Coaxial Cable Assembly: Custom vs Off-the-Shelf Solutions
A comprehensive guide to help engineers and procurement teams decide between custom and standard coaxial cable assemblies—covering cable types, connector options, impedance matching, and cost-benefit analysis.
Table of Contents
1. What is a Coaxial Cable Assembly?
A coaxial cable assembly consists of a coaxial cable terminated with connectors at one or both ends, ready for immediate installation. The term "coaxial" refers to the cable's construction: a central conductor surrounded by insulation, a metallic shield, and an outer jacket—all sharing a common geometric axis.
Coaxial cables are designed to transmit high-frequency electrical signals with minimal interference. Unlike standard wire harnesses that simply conduct electricity, coaxial assemblies maintain signal integrity through their controlled impedance design—a critical factor for RF, video, and data transmission applications.
Key Components of a Coaxial Cable:
- Center Conductor: Solid or stranded copper/copper-clad steel carrying the signal
- Dielectric Insulation: PE, PTFE, or foam separating conductor from shield
- Metallic Shield: Braided copper, foil, or combination for EMI protection
- Outer Jacket: PVC, PE, or LSZH protection against physical damage
The global cable assembly market reached USD 178.90 billion in 2024 and is projected to grow to USD 253.81 billion by 2030. Within this market, custom coaxial assemblies represent a significant segment, driven by increasing demand in telecommunications, aerospace, defense, and medical device industries.
2. Understanding Coaxial Cable Types
Coaxial cables are designated by "RG" numbers (Radio Guide), a classification system originally developed by the U.S. military. While dozens of RG types exist, the most commonly used in commercial and industrial applications are RG58, RG59, RG6, RG11, and RG213/214 for high-power applications.
| Cable Type | Impedance | OD (mm) | Frequency | Primary Applications |
|---|---|---|---|---|
| RG58 | 50Ω | 4.95 | DC - 3 GHz | RF communications, ham radio, test equipment |
| RG59 | 75Ω | 6.15 | DC - 1 GHz | CCTV, analog video, short-run broadcast |
| RG6 | 75Ω | 6.86 | DC - 3 GHz | CATV, satellite, digital video |
| RG11 | 75Ω | 10.3 | DC - 3 GHz | Long-distance CATV, trunk lines |
| RG174 | 50Ω | 2.79 | DC - 1 GHz | GPS, WiFi antennas, space-constrained applications |
| RG213/214 | 50Ω | 10.3 | DC - 11 GHz | High-power RF, military, broadcast |
| LMR-400 | 50Ω | 10.3 | DC - 6 GHz | Cellular base stations, low-loss applications |
RG58 vs RG59: Don't Confuse Them!
Despite similar names, RG58 (50Ω) and RG59 (75Ω) serve completely different purposes. Using the wrong impedance cable will cause signal reflection, standing waves, and potential equipment damage. Always verify impedance requirements before specifying cable type.
Attenuation Comparison
Signal attenuation (loss) increases with frequency and cable length. This is particularly critical when selecting cable for long runs or high-frequency applications:
| Cable Type | @ 100 MHz | @ 400 MHz | @ 1 GHz | @ 2.4 GHz |
|---|---|---|---|---|
| RG58 | 5.3 dB/100ft | 11.2 dB/100ft | 21.5 dB/100ft | 35.8 dB/100ft |
| RG6 | 2.0 dB/100ft | 4.3 dB/100ft | 6.8 dB/100ft | 11.5 dB/100ft |
| LMR-400 | 1.5 dB/100ft | 3.0 dB/100ft | 4.8 dB/100ft | 7.6 dB/100ft |
3. Custom vs Off-the-Shelf: Key Differences
The decision between custom and off-the-shelf (OTS) coaxial cable assemblies affects your project's cost, lead time, and performance. Understanding the trade-offs helps make the right choice for your application.
