How to Select Coaxial Cable Assemblies for Test and Measurement Equipment - Micro Coaxial Cable factory-(FRS)

In the realm of test and measurement (T&M), precision is non-negotiable. Whether calibrating radar systems, validating 5G components, or analyzing signal integrity in aerospace applications, the accuracy of results hinges on every link in the measurement chain. Among these critical links, coaxial cable assemblies stand out as unsung heroes—their performance directly impacts signal fidelity, measurement repeatability, and ultimately, the reliability of data. Choosing the right coaxial cable assemblies for T&M equipment is not merely a technical detail; it is a decision that can make or break the integrity of your testing processes.

This guide breaks down the key considerations for selecting coaxial cable assemblies tailored to test and measurement applications, ensuring your equipment delivers consistent, accurate results even in the most demanding scenarios.

Understanding the Role of Coaxial Cable Assemblies in T&M

Coaxial cable assemblies are designed to transmit high-frequency signals with minimal loss, interference, or distortion—qualities that are paramount in T&M. Unlike standard coaxial cables used in consumer electronics, those for test and measurement must handle a broader range of frequencies (from DC to hundreds of GHz), maintain stable performance across repeated use, and withstand rigorous environmental conditions, from lab benches to field testing.

In T&M setups, these assemblies connect instruments (such as oscilloscopes, spectrum analyzers, and signal generators) to devices under test (DUTs). Any inefficiency in the cable—whether due to signal loss, impedance mismatch, or EMI susceptibility—can introduce errors into measurements, leading to incorrect conclusions, failed certifications, or costly redesigns. Thus, selecting the right assembly requires a deep dive into its technical specifications and how they align with your specific testing needs.

Key Considerations for Selecting Coaxial Cable Assemblies

1. Electrical Performance: The Foundation of Accuracy

Electrical performance is the cornerstone of any coaxial cable assembly for T&M. Three parameters demand primary attention:

• Impedance Matching: Impedance is the resistance a cable presents to the flow of alternating current. For T&M, 50Ω is the standard impedance (75Ω is common in video/audio, but rare in high-frequency testing). Mismatched impedance (e.g., a 50Ω cable connected to a 75Ω instrument) causes signal reflections, measured as Voltage Standing Wave Ratio (VSWR). A VSWR of 1.2:1 or lower is ideal for T&M, as higher ratios indicate significant signal loss and measurement inaccuracy.
• Attenuation: Attenuation refers to signal loss over distance, measured in dB per meter. It increases with frequency—for example, a cable that performs well at 1 GHz may lose 30% of its signal at 18 GHz. For high-frequency T&M (e.g., 5G mmWave testing at 28 GHz or 39 GHz), low-attenuation cables are critical. Look for assemblies with dielectric materials like PTFE (Teflon) or foam polyethylene, which minimize loss at high frequencies.
• Bandwidth: Bandwidth defines the range of frequencies a cable can transmit without significant distortion. T&M applications vary widely—from DC testing in power systems to 110 GHz in advanced radar testing. Ensure the cable’s bandwidth exceeds your maximum test frequency to avoid signal degradation. For example, a cable rated for 67 GHz is unsuitable for 70 GHz mmWave testing, even if it “works”—the resulting signal distortion will compromise data integrity.

2. Mechanical Durability: Withstanding the Rigors of Testing

Test and measurement environments are rarely gentle. Cables are frequently connected, disconnected, bent, and moved—sometimes in tight spaces or harsh conditions. Mechanical durability directly affects lifespan and performance consistency:

• Flexibility and Bend Radius: In lab setups, cables often navigate around equipment, requiring flexibility. However, excessive bending can damage the inner conductor or dielectric, increasing attenuation. Check the minimum bend radius (both static and dynamic) specified by the manufacturer. For example, a cable with a 10mm static bend radius and 20mm dynamic radius is better suited for frequent movement than one with a 25mm static radius.
• Connector Quality: Connectors are the weakest points in any assembly. Poorly designed connectors cause signal reflections, corrosion, and intermittent connections. For T&M, precision connectors like SMA (up to 18 GHz), 3.5mm (up to 34 GHz), 2.92mm (up to 40 GHz), and 1.85mm (up to 67 GHz) are standard. Look for connectors with gold plating (for corrosion resistance) and precision machining (to ensure consistent mating). Avoid “cheap” connectors—they may save cost upfront but lead to frequent replacements and measurement errors.
• Abrasion and Tensile Strength: Cables used in field testing (e.g., aerospace or outdoor telecom) must resist abrasion, moisture, and physical stress. Assemblies with ruggedized jackets (e.g., polyurethane or silicone) and strain relief at the connector-cable junction offer better durability in such environments.

