电缆的差分特性阻抗（120欧姆）及插入损耗的测量方法

[{"insert":"本文档介绍一种测量电缆的差分特性阻抗（120欧姆）及插入损耗的方法\n测量使用的仪器：Keysight E5080A ; 50/120 欧姆平衡转换器（Balun）;120欧姆纯电阻（用于校准）\nl 差分120欧姆特性阻抗的测量方法\n测试装置示意图：\n"},{"insert":{"image":"https://community-1252773949.cos.ap-guangzhou.myqcloud.com/article/2032/be19eeff7326763b.png"}},{"attributes":{"align":"center"},"insert":"\n"},{"insert":"步骤：\n1. 在E5080A 上设置好起止频率（例：300KHz--10MHz），自定义校准件型号（如120）注意阻抗设置成120欧姆，网分系统阻抗设置成120欧姆。测量S11,Format设置成Real\n "},{"insert":{"image":"https://community-1252773949.cos.ap-guangzhou.myqcloud.com/article/2032/dbf60f5dcc7441a6.png"}},{"insert":"   "},{"attributes":{"align":"center"},"insert":"\n"},{"insert":{"image":"https://community-1252773949.cos.ap-guangzhou.myqcloud.com/article/2032/83cc42298b3cb654.png"}},{"attributes":{"align":"center"},"insert":"\n"},{"insert":"2. Balun单端端口连接E5080A PORT1,平衡端口连接夹具。如果没有夹具，可以不用连接夹具。\n"},{"insert":{"image":"https://community-1252773949.cos.ap-guangzhou.myqcloud.com/article/2032/6545918be39777ef.png"}},{"attributes":{"align":"center"},"insert":"\n"},{"insert":"3. 在夹具端口（Balun平衡端口）进行三步校准（开路，短路，负载）。开路校准时，保持夹具两个端口开路，短路校准时，短接夹具两端口，负载校准时，在夹具两端口之间连接120欧姆纯电阻。\n"},{"insert":{"image":"https://community-1252773949.cos.ap-guangzhou.myqcloud.com/article/2032/283fcfabd90c014b.png"}},{"insert":" "},{"insert":{"image":"https://community-1252773949.cos.ap-guangzhou.myqcloud.com/article/2032/14a943a46e3c1a96.png"}},{"attributes":{"align":"center"},"insert":"\n"},{"insert":{"image":"https://community-1252773949.cos.ap-guangzhou.myqcloud.com/article/2032/a2b4ee537c3071f5.png"}},{"attributes":{"align":"center"},"insert":"\n"},{"insert":"4. 校准完成后，把被测件的一对电缆连接到夹具上，进行测试\n"},{"insert":{"image":"https://community-1252773949.cos.ap-guangzhou.myqcloud.com/article/2032/399ed01dac38d5dc.png"}},{"attributes":{"align":"center"},"insert":"\n"},{"insert":{"image":"https://community-1252773949.cos.ap-guangzhou.myqcloud.com/article/2032/a885ce4991f11efd.png"}},{"attributes":{"align":"center"},"insert":"\n"},{"insert":"5. 被测电缆一端连接到夹具上，另一端保持开路，测试S11值；另一端保持短路时，测试S11值。计算开短路阻抗。\n"},{"insert":{"image":"https://community-1252773949.cos.ap-guangzhou.myqcloud.com/article/2032/4595231a265d0b63.png"}},{"attributes":{"align":"center"},"insert":"\n"},{"insert":"\t式中："},{"attributes":{"color":"#000000"},"insert":"Z"},{"attributes":{"color":"#000000","script":"sub"},"insert":"r  "},{"insert":"---开短路阻抗\n\t      "},{"attributes":{"color":"#000000"},"insert":"Z"},{"attributes":{"color":"#000000","script":"sub"},"insert":"0a ---"},{"insert":"基准阻抗，单位为欧姆（即120欧姆）\n\t      "},{"attributes":{"color":"#000000"},"insert":"S"},{"attributes":{"color":"#000000","script":"sub"},"insert":"aa ---"},{"insert":"即S11值\n\t此过程在网分中有工具可自动计算得出开短路阻抗：MeasSetup--Conversions--Z-Relfect\n"},{"insert":{"image":"https://community-1252773949.cos.ap-guangzhou.myqcloud.com/article/2032/1f73adfcc76d1c45.png"}},{"attributes":{"align":"center"},"insert":"\n"},{"insert":"6. 