluate several evolving technological trends.
Next-generation defense power converters utilize Silicon Carbide (SiC) and Gallium Nitride (GaN) switches operating at high dV/dt rates. This generates intense high-frequency conducted noise up to several hundred megahertz. Modern Tempest filters must integrate advanced HF absorption materials to prevent high-order harmonic radiation without increasing total footprint.
Procurement specs increasingly combine TEMPEST information security requirements with High-Altitude Electromagnetic Pulse (HEMP) survivability into a single integrated line filter assembly. Combining high-energy Metal Oxide Varistors (MOVs) and spark gaps with 100 dB Tempest filtering eliminates the need for separate cascaded enclosures, reducing facility installation costs and space constraints.
Facility engineers require modular, pre-tested penetration panels that can be rapidly bolted or welded directly to shielded enclosure walls. Future procurement standards favor drop-in filters equipped with integrated RF gaskets, precision ground flanges, and tool-less maintenance access to minimize field assembly errors and ensure airtight RF shielding integrity.
Why OEMs & Defense Contractors Choose Astrodyne TDI
Selecting a supplier for Tempest EMI Filters requires complete confidence in engineering rigor, material traceability, and manufacturing quality control. A single breach in filter performance can compromise confidential communications or fail facility accreditation inspections.
Astrodyne TDI brings six decades of specialized power conversion and electromagnetic filter manufacturing experience. Our fully integrated US and global manufacturing facilities operate under stringent ISO 9001:2015 and ISO 13485 quality management systems.
In-house electromagnetic modeling, proprietary core winding, and customized filter topologies.
Hardened against extreme thermal shock, shock/vibration, and environmental moisture (MIL-STD-810).
ISO 9001:2015 & ISO 13485 certified facilities with end-to-end component traceability.
Direct technical sales support, distributor networks, and defense supply chain compliance.
Engineering FAQ
Get expert technical answers to common queries asked by systems integrators, defense procurement officers, and facility shielding engineers when selecting Tempest filtering solutions.
A Tempest EMI Filter is engineered specifically to prevent compromising emanations (unintentional electromagnetic radio-frequency signals) from escaping sensitive tactical hardware, cryptographic suites, or shielded facility boundaries (SCIFs). While standard commercial EMI filters focus primarily on passing regulatory conducted emission tests (such as CISPR 32 or FCC Part 15) between 150 kHz and 30 MHz, Tempest filters deliver extreme insertion loss—typically 100 dB attenuation across a massive spectrum from 10 kHz to 10 GHz and beyond.
Structurally, Tempest filters feature heavy-duty multi-cavity metallic enclosures, feed-through capacitor construction, high-permeability magnetic chokes, and specialized RF grounding interfaces to eliminate radiative leakage bypass paths.
Tempest EMI filters are designed to satisfy demanding international compromise-emanation and electromagnetic compatibility standards, including:
Achieving 100 dB insertion loss at lower frequencies (10 kHz to 100 kHz) traditionally requires large line-to-ground Y-capacitors. However, large Y-capacitors increase AC earth leakage currents at fundamental line frequencies (50 Hz/60 Hz/400 Hz), which can trip Residual Current Devices (RCDs) or present electrical safety hazards to operators touching ground enclosures.
Astrodyne TDI overcomes this challenge by utilizing proprietary magnetic circuit designs, high-permeability nanocrystalline core materials, multi-stage common-mode inductance networks, and balanced filter topologies. This approach achieves maximum stop-band attenuation while maintaining ground leakage currents well within safe limits specified by military and industrial electrical codes.
3-Phase Delta Tempest Filters: Designed for 3-wire three-phase power distribution systems without a distributed neutral line. They filter line-to-line and line-to-ground common-mode and differential-mode noise across all three phase conductors.
3-Phase WYE Tempest Filters: Engineered for 4-wire three-phase distributions that include a neutral conductor. In WYE architectures, compromising noise signals can bypass 3-wire filters by propagating along the neutral line. Therefore, Astrodyne TDI's 4-wire WYE Tempest filters incorporate high-attenuation filtering components on the neutral line, ensuring full 100 dB attenuation across all phase lines and neutral simultaneously.
Proper physical installation is critical to maintaining shield integrity. Astrodyne TDI offers multiple mounting and penetration configurations for Tempest facility filters, including:
Yes. Many defense and high-security programs involve custom mechanical envelopes, non-standard operating voltages (such as 400 Hz naval grid power or 28 VDC/270 VDC military buses), or unique connector requirements (such as MIL-DTL-38999 circular connectors). Our engineering team works directly with your mechanical and electrical design leads to modify standard platforms or build custom ground-up Tempest filter assemblies tailored to your exact system requirements.
Procurement managers and engineering specialists can immediately access complete technical literature and catalog specifications by clicking the Get Catalog button on this page. For project-specific quotes, custom mechanical envelope requests, or compliance reviews, contact our technical sales team directly or use our online Talk to an Engineer interface.
Download our complete EMI/EMC shielding catalog or speak directly with an application engineer to review your insertion loss and facility compliance specifications.