3. Environmental Compatibility: Adapting to Conditions

T&M is not limited to climate-controlled labs. Cables may face extreme temperatures, humidity, vibration, or EMI (Electromagnetic Interference).

• Temperature Range: For industrial or aerospace testing, cables must perform across wide temperatures. Standard lab cables typically operate between -20°C to 70°C, but specialized assemblies can withstand -55°C to 125°C or higher, ensuring stability in engine bays or polar fieldwork.
• EMI Shielding: In noisy environments (e.g., near power lines or high-frequency transmitters), EMI can corrupt signals. Coaxial cables use braided shields (typically copper or aluminum) and sometimes foil layers to block interference. For T&M, a shield coverage of 90% or higher is recommended—some high-performance assemblies offer 95-98% coverage for critical applications like military radar testing.
• Moisture and Chemical Resistance: Outdoor or industrial testing may expose cables to rain, oils, or chemicals. Jackets made from materials like PTFE or ethylene propylene diene monomer (EPDM) resist moisture and chemical degradation, preventing signal loss or cable failure.

4. Application-Specific Requirements

No single coaxial cable assembly works for all T&M scenarios. Your choice must align with your unique application:

• High-Power Testing: Applications like RF amplifier testing require cables that handle high power (up to kilowatts). These assemblies use thicker inner conductors and heat-resistant dielectrics to prevent melting or signal breakdown.
• Phase Stability: In phased-array antenna testing or interferometry, maintaining phase consistency is critical. Phase-stable cables minimize phase drift caused by temperature changes or bending, ensuring measurements remain accurate over time.
• Low-Loss for Long Runs: When testing large systems (e.g., satellite ground stations), cables may need to span meters. Low-loss designs (e.g., those with foam dielectric or silver-plated conductors) reduce signal degradation over distance.

5. Compliance and Quality Assurance

In regulated industries (e.g., aerospace, defense, telecom), compliance with standards is mandatory. Look for coaxial cable assemblies certified to ISO 9001 (quality management), RoHS (environmental safety), or MIL-STD (military specifications). Reputable manufacturers provide test reports for each assembly, verifying VSWR, attenuation, and phase stability—critical for audits and traceability.

Why FRS Stands Out for Test and Measurement Coaxial Cable Assemblies

When it comes to selecting coaxial cable assemblies for test and measurement, FRS has established itself as a trusted partner for engineers and technicians worldwide. With decades of expertise in high-frequency connectivity, FRS designs and manufactures assemblies that meet the most stringent T&M requirements.

FRS coaxial cable assemblies are engineered for precision: every unit undergoes rigorous testing to ensure impedance matching (VSWR < 1.2:1 up to 67 GHz), low attenuation across broad bandwidths (DC to 110 GHz), and exceptional phase stability. Our connectors—from SMA to 1.0mm (for 110 GHz applications)—are precision-machined and gold-plated, ensuring reliable mating and corrosion resistance even after thousands of connections.

Understanding the demands of diverse environments, FRS offers ruggedized options with abrasion-resistant jackets, wide temperature ranges (-55°C to 150°C), and EMI shielding exceeding 95%. Whether you’re testing 5G components in a lab, validating radar systems in the field, or conducting high-power amplifier tests, FRS assemblies deliver consistent performance, test after test.

Backed by ISO 9001 certification and full compliance with MIL-STD and RoHS standards, FRS provides traceable test reports for every assembly, giving you confidence in your measurements. Our team of engineers also offers custom solutions, tailoring cable length, connectors, and materials to your specific T&M needs.

For test and measurement equipment that demands accuracy, durability, and reliability, FRS coaxial cable assemblies are the choice of professionals who refuse to compromise on performance.