<p><strong>一、天线原理</strong></p>
<p><strong>1.1 天线的定义：</strong></p>
<p>Ø 能够有效地向空间某特定方向辐射电磁波或能够有效的接收空间某特定方向来的电磁波的装置。</p>
<p><strong>1.2 天线的功能：</strong></p>
<p>Ø 能量转换-导行波和自由空间波的转换;</p>
<p>Ø 定向辐射(接收)-具有一定的方向性。</p>
<p><strong>1.3 天线辐射原理</strong></p>
<p><img alt="1" data-entity-type="file" data-entity-uuid="01628c00-ef29-4725-8b95-38858ec4bb0a" src="/sites/default/files/inline-images/1111500%2021.png" /></p>
<p><strong>1.4 天线参数</strong></p>
<p>u辐射参数</p>
<p>Ø半功率波束宽度、前后比;</p>
<p>Ø极化方式、交叉极化鉴别率;</p>
<p>Ø方向性系数、天线增益;</p>
<p>Ø主瓣、副瓣、旁瓣抑制、零点填充、波束下倾 …</p>
<p>u电路参数</p>
<p>Ø电压驻波比 VSWR、反射系数Γ、回波损耗RL;</p>
<p>Ø输入阻抗 Zin、传输损耗 TL;</p>
<p>Ø隔离度 Iso;</p>
<p>Ø无源三阶互调 PIM3 …</p>
<p>u天线旁瓣</p>
<p><img alt="1" data-entity-type="file" data-entity-uuid="f9abe3a3-9a07-4aae-b5ac-b7015c02ef64" src="/sites/default/files/inline-images/1111500%2020.jpg" /></p>
<p>u水平面波束宽度</p>
<p><img alt="1" data-entity-type="file" data-entity-uuid="01118860-17b9-44e6-bac7-ec699ae0bb49" src="/sites/default/files/inline-images/1111500%2019.jpg" /></p>
<p>u前后比:指定向天线的前向辐射功率和后向±30°内辐射功率之比</p>
<p><img alt="1" data-entity-type="file" data-entity-uuid="bbc3fb3c-4087-4a43-91cc-9b0467873115" src="/sites/default/files/inline-images/1111500%2018.jpg" /></p>
<p>u增益和天线尺寸及波束宽度的关系</p>
<p>将“轮胎”压扁，信号就越集中，增益就越高，天线尺寸就越大，波束宽度越窄;</p>
<p><img alt="1" data-entity-type="file" data-entity-uuid="0879785a-1424-4f6a-a2d0-c32c79d7dfbc" src="/sites/default/files/inline-images/1111500%2017%E2%80%98%E2%80%99.jpg" /></p>
<p><strong>u天线增益的几个要点：</strong></p>
<ul>
<li>
<p>Ø天线是无源器件，不能产生能量。</p>
<p>天线增益只是将能量有效集中向某特定方向辐射或接受电磁波的能力。</p>
</li>
<li>
<p>Ø天线的增益由振子叠加而产生。</p>
<p>增益越高，天线长度越长。</p>
<p>增益增加3dB，体积增大一倍。</p>
</li>
<li>
<p>Ø天线增益越高，方向性越好，能量越集中，波瓣越窄。</p>
</li>
</ul>
<p><strong>1.5 辐射参数</strong></p>
<p>u极化:指电场矢量在空间运动的轨迹或变化的状态。</p>
<p><img alt="1" data-entity-type="file" data-entity-uuid="8bcce9fe-3d0c-41a7-8f0c-d8c013d7bca3" src="/sites/default/files/inline-images/1111500%2016.jpg" /></p>
<p><strong>1.6 电路参数</strong></p>
<p>u回波损耗</p>
<p><img alt="1" data-entity-type="file" data-entity-uuid="c6526aae-83a2-49a6-8be7-06e4bd77109b" src="/sites/default/files/inline-images/1111500%2015.jpg" /></p>
<p>此例中，回波损耗为 10log(10/0.5) = 13dB</p>
<p>VSWR(驻波比) 是对此现象的另一种度量方法</p>
<p>u隔离度 : 是某一极化接收到的另一极化信号的比例</p>
<p><img alt="1" data-entity-type="file" data-entity-uuid="7c278cee-aba0-45e9-baac-95521d847b38" src="/sites/default/files/inline-images/1111500%2014.jpg" /></p>
<p><strong>u无源交调(PIM)：</strong></p>
<p>当两个频率f1和f2输入到天线，由于非线性效应，天线辐射的信号除频率f1 和f2 外，还包括有其他频率，如2f1-f2 和2f2-f1 (3阶)等。</p>
<p><img alt="1" data-entity-type="file" data-entity-uuid="f3fa33af-6af4-4110-baac-9afd535c1e0f" src="/sites/default/files/inline-images/1111500%2013.jpg" /></p>
<p><strong>二、天线产品</strong></p>
<p><strong>2.1 天线命名方式</strong></p>
