Kableeynta Coaxial Dheerka Raadiodka RF

Faallo kabadhka coaxial waa quruumo muhim ah si loo xaqiijiiyo awooddu, jiridduna iyo xawaalaha loo isticmaalo sida televishanka, xuska internet, xiriirka satelaytka, iyo nidaamka CCTV. Kabadhka coaxial, oo leh miyankii dhexe, dielectric insulating, gurguurta fulka, iyo jaako ee sare, waxay leeyihi kharashada siiyaha, kala duwanaanshaha, jajab, xadgudub, ama xirada, taas oo ka qabasa awoodda. Faallooyinka sax ah ayaa ka heli kharashadaas, si loo sameeyo isdiiwaangelinta ama beddelidaa ka hor inta la qaad ama marka la xidhay. Quruumada ayaa leh talaabaha iyo alaabta saxda, kila mid ayaa la xidhay dusha kabadhka. Ee horay marka la bilaabo faallooyinka, iska qoristii waa qaadka ugu horreya. Ka qoristi dherigga kabadhka oo dhan ee jidhka: hubi cuta, cracka, ama kinkka ee jaako sare, taas oo kara fulka loogu dhaafayo biyaha ama xirada. Ka qoristi xidhka (tusaale ahaa, F type, BNC, N type) ee jidhka, pinna badan oo xiran, ama xidhka laabta, sidaas darteed waxay kara kharashada siiyaha. Hubi in xidhka ayaa la xidhay ama la buuxiyay, laakiin ma jirto fogaan ee xidhka iyo jaako kabadhka, taas oo kara siiyaha la laabto. Wixii loo arki karo ee jidhka waxay noqon kartaa in la beddelo ama la isdiiwaango kabaca in la bilaabo faallooyinka elektaroonika. Qaadkii xiga waa faallo kontinuity, taas oo mujiyo in miyankii dhexe iyo gurguurta ay yihiin aan jajabin. Multimeter, oo ku set in kontinuity ama xawaalaha muqusha, waxaa loo isticmaala: la socda midabka kala duwan ee miyankii dhexe ee kabadhka oo kala duwan iyo midabka kale ee miyankii dhexe ee xagga kale ee kabadhka. Xawaalaha xiran (dheer ugu yaraan 0 ohms) ayaa mujiyo kontinuity; xawaalaha weyn (infinity) ayaa mujiyo jajabka miyankii dhexe. Dib u samee quruumadaas gurguurta, la socda midabka kala duwan ee gurguurta ee xagga kala duwan. Quruumadaas ayaa xaqiijiyaa in dhammu ayaan lahayd, muhim in la siiyo siiyaha. Faallo impedans waa muhim, sida kabadhka coaxial ayaa lagu sameeyay si ay u leeyihiyo impedans (waxaa jira 50 ohms ee deyta iyo RF, 75 ohms ee video iyo CATV) si loo korkariyo siiyaha iyo kharasha. Alaabta impedans ama alaabta reflectometer ee waqtiynta (TDR) ayaa qaybi jiridda impedans ee kabadhka. TDR waxay soo diraya pulsa siiyaha kabadhka iyo ka analaysi xirada: impedans sax ah waxay soo jeedaya siiyaha yar, haddii kala duwan (tusaale ahaa, midabka dielectric la jidhay ama xidhka) waxay soo jeedaya xirada weyn, taas oo mujiya gobalka iyo weyniisa. Tusaale ahaa, qoristii TDR oo mujiya in dibadda ayaa 10 mita jiraa kala duwanaanshaha impedans ee gobalkaas, waxaa ka mid noqnoqda dielectric la daray ama xidhka la sameeyay aan sax ahayn. Kharashada siiyaha, ama attenution, waxaa lagu qiyaasaa oo isticmaalaya alaabta network analyzer ama alaabta siiyaha generator la xidhay power meter. Attenuation waxay kordhiyaa in la xiraa dherigga kabadhka iyo sawirka, sidaa darteed faallo waa in la sameeyo sawirka kabadhka ayaa isticmaalaa (tusaale ahaa, 1 GHz ee televishanka). Xidh alaabta generator siiyaha ee kabadhka oo kala duwan iyo power meter ee kale ee xagga kale ee kabadhka; kala iyo kharashada loo diray iyo loo helay waa attenution in dB. Xaqiijii natiijada kabadhka specifikishada - attenution weyn waxay mujiya kartaa dielectric la jidhay, biyo la gudbiyay (taas oo kordhiya kharasha), ama xidhka aan sax ahayn. Tusaale ahaa, 100 RG 6 kabadhka waa inuu leeyahay ~6 dB kharasha ee 1 GHz; qoristii 12 dB waxay mujiya in jidh jiraa. Faallo shorts waa qaad muhim kale, sida short ee miyankii dhexe iyo gurguurta ayaa siiyaha la jebin kara. Ii isticmaal multimeter ee ku set in xawaalaha, la socda midabka kala duwan ee miyankii dhexe iyo midabka kale ee gurguurta ee xagga kala duwan ee kabadhka. Xawaalaha xiran waxay mujiya in jidh jiraa, waxaa ka mid noqnoqda dielectric la jidhay oo kara miyankii iyo gurguurta la xidhay, ama xidhka aan sax ahayn. Shorts ayaa jiraa oo kale ee splices, sidaa darteed qoristi kala duwan splices haddii kabadhka leeyahay jiridda badan. Faallo xirada ayaa ka qaybi EMI (electromagnetic interference) ama RFI (radio frequency interference) oo kara siiyaha la jebin kara. Spectrum analyzer oo xidh kabadhka ayaa ka heli kharashada siiyaha ee joogga sawirka loo isticmaalo. Alernatively, ee nidaamka lahayd, hubi in jiraa kharashada (tusaale ahaa, barafka ee televishanka) ama xarafka, taas oo mujiya xirada. Tani waa muhim in kabadhka la dhaafay joogga xariiqa deynta ama alaabta soo saarista, sida EMI/RFI kara kabadhka aan sax ahayn ee gurguurta. Kabadhka dheer ama kabadhka la dhaafay qolalka, OTDR (optical time domain reflectometer) ma la isticmaali karo kabadhka coaxial, laakiin TDR waa alaabta kale, sidaas darteed, si loo helo jidhka la ma xidhin kara. Ka dib marka la isdiiwaango ama la sameeyay, dib u qiyaasiwada waxay xaqiijiyaa in kabadhka ay fuliya awoodda. Isticmaal natiijada faallo, oo leh taariikhda, alaabta isticmaalay, iyo qoristii, waxay noqon kartaa xagga ugu horreya ee dib u xidhidda ee la xidhay. Guud ahaan, faallo kabadhka coaxial waa leh iska qoristii, iska kontinuity, qiyaasinta impedans, faallo attenution, helitaanka short, iyo tafatirka xirada, isticmaalaya alaabta sida multimeters, TDRs, power meters, iyo spectrum analyzers si loo xaqiijiiyo siiyaha in nidaamka lahayd.