When looking for a cable to connect an antenna, you need to consider different parameters:
In this post I’ve tried to list some of the mostly used cable and connectors for connecting LoRaWan antennas.
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IoT design a usually a matter of antenna as already seen in different previous blog post. Antenna performance is the assurance of your capacity to deploy your object in larger zone and a way to save energy by reducing transmission power.
As we will see, if you get a hardware component and simply put it in a box its radio behavior will be totally different as the box is impacting the transmission.
This post will practically show you the impact of a box on a device radio quality.
Episode 3 & 4 of my Youtube series about LPWAN is about antennas for LPWAN and impact on object design. The episode 4 go deeper on the way to improve radio performance by tuning and adapting antennas with matching circuit.
As usual, this series of post are summarizing in English the content of my French video on youtube.
I’m using different GPS antennas with different price, size and gain and I had never compared the result in a real live test. So now it is done and the result are good to share.
My test condition are quite bad and we can’t really consider this as a scientific bench but, experimentally it sounds like a real life test.
So the test is to connect an antenna to a TD1204 with a GPS code on it and test the time it makes to fix the position and get some note about signal level, satellites in view… I used in fact 2 TD1204 : one with a reference antenna to ensure we have equivalent condition from one test to the others. The tests are made indoor where the sensitivity is an important factor. This post detail the results.
Today Sigfox is releasing a really good document about antenna design. This pretty document can be found following this link (available on July 7th). This document from TI also contains really well detailed information about the alchemy of antennas and the different kind of product you can find. From Silicon Labs you also have an interesting development kit for 868 antennas with performance published in this application note.
This is to say antenna is one of the most important part of a 868 object, as for Sigfox as for LoRa where the problem is basically the same. I discussed with different sigfox object designed and every-time the antenna was a big project issue. Some has payed about 10-15k€ to get a custom optimized design.
I never experiment a custom design but I made test with various antennas and the purpose of this post will be to give you my feedback on the different solutions.
This morning, some colleagues helped me to test the rf performance of one of my sigfox tracker. I’m really not an RF expert, I try to improve but there still be a long way to go…
In this design I’m using a TD1204 and a Wurth smd 868 antenna ; I have a 100 ohm impedance net between both (sure it is bad) and LC circuit (that sound not to be the good one – btw).