Cat 7 twisted pair cables are divided into F and FA types. The F type operates at a frequency of 600 MHz, while the FA type operates at 620 MHz.
Cat 7 cables are primarily designed to support the demands of 10-gigabit Ethernet technology. Unlike unshielded twisted pair (UTP) cables, they are shielded twisted pair cables(STP). Consequently, they offer a comprehensive attenuation-to-crosstalk ratio of at least 500 MHz and an overall bandwidth of 600 MHz, which is more than double that of Cat 6 and Cat 6a cables. The transfer rate can reach up to 10 Gbps. In Cat 7 cables, each pair of wires is individually shielded, and all four pairs are wrapped together in an overall shield. This additional layer makes the diameter of Cat 7 cables larger than their predecessors. A key distinction lies in the ability of its connecting hardware: Cat 7 systems require connectors that provide a minimum of 60 dB of crosstalk attenuation at 600 MHz.
Compared to Cat 5e cables, and Cat 6 cables, Cat 7 cables offer significantly higher transmission bandwidth, with a minimum of 600 MHz. The Cat 7 cabling system is not backward-compatible with the RJ-45 connectors used in previous cabling systems.
A. Key developments in Cat 7 cables include:
- On June 29, 1999, at a meeting of ISO/IEC, JTCL/SC, and 25/WG3 in Berlin, Germany, 69 experts unanimously agreed to incorporate the Cat 7 connector solution, GG45-GP45, proposed by Nexans, into the international wiring standard ISO/IEC 11801.
- On August 27, 2001, at an ISO/IEC meeting in Germany, Nexans suggested that IEC60603-7-7 be finalized as the Cat 7 interface standard.
- Cat 7 cables typically use a skin-foam-skin single-wire structure.
- The outer diameter of the copper conductor in Cat 7 cables is chosen to be around 22AWG (some advocate for 19AWG).
- The bandwidth of Cat 7 cables is 600 MHz.
- The test frequency range for network analyzers is 0.064~1000 MHz.
- The permanent link distance is 90 meters.
- The insertion loss is approximately 2 dB (with a 3-meter reduction for horizontal cables or a 2-meter patch cord).
- The near-end crosstalk loss is between 5.1 and 7 dB.
- The ACR is -1.9 dB.
- The far-end crosstalk is 45.3 dB.
- The return loss is 8.4 dB.
- The delay is 45 ms.
- The delay skew is 44 ms.
- The DC loop resistance is 34 Ω.
- The coupling attenuation is 64.4 dB.
B. Interface
When drafting the Cat 7 standard, there were significant changes in network interfaces. Eight types of connectors were proposed: two "RJ" style and six "non-RJ" style. In January 1999, the ISO technical committee decided to select one "RJ" and one "non-RJ" style interfaces for further study. At the ISO/IEC JTC1/SC 25/WG3 working group meeting in August 2001, ISO once again confirmed the Cat 7 standard would include both "RJ-type" and "non-RJ-type" interfaces.
C. Cat 7 Twisted Pair Cable Structure
The structure of Cat 7 twisted pair cables is shown in Table 1.
Table 1: Cat 7 Twisted Pair Cable Structure
STP SFTP
Conductor 22/23AWG Solid Copper 22/23AWG Solid Copper
Insulation Polyethylene Polyethylene
Shielding Aluminum Foil Individual Shield Aluminum Foil Individual Shield + Copper Wire Braided Overall Shield
Drain Wire 7/0.2mm None
Sheath PVC/LSZH PVC/LSZH
- Physical Structure of Cat 7 Twisted Pair Cable
Figure 1.(The physical structure of Cat 7 twisted pair cables)
D. Operational Frequency Bandwidth of Cat 7 Twisted Pair Cable
The operational frequency bandwidth of Cat 7 twisted pair cables ranges from 1 to 600 MHz (universal standard) and 1 to 1000 MHz.
E. Physical Characteristics of Cat 7 Twisted Pair Cable
□ Transmission speed (NVP): 79%.
□ Maximum Relative Capacitance: 5.6 nF/100m.
□ Maximum DC Resistance Unbalance: 5%.
□ Maximum Propagation Delay Skew: 30 ns/100m.
□ Maximum Propagation Delay: 536 ns/100m @ 100 MHz.
□ Rated Voltage: 60 Vrms.
□ Maximum Tensile Load: 80 N.
□ Operating Temperature: -20°C to +60°C.
□ Storage Temperature: -5°C to +50°C.
□ Flame Retardancy: Passes IEC 332-1 (FRRVC & LSOH sheath).
