Micro Coaxial Cable

Measuring the impedance of a micro coaxial cable is essential for ensuring signal integrity in high-frequency applications like medical devices, aerospace systems, smartphones, and compact RF modules. Unlike larger coax, micro coax (like 0.81mm, 1.13mm, or 1.37mm diameter cables) presents unique challenges due to its tiny size. Here’s a reliable, step-by-step method using professional equipment:

Why Micro Coax is Different:

Extremely Small Conductors: Direct probe contact or clamping can easily deform the fragile center conductor and thin dielectric, invalidating the measurement.
Shield Vulnerability: Even gentle pressure can displace the braid or foil shield, altering its impedance characteristics.
Fixtures are Critical: Specialized test fixtures or connectors are almost always mandatory.

Equipment You’ll Need:

Vector Network Analyzer (VNA): Essential for measuring complex impedance (magnitude and phase).
Calibration Standards (Cal Kit): Precisely matched to the connectors you’ll use (e.g., SMA, 2.92mm, 1.85mm). Calibrate the VNA at the fixture planes.
Test Fixtures (Crucial for Micro Coax):
- Jig/Launch Fixtures: Designed with precision grooves or clamps to hold the micro coax perfectly aligned without crushing it. Examples include GGB’s Picoprobe Model 40A/67A series or custom jigs.
- Micro-Coaxial Connectors: Cable assemblies terminated with precision micro-coaxial connectors compatible with your VNA ports.
- RF Probes (e.g., Wafer Probes): Ground-Signal-Ground (GSG) or Ground-Signal (GS) probes with tip pitches matching the cable’s scale. Require extremely careful handling and specialized probe stations.
Connectorization: Professionally soldering or crimping precision micro-coax connectors to the cable ends, providing stable VNA interfaces.
Cable Preparation Tool: Sharp coax stripper specific to the exact cable size for clean, length-controlled access to center conductor and shield without nicking.

Step-by-Step Measurement Process:

Prepare the Sample: Cut a clean length of micro coax. If using connectors, have them professionally installed per manufacturer specs. If using a jig/probe station, carefully prepare the cable ends: strip the jacket precisely to expose a controlled length of the shield, then carefully strip the dielectric to expose a controlled length of the center conductor, ensuring no deformation.
Connect/Install in Fixture:
- **(Connectors):** Connect directly to VNA Ports 1 and 2.
- **(Jig):** Secure the prepared cable ends into the jig’s grooves or clamps following instructions. Crucial: Apply minimal pressure – just enough to ensure good electrical contact without deforming the cable structure.
- **(Probes):** Carefully lower the probes onto the prepared center conductor and shield points on each end. Use microscope alignment. Apply minimum pressure for contact.
VNA Calibration: Perform a full 2-port calibration (SOLT – Short, Open, Load, Thru) at the point of contact. This removes errors from VNA, cables (if any), and test fixture up to the cable interfaces.
- For jigs/probes: Calibrate using standards mounted within the jig/probe station itself if possible, or directly at the probe tips.
- For connectors: Calibrate at the connector end-face.
Measure S-Parameters:
- Set the VNA frequency range appropriate for your application (e.g., DC to 20+ GHz for many micro coax).
- Ensure the VNA sweep covers the relevant frequencies for your application.
- Measure the full 2-port S-parameters (S11, S21, S12, S22).
Convert to Impedance (Z): Use the VNA’s built-in math functions:
- S11 to Input Impedance (Port 1): Measure S11. Use the VNA’s S11 to Z function (or Smith Chart display). For a precise characteristic impedance (Z₀) measurement over a length, the method below is preferred.
- Calculating Characteristic Impedance (Z₀) Directly (Best Method): For a section of uniform line (your cable), Z₀ = √(Z_short * Z_open). Measure the cable with the far end terminated:
  - Terminate the cable at Port 2 with a high-quality SHORT circuit. Measure the input impedance at Port 1 (Z_short).
  - Terminate the cable at Port 2 with a high-quality OPEN circuit. Measure the input impedance at Port 1 (Z_open).
  - Calculate: Z₀ = sqrt(Z_short * Z_open). Modern VNAs often automate this calculation as a complex result across frequency.
Review Results: Look at the Smith Chart or the complex Z trace (Real & Imaginary parts) vs. Frequency.
- Ideal Behavior: Z₀ should be relatively constant across the usable frequency range of the cable (specified by manufacturer). Real part should be near nominal (e.g., 50 Ohms), Imaginary part near 0 Ohms.
- Deviations: Large spikes, dips, or significant changes in Real/Imag parts indicate potential measurement errors (poor calibration, fixture issue) or cable defects. Consistent offset may indicate nominal impedance differs from target.

Key Considerations & Tips:

Gentle Handling is Paramount: Micro coax measurement is an exercise in precision and care. Avoid any kinking, bending, or excessive force.
Fixtures Determine Accuracy: The quality and correct usage of your jig, probes, or connectors determine the accuracy more than the VNA itself. Invest in good fixtures or accurate termination.
Calibration is Sacred: Any calibration mistake ruins the measurement. Double-check standards and connections.
Length Matters: For Z₀ calculation via short/open method, the cable section needs to be long enough to provide a clear measurement but not so long that losses dominate at high frequencies.
Use Manufacturer Specs: Compare your measured Z₀ to the cable manufacturer’s specifications. Minor variations are normal, significant deviations suggest a problem.
Reference Plane: Be mindful of where the calibration reference plane is set. You want it right at the cable interface.
Alternative: TDR: Time Domain Reflectometry (TDR) with a sampling oscilloscope and suitable high-bandwidth fixture can measure impedance, but a VNA provides superior accuracy and frequency-domain insight for micro coax.

