Coaxial Cable Types: A Complete Guide to Impedance, Connectors, RF Performance and Cable Assemblies

A coaxial cable is a shielded electrical cable designed to transmit high-frequency signals through a center conductor surrounded by dielectric insulation and an outer conductive shield. A typical coax cable includes four main layers: the center conductor, dielectric insulation, metallic shielding, and an outer protective jacket.

This construction helps control electromagnetic interference and maintain stable signal transmission, which is why RF coax cable is widely used in communication, antenna, video, automotive, medical, and industrial applications.

Different coaxial cable types vary in impedance, diameter, attenuation, shielding effectiveness, flexibility, and usable frequency range. This blog explains common RG cables, 50Ω vs 75Ω designs, connectors, performance factors and how to select the right coaxial cable assembly for your application.

What Is a Coaxial Cable?

A coaxial cable is a type of electrical cable designed to carry high-frequency signals while controlling impedance and reducing electromagnetic interference. The name “coaxial” comes from its structure: the center conductor and the outer conductive shield are arranged around the same geometric axis.

Unlike a basic insulated wire, a coax cable uses several coordinated layers to maintain stable RF performance.

What Are the Main Parts of a Coaxial Cable?

Center Conductor → Dielectric → Shield → Outer Jacket

Center Conductor – Carries the RF or electrical signal.
Dielectric – Keeps the conductor centered and helps maintain the cable’s electrical characteristics and impedance.
Shield – Provides the signal return path and helps reduce EMI/RFI interference.
Outer Jacket – Protects the cable from abrasion, moisture, chemicals, and mechanical damage.

This layered coaxial cable structure is what makes coax suitable for RF, antenna, communication, video, and other high-frequency applications. In a finished coaxial cable construction, each layer must be selected together because conductor size, dielectric geometry, shielding, and jacket material all affect performance.

How Does a Coaxial Cable Work?

A coaxial cable works by carrying an RF or high-frequency electrical signal through the center conductor while the surrounding outer conductor provides the return path. Together, these two conductors form a controlled coaxial transmission line.

The dielectric keeps the center conductor accurately spaced from the shield, helping maintain the required impedance, typically 50Ω or 75Ω. Proper coaxial cable shielding also reduces external EMI/RFI and limits signal radiation from the cable.

A simple signal path looks like this:

RF Source → Coaxial Cable → Connector → Antenna / Device

For reliable transmission, the cable, connector, and termination should maintain consistent impedance. Any significant impedance discontinuity can cause part of the coaxial cable signal to reflect back toward the source, increasing return loss and reducing RF performance.

This is why an RF signal cable must be selected and assembled with careful control of impedance, shielding, connector quality, and termination.

What Are the Main Types of Coaxial Cable?

There are seven types of coaxial cable, and they are best classified first by physical construction rather than by RG number. Different designs provide different balances of flexibility, shielding, size, power handling, and RF performance.

In our engineering reviews, we normally select the cable construction first based on routing, frequency, loss, movement, and installation requirements, and then narrow the choice to a specific RF coax cable or manufacturer part number.

1.Flexible Coaxial Cable

Flexible coaxial cable typically uses a stranded or flexible center conductor with a braided outer shield. It is easy to route and is commonly used inside equipment, test systems, antennas, and general RF coax cable assemblies.

2.Semi-Rigid Coaxial Cable

A semi rigid coax cable uses a solid metal outer conductor, which provides stable geometry, strong shielding, and consistent RF performance. However, it has limited flexibility and is normally formed to a fixed shape during installation.

3.Hand-Formable Coaxial Cable

Hand-formable coax provides a compromise between flexible and semi-rigid designs. It can be bent and shaped during installation while maintaining better dimensional stability than conventional flexible coax.

4.Hardline Coaxial Cable

Hardline coaxial cable uses a larger and more rigid outer conductor and is designed for low-loss, high-power transmission. It is commonly used in telecommunications infrastructure, antenna systems, and other long RF transmission paths.

5.Micro-Coaxial Cable

Micro coaxial cable is designed for compact, lightweight, and high-density electronic systems. Its small diameter makes it suitable for cameras, displays, medical electronics, portable devices, and other applications where routing space is limited.

