干(gan)線(xian)(xian)(xian)放(fang)大(da)器是主(zhu)干(gan)線(xian)(xian)(xian)纜傳(chuan)(chuan)輸(shu)鏈路上(shang)的(de)(de)(de)雙(shuang)向(xiang)信(xin)號處(chu)理放(fang)大(da)設(she)備。當(dang)主(zhu)干(gan)線(xian)(xian)(xian)纜傳(chuan)(chuan)輸(shu)距離長，或鏈路中(zhong)負(fu)載器件數量較多，雙(shuang)向(xiang)信(xin)號損耗過大(da)，來自信(xin)號源（下行）或來自天線(xian)(xian)(xian)（上(shang)行）的(de)(de)(de)信(xin)號強(qiang)度偏低，相關指標將不(bu)能滿足設(she)計的(de)(de)(de)技術要求，將直接(jie)影響到室內天線(xian)(xian)(xian)的(de)(de)(de)端口(kou)發射功率和基站接(jie)收機(ji)（中(zhong)繼臺)）的(de)(de)(de)端口(kou)的(de)(de)(de)接(jie)收功率，這就必(bi)須在主(zhu)干(gan)線(xian)(xian)(xian)纜傳(chuan)(chuan)輸(shu)鏈路中(zhong)的(de)(de)(de)適(shi)當(dang)位置(zhi)增加干(gan)線(xian)(xian)(xian)放(fang)大(da)器設(she)備。

干線(xian)放(fang)(fang)大(da)器具有(you)(you)雙向信號放(fang)(fang)大(da)功(gong)能，上行(xing)(xing)(xing)(xing)/下(xia)行(xing)(xing)(xing)(xing)信號處理(li)及放(fang)(fang)大(da)電路(lu)獨(du)立分(fen)開，上行(xing)(xing)(xing)(xing)/下(xia)行(xing)(xing)(xing)(xing)放(fang)(fang)大(da)功(gong)率可單獨(du)調(diao)節，可根據(ju)實際要求進(jin)(jin)行(xing)(xing)(xing)(xing)現場測驗后對(dui)上行(xing)(xing)(xing)(xing)/下(xia)行(xing)(xing)(xing)(xing)信號增益(yi)進(jin)(jin)行(xing)(xing)(xing)(xing)分(fen)別設置(zhi)，這樣極(ji)大(da)地(di)(di)方便了(le)系統調(diao)試，從而更有(you)(you)效地(di)(di)保證了(le)系統的(de)安全穩定性和建筑物內(nei)電磁環(huan)境滿足國家有(you)(you)關標準。