F. Electrical Performance Parameters of Cat 7 Twisted Pair Cable
The electrical performance parameters of Category 7 twisted pair cables are listed in Table 3.
Table 3: the electrical performance parameters table for Cat7 twisted-pair cables
| Frequency（MHz） | Near-End Crosstalk (NEXT) (dB/100m) minimum/worst/standard value ≥ | Attenuation (dB/100m) ≤ | Return Loss (dB) minimum/worst/standard value ≥ | Signal-to-Noise Ratio (SNR) (dB/100m) minimum/worst/standard value ≥ |
| 1 | 90.0/100.0/80.0 | 2.0 | 20.0/23.0/20.0 | 88.0/98.0/80.0 |
| 4 | 90.0/100.0/80.0 | 3.6 | 23.0/26.0/23.0 | 86.4/96.0/76.4 |
| 10 | 90.0/100.0/80.0 | 5.7 | 25.0/28.0/25.0 | 84.3/94.0/74.3 |
| 16 | 90.0/100.0/80.0 | 7.2 | 25.0/28.0/25.0 | 83.3/92.0/72.8 |
| 20 | 90.0/100.0/80.0 | 8.1 | 25.0/28.0/25.0 | 82.5/91.0/71.9 |
| 31.25 | 90.0/100.0/80.0 | 10.1 | 23.6/26.0/23.6 | 80.0/90.0/69.9 |
| 62.5 | 90.0/100.0/75.5 | 14.5 | 21.5/24.0/21.5 | 76.0/85.0/61.0 |
| 100 | 90.0/100.0/72.4 | 18.5 | 20.1/23.0/20.1 | 72.5/75.0/53.9 |
| 200 | 90.0/100.0/67.9 | 26.8 | 18.0/23.0/18.0 | 65.0/70.0/41.1 |
| 250 | 95.0/90.0/66.5 | 30.2 | 17.3/23.0/17.3 | 50.0/58.0/36.3 |
| 300 | 95.0/90.0/65.3 | 33.3 | 17.3/23.0/17.3 | 59.0/55.0/32.0 |
| 600 | 80.0/90.0/60.8 | 48.9 | 17.3/20.0/17.3 | 32.0/50.0/11.9 |
| Frequency(MHz) | Equal-Level Far-End Crosstalk (ELFEXT) (dB/100m) guaranteed/typical/standard value ≥ | Power Sum Near-End Crosstalk (PSNEXT) (dB/100m) minimum/worst/standard value ≥ | Power Sum Attenuation to Crosstalk Ratio (PSACR) (dB/100m) minimum/worst/standard value ≥ | Power Sum Equal-Level Far-End Crosstalk (PSELFEXT) (dB/100m) minimum/worst/standard value ≥ |
| 1 | 85.0/90.0/80.0 | 87.0/97.0/77.0 | 85.0/95.0/75.0 | 82.0/87.0/77.0 |
| 4 | 85.0/90.0/80.0 | 87.0/97.0/77.0 | 83.4/93.0/73.4 | 82.0/87.0/77.0 |
| 10 | 79.0/90.0/74.0 | 87.0/97.0/77.0 | 81.3/91.0/71.3 | 76.0/87.0/71.0 |
| 16 | 74.9/90.0/69.9 | 87.0/97.0/77.0 | 80.3/89.0/69.8 | 71.9/87.0/66.9 |
| 20 | 73.0/90.0/68.0 | 87.0/97.0/77.0 | 79.5/88.0/68.9 | 70.0/87.0/65.0 |
| 31.25 | 69.1/90.0/64.1 | 87.0/97.0/77.0 | 77.0/87.0/66.9 | 66.1/87.0/61.1 |
| 62.5 | 63.1/85.0/58.1 | 80.0/97.0/72.5 | 73.0/82.0/58.0 | 60.1/82.0/55.1 |
| 100 | 59.0/80.0/54.0 | 87.0/97.0/69.4 | 69.5/72.0/50.9 | 56.0/77.0/51.0 |
| 200 | 53.0/75.0/78.0 | 87.0/97.0/64.9 | 62.0/67.0/38.1 | 50.0/72.0/45.0 |
| 250 | 51.0/70.0/46.0 | 92.0/87.0/63.5 | 47.0/55.0/33.3 | 48.0/67.0/43.0 |
| 300 | 49.5/66.0/44.5 | 92.0/87.0/63.3 | 56.0/52.0/29.0 | 46.5/63.0/41.5 |
| 600 | 43.4/60.0/38.4 | 77.0/87.0/57.8 | 29.0/47.0/8.9 | 40.4/57.0/35.4 |