6.Twinaxial Cable

A twinax cable contains two inner conductors inside a common shield and is commonly used for differential signaling. Structurally, it differs from conventional coax, which uses a single center conductor.

7.Triaxial Cable

A triaxial cable adds an additional conductive shield around a conventional coaxial structure. This extra layer can provide improved isolation or guarding for specialized instrumentation, measurement, broadcast, and precision signal applications.

Coaxial Cable Type Comparison

Type	Flexibility	Shielding	Relative Size	Typical Applications
Flexible Coax	High	Braided / foil + braid	Small–Medium	RF assemblies, antennas, test equipment
Semi-Rigid Coax	Low	Solid metal outer conductor	Small–Medium	RF and microwave modules
Hand-Formable Coax	Medium	Formable metal outer conductor	Small–Medium	RF equipment and internal routing
Hardline Coax	Very Low	Rigid metal outer conductor	Large	Telecom, antennas, high-power RF
Micro-Coax	High	Miniature shield construction	Very Small	Cameras, displays, compact electronics
Twinax	Medium–High	Common outer shield	Varies	Differential data signals
Triaxial Cable	Varies	Dual shielding structure	Medium	Precision measurement and instrumentation

What Are the Most Common RG Coaxial Cable Types?

RG coax cable types are widely used in RF, antenna, communication, video, automotive, test, and industrial applications. Different RG cable types vary in impedance, coaxial cable size, dielectric material, shielding, flexibility, attenuation, and temperature capability.

The table below provides a practical comparison of common RG coaxial cables. Exact specifications vary by construction and manufacturer, so always verify the supplier datasheet before final selection.

Cable	Impedance	Approx. OD	Relative Loss	Flexibility	Typical Application
RG58	50 Ω	~5.0 mm	Medium	High	RF, antennas, test cables, radio
RG174	50 Ω	~2.8 mm	High	High	GPS, automotive, compact RF assemblies
RG178	50 Ω	~1.8 mm	High	High	Compact RF, aerospace, internal equipment
RG316	50 Ω	~2.5 mm	Medium-High	High	RF assemblies, test equipment, aerospace
RG142	50 Ω	~5.0 mm	Medium-Low	Medium	High-temperature RF and microwave
RG400	50 Ω	~5.0 mm	Medium-Low	Medium	Aerospace, military, high-temperature RF
RG214	50 Ω	~10.8 mm	Low	Low-Medium	High-power RF and communication systems
RG59	75 Ω	~6.1 mm	Medium	High	Video, CCTV, legacy RF systems
RG6	75 Ω	~6.9 mm	Low	Medium	CATV, broadband, satellite
RG11	75 Ω	~10.3 mm	Lower	Low	Long cable runs, CATV, broadband

Note: OD and relative loss are typical references only. Actual values depend on the specific cable construction and manufacturer.

Choosing between these RG cable types requires a closer look at their size, flexibility, RF performance, and intended application.

1.RG58 Coaxial Cable

RG58 coax is a 50Ω flexible cable with an OD of approximately 5 mm. It is widely used for RF equipment, antennas, radio, and test cable assemblies.

Selection concern: Check frequency, attenuation, shielding, and cable length, especially for higher-frequency or longer runs.

2.RG174 Coaxial Cable

RG174 coax is a compact 50Ω flexible cable with an OD around 2.8 mm.

Typical applications: GPS, automotive antennas, wireless modules, and compact RF assemblies.

Selection concern: Its small diameter improves routing flexibility but generally results in higher attenuation than larger coax.

3.RG178 Coaxial Cable

RG178 coax is a very small 50Ω cable, typically around 1.8 mm OD, often using a PTFE dielectric.

Typical applications: Aerospace electronics, RF modules, instrumentation, and space-constrained assemblies.

Selection concern: Small dimensions require careful connector termination and process control.

4.RG316 Coaxial Cable

RG316 coax is a flexible 50Ω cable with an OD around 2.5 mm and is commonly selected for RF cable assemblies.

Typical applications: RF equipment, antennas, test systems, aerospace, and instrumentation.

Selection concern: Verify attenuation and connector compatibility for the required operating frequency.

5.RG142 Coaxial Cable

RG142 is a 50Ω coax typically around 5 mm OD with good temperature capability and relatively stable RF performance.

