What is Cat7 Cable?

Cat 7 cable or Category 7(Simply referred to as Cat7)  twisted-pair cables are divided into F/UTP and SF/UTP. F/UTP cables have a transmission frequency of 600MHz, while SF/UTP cables have a transmission frequency of 620MHz.

 

Cat 7 cables are primarily designed to accommodate the application and development of 10 Gigabit Ethernet technology. However, these are not unshielded twisted-pair cables; they are shielded twisted-pair cables. Therefore, they can provide a minimum of 500MHz of integrated crosstalk attenuation ratio and an overall bandwidth of 600MHz, which is more than twice that of Cat 6 and Cat 6a cables, with a transmission rate of up to 10Gbps.

In a Cat 7 cable, each pair of wires has its own shielding layer, and all four pairs are further surrounded by a common, larger shielding layer. Physically, the additional shielding makes the diameter of a Cat 7 cable larger. Another important difference lies in the capabilities of its connectivity hardware; a Cat 7 system requires RJ45 connectors to provide a minimum of 60dB of integrated crosstalk near the end at 600MHz.

 

Compared to Cat 5 cables, Cat 5e cables, and Cat 6 cables, Cat 7 cables have a higher transmission bandwidth, at least 600MHz. The Cat 7 cabling system is not compatible with the previous RJ-45 systems.

(1)  On June 29, 1999, at the ISO/IEC JTCL/SC 25/WG3 meeting in Berlin, Germany, the 69 experts present unanimously agreed to include the Cat 7 components solution GG45-GP45, submitted by Nexans, into the international cabling standard ISO/IEC 11801.

 

(2)  On August 27, 2001, at the ISO/IEC meeting held in Germany, Nexans proposed that IEC60603-7-7 be finally determined as the Cat 7 interface standard.

 

(3)  Cat 7 cables generally use a skin-foam-skin insulation structure.

 

(4)  The outer diameter of the copper conductor for Cat 7 cables is chosen to be around 22AWG (some advocate for 19AWG).

 

(5)  The bandwidth of Cat 7 cables is 600MHz.

 

(6)  The testing frequency range of network analyzers is 0.064~1000MHz.

 

(7)  The permanent link shall be 90m.

 

(8)  Insertion loss is about 2dB (horizontal cable reduced by approximately 3m, or patch cord is 2m).

 

(9)  Near-end crosstalk loss is 5.1~7dB.

 

(10)  ACR is -1.9dB.

 

(11)  Far-end crosstalk is 45.3dB.

 

(12)  Return loss is 8.4dB.

 

(13)  Delay is 45ms.

 

(14)  Delay skew is 44ms.

 

(15)  DC loop resistance is 34Ω.

 

(16)  Coupling attenuation is 64.4dB.

 

 

When the Cat 7 standards were initially drafted, there was a significant change in network interfaces, and eight types of interfaces were proposed. Out of these, two were "RJ" style and six were "non-RJ" style. In January 1999, the ISO technical committee decided to select one "RJ" and one "non-RJ" style interface for further study. At the ISO/IEC JTC1/SC 25/WG3 working group meeting in August 2001, the ISO organization reaffirmed that Cat 7 standards would be divided into "RJ" and "non-RJ" types of interfaces.

 

 

The structure of the Cat 7 twisted-pair cable is shown in Table 1.

 

Table 1 Structure of Cat 7 Twisted-Pair Cable

 

Feature	STP	SFTP
Conductor	Single-strand pure copper 22/23AWG	Single-strand pure copper 22/23AWG
Insulation	Polyethylene	Polyethylene
Shielding	Aluminum foil, individual shielding	Aluminum foil, individual shielding + copper wire braiding, overall braided shielding
Drain Wire	7/0.2mm	N/A
Sheath	PVC /LSZH(Low smoke zero halogen)	PVC / LSZH (Low smoke zero halogen)

 

 

The physical structure of the Cat 7 twisted-pair cable is as illustrated in figures below.

Figure: Physical Structure Diagram of Cat 7 Twisted-Pair Cable

 

 

The operating frequency range of Cat 7 twisted-pair cable is divided into 1~600MHz (standard) and 1~1000MHz.

 

 

Nominal Velocity of Propagation (NVP): 79%.

Maximum Relative Capacitance: 5.6nF/100m.

Maximum DC Resistance Unbalance: 5%.

Maximum Propagation Delay Skew: 30ns/100m.

Maximum Propagation Delay: 536ns/100m @ 100MHz.

Rated Voltage: 60Vrms.

Maximum Tensile Load: 80N.

Operating Temperature: -20°C to +60°C.

Storage Temperature: -5°C to +50°C.

Degree of Flame Retardance: Passes IEC 332-1 (FRRVC & LSOH sheathing).

 

 

The electrical performance parameters of Cat 7 twisted-pair cable are shown in Table 2.

 

Table 2 Electrical Performance Parameters of Cat 7 Twisted-Pair Cable