Five points of understanding about semi-rigid cable assemblies

The most basic form of a semi-rigid cable assembly is a coaxial transmission line made up of metal tubes. Wherein, the metal tube is generally a copper tube forming an outer conductor, and a wire conductor is arranged along a center line of the copper tube. The central wire conductor is instead supported by a dielectric material and thereby remains above the same central axis of the outer conductor.

The following are the five most important insights about semi-rigid cables:

1. Independent microwave components

It is extremely important to realize that the semi-rigid cable assembly itself is a key microwave component. This means that the specifications of a semi-rigid cable are as important as the specifications of any coupler, bridge, and amplifier. If properly manufactured, the cable can successfully achieve predictable stability in connecting other components of the system. If any good link budget analysis is studied, it can be found that under the predetermined frequency, electrical parameters including attenuation and voltage standing wave ratio play a vital role in the transmission and reception of RF signals. . Compared to semi-rigid cables and standard RG-type cables, each connector is installed with a brazed connector for semi-rigid cable assemblies when space is appropriate and requires careful inspection and thermal cycling and other required tests. The time required may be as long as an hour or an hour; in contrast, a crimped RF connector for a flexible (non-semi-rigid) coaxial cable can be used in one minute or less. Complete the installation within.

2. Broadband application range

Semi-rigid cable assemblies typically support RF signal transmission within 65 GHz. In addition, although not infrequently used, cable assemblies terminated with 1.0mm connectors enable high frequency applications up to 110 GHz. Semi-rigid coaxial cables vary in size and range in diameter from 0.020 inches to 0.250 inches. Among the Pasternack products, 0.141-inch and 0.086-inch cables are popular. In addition, 0.047-inch diameter cables that use increasingly smaller connectors are becoming more popular with users because they support higher and higher frequencies. The 0.141" diameter semi-rigid coaxial cable is terminated with a high frequency SMA or 2.92mm connector and can be used up to 27 GHz. Although the 0.086-inch diameter semi-rigid coaxial cable is often used in conjunction with HYEC.com/en/SMA-Connector.html target='_blank'>SMA connectors, it can operate up to 65 GHz if it is terminated by a 1.85 mm connector.

3, shaping and maintaining shape

For such cable assemblies, they can be embedded in the designed system, often requiring precise shaping into a variety of shapes. As the name implies, a semi-rigid coaxial cable is a cable that not only has insufficient rigidity to maintain its shape, but also has insufficient rigidity to be manually bent. Modeling a semi-rigid cable into the desired shape is a risky job. To prevent damage to the outer wall, special tools should be used to bend or shape the cable. In addition, it is very difficult to change the shape of such a cable after it has been shaped into a specific shape. This is because the shape change often causes damage to the outer conductor, which in turn causes fine lines in the outer wall and ultimately affects the electrical performance of the cable assembly. Therefore, although such coaxial cables made of aluminum and soft copper are easy to shape and bend manually, it is recommended to use special tools for such operations to minimize the risk of cable damage.

Although shapeable or semi-flexible coaxial cables are often classified as semi-rigid coaxial cables, they are in fact used as another type of common coaxial cable that is different from semi-rigid coaxial cables. The shapeable semi-rigid coaxial cable uses a spirally wound conductive foil that is overcoated with a tin outer braid, so that the outer conductor is somewhat softer than the solid metal outer conductor. Although the shapeable semi-rigid coaxial cable can be used as a replacement for semi-rigid coaxial cable, its shape is generally changed by the process, so it can only maintain the general shape, and the conformality of the standard semi-rigid coaxial cable is not comparable. This type of increasingly flexible cable replacement has become extremely popular because complex routing and assembly drawings are not required under normal installation conditions. Such hand-mouldable cables allow for the addition of their length in micro-increments at the time of purchase, so they allow for the shape to be shaped as the product is assembled. In addition, such cables also have the advantage of being semi-rigid coaxial cables with electrical properties close to the solid outer wall, lower production costs, and optional jacket material.

4, phase stability

Because semi-rigid coaxial cables are made of high quality materials, they have higher electrical stability than flexible coaxial cables that use wire braided outer conductors. The properties of metals and dielectric materials change with temperature changes, so the use of steady-phase cables is important for many critical systems. In addition, amplitude-matched semi-rigid cables are often used in systems where phase length control is required. This is especially true for antenna systems that have a mutual array antenna. This is due to the fact that in such antenna systems, the phase of the input signal has an important role in the electrical control of the main beam of the antenna array. Modern mobile communication systems use this technology to optimize coverage under varying conditions to achieve the goal of reducing the number of antennas required for system performance optimization.

5. Low Passive Intermodulation (PIM)

Semi-rigid cable assemblies are typically made of a non-ferrous metal material (importantly copper). This type of copper tube semi-rigid coaxial cable has excellent passive intermodulation performance when it is equipped with a suitable connector, making it a modern multi-frequency wireless communication system including distributed antenna system (DAS) related equipment. The ideal choice. As the demand for full coverage increases, the distributed antenna system market requires an increasing number of low-passivity intermodulation products, including power splitters, combiners, amplifiers, and even high-end test equipment. Because the semi-rigid cable assembly can meet the RF power and passive intermodulation requirements of modern wireless communication systems, it is a natural fit for the above applications.

In summary, 甬電子 believes that semi-rigid cable assemblies are a vital microwave device and are active in countless RF applications around the world. Although semi-rigid technology is not a new technology, semi-rigid components are still a popular choice for engineers because of its broadband characteristics, reliable electrical performance and phase stability.