Typical applications: Microwave equipment, aerospace, RF systems, and high-temperature environments.

Selection concern: Larger size and lower flexibility should be considered when routing space is limited.

6.RG400 Coaxial Cable

RG400 coax is a 50Ω high-performance cable commonly used where temperature resistance and strong shielding are required.

Typical applications: Aerospace, military, RF test equipment, communication, and demanding industrial systems.

Selection concern: Higher performance generally comes with higher material cost than general-purpose coax such as RG58.

7.RG214 Coaxial Cable

RG214 is a larger 50Ω coax, typically around 10.8 mm OD, designed for lower loss and higher power handling than many smaller flexible cables.

Typical applications: RF transmitters, communication equipment, antennas, and high-power RF systems.

Selection concern: Its larger diameter increases weight and requires larger connectors and more routing space.

8.RG59 Coaxial Cable

RG59 coax is typically a 75Ω cable with an OD around 6 mm.

Typical applications: Video, CCTV, broadcast, and some legacy RF systems.

Selection concern: For longer or higher-frequency 75Ω runs, lower-loss alternatives may be more appropriate.

9.RG6 Coaxial Cable

RG6 coax is a 75Ω cable widely used for broadband, CATV, satellite, and video transmission.

Typical applications: Television distribution, broadband networks, satellite systems, and building communication infrastructure.

Selection concern: Shield construction and connector compatibility can vary considerably between RG6 products.

10.RG11 Coaxial Cable

RG11 coax is a larger 75Ω cable, typically around 10 mm OD, designed for lower attenuation over longer cable runs.

Typical applications: CATV backbones, broadband distribution, and long-distance video/RF connections.

Selection concern: Lower loss comes with greater size, weight, bend radius, and installation difficulty.

At Yihetai, we recommend confirming the impedance, conductor and dielectric materials, shield construction, cable OD, temperature rating, attenuation requirement, connector type, cable length, and applicable cable datasheet before production.

What Does Coaxial Cable Impedance Mean?

Coaxial cable impedance is the cable’s characteristic impedance for high-frequency signals. It is not the same as DC resistance measured with an ohmmeter. Instead, coax impedance is determined by the geometry and materials of the transmission line.

The main factors include:

Center conductor diameter
Distance between the center conductor and shield
Dielectric material and dielectric constant
Shield geometry

Common values are 50 ohm coax for RF, wireless, antenna, and test applications, and 75 ohm coax for video, broadcast, and CATV systems.

Maintaining consistent characteristic impedance is important because impedance changes can cause signal reflections, higher VSWR, and degraded RF performance.

How Does Cable Length Affect Coaxial Cable Performance?

Coaxial cable length directly affects RF performance because attenuation accumulates along the cable:

Longer Cable → More Attenuation → Lower Signal at the Load

This is especially important for antennas, GPS, Wi-Fi, RF test equipment, remote sensors, and other applications where RF cable length can directly affect the available signal level.

For example, if a cable has an attenuation of 0.30 dB/m at the specified operating frequency, a 1 m cable contributes about 0.30 dB of cable loss, while a 5 m cable contributes about 1.50 dB before connector and transition losses are considered.

What Parameters Should Be Controlled in a Coaxial Cable Assembly?

In production, coax cable loss by length is only one part of the specification. Common engineering parameters include:

Parameter	Why It Matters
Finished Cable Length	Determines routing and total RF attenuation
Length Tolerance	Ensures repeatable installation and RF path length
Cable Impedance	Typically 50Ω or 75Ω depending on the system
Attenuation at Specified Frequency	Defines acceptable signal loss
VSWR / Return Loss	Checks impedance matching of the finished assembly
Insertion Loss	Measures total RF loss through the assembly
Cable OD	Affects connector, routing and strain-relief compatibility
Minimum Bend Radius	Prevents deformation and RF performance changes
Strip Dimensions	Controls the cable-to-connector transition
Crimp / Solder Parameters	Affect mechanical retention and RF termination quality
Center Contact Position	Helps maintain the intended connector interface geometry

Is There a Maximum Coaxial Cable Length?