Conclusion:

Accurately measuring micro coax impedance requires specialized fixtures (jigs, probes, or precision connectors) and careful VNA calibration at the point of contact. Avoid direct clamping or probing of the fragile cable body. Prepare cable ends meticulously. Use the short/open termination method with your VNA’s S-parameter measurements and the calculation Z₀ = sqrt(Z_short * Z_open) for the most reliable determination of characteristic impedance across frequency. Precision, care, and good calibration are the keys to success. Always cross-reference your results with the cable manufacturer’s data sheet for your specific part number.

The relentless pursuit of lighter, faster, and more capable aerospace platforms demands technological advancements in every component, down to the wire. Micro-coaxial cables (micro-coax) stand at the forefront of this evolution, serving as the indispensable high-performance interconnect solution powering critical data transmission, radar systems, communication links, and navigation functions in aircraft, spacecraft, satellites, and UAVs. Their unique ability to operate reliably in the unforgiving aerospace environment makes them not just components, but foundational enablers of modern aerospace deve.

Neural recording technology has revolutionized our understanding of the brain’s complex functions, enabling breakthroughs in neuroscience research, clinical diagnostics, and neuroprosthetics. At the heart of this technology lies a critical component: micro-coaxial cables. Unlike conventional cables, these ultra-miniature transmission lines are engineered to meet the unique demands of neural interfaces—delivering high-fidelity signal transmission, biocompatibility, and mechanical flexibility in constrained biological environments. The Unique Demands of Neural Recording on Micro-Coaxial Cables Neu.

Addressing the Signal Integrity Challenges in AVs‌High-Frequency Demands‌‌Sensor Type‌:‌LiDAR‌: Operates at 905 nm or 1550 nm wavelengths, requiring cables handling 10–100 Gbps.‌79 GHz Radar‌: Demands cables stable up to 110 GHz for precise object detection.‌Issue‌: Traditional cables suffer from skin effect losses (>3 dB/m at 77 GHz) and phase instability (±5°/m).‌Micro-Coax Solution‌: Silver-plated conductors and air-enhanced PTFE dielectrics reduce attenuation to ‌0.8 dB/m at 100 GHz‌.‌Harsh Environmental Conditions‌‌Temperature Swings‌: -40°C to +125°C in engine compartments.‌Vibration‌: Up to 20.

In the relentless push for smaller, faster, and more connected devices, reliable high-frequency signal transmission has become mission-critical. Whether it’s inside the latest medical imaging device, a 5G base station, or a cutting-edge aerospace sensor, signals need to travel flawlessly. This is where the demand for custom-configured micro-coaxial cable assemblies is experiencing a significant surge. Let’s explore why this trend is accelerating and how it solves real-world engineering challenges. The Problem: Off-the-Shelf Often Falls Short Standard cable assemblies have their place.

Introduction The miniaturization of electronic devices demands precision in micro-coaxial cable design, where traditional methods face bottlenecks in efficiency and performance prediction. AI-powered tools are revolutionizing this niche by solving three critical pain points: signal integrity optimization, manufacturing cost reduction, and rapid prototyping. Key AI Applications and Benefits 1. Predictive Modeling for Signal Loss Mitigation AI algorithms (e.g., neural networks trained on S-parameter datasets) can simulate electromagnetic behavior under varying frequencies with 95%+ accuracy,.

Choosing the right cable for your project can be confusing, especially when faced with terms like “micro coaxial” and “standard coaxial.” While both transmit signals efficiently, they serve very different purposes. Understanding their key differences is crucial for making the right choice. Let’s break it down clearly. What is Coaxial Cable? (The Core Concept) Both types share the same fundamental design, often called “coax”: Center Conductor: Carries the main electrical signal. Dielectric Insulator: Surrounds the center conductor, maintaining it.

Can't find what you're looking for?

Our customer support team is ready to assist you with any questions or concerns.

Search FAQs

Cable Pulling Tools for Easy Installation

Installing cables, whether for electrical systems, data networks, or telecommunications, can be a challenging task without the right tools.

How to choose Coaxial Cable Assemblies for radio systems

Selecting the right coaxial cable assemblies is critical for optimizing the performance, reliability, and longevity of radio systems. Whet.

How to Select Micro Coaxial Cable Specifications

Define Transmission Requirements‌‌Frequency & Bandwidth‌: Choose cables based on signal type and frequency range. For example:‌High-f.

What is a flexible micro coaxial cable and why it’s ideal for foldable phones

Introduction In a foldable phone, two or more rigid printed circuit boards must move relative to each other through a hinge while maint.

Cable Trays and Ladders for Commercial Installations

In the complex web of electrical and data systems that power modern commercial buildings, cable management is a critical yet often overloo.

What is a 90Ω micro coaxial cable and why it’s used for MIPI DSI/CSI‑2 links

Introduction MIPI interfaces—MIPI DSIfor displays and MIPI CSI‑2for cameras—are now the default high‑speed, low‑power links in mobile, .

1.13mm micro coaxial cable - Micro Coaxial Cable factory-(FRS)

How to Measure the Impedance of a Micro Coaxial Cable