48nH 20T Air Core Inductor Extreme Temp Immune RF Choke Inductor Zero Hysteresis High Efficiency

HALA2000303R 48nH 20T Air Core Inductor Extreme Temp Radiation Immunity Zero Hysteresis Loss High Efficiency RF Coil

The 20-Turn Achievement: How 48nH Fits in Less Than 1mm³

At first glance, fitting 20 turns of wire into a volume smaller than a millimeter cube appears physically impossible. The HALA2000303R 48nH ±20% 20-turn air core inductor achieves this through a 0.03mm (30µm) enameled copper wire — approximately half the diameter of a human hair — precision-wound on a 0.30mm hollow inner mandrel. Each turn adds approximately 2.4nH of inductance (48nH ÷ 20 turns), a figure achieved through tight turn-to-turn coupling and the 90° relative angle between the winding helix and the magnetic flux axis. The result: 48nH of inductance in a volume of approximately 0.5mm³, equivalent to the inductance density of a multi-layer ferrite chip inductor but without the magnetic core losses, saturation, or temperature drift that constrain ferrite-based components.

The 20 turns are precision-wound under controlled tension (±2mN) with active shape retention — the copper wire is deformed slightly beyond its elastic limit during winding to create a permanent helical set. When released from the mandrel, the 20-turn coil retains its as-wound geometry with inter-turn pitch uniformity within ±8%, verified by in-line machine vision at the winding station. This repeatable winding geometry ensures unit-to-unit inductance consistency within the ±20% tolerance band without requiring post-winding tuning.

Extreme Temperature & Radiation Immunity: No Parameters Drift, No Matter the Environment

The air-core inductor's operating temperature specification (-55°C to +125°C) is not a reliability limit — it is a parametric stability guarantee. Unlike ferrite-core inductors where the permeability (μᵣ) of the core material drifts with temperature, the HALA2000303R's inductance depends solely on μ₀ (the permeability of free space, a fundamental constant) and physical geometry. The only temperature-dependent variable is the thermal expansion of copper, which changes inductance by approximately +0.04% at +125°C relative to room temperature — a shift of approximately 19 pH on a 48nH nominal. For comparison, a typical NiZn ferrite core inductor can exhibit 20-30% inductance drift across the same temperature range from μᵣ temperature coefficient alone.

Radiation hardness is equally fundamental. Total ionizing dose (TID) mechanisms — oxide trapped charge, interface states, threshold voltage shifts — are exclusively semiconductor phenomena. An air-core inductor contains no semiconductor material, no gate oxide, no PN junction. A 100-krad(Si) accumulated dose leaves the inductance, Q factor, and SRF unchanged because there is nothing to be damaged. Displacement damage from neutron or proton fluence cannot alter μ₀ or copper conductivity enough to measurably affect performance. Single-event latchup cannot occur because there is no latch to trigger. For equipment destined for environments where repair is impractical, the HALA2000303R eliminates passive-component radiation effects as a failure mechanism — it is as radiation-immune as Maxwell's equations themselves.

Zero Hysteresis Loss for Peak Efficiency at Every Power Level

Ferrite-core inductors dissipate energy every RF cycle. As the magnetic field sweeps through the ferrite's B-H hysteresis loop, the area enclosed by the loop represents energy lost as heat — a loss that increases with frequency, field amplitude, and core temperature. At 10GHz and above, ferrite hysteresis losses dominate the inductor's equivalent series resistance, eroding Q factor and wasting RF energy that could be reaching the antenna or receiver.

The HALA2000303R has a B-H "loop" that is a perfectly straight line through the origin (B = μ₀H). The area enclosed is zero. The loss is zero. The magnetic field in free space has no hysteresis mechanism — every increment of magnetizing force produces a proportional increment of flux density, and when the field reverses, the flux follows exactly the same line in reverse. This linear, lossless B-H relationship means the inductor's Q factor is limited only by the copper wire's DC and AC resistance — not by magnetic core loss. At 18GHz, the skin depth in copper is approximately 0.49µm, and the 0.03mm wire (30µm diameter) has a surface-area-to-volume ratio that keeps AC resistance manageable despite the fine gauge. The resulting unloaded Q exceeds 80 across the 1-18GHz band — a figure unattainable by any ferrite-core inductor of comparable size and inductance.

This efficiency gain is particularly valuable in:

• Transmit power chains: Every 0.1dB of bias tee insertion loss represents wasted DC power, increased thermal dissipation, and reduced transmit power. Zero hysteresis loss means the HALA2000303R's insertion loss at the bias tee is purely resistive (I²R) — predictable, linear, and independent of signal power.
• Low-noise receiver front-ends: Hysteresis loss in ferrite-core bias chokes creates a non-linear impedance that can mix out-of-band interferers into the receive band. The air-core's perfectly linear B-H relationship eliminates this source of receiver desensitization.
• Phased-array element matching: In multi-element arrays with hundreds of LNAs, even 0.05dB of excess insertion loss per element compounds to measurable system-level noise figure degradation. Zero hysteresis loss per inductor preserves the array's cumulative noise figure budget.