There is no universal coaxial cable maximum length. The acceptable length depends on:

Operating Frequency + Cable Attenuation + Connector Loss + Required Signal Margin

For this reason, engineers selecting coaxial cable length should calculate the complete RF loss budget rather than choosing a maximum distance from a generic chart.

Coaxial vs Twinaxial vs Triaxial Cable: What Is the Difference?

Although coaxial, twinaxial, and triaxial cables are all shielded signal cables, their internal conductor and shield structures are different. Understanding coax vs twinax and coax vs triax is important because these cables are designed for different electrical interfaces and cannot normally be substituted for one another.

Below table for your check:

Cable Type	Signal Conductors	Shield Structure	Typical Use
Coaxial	1	Main outer shield	RF, antenna, video
Twinaxial	2	Shared outer shield	Differential / high-speed signals
Triaxial	1	Additional shield layer	Precision / specialized signals

Coaxial Cable

A standard coaxial cable contains one center signal conductor surrounded by dielectric insulation and an outer conductive shield.

Center Conductor → Dielectric → Shield → Jacket

The center conductor and shield form a controlled-impedance transmission line, commonly 50Ω or 75Ω. Coax is widely used for RF antennas, GPS, radio, CCTV, test equipment, and other high-frequency applications.

Its major engineering requirements include impedance control, attenuation, shielding effectiveness, connector compatibility, and termination quality.

Twinaxial Cable

A twinaxial cable, often called twinax cable, contains two insulated inner conductors inside a common shield.

Conductor A + Conductor B → Dielectric / Filler → Shield → Jacket

The two conductors are commonly used as a balanced or differential pair, making twinax suitable for applications such as:

High-speed data transmission
Differential signal links
Industrial communication
Data-center interconnects
Aerospace and electronic systems

The key difference in coaxial vs twinaxial cable is therefore the signal path: coax normally uses one center conductor with the outer conductor as the return path, while twinax uses two inner conductors to carry the differential signal.

For twinax assemblies, engineers also need to control pair geometry, conductor spacing, skew, shielding, and termination symmetry.

Triaxial Cable

A triaxial cable, or triax cable, is structurally similar to coax but includes an additional concentric conductive layer.

A typical construction is:

Center Conductor → Dielectric → Inner Shield → Insulation → Outer Shield → Jacket

The additional shield allows the inner and outer shields to perform different electrical functions depending on the system design. This makes triax useful in specialized applications requiring greater isolation or very low-noise signal transmission, including:

Precision measurement equipment
Sensitive instrumentation
Certain broadcast and camera systems
Low-current measurement applications
Specialized laboratory equipment

Compared with standard coax, triaxial cable is generally larger, more complex to terminate, and requires connectors specifically designed for the additional conductor/shield structure.

Coax vs Twinax vs Triax: Which Should You Choose?

The choice should be based primarily on the system interface rather than simply on shielding level.

Choose coaxial cable for single-ended RF, antenna, video, and other controlled-impedance signals.
Choose twinax cable when the equipment uses a balanced or differential signal pair.
Choose triaxial cable when the application requires an additional shield or guard conductor for enhanced isolation or specialized measurement.

What Is a Coaxial Cable Assembly?

A coaxial cable assembly is a finished RF interconnection made from a coaxial cable, one or more RF connectors, controlled termination, strain relief, and required electrical or RF testing.

Coaxial Cable + RF Connector(s) + Termination + Strain Relief + Testing = Coaxial Cable Assembly

Unlike bulk coax cable, which is supplied without terminations, a coax cable assembly is cut to a defined length and terminated with connectors that match the cable, impedance, frequency, and application requirements.

Common configurations include:

SMA Cable Assembly

An SMA cable assembly is widely used in compact RF, antenna, wireless, test, and communication equipment. SMA connectors are threaded and commonly used in 50Ω systems.

BNC Cable Assembly

A BNC cable assembly uses a bayonet-style connector for quick connection and disconnection. It is common in RF test equipment, instrumentation, video, and communication systems.

TNC Cable Assembly

TNC connectors use a threaded coupling and are often selected where better resistance to vibration or accidental disconnection is required.

N-Type Cable Assembly

N-Type assemblies are commonly used in RF infrastructure, antennas, communication equipment, and applications requiring a larger, mechanically robust connector.