Custom Coaxial Assemblies
- Exact lengths—no excess cable to manage
- Any connector combination possible
- Enhanced shielding options available
- Custom labeling and color coding
- Test reports and traceability
- Specialty jacket materials (PTFE, silicone)
Typical Lead Time: 2-4 weeks
MOQ: Often 10-25 pieces
Off-the-Shelf Assemblies
- Immediate availability from stock
- Lower unit cost for standard configs
- No minimum order quantity
- Consistent, proven quality
- Easy replacement and spare parts
- Multiple supplier options
Typical Lead Time: Same day to 3 days
MOQ: 1 piece
"I've seen engineers spend hours routing excess cable from off-the-shelf assemblies through cable trays, only to create EMI issues from the coiled excess. A custom-length cable costs a few dollars more but saves installation time and improves system performance. The math almost always favors custom for production quantities above 25 units."
— Hommer Zhao, WireHarnessProduction
4. When to Choose Custom Coaxial Assemblies
Custom coaxial cable assemblies are particularly valuable for applications where standard solutions fall short. Here are the scenarios where custom makes the most sense:
1. Aerospace & Defense Applications
Military and aerospace systems demand cables that perform from -55°C to +200°C, withstand extreme vibration, and meet MIL-SPEC requirements. Semi-rigid coaxial cables are often customized with specific bend configurations for radar systems, avionics, and satellite communications.
2. Medical Device Integration
Medical wire harness manufacturers often produce custom coaxial assemblies for ultrasound probes, patient monitoring, and diagnostic imaging. These require biocompatible materials, precise impedance control, and cleanroom assembly.
3. Tight Space Constraints
When equipment enclosures don't allow for standard cable lengths or bend radii, custom assemblies solve the problem. Right-angle connectors, specific jacket colors for identification, and exact-length cables eliminate routing challenges.
4. Production Quantities Over 25 Units
The economies of scale tip toward custom assemblies once you're ordering more than 25 pieces. Setup costs get amortized, per-unit pricing improves, and you eliminate the labor cost of managing excess cable lengths.
5. Harsh Environment Requirements
Applications exposed to UV, chemicals, extreme temperatures, or continuous flexing need specialized materials. Custom assemblies can specify PTFE dielectrics, double-shielded construction, and outdoor-rated jackets not available in standard products.
5. When Off-the-Shelf Solutions Make Sense
Off-the-shelf coaxial assemblies aren't just a compromise—they're often the optimal choice for many applications. Leading suppliers like L-com offer over 375 models covering most standard configurations.
Ideal Scenarios for Off-the-Shelf:
- Prototype development and testing
- Laboratory test setups
- Maintenance and replacement needs
- Standard CCTV installations
- Consumer electronics integration
- Low-volume production (under 25 units)
- Urgent project timelines
- Standard home/office networking
Many organizations use a hybrid approach: off-the-shelf for prototypes and R&D, then transition to custom assemblies for production. This balances speed-to-market with cost optimization. See our guide on custom cable assembly process for transitioning from prototype to production.
6. Connector Types for Coaxial Cables
Selecting the right connector is just as important as choosing the cable. Connectors affect impedance matching, frequency performance, durability, and ease of installation. Here's a comprehensive guide to common coaxial connectors:
50Ω RF Connectors (Signal Transmission)
| Connector | Frequency | Coupling | Best For |
|---|---|---|---|
| BNC (50Ω) | DC - 4 GHz | Bayonet | Test equipment, oscilloscopes, radio |
| TNC | DC - 11 GHz | Threaded | Vibration environments, cellular |
| N-Type | DC - 11 GHz | Threaded | High power, base stations, weatherproof |
| SMA | DC - 18 GHz | Threaded | Microwave, GPS, WiFi antennas |
| SMB | DC - 4 GHz | Snap-on | Telecommunications, automotive |
| MCX | DC - 6 GHz | Snap-on | Space-constrained, GPS, cellular |
75Ω Video Connectors
| Connector | Frequency | Coupling | Best For |
|---|---|---|---|
| F-Type | DC - 1 GHz | Threaded | CATV, satellite, home installations |
| BNC (75Ω) | DC - 2 GHz | Bayonet | Broadcast video, CCTV, SDI |
| RCA | DC - 100 MHz | Push-on | Consumer audio/video |
Connector Mating Cycles
Each connector type has a rated number of mating cycles (connect/disconnect operations). SMA connectors are typically rated for 500 cycles, while BNC connectors can handle 1,000+ cycles. For applications with frequent connections, factor durability into your connector selection.