<p><img alt="1" data-entity-type="file" data-entity-uuid="209679e1-4620-41ff-a90b-bfb5e786fac7" src="/sites/default/files/inline-images/1111500%2012.jpg" /></p>
<p><strong>天线类别:</strong></p>
<p>ODP(室外定向板状天线),OOA(室外全向天线),IXD(室内吸顶天线),OCS(室外双向天线)，OCA(室外集束天线)，OYI(室外八木天线)，ORA(室外抛面天线)，IWH(室内壁挂天线)等等.</p>
<p><strong>半功率角:</strong></p>
<p>032,065,090,105,360(基站天线)</p>
<p>020，030，040，050，060，075，090，120，160，360(直放站天线)</p>
<p><strong>极化方式：</strong></p>
<p>R(双极化)，V(单极化)</p>
<p><strong>增益：</strong></p>
<p>按照实际指标，目前最大为21dbi</p>
<p><strong>接头类型：</strong></p>
<p>D(Din头)，N(N型头)，S(SMA头)，T(TNC头)等等</p>
<p><strong>频段：</strong></p>
<p>规格代码：罗马字母表示第几代产品.后面字母和数字表示电调下倾角、赋形、电调等信息.F赋型;V电调;RV远程电调</p>
<p><strong>2.2基站天线</strong></p>
<p><img alt="1" data-entity-type="file" data-entity-uuid="d4fe4f05-b922-43fd-941b-c33c23fe3085" src="/sites/default/files/inline-images/1111500%2011.jpg" /></p>
<p>全向天线</p>
<p><img alt="1" data-entity-type="file" data-entity-uuid="941e815e-d4fd-4e5d-9f73-ffa4bf0dc94c" src="/sites/default/files/inline-images/1111500%2010.jpg" /></p>
<p>双频天线</p>
<p><img alt="1" data-entity-type="file" data-entity-uuid="1d33870a-7617-4878-85f8-a179b4303e13" src="/sites/default/files/inline-images/1111500%209.jpg" /></p>
<p>三频天线</p>
<p><img alt="1" data-entity-type="file" data-entity-uuid="9fe04f58-f635-49de-ab3c-50d4b55d7026" src="/sites/default/files/inline-images/1111500%208.jpg" /></p>
<p><strong>2.3 分布系统天线</strong></p>
<p><img alt="1" data-entity-type="file" data-entity-uuid="fc644d93-3001-4cdc-b97f-1c654e5b1d63" src="/sites/default/files/inline-images/1111500%207.jpg" /></p>
<p>烟感器型吸顶天线</p>
<p><img alt="1" data-entity-type="file" data-entity-uuid="f41f9593-e098-4d2b-8f74-f8cf63bf93aa" src="/sites/default/files/inline-images/1111500%206.jpg" /></p>
<p>灯型吸顶天线</p>
<p><img alt="1" data-entity-type="file" data-entity-uuid="1a5c412f-0f78-466f-88c0-676ba438f0fd" src="/sites/default/files/inline-images/1111500%205.jpg" /></p>
<p>壁挂天线</p>
<p><strong>2.4 室外天线</strong></p>
<p>施主天线： Ø窄波束、方向性强 Ø高前后比</p>
<p><img alt="1" data-entity-type="file" data-entity-uuid="e859ac10-a6b7-4b3a-90ca-98935b395356" src="/sites/default/files/inline-images/1111500%204.jpg" /></p>
<p>八木天线</p>
<p><img alt="1" data-entity-type="file" data-entity-uuid="0a3295d9-fbc7-4b09-9839-5cdd31b39cc3" src="/sites/default/files/inline-images/1111500%203.jpg" /></p>
<p>角反射天线</p>
<p><img alt="02" data-entity-type="file" data-entity-uuid="717f5b09-39cf-467d-b2b1-8a9ca707d22a" src="/sites/default/files/inline-images/1111500%202.jpg" /></p>
<p>抛物面天线</p>
<p><strong>用户天线</strong></p>
<p><img alt="1" data-entity-type="file" data-entity-uuid="8844f55a-8165-4239-a782-7d7ee5572ec4" src="/sites/default/files/inline-images/1111500%201.jpg" /></p>
<p>来源：<a href="https://mp.weixin.qq.com/s/lkyGJ5aR4WIRu8_1jeBnig">滤波器</a></p>