MCX and MMCX Cable Assembly

MCX and MMCX cable assembly designs are compact and suitable for space-constrained RF equipment, GPS, antennas, and small electronic devices.

U.FL / I-PEX RF Cable Assembly

U.FL / I-PEX-style assemblies use very small RF connectors, typically with micro-coax cable, for Wi-Fi, Bluetooth, GPS, cellular modules, and compact electronics.

What Are the Most Common Coaxial Cable Connectors?

A coaxial cable connector provides the mechanical and electrical interface between a coax cable and RF equipment. Different coax connector types are designed for different impedance, frequency, size, locking, and environmental requirements, so connector selection should always be matched to both the cable and the application.

Below provides a quick comparison of the most common coaxial cable connectors.

Connector	Typical Impedance	Relative Size	Typical Applications	Key Advantage
SMA	50Ω	Small	Antennas, GPS, RF modules, test equipment	Compact, threaded connection, high-frequency capability
SMB	50Ω / 75Ω	Small	Automotive, telecom, instrumentation	Quick snap-on connection
SMC	50Ω / 75Ω	Small	RF equipment, instrumentation	Compact threaded connection
BNC	50Ω / 75Ω	Medium	Test equipment, video, instrumentation	Fast bayonet coupling
TNC	Typically 50Ω	Medium	Antennas, industrial RF, communication systems	Threaded retention for vibration resistance
N-Type	Typically 50Ω; 75Ω versions exist	Large	Base stations, antennas, outdoor RF	Robust construction and higher-power capability
F-Type	75Ω	Medium	CATV, satellite, broadband	Simple, economical 75Ω connection
MCX	Typically 50Ω	Small	GPS, automotive, wireless equipment	Compact snap-on interface
MMCX	Typically 50Ω	Very Small	GPS, RF modules, portable electronics	Miniature size and rotating snap-on interface
U.FL / I-PEX	Typically 50Ω	Ultra-Miniature	Wi-Fi, Bluetooth, GPS, IoT modules	Very small PCB-level RF connection

How Do You Match a Coaxial Cable With the Right Connector?

Correct coax cable connector selection requires more than checking whether the connector can physically fit the cable. In production, the cable and connector must be treated as one RF transmission system.

Engineers normally verify:

Impedance — 50Ω or 75Ω must match the system.
Frequency range — the connector must support the required operating frequency.
Cable OD — must fit the connector body, ferrule, and strain-relief structure.
Dielectric OD — affects the cable-to-connector impedance transition.
Center conductor size — must match the center contact or pin.
Shield / braid dimensions — must suit the ferrule or shield termination.
Termination method — crimp, solder, clamp, or compression.
Connector configuration — straight or right-angle.
Environmental requirements — temperature, vibration, moisture, corrosion.
Mating cycles — important for frequently connected RF interfaces.

For example, RF connector datasheets may specify a particular compatible RG cable family, 50Ω or 75Ω impedance, crimp method, operating frequency, and connector orientation. Some N-type connectors are explicitly specified for RG142, RG223, RG400 and similar cables, while other connector families are matched to smaller cables such as RG178.

A connector can mechanically fit a coaxial cable but still be electrically unsuitable for the required frequency or impedance.

In production, we also control strip length, dielectric position, braid preparation, center-contact termination, ferrule crimp dimensions, cable pull force, and finished length tolerance. These small dimensional details can directly affect the RF performance and mechanical reliability of the finished RF cable connector assembly.

What Causes Signal Loss in Coaxial Cable?

Coaxial cable signal loss is mainly caused by attenuation along the cable and additional losses at connectors, terminations, and impedance discontinuities.

A useful rule is:

Higher Frequency + Longer Cable → Generally Higher Attenuation

The main factors affecting coaxial cable loss include:

Cable length
Operating frequency
Conductor resistance
Dielectric loss
Cable diameter and construction
Connector loss
Impedance mismatch
Tight bending or poor installation

Larger, well-designed low loss coax cable can reduce attenuation, but the final RF performance still depends on the complete cable assembly.

What Is Coaxial Cable Attenuation?

Coax attenuation is the gradual reduction in signal power as an RF signal travels through the cable. It is commonly specified in dB per unit length at a given frequency, such as dB/100 m or dB/100 ft.