7. Impedance Matching: 50Ω vs 75Ω
Understanding impedance is fundamental to coaxial cable selection. Using mismatched impedance causes signal reflection, standing wave ratio (SWR) problems, and potential equipment damage.
50 Ohm Coaxial
Optimized for power transmission with balanced compromise between signal attenuation and power handling.
Common Applications:
- Two-way radio and ham radio
- Cellular base stations
- Test and measurement equipment
- WiFi and GPS antennas
- Radar and microwave systems
Cable Types: RG58, RG174, RG213, LMR-400
Connectors: BNC, TNC, N-Type, SMA
75 Ohm Coaxial
Optimized for signal quality with lowest attenuation characteristics—ideal for video transmission.
Common Applications:
- CCTV and security systems
- Cable television (CATV)
- Satellite TV receivers
- Broadcast video and SDI
- Digital signage
Cable Types: RG59, RG6, RG11
Connectors: F-Type, BNC (75Ω)
"The most common mistake I see is engineers using 75Ω video cable for RF transmitter applications because 'it was in stock.' The impedance mismatch causes reflected power that can damage transmitter finals. Always match your cable impedance to your system—there's no workaround."
— Hommer Zhao, WireHarnessProduction
8. Critical Specifications for Selection
Beyond impedance, several specifications determine whether a coaxial cable assembly will perform in your application. Here's what to evaluate:
Attenuation (Signal Loss)
Measured in dB per unit length at specific frequencies. Lower is better. Attenuation increases with frequency and cable length. For long runs or high-frequency applications, choose low-loss cables like LMR-400 over RG58.
Rule of thumb: If total attenuation exceeds 3 dB, consider a lower-loss cable or amplification.
Velocity of Propagation (VoP)
The speed of signal travel through the cable expressed as a percentage of the speed of light (typically 66-88%). Important for timing-critical applications and cable length calculations.
Typical values: Solid PE = 66%, Foam PE = 78-83%, PTFE = 69-70%
Shielding Effectiveness
Determines EMI/RFI rejection. Single braid provides 85-95% coverage; double braid or braid+foil provides 95-100% coverage. Critical for sensitive instrumentation and noisy environments.
For industrial environments: Specify double-shielded cables for best noise immunity.
Minimum Bend Radius
The tightest bend the cable can make without performance degradation. Exceeding minimum bend radius causes impedance changes and increased VSWR. RG58 has ~25mm minimum bend radius; larger cables require more space.
Temperature Rating
Standard PVC jackets handle -20°C to +75°C. For extended range, specify PTFE (Teflon®) dielectric and silicone or FEP jackets that handle -55°C to +200°C.
Power Handling
Maximum RF power the cable can handle without overheating. Larger diameter cables handle more power. Critical for transmitter applications—always derate by 50% for continuous operation.
Coaxial Cable Selection Checklist
- Impedance (50Ω or 75Ω)
- Operating frequency range
- Total cable run length
- Maximum acceptable attenuation
- Connector types both ends
- Environmental conditions
- Temperature range
- Flex/bend requirements
- Shielding requirements
- Industry certifications needed
9. Cost Analysis and ROI
The true cost of coaxial cable assemblies extends beyond the purchase price. Understanding total cost of ownership helps justify custom vs. off-the-shelf decisions.
| Cost Factor | Off-the-Shelf | Custom |
|---|---|---|
| Unit Price (qty 100) | $8-15 | $12-25 |
| Setup/NRE Cost | $0 | $0-200 |
| Installation Labor | Higher (excess cable) | Lower (exact fit) |
| Lead Time | 1-3 days | 2-4 weeks |
| Documentation | Generic datasheet | Custom test reports |
| Warranty Support | Standard | Application-specific |
ROI Calculation Example
Scenario: 500 coaxial cables needed for test equipment production
Off-the-Shelf Approach:
- • 500 × $10 cables = $5,000
- • 500 × 5 min install labor = 42 hours
- • 42 × $50/hr = $2,100 labor
- • Total: $7,100
Custom Approach:
- • 500 × $15 cables = $7,500
- • $150 NRE/setup
- • 500 × 2 min install labor = 17 hours
- • 17 × $50/hr = $850 labor
- • Total: $8,500
In this case, off-the-shelf is $1,400 cheaper. But at 1,000 units, custom becomes more economical due to reduced labor costs. Run your own numbers based on actual volumes.
