Is ón Eoraip a tháinig an córas sreangaithe sciath. Is ciseal sciath miotail é a chuirtear leis an taobh amuigh den ghnáthchóras sreangaithe gan sciath. Úsáidtear machnamh, ionsú agus éifeacht craiceann an chiseal sciath miotail chun trasnaíocht leictreamaighnéadach agus radaíocht leictreamaighnéadach a chosc. Úsáideann an córas sciath go cuimsitheach prionsabal cothromaíochta péire casta agus éifeacht sciath an chiseal sciath, agus mar sin tá tréithe comhoiriúnachta leictreamaighnéadacha (EMC) an-mhaith aige.
Ciallaíonn comhoiriúnacht leictreamaighnéadach (EMC) go bhfuil cumas áirithe ag trealamh leictreonach nó córais líonra chun cur i gcoinne trasnaíochta leictreamaighnéadach, agus nach féidir leis an radaíocht leictreamaighnéadach iomarcach a ghiniúint ag an am céanna. Is é sin le rá, tá sé riachtanach go bhféadfaidh an gléas nó an córas líonra oibriú de ghnáth i dtimpeallacht leictreamaighnéadach sách dian, agus ag an am céanna ní féidir leis na tonnta leictreamaighnéadacha iomarcacha a radú chun cur isteach ar ghnáthghníomhú gléasanna agus líonraí eile máguaird.
The balanced characteristics of U/UTP (unshielded) cables are not only determined by the quality of the components themselves (eg twisted pairs), but are also affected by the surrounding environment. Because metal around U/UTP (unshielded), hidden "ground", pulling during construction, bending, etc. will destroy its balance characteristics, thereby reducing EMC performance.
Mar sin, níl ach réiteach amháin ann chun tréithe cothromaithe marthanacha a fháil: cuir na croíleacáin go léir le ciseal breise de scragall alúmanaim. Tugann scragall alúmanaim cosaint do na croítheidil péire casta, agus cruthaítear go saorga timpeallacht chothromaithe do cháblaí U/UTP (gan sciath). Dá bhrí sin foirmítear an rud ar a dtugaimid anois cábla sciath.
Tá prionsabal sciath an chábla sciath difriúil ó phrionsabal cealaithe cothromaithe an phéire casta. Is é an cábla sciath ná sraith amháin nó dhá shraith de scragall alúmanaim a chur ar an taobh amuigh de na ceithre phéire péire casta, agus úsáid a bhaint as an miotail chun prionsabail na dtonnta leictreamaighnéadacha a léiriú, a ionsú agus a chraiceann (an treocht a thugtar air) . Ciallaíonn an éifeacht craiceann go bhfuil claonadh ann dáileadh an tsrutha i dtrasghearradh an tseoltóra a dháileadh ar dhromchla an tseoltóra le méadú ar an minicíocht. Téann trasnaíocht leictreamaighnéadach isteach sa chábla, ach cuireann sé cosc ar an comhartha inmheánach ó radiaíocht amach, ag cur isteach ar obair trealaimh eile.
Experiments show that electromagnetic waves with frequencies exceeding 5MHz can only pass through 38μm thick aluminum foil. If the thickness of the shielding layer exceeds 38 μm, the frequency of electromagnetic interference that can enter the cable through the shielding layer is mainly below 5MHz. For low-frequency interference below 5MHz, the balance principle of twisted pair can be applied to effectively cancel.
According to the earliest definition of wiring, it is divided into two types: unshielded cable-UTP and shielded cable-STP. Later, with the development of technology and different craftsmanship, many different types of shielding were derived. F/UTP Foil Screened Cable Single-layer aluminum foil shielding structure 2． Foil and Braid Screened Cable Double-layer shielding structure of aluminum foil and copper braid a) SF/UTP aluminum foil and copper braid wrapped on the outer layer of four pairs of wires at the same time b) S/FTP (PIMF) wire pair single pair of aluminum foil shielding plus The copper braided mesh PIMF =Pair in Metal Foil wrapped on the outer layer of the four pairs of wires.
The shielded cable's resistance to external interference is mainly reflected in: the integrity of signal transmission can be guaranteed by the shielding system. The shielded wiring system can prevent the transmitted data from being affected by external electromagnetic interference and radio frequency interference. Electromagnetic Interference (EMI) is mainly low frequency interference. Motors, fluorescent lamps and power lines are common sources of EMI. Radio frequency interference (RFI) is high frequency interference, mainly radio frequency interference, including radio, television broadcast, radar and other wireless communications.
Maidir le friotaíocht le trasnaíocht leictreamaighnéadach, is é sciath braidáilte an rogha is éifeachtaí, is é sin, sciath mogalra miotail, mar gheall ar a fhriotaíocht íseal chriticiúil. Maidir le trasnaíocht radaimhinicíochta, is é an sciath scragall miotail an ceann is éifeachtaí, toisc go gceadaíonn an bhearna a chruthaíonn an sciath mogalra miotail do chomharthaí ardmhinicíochta dul isteach agus imeacht faoi shaoirse. Maidir leis an réimse trasnaíochta measctha minicíochta ard agus íseal, ba cheart an modh sciath comhcheangailte de chiseal scragall miotail agus mogalra miotail a úsáid, is é sin, an cábla sciath dúbailte i bhfoirm S/FTP, is féidir a dhéanamh. an sciath mogalra miotail atá oiriúnach do chur isteach ar an raon minicíochta íseal, agus an sciath scragall miotail Oiriúnach do chur isteach ar an raon ardmhinicíochta.
The single-layer thickness of the aluminum foil shielding layer in the IBM ACS shielded cable reaches 50-62 μm, which has a more complete shielding effect. At the same time, because only a single layer of shielding is used, it will be simpler for construction, easy to install, and not easy to cause artificial damage during the construction process, and the thickness of the aluminum silk can withstand greater destructive force. This can provide users with higher quality transmission performance.