Attenuation generally increases with frequency and cable length, which is why coax cable attenuation should always be checked at the actual operating frequency.

What Is Insertion Loss?

Insertion loss is the total signal loss introduced when a cable assembly is inserted into an RF system. It can include:

Cable attenuation
Connector loss
Termination loss
Mismatch-related loss

For a finished assembly, RF cable loss is therefore not determined by the bulk cable alone.

What Is the Difference Between 50 Ohm and 75 Ohm Coaxial Cable?

50-ohm and 75-ohm coaxial cables use different characteristic impedances and are generally selected for different RF, data, video, and communication systems. The key difference is not ordinary DC resistance; it is the cable’s characteristic impedance, which must match the connected equipment and RF connectors.

Feature	50 Ohm Coax	75 Ohm Coax
Typical Applications	RF, antennas, radio, wireless, test equipment	Video, broadcast, CCTV, CATV
Common Cables	RG58, RG174, RG316, RG400	RG59, RG6, RG11
Connector Requirement	50Ω-compatible connector/interface	75Ω-compatible connector/interface
Main Concern	Impedance matching	Impedance matching

How Do You Choose the Right Coaxial Cable?

The best coax cable selection starts with the electrical requirements, then moves to mechanical, environmental, connector, and testing requirements. There is no single best coax cable for every application.

A practical coaxial cable selection guide follows this sequence:

Step 1: Determine Required Impedance：50Ω or 75Ω
Step 2: Define Operating Frequency
Step 3: Determine Cable Length
Step 4: Check Allowable Insertion Loss
Step 5: Consider Power Handling
Step 6: Check Cable OD and Routing Space
Step 7: Check Flexibility and Bend Radius
Step 8: Define Shielding Requirements
Step 9: Select Compatible Connectors
Step 10: Confirm Temperature and Environment
Step 11: Define Required Testing

How Do You Choose the Right Coaxial Cable Assembly?

Choosing a finished RF cable assembly requires more than selecting the coaxial cable itself. The cable, connectors, length, termination, mechanical design, and RF performance requirements must all be defined as one complete assembly.

Key parameters for coaxial cable assembly selection include:

Cable Type – such as RG58, RG174, RG316, RG400, or another specified coax
Connector A – exact connector type and part number
Connector B – matching equipment interface
Connector Orientation – straight or right-angle
Assembly Length – finished end-to-end cable length
Length Tolerance – allowable production variation
Frequency Range – required operating band
Impedance – typically 50Ω or 75Ω
Insertion Loss Requirement – allowable RF signal loss
VSWR / Return Loss – required impedance-matching performance
Bend / Flex Requirement – static routing or repeated movement
Strain Relief – heat shrink, boot, overmold, or other protection
Environment – temperature, vibration, moisture, chemicals, sealing
Testing – continuity, insertion loss, VSWR, return loss, TDR, or mechanical tests as required

A custom coaxial cable or custom RF cable should therefore be specified as a complete coax cable connector assembly, not as separate cable and connector components.

Why Choose Yihetai for Custom Coaxial Cable Assemblies?

For OEM projects, a reliable coaxial cable assembly manufacturer should be able to control not only cable and connector selection, but also stripping, shield preparation, termination, testing, and production consistency. Yihetai supports customized cable and harness projects from engineering review through production.

25+ Years of Cable and Harness Manufacturing Experience
Custom Cable and Connector Configurations
Prototype to Production Support
Controlled Cable Preparation and Termination
Electrical Testing and Traceability
Automotive and Industrial Manufacturing Experience
Engineering Support for OEM Projects

Conclusion

Coaxial cables come in many different types, and choosing the right coaxial cable requires more than selecting an RG number. Impedance, operating frequency, attenuation, cable length, shielding, connector compatibility, and environmental conditions should all be considered together.

For a finished coaxial cable assembly, termination quality, strip dimensions, shield preparation, connector installation, and testing also affect RF performance.

If you are developing a custom coaxial cable assembly or RF cable assembly, send Yihetai your drawing, BOM, cable and connector part numbers, or sample for engineering review and quotation from an experienced coaxial cable assembly manufacturer.