涂鸦无线模组 集成应用建议 Layout Guide for Antenna/Module
由于模组带板载天线型为预先设计好的天线，其最终性能特性取决于产品的结构、材质，以及模块放置的位置、底板的尺寸形状等等因素，故产品性能以整机实际测试为准。
1、模组水平摆放
针对我司3S等形态的贴片模组，如果天线的馈电点在模组的右侧，模组基本贴在底板的右侧；天线馈电点在模组的左侧，模组基本贴在底板的左侧。即尽量保证模组放置在底板的边缘，天线朝外，模组的GND与底板的GND平齐，并且保证充分连接。
天线区域（含模组天线净空区）下方净空，禁止有PCB基材，禁止布线，禁止任何结构干涉天线。
对于U形态模组如果贴片形式焊接在客户底板上，通常贴到底板后天线频点会往低频偏移，此时如果保证天线短路点远离短边的边缘，可以抵消这部分偏移的影响：
2、模组垂直于底板放置
对于直插类即模组垂直于底板焊接安装的方式：模组需要放置于底板边缘，模组的TOP层朝外，参考下图。
佐证的仿真数据如下：
另外上述这种放置方式，由于模组另一边缺GND，会影响天线性能，解决方法是借用外壳、底板或其他结构上的金属作为GND，来提高天线性能。借用GND这个方法，使用时需要评估，调试天线S11 <-5dB 时，模块性能基本正常。
3、模组嵌入底板，天线区域镂空处理
这种放置形式，模组天线被底板GND遮挡，严重影响天线性能，解决方法是可在底板上开槽，减小对天线的干扰。
4、成品外壳材质建议
外壳建议使用塑料材质如ABS、PC或其他介电常数相近的材质，外壳与天线保持一定的距离，天线辐射方向外壳不可使用金属材质、或在塑料壳体表面使用含有金属成分的喷漆和镀层，天线周围避免使用金属螺丝、金属铆钉或其他金属件影响天线的辐射。外壳距离模组天线尽量远离，例如距离8mm以上，越远离对天线的干扰越小。天线外壳有金属对天线影响极大，产品设计时如必须使用金属，请咨询专业天线公司进行评估。
5、其他布局要点整理
1）模块，特别是天线区域，远离喇叭、电池、电源开关、Camera、LCD、网口、HDMI、USB 或其他高速信号传输口30mm以上，避免干扰。
2）天线区域下方GND净空，禁止布线，禁止有其他介质层，禁止任何结构干涉天线。
3）天线附近30mm内禁止其他同频率或相近频率的信号干扰。
4）天线辐射方向禁止金属遮挡。
5）由于模组板载天线性能有限，建议在条件允许下，优先选用外接天线（例如选配IPEX接口的模组，搭配合适的外置FPC天线）。
6、应用补充说明
1）本帖仅是对客户在产品设计时，针对选配模组的布局提供一个初步的认识，文中举例的一些情况下变量的数值并非绝对，具体性能以实际整机测试为准。
2） 初始设计完成后，每次改版，特别是天线附近发生较大改动的，建议重新评估天线的性能。
3） 建议产品设计完成后，对整机天线性能根据产品定义进行测试，确认天线性能是否符合整机要求。例如联系天线暗室，进行TRP、TIS等整机辐射测试
。
4）常规的电子产品，在设计后可以通过无线距离拉距测试及网络分析仪测试天线驻波和增益等确认基本的性能参数。
1. Overview:
Tuya RF modules are used in various terminal products. The modules needs to be assembled reasonably to ensure the clearance area around the antenna so that the wireless performance can be fully exerted. Taking the bulb lamp as an example, there are usually two assembly methods to solder module to the lamp driving board:
A. SMT welding.
B. Solder to lamp driving board by though hole header.
At the same time, there are usually two types of module antennas:
A. On board PCB antenna or external soft PCB antenna .
B. External soft antenna or spring antenna.
2. Key points for the antenna layout on plug-in module
The module assembled to the lamp driver board by the header or though-hole pad, because the base of the lamp，the aluminum housing，and aluminum PCBA on which the lamp beads are located are made of metal , and wireless signals cannot pass though these metal materials, so it is important to ensure the PCB antenna can across the aluminum PCBA and deep into the front part of the lamp. Under the premise of not affecting light source illumination quality, the closer the antenna is to the front of the lamp, the better the wireless signal transmit
below shows a wrong operation which the header is too close to the PCB antenna.In layout design, please keep the clearance near the antenna, especially the metal pin headers should also be kept away, keeping a distance more than 8mm from the antenna.
Figure 1 The metal pin header is too close to the PCB antenna
Figure2 can be used as an reference when the customer lays out the module. At the same time, the crystal, RF Soc and other devices of the module should be as far away as possible from the heating of the driving base plate / light source area to avoid the local temperature rise is too high and the surface temperature of the core device exceeds 105 ° C.
Figure2 reference when the customer lays out the module.
3.Key points of Layout design for SMD modules
If the module must be placed on the lamp driver board due to design limitations, you can refer to the three assembly methods shown in Fig 3, Fig 4,and Fig 5 below to ensure there is no PCB with/without copper or components in the area under the antenna. The copper around antenna will affect the resonance point of the antenna, and PCB material close to antenna will reduce the antenna radiation efficiency
The key points of the above solutions:
1)Make sure there is no PCB material directly below or directly above the PCB antenna.
2)Make sure the area around the PCB antenna is far away from the copper.
This will maximize radiation effect of the antenna.
4.The module with external antenna
For the module with external antenna, ensure the antenna is as far as possible away from the base and aluminum housing of lamp which is made by aluminum and the aluminum PCBA under the premise of not affecting light source illumination quality. Fig. 6 shows a monopole spring antenna and a monopole soft antenna.
Fig6 A monopole spring antenna and a monopole soft antenna.
Fig. 7 below shows a module with an external antenna. The module antenna passes through the aluminum PCBA vertically and is above the aluminum PCBA.The green arrows indicate the direction of the strongest radiation of antenna; the orange arrows indicate the directions of the weakest radiation of antenna.
Make sure no metal parts around the spring antenna, which will greatly impact the transmission of wireless signals. Make sure the spring antenna is in the center and as far as possible away from the aluminum housing, and the vertical height of the aluminum housing should be lower than the antenna’s.
Fig7 Directions of antenna signal
Fig. 8 below shows the wrong assembly method of antenna. The antenna of the module is completely blocked under the aluminum PCBA and the wireless signal cannot pass though, which ultimately affects the wireless signal quality of the lamp.
Fig8 Wrong assembly method of antenna
If it is limited by the structure, the antenna can't be soldered to the RF module directly, you can make a exposed pads with size not bigger than 2 * 3mm on lamp driver board to solder the soft antenna, ensure the antenna is placed at the front part of the lamp. The purpose of choosing a soft antenna is that it can be bent arbitrarily to adapt to the structure of the lamp, but please ensure there are no metal parts around the soft antenna, and the length of the soft antenna is enough to deep into the front of the lamp.
5. Antenna Isolation in Muti-antenna coexistence system
Antenna isolation is a measure of how tightly coupled antennas are. It is a must be tested item in Muti-antenna coexistence system. For instance gateway product. Therefore, the isolation should be as large as possible(More than 15dB).
Antenna isolation can be increased by:
1.Increasing the physical separation between the antennas.
2.Making vertical or different polarization for the antennas(Reducing the correlation coefficient between the antenna's radiation patterns).
。