SparkFun Forums 

Where electronics enthusiasts find answers.

User avatar
By Termi15
#203774
Hi,
I have a M6E-nano rfid reader and a UHF RFID Antenna (TNC). I'm trying to do so that the sensor can read badge also if they are not in direct contact with the antenna. For example if someone walk in the area of the antenna but with the badge in a pocket or in a backpack. My question is: There is a way to make so? I have to change the parameters of the program that i'm using (URA by jadak)? I have to change some eletronic components in my system? Or simple there isn't a way to do so?
By paulvha
#203794
The Sparkfun hookup guide provides good info about external antenna :
https://learn.sparkfun.com/tutorials/si ... al-antenna

Next to external power supply, you need to think about the terminal aspects. The Nano can get very hot with high dbm and the chip on the board may need more cooling capacity.

Depending on the position of the antenna you will pick up the tag in someone pocket, although it is very common to hold your badge against an " antenna" for controlled access. You only need less read power, which is more healthy according to some investigation.
The M6E has only 1 antenna connection, but with an external antenna multiplexer you could connect more.The latest UAR (4.3.40.40) seems to have support to drive GPIO's, for multiplexer selection but I have not tried that. It may require some extra programming though.
User avatar
By TS-Mark
#204333
Hi Termi15,

You may want to look into different antenna types with a different polarization but different antenna types have their own pros and cons that you will want to be aware of. The UHF Antenna SparkFun sells has a linear vertical polarization meaning the signal waves propagate in a linear vertical pattern directly away from the antenna. This type of polarization has a better overall range than say, a circular polarized antenna, but you need to have the correct position (eg. directly in front of the antenna) to take advantage of that increase in range. If you want to learn more, I would recommend researching "Antenna Polarization".

The Range Test example from our Hookup Guide gives a good description of this as well as explains some of the limiting factors that will drastically reduce your read range with RFID. Things like metal, water, and alignment will reduce your read range. So in your experiment, with the tag being in someone's pocket or bag, the person's body is acting as a major RF interference so your read range is going to drop significantly. You can counter this by increasing the read power but as Paul mentioned in his post, increasing that read power brings up other issues you will need to address. The "Using an External Antenna" and "Thermal Considerations" sections of the Hookup Guide I linked above will have more information about those concerns. The Design Guide for the M6E Nano will have helpful information about those factors as well.

I hope this helps explain the causes of your issues and gives you some options to look into to work around them. Let us know if you have any other questions or concerns about the Simultaneous RFID Reader or our other UHF RFID products and we would be happy to help as much as we can.
User avatar
By Termi15
#204390
Thank you for your answers. Yesterday i find a new problem. I managed to reach the tag also if they are in a pocket, but when i disconnected the sensor from URA , cooler it and, re-tried the experiment the sensor didn't reachs the tag in the pocket. So, the problem is this: somethings the sensor works very well, and sometimes it gives problems. Do you know why?
By paulvha
#204393
In order to help : Can you share more about the setup ?

Hardware connection, power supplies used, antenna used, pictures of board etc.
Trace information or error messages from the URA etc.

Also when you reconnected to the URA, have you set the power-parameters correct again. I made a lot of times mistakes to not set them correctly.
User avatar
By Termi15
#204457
URA doesn't give any error message, the problem is simply that sometimes it works good, and sometimes bad. If you want I can write you privately and give you the sensor configuration.