Currently, there is some confusion in the market regarding the definitions of RG405 and 0.086” cables, with common names including RG405, Semi-Rigid 86, and Semi-Flexible 086. In accordance with standard specifications, their official name should be 0.086” (approximately 0.085”) cables. For the convenience of reference, they are commonly referred to as 086 cables in the industry. For instance, the corresponding model of TIMES MICROWAVE is SR-086, while that of Mini-circuits is the 086 Series Hand-Flex.
1. Core Concepts and Classification Definition
Distinction in Name Meanings
"086" refers to the diameter of the outer shielding layer of the cable, with the unit being 0.086 inches; "RG405" is a cable designation under the U.S. Military Standard (MIL) system and serves as a standardized specification identifier.
Subtypes of 086 Cables
Based on structure and protective properties, 086 cables can be divided into three categories: 086 Semi-Rigid Cables, 086 Semi-Flexible Un-jacket Cables, and 086 FEP jacket Cables.
Supplementary Information on Related Models
There is also the 085 model cable available in the market. A typical product is the UT-085 from MICOR-COAX, whose structure and parameters are identical to those of the U.S. military standard model M17/133-00007 (i.e., RG405).
Historic Information
It is particularly important to note that, according to public information, MICRO-COAX (founded in 1962) is the inventor of semi-rigid cables, and TIMES MICROWAVE (founded in 1945) is the inventor of semi-flexible cables (invented in 1966). Currently, both companies are subsidiaries of the Amphenol Group.
2. Core Differences Between Semi-Flexible and Semi-Rigid Cables
The key differences between semi-flexible and semi-rigid cables lie in the material and structure of the outer conductor:
The outer conductor of a semi-rigid cable is made of a copper tube or aluminum tube, featuring a relatively rigid structure.
The outer conductor of a semi-flexible cable is a tin-plated braided layer, which has a certain degree of flexibility.
For semi-flexible cables with a jacket, the jacket material is usually FEP (Fluorinated Ethylene Propylene Copolymer), LSZH (Low Smoke Zero Halogen) PE, or PVC (Polyvinyl Chloride).
3. Standard Definition of RG405 Cables by U.S. Military Standard (MIL-DTL-17/133)
In the U.S. military standard MIL-DTL-17/133, the model range of RG405 cables covers from M17/133-RG405 to M17/133-00018, totaling 19 subdivided models. Taking the basic model M17/133-RG405 as an example, its core parameter specifications are as follows:
Inner Conductor: Single-strand silver-plated copper-clad steel, with a diameter specification of 0.0201 ± 0.0005 inches (converted to 0.51 ± 0.01 mm).
Insulator: Made of PTFE (Polytetrafluoroethylene) material, with a diameter of 0.066 ± 0.002 inches (converted to 1.68 ± 0.05 mm).
Outer Conductor: Copper tube material, with a diameter of 0.0865 ± 0.001 inches (converted to 2.2 ± 0.03 mm).
Weight: 15.3 pounds per 1000 feet (approximately 304.8 meters) (equivalent to 6.94 kilograms), or 22.87 kg/km.
It should be noted that this U.S. military standard does not clearly specify the electroplating type of the outer conductor. Common treatment methods in the industry include four types: tin plating, silver plating, ternary alloy plating, and bare copper.
4. Basic Definitions of RG405 and 0.086” (086) Cables
Category
Core Definition
RG405
1. A semi-rigid coaxial cable specified in accordance with the MIL-C-17 standard; 2. With an outer diameter specification of 0.086 inches (approximately 2.2 mm); 3. Commonly referred to as "RG405/U" in the industry
0.086” (086) Cable
1. An industry-general term, referring to semi-rigid or semi-flexible coaxial cables with an outer diameter of 0.086 inches (approximately 2.2 mm); 2. Its size is basically the same as that of RG405, but it is not mandatory to meet the requirements of the U.S. Military Standard (MIL)
5. Common Characteristics of RG405 and 0.086” Semi-Rigid Cables
Size Specification: The outer diameters of the two are similar, both being approximately 2.20 mm (corresponding to 0.085-0.086 inches).
Structural Composition: The semi-rigid types both adopt a solid copper outer conductor, a PTFE dielectric layer, and a silver-plated copper inner conductor.
Frequency Performance: They can support a maximum operating frequency of 20 GHz.
Application Scenarios: Widely used in microwave modules, test cables, and RF connectors (such as SMA, 2.92 mm models, etc.).
6. Comparison of Differences Between RG405 and 0.086” Semi-Rigid Cables
Characteristic Dimension
RG405
0.086” Semi-Rigid Cable
Implementation Standard
Clearly defined by the U.S. Military Standard MIL-C-17
Only follows industry-general dimensions, and may or may not meet the requirements of the U.S. Military Standard (MIL)
Naming Convention
Uniformly referred to as RG405 (U.S. military standard code)
Manufacturers usually name it "0.086 Semi-Rigid"
Specification Tolerance
Parameters such as outer diameter, impedance, attenuation, and shielding must strictly meet the tolerance requirements of the U.S. military standard
Specifications vary by manufacturer, and some products may meet or exceed the RG405 standard
Impedance Characteristic
The nominal impedance is 50Ω, and the parameter is fixed
Usually 50Ω, but there may be differences among products from different manufacturers
Certification Level
Can meet the requirements of military/aerospace applications
7. Actual Market Application Situation
Terminology Usage Habits: Most manufacturers have the phenomenon of mixed terminology use, regarding "RG405" and "0.086” cable" as equivalent concepts.
Selection Suggestions: If the application scenario is in the military or aerospace field, it is necessary to clearly require RG405 cables that comply with the MIL-DTL-17 specification; if only the size and basic performance are concerned, selecting "086 cables" can meet the needs.
Summary: RG405 is the standard name of 0.086” semi-rigid coaxial cables under the U.S. military standard system. All RG405 cables belong to the category of 086 cables, but not all 086 cables comply with the official standards of RG405.
Appendix 1
Diagram of SMA connectors assembled to three different types of 086 cables. All three types of cables can be assembled using the same connector, and users can select different 086 cables according to different application scenarios.
Semi-rigid 086 can be formed into shape and keep their shape.
Semi-flexible 086 has more flexibility, semi-flexible 086 with jacket protect the corrode to the outer conductor.
Appendix 2
Parameter Table of RG405/086 Cable Products from Well-Known Manufacturers
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