10. Working with Custom Coaxial Manufacturers
Getting successful custom coaxial cable assemblies requires clear communication with your manufacturer. Here's how to ensure smooth collaboration:
Information to Provide for Custom Quotes
- 1Cable type and impedance (e.g., RG58, 50Ω) or specify if you need recommendations
- 2Connector types for each end (e.g., BNC male to SMA male)
- 3Overall length and tolerance (±0.5" typical, tighter tolerances available)
- 4Operating frequency range and maximum attenuation acceptable
- 5Environmental requirements (temperature, outdoor use, chemical exposure)
- 6Testing requirements (continuity, VSWR, insertion loss, hipot)
- 7Certifications needed (UL, RoHS, MIL-SPEC, etc.)
- 8Quantity and delivery schedule
For detailed guidance on submitting RFQs, see our Wire Harness RFQ Checklist. The principles apply equally to coaxial cable assemblies.
When evaluating manufacturers, look for those with experience in your specific industry. See our guide on how to choose a wire harness manufacturer for comprehensive evaluation criteria.
11. Frequently Asked Questions
What is the difference between 50 ohm and 75 ohm coaxial cable?
50 ohm coaxial cables (like RG58) are optimized for RF power transmission and are used in radio communications, test equipment, and cellular systems. 75 ohm cables (like RG59, RG6) are optimized for video signal transmission with lower attenuation and are used in CCTV, television, and broadband applications. Never mix impedances—it causes signal reflection and potential equipment damage.
When should I choose custom coaxial cable assemblies over off-the-shelf?
Choose custom coaxial cables when you need specific lengths without excess cable, specialized connectors or configurations, enhanced shielding for harsh environments, tight space constraints, or applications in aerospace, military, or medical industries with strict requirements. For production quantities over 25 units, custom usually becomes cost-effective.
What are the most common coaxial cable connectors?
Common 50Ω connectors include BNC, TNC, SMA, and N-Type, used for RF communications. Common 75Ω connectors include F-Type and BNC (75Ω version), used for video and CATV applications. Connector selection depends on frequency requirements, environmental conditions, and connection/disconnection cycles.
What is the typical lead time for custom coaxial cable assemblies?
Standard custom coaxial cable assemblies typically have a lead time of 2-4 weeks for production quantities. Simple configurations may be available in 5-7 business days, while complex assemblies with specialized connectors or certifications may require 4-8 weeks. Always confirm lead times during quoting.
How do I specify a custom coaxial cable assembly?
To specify a custom coaxial assembly, provide: cable type and impedance (50Ω or 75Ω), connector types for each end, overall length with tolerance, operating frequency range, environmental requirements (temperature, flexibility, UV exposure), shielding requirements, and any applicable industry standards (MIL-SPEC, UL, etc.).
Can I use RG6 cable for RF applications?
RG6 is a 75Ω cable designed for video/CATV applications. While it can physically carry RF signals, the impedance mismatch with 50Ω RF systems causes significant signal reflection and VSWR issues. Use RG58, RG213, or LMR-400 for 50Ω RF applications.
Conclusion
Choosing between custom and off-the-shelf coaxial cable assemblies isn't a one-size-fits-all decision. Off-the-shelf works well for prototyping, low volumes, and standard applications. Custom assemblies deliver value when you need exact specifications, are producing in volume, or face demanding environmental requirements.
The key is matching your solution to your actual requirements—not over-specifying (wasting money) or under-specifying (risking performance failures). Use the specifications and guidelines in this article to make informed decisions for your coaxial cable needs.
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Hommer Zhao
Founder & Technical Director, WireHarnessProduction
With over 15 years of experience in cable assembly manufacturing, Hommer leads technical operations and helps customers optimize their wire harness and cable assembly solutions. He specializes in RF, medical device, and industrial applications.