Hi,
I use a a ceramic chip antenna, RFANT3216120A5T by Walsin, connect to DA14580 with a 6.8nH inductor and 50 ohm Impedance Transmission Line according to RFANT3216120A5T datasheet, and a 3.9nH inductor according to AN-B-018 section 3.7.
我的电路板只能在大约2米处被检测到。
Is there anything I forget to place on the board?
Daniel
Device:
Hi daniel59,
The range of a device (antenna) depends on multiple factors, impedance matching, placement on the PCB, trace length, etc, even not proper soldering on a ceramic antenna on the PCB can cause range issues. You can have a look at the IoT reference design documents, the IoT uses a Ceramic Antenna and use this as a reference.
Thanks MT_dialog
Hi MT_dialog,
I find the IoT project use a Pi matching, without the 3.9nH inductor. It's different from AN-B-018 section 3.7. Why?
Daniel
Hi daniel59,
Because it uses a different antenna, the AN-B-018 document deals mostly with PCB antennas and not ceramic antennas. Apparently there was no need for additional matching on IoT and thats why they didn't place that inductor. I suppose that the improvement with the additional inductor was minor.
Thanks MT_dialog
Hi MT_dialog,
I found the note on the antenna datasheet....it said "The antenna matching network values here are used when antenna is mounted on evaluation board"......
I think maybe this is my problem....
那么我如何计算我的电路板的匹配组件？是否有任何在线RF计算器推荐？
Daniel
Hi daniel59,
When knowing the antenna impedance (this should be measured in the full application with plastics using a network analyser), and knowing that the RFIO of the 580 is 50 Ohm, one can calculate the required values for a PI-network matching filter. After doing so you should repeat the measurement and the result should be close to 50 Ohm. You will be able to find a tool for determining the matching components parts in the following linkhttp://www.fritz.dellsperger.net/smith.html.
Thanks MT_dialog
Hi MT_dialog,
If I have antenna s-parameter file, like Johanson's antenna 2450AT07A0100, do I still need the network analyser? or I can pick one with 2.44Ghz frequency into the smith chart from .s1p file?
Daniel
Hi daniel59,
最好的是测量匹配网络输出的天线阻抗，而无需匹配网络和580连接。删除e.g.用于此的耦合电容器。在完整的应用中进行，所以包括电池/封面/塑料。可以进行S-PAR文件。
After having determined the matching filter network values, the impedance must be verified at the matching network input, without 580 being connected. All not so easy and RF experience is required.
If the board design around the antenna is very similar to that of the antenna supplier (used when creating the S-par file) and covers etc are relatively far away, you could try to simply use the S-par file provided by the antenna supplier. Please note to route a 50 Ohm track from 580 to the antenna/antenna matching network.
Thanks MT_dialog
Hi MT_dialog,
I read something about antenna, but still have a question....
Is antenna impedance changing with different board? if it doesn't change, I route a 50 Ohm track from 580 to the antenna/antenna matching network, it can be matched all situation.
And Why it will change?
I asked Walsin, and they say the antanna impedence is 50 Ohm, so can I simply route a 50 Ohm track between antenna and 14580?
Daniel
Hi MT_dialog,
所以我仍然需要VNA来确保最佳表现？
Daniel
嗨丹尼尔，
通常在SMD天线上，50欧姆的轨道足够，以便实现天线的良好性能，关于电路板的Surnounds和通常在印刷天线中应用的PCB，但Suroundings也可以影响SMD天线的性能（来自封印等的反射可能会影响性能）。因此，如果您使用50欧姆SMD天线，PCB上的轨道为50欧姆，您的设备应该是OK。如果如果应用上述设备并且您仍然获得较差的范围，那么您必须开始寻找备用问题（2米对于天线相当低），所以也许这是一个装配问题或可以是未经限制的XTAL16或切换其中一个引脚，导致XTAL16（P1_2或P1_3）上的串扰，具体取决于您的包装。如果您想达到天线的最佳性能，那么这是需要RF工程师的东西。
Thanks MT_dialog
Hi MT_dialog,
谢谢您的回答！
我会寻找这些问题。
And one more question, if I use the 50 Ohm SMD antenna, and the track on PCB is at 50 Ohm, if I place a shunt 3.9nH inductor according to AN-B-018 section 3.7, which says it will ensure best RF sensitivity and highest RF output power, will the antenna be dismatched?
Daniel
Hi daniel59,
嗯，额外的电感是一个额外的匹配组件，如果您的天线已匹配，我假设它会影响天线的性能但不在大扩展中，我的意思是它不会减少天线的范围大价值。
Thanks MT_dialog
Hi MT_dialog,
我明白了，谢谢！
Daniel