计算特性阻抗\n\t特性阻抗等于开路阻抗和短路阻抗的值相乘并开平方的值\n"},{"insert":{"image":"https://community-1252773949.cos.ap-guangzhou.myqcloud.com/article/2032/e0d65f9edad26c5d.png"}},{"attributes":{"align":"center"},"insert":"\n"},{"insert":"\t式中Z为特性阻抗，Z1为开路阻抗，Z2为短路阻抗。\n7. 根据步骤5分别marker各频点的开短路阻抗，根据步骤6计算相应的特性阻抗。\n\t例如：\n\t F=5.005MHz时开路阻抗 285.58欧姆\n"},{"insert":{"image":"https://community-1252773949.cos.ap-guangzhou.myqcloud.com/article/2032/a727907b08ff53f4.png"}},{"attributes":{"align":"center"},"insert":"\n"},{"insert":"\tF=5.005MHz时短路阻抗39.99欧姆\n"},{"insert":{"image":"https://community-1252773949.cos.ap-guangzhou.myqcloud.com/article/2032/757e08b93c31a7c8.png"}},{"attributes":{"align":"center"},"insert":"\n"},{"insert":"\t计算："},{"insert":{"image":"https://community-1252773949.cos.ap-guangzhou.myqcloud.com/article/2032/f05a5685326de3de.png"}},{"insert":"欧姆\n8. 可以把测试开短路阻抗的S曲线保存成数据格式（CSV），然后在excel里自动得出特性阻抗曲线\n"},{"insert":{"image":"https://community-1252773949.cos.ap-guangzhou.myqcloud.com/article/2032/45ae979d854220ea.png"}},{"attributes":{"align":"center"},"insert":"\n"},{"insert":"l 电缆的插入损耗测量方法\n\t测试装置示意图\n"},{"insert":{"image":"https://community-1252773949.cos.ap-guangzhou.myqcloud.com/article/2032/acbe2e059e057b58.png"}},{"attributes":{"align":"center"},"insert":"\n"},{"insert":"1. 在E5080A上设置起止频率（电缆工作频率 300KHz--3MHz），测试S参数设置为S41（2端口网分可用S21）\n"},{"insert":{"image":"https://community-1252773949.cos.ap-guangzhou.myqcloud.com/article/2032/11f082f1ceb1c2a9.png"}},{"attributes":{"align":"center"},"insert":"\n"},{"insert":"2. 按示意图连接Balun和仪器端口\n"},{"insert":{"image":"https://community-1252773949.cos.ap-guangzhou.myqcloud.com/article/2032/e8209574b8315702.png"}},{"attributes":{"align":"center"},"insert":"\n"},{"insert":"3. 校准S21\n"},{"insert":{"image":"https://community-1252773949.cos.ap-guangzhou.myqcloud.com/article/2032/56b0a5d3a40089a0.png"}},{"insert":" "},{"attributes":{"align":"center"},"insert":"\n"},{"insert":{"image":"https://community-1252773949.cos.ap-guangzhou.myqcloud.com/article/2032/4b1ff5364efed680.png"}},{"attributes":{"align":"center"},"insert":"\n"},{"insert":"4. 连接被测电缆测试插损\n"},{"insert":{"image":"https://community-1252773949.cos.ap-guangzhou.myqcloud.com/article/2032/6e8a787b3f399e3b.png"}},{"attributes":{"align":"center"},"insert":"\n"},{"insert":{"image":"https://community-1252773949.cos.ap-guangzhou.myqcloud.com/article/2032/33c9c3e44b424a54.png"}},{"insert":" "},{"attributes":{"align":"center"},"insert":"\n"},{"insert":"5. Marker标记需要测的频点插损值\n"},{"insert":{"image":"https://community-1252773949.cos.ap-guangzhou.myqcloud.com/article/2032/e9d742ca2c86c8d2.png"}},{"attributes":{"align":"center"},"insert":"\n\n"},{"insert":"——转自 君鉴科技/付飞黄"},{"attributes":{"align":"right"},"insert":"\n"}]