The advantages of using shielded systems can be technically demonstrated through different complex parameters such as coupling attenuation, shielding efficiency and transfer impedance. But from a user's point of view, what may make the most sense is the practical advantage of a shielded cable-based cabling solution in the ever-increasing world of high-speed networking applications.

Today, more and more network applications require shielded cables and shielded cabling solutions. In fact, network equipment manufacturers have installed shielded connectors to avoid electromagnetic radiation and improve immunity to interference without the use of very complex and sensitive digital signal processing DSP technology. Even those network equipment with filters and boost circuits designed into the circuit can still benefit from a shielded cabling system. The acquired EMI from the surrounding environment must be filtered, dissipated and compensated in the instrument. The less external noise is affected, the cheaper the DSP equipment required.

But why does electromagnetic noise or interference continue to affect our networks? EMI is random noise caused by electric and magnetic fields. Various electronic devices, such as fluorescent lamps, power lines, radios, televisions and mobile phones and computers, can cause electromagnetic interference. When too much EMI or noise is picked up by the signal being transmitted, the receiver may perceive the data to be incorrect. When the client receives incorrect data, the network card in the device will find the error and ask the sender to resend it. In this way, valuable time is wasted due to the transmission and retransmission of the same data, thereby reducing the overall data transmission volume of the network. The aggravation of these transitions can affect the operating efficiency of the network.

Proponents of UTP cables firmly believe that electromagnetic noise can be counteracted by balancing (twisting) the cable. This means that EMI is first picked up by the UTP cable and then cancelled out. Until now, it's just simple balancing and filtering at work. However, a new generation of high-speed network applications is being developed, and with it, new environmental pollution is generated. The ever-increasing speed needs to be driven by new technologies that extend the bandwidth, which will be affected by more EMI sources and bring about new problems. Moreover, the increase in automation equipment on desks has brought more high-frequency electromagnetic fields to pollute the environment.

While EMI simply affects the usage of a subset of Internet users, being an information source may provide an opportunity for some criminal activity. Therefore, many cabling systems installed by government, military or financial institutions must be protected as necessary for security reasons. In order to prevent some important telephones from being eavesdropped or interfering with the security system, use shielded cables for wiring.

Proponents of UTP cables will continue to maintain their solutions in some places where the electromagnetic environment is relatively harsh. In fact, perfectly balanced cables do have the ability to resist EMI. However, an ideal balance cannot exist. Do you know what happens to a "perfect" pair after installation? In fact it is impossible to keep a perfect pair - ie the balance is broken. You can expect your cables not to bend during installation, or you can use shielded cables for the necessary protection.

In addition, since the length of the twisted pair of the core wire cannot be infinitely reduced, the balance and filtering effect of the twisted pair of the wire pair can only reach 30-40MHz. High-speed network applications such as Gigabit Ethernet, 622Mbps ATM and 2.5Gbps ATM require the use of complex encoding methods and operation in high frequency bands above 100MHz, all of which result in more signal degradation due to EMI. Therefore, the protection provided by shielded cables has more practical significance for ensuring the operational performance of the network.

In addition, the balanced characteristics of UTP cables are not only determined by the quality of the components themselves (such as twisted pairs), but will be affected by the surrounding environment. This means that if the cables are not sufficiently "separated" or independent of the environment, the balanced properties can be broken. Under ideal conditions, the signal generated by network equipment is perfectly symmetrical, but it can be corrupted by unbalanced transmission channels such as cables. This means that the impedance of the ground wire must remain constant throughout the link. And it is required that no metal objects exist near the unshielded wiring system, because any piece of metal around the cable will destroy the balance characteristics of the UTP cable, thereby affecting the EMC performance.

In fact, when we install cables, we usually run them through metal conduits, plastic conduits, or other protections with different grounding impedances. Therefore, there is only one solution to obtain long-lasting ground performance: add an extra layer of aluminum foil to ground on all cores. The aluminum foil adds protection to the fragile twisted-pair conductors while artificially creating a balanced environment for the UTP cable. This means that shielding solutions based on shielded cables are environment independent, i.e. independent of the environment.

The manufacture of shielded cables is quite professional, but since the problem of EMI has been fully considered in the design of the shielded wiring system, the installation of shielded cables is quite easy. Installation of shielded cabling systems does not need to be as stringent as unshielded systems. For example, the minimum distance requirement is that the minimum distance allowed between UTP cables and power lines is 3 times that of shielded cables.

The advantage of shielded cable compared to UTP cable is that it is aimed at the deepening of EMI impact caused by the widespread use of electronic equipment. Moreover, the increase in network application rate means that the network will be more sensitive to EMI.