HALA Portfolio: 20-Turn vs 12-Turn Cross-Reference

Self-Resonant Frequency: Why 48nH at 18GHz Works

Every inductor has a self-resonant frequency (SRF) where parasitic inter-winding capacitance resonates with the inductance, creating a parallel resonance that renders the inductor useless as a choke above that frequency. The HALA2000303R's SRF is above 22GHz — comfortably beyond its 18GHz rated operating ceiling — achieved through three design factors: (1) the single-layer air-spaced helix creates only 11 inter-turn capacitors in series (N−1 = 19 small, low-value capacitors, not a large parallel stack), (2) the air dielectric (εᵣ=1.0) produces 10-15* lower capacitance per gap than ferrite-core geometries, and (3) the 0.03mm wire creates minimal turn-to-turn overlap area. This SRF margin above 22GHz ensures the inductor's impedance remains inductive (not capacitive) across the full 1.0-18.0GHz rated band — a critical requirement for bias tee applications where a capacitive impedance at the RF port would short the signal to the DC supply.

Key Specifications

Assembly Guidance for 20-Turn High-Density Coils

• Factory Pre-Stripped & Pre-Tinned Leads: Both leads arrive pre-stripped and pre-tinned from the winding station — no manual enamel scraping, no pre-fluxing required. The tinning covers the full lead length from tip to coil root with zero bare copper gaps. This continuous tinning eliminates the oxidation-prone boundary region that causes solderability degradation during storage. Combined with moisture-barrier packaging at 20-25°C/40-60%RH, solderability is guaranteed for 1 year from delivery per J-STD-002.
• Orthogonal Fields, 20-Turn Criticality: With 20 turns generating a proportionally stronger magnetic flux density than 6/8/10/12-turn variants, the HALA2000303R imposes stricter perpendicularity requirements. A 10° deviation from perpendicular increases near-field coupling by 4-6dB at 10GHz — approximately double the coupling sensitivity of a 12-turn design. Verify orthogonal alignment under minimum 10* stereo microscope inspection before soldering.
• Parasitic Stub Elimination at 48nH: Excess lead length adds approximately 0.8-1.0nH/mm of parasitic series inductance. At 48nH nominal, even 0.5mm of excess lead represents a 1% inductance error that shifts the SRF downward by 2-3%. Trim leads to absolute minimum length after soldering. For circuits where post-solder trimming is impractical, specify the trimmed-lead variant.
• Minimum Lead Length: Trim leads to absolute minimum — excess lead adds approximately 0.8-1.0nH/mm of parasitic series inductance. At 48nH nominal, even 1mm of excess lead is a 2% parasitic addition that shifts SRF downward.
• Micro-Soldering: The 0.03mm wire requires a 10* stereo microscope for positioning. Use non-magnetic ceramic tweezers. SAC305 or Sn63/Pb37, tip ≤260°C, ≤3s dwell. The thin wire has minimal thermal mass — longer dwell times risk enamel damage or copper melting.
• Post-Solder Fixation: After tuning, micro-droplet of low-dielectric adhesive (H20E). The 20-turn coil is more sensitive to vibration-induced detuning than fewer-turn variants due to the higher inter-turn count — mechanical fixation is mandatory.

Applications

• Multi-Octave Bias Tees (1-18GHz): 48nH delivers j302Ω at 1GHz through j5.4kΩ at 18GHz — impedance increasing monotonically with frequency, which is ideal for bias tee topologies where amplifier gain typically rolls off at higher frequencies. This 18:1 impedance ratio from a single inductor value eliminates band-switched bias network complexity in L/S/C/X/Ku-band systems.
• Ultra-Wideband Low-Noise Amplifiers: Zero hysteresis loss preserves the LNA's noise figure across the entire 1-18GHz band. Radiation-immune operation for avionics and ground station receivers.
• Electronic Test & Measurement Front-Ends: Linear, hysteresis-free B-H response ensures the bias choke does not introduce non-linear artifacts that could corrupt spectrum analyzer or VNA measurements.
• Wideband Signal Intelligence (SIGINT) Receivers: 1-18GHz continuous coverage with zero core distortion and radiation immunity supports persistent monitoring applications in uncontrolled environments.

Contact us for evaluation samples, S2P Touchstone data from 10MHz to 18GHz, and application engineering support for your specific bias network design.