RG400 Cable Double Shield is a high-performance 50-ohm coaxial RF cable designed for reliable transmission of radio frequency signals in demanding electrical and electronic environments. It is commonly selected for applications where excellent shielding, stable impedance, mechanical durability, and reliable high-frequency performance are required.

The defining feature of an RG400 Double Shielded Cable is its dual shielding construction. The cable typically uses two layers of metallic shielding around the dielectric, providing strong protection against electromagnetic interference (EMI), radio frequency interference (RFI), and unwanted signal leakage.

Compared with a standard single-shield coaxial cable, a double-shielded configuration provides an additional barrier against external electromagnetic noise. This makes RG400 Cable Double Shield particularly useful in aerospace, defense, telecommunications, instrumentation, industrial electronics, RF testing, navigation, and communication systems.

RG400 is also known for its relatively compact construction, flexibility, and ability to operate across a broad RF frequency range. The combination of electrical performance and mechanical flexibility makes it suitable for installations where semi-rigid cable is not practical.

Introduction to RG400 Cable Double Shield

RF systems require controlled transmission paths because high-frequency signals can be affected by electromagnetic interference, impedance mismatch, attenuation, and signal reflections.

An RF cable must therefore do more than simply carry an electrical signal. It needs to maintain a controlled impedance while protecting the signal from external interference.

RG400 Cable Double Shield addresses these requirements through its coaxial construction and dual shielding arrangement.

A typical RG400 cable consists of:

• Center conductor

• Dielectric insulation

• First metallic shield

• Second metallic shield

• Outer protective jacket

The combination of these layers provides electrical isolation, mechanical protection, and improved shielding effectiveness.

Why Is Double Shielding Important?

Shielding is particularly important in RF systems because electromagnetic energy can enter or escape from a cable.

External interference can originate from:

• Motors

• Power supplies

• Switching circuits

• RF transmitters

• Digital electronics

• Cellular equipment

• Industrial machinery

• Radar systems

• Other communication systems

A double-shielded cable introduces an additional conductive barrier between the center conductor and the surrounding environment.

This can help reduce:

• Electromagnetic interference

• Radio frequency interference

• Signal leakage

• Crosstalk

• External noise

• Unwanted coupling

For sensitive RF equipment, this additional shielding can be an important factor when selecting an RF cable.

Construction of RG400 Double Shielded Cable

Center Conductor

The center conductor is responsible for carrying the RF signal.

RG400 constructions commonly use a stranded copper-based center conductor, often with silver plating depending on the particular manufacturer's specification.

A stranded conductor contributes to the cable's flexibility while maintaining suitable electrical conductivity for RF applications.

The center conductor influences:

• Signal attenuation

• Power handling

• Flexibility

• Electrical resistance

• Frequency performance

Dielectric Insulation

The dielectric surrounds the center conductor and maintains the required spacing between the conductor and shielding system.

PTFE is commonly used in high-performance RG400 constructions.

PTFE offers:

• Low dielectric loss

• High temperature resistance

• Good chemical resistance

• Stable electrical characteristics

• Excellent insulation performance

First Shield

The first shielding layer surrounds the dielectric.

This conductive layer helps prevent RF energy from escaping and reduces external interference entering the signal path.

Second Shield

The second metallic shield provides an additional layer of protection.

The combination of the two shielding layers is one of the defining characteristics of RG400 Cable Double Shield.

Outer Jacket

The outer jacket protects the internal cable structure from:

• Abrasion

• Moisture

• Chemicals

• Mechanical stress

• Environmental exposure

Depending on the specific construction, jacket materials and environmental ratings may vary.

RG400 Cable Double Shield Specifications

Exact specifications can vary by manufacturer and cable construction. The following values represent commonly associated characteristics and should be verified against the product datasheet for a specific cable.

RG400 Cable Double Shield Frequency Performance

The operating frequency of RG400 depends on the specific cable design, connector configuration, cable length, installation conditions, and manufacturer's specifications.

RG400 is commonly used in RF systems extending into the microwave frequency range.

When operating at higher frequencies, engineers should evaluate:

• Insertion loss

• Return loss

• VSWR

• Connector performance

• Cable length

• Temperature

• Power handling

The cable should always be selected according to its specified performance at the actual operating frequency rather than relying only on its RG designation.

Characteristic Impedance of RG400 Cable

RG400 is generally designed around a 50-ohm characteristic impedance.

Maintaining 50-ohm impedance throughout an RF transmission system is important because impedance discontinuities can produce signal reflections.

A typical RF signal path may contain:

Transmitter → RF Connector → RG400 Cable → RF Connector → Receiver

Every transition in this path should maintain appropriate impedance.

Poor impedance matching can increase:

• Reflected power

• VSWR