Hi all,
I am having issues with testing my SparkFun Simultaneous RFID reader using an external antenna.
I am conducting a university project, and am relatively new to RFID. I am using the SparkFun Simultaneous RFID reader with the SparkFun UHF TNC external antenna. I am using the UHF Gen2 adhesive RFID tags, and am using the Universal Reader Assistant software to display the tag data. I followed the instructions as provided in the guide and tested the reader using the PCB antenna. I had no issues during the initial testing using the onboard PCB antenna. Everything seemed to work as it should have. I then activated the antenna by desoldering the PCB antenna select pad and soldering the external antenna select pad. I have done this, and there does not seem to be any issue with soldering. I then connected the antenna to the reader similarly to as shown in the guide and mounted it on a tripod.
I have tested the reader with the antenna for a number of hours and it does not seem to have read anything. No tag data shows up on the URA display, whereas it did when I tested the reader using the PCB antenna. Using a multimeter, I tested the voltage difference between the antenna select and ground and this gave me 0.00V while the battery was connected. I am unsure if this is meant to be pulled LOW or HIGH.
When I began testing, the battery that I was using was flat, so my initial thought was that this was a power issue. I thought that by charging the battery it would fix my issue. I have charged the battery and it still is not working. I do not believe that it is a connection issue. I say this because the URA still picks up the reader connected via USB to serial to my laptop and there are no issue with my laptop USB ports. I also do not believe that any of the cables I am using are the issue, because they do not appear to be damaged. Finally, I do not believe it to be a reader issue, as the reader was working perfectly when I was using the PCB antenna.
Is there any way that I can verify that I have an issue with the antenna? Or, based on the information that I have provided above, is there something that I am doing wrong when I am testing. As noted before, I had no problems while testing the reader using the PCB antenna, so I have narrowed the issue down to either that I have soldered incorrectly or there is an issue with the external antenna. I have added photos of my reader before and after I soldered the external antenna select pad.
Thanks in advance,
Luke Balia
lbalia@student.unimelb.edu.au
https://photos.google.com/photo/AF1QipP … YD7-Wj9G-s
https://photos.google.com/photo/AF1QipM … 2O3f1DAoiM
I don’t seem to be able to open the links for the photos (I get a 404 : The requested URL was not found on this server. ). However:
what happens if you undo the change and move back to the onboard antenna. does it work again ?
What settings do you apply in the URA ? are they different then when you use the (working) on-board antenna?
What is the resistance of the external (none connected) antenna as measure with your multimeter ?
It is not clear to me what you measure here :“Using a multimeter, I tested the voltage difference between the antenna select and ground and this gave me 0.00V while the battery was connected.” can you explain that more ?
Hi Paul,
In answer to your questions:
Basically, those photos are of the reader before and after I desoldered and soldered the relevant pads to enable the external antenna.
I re-enabled the onboard antenna and the reader immediately worked again.
In the URA I used all the default settings (baud rate 115200, region NA2, read continuously, maximise tag read rate, tags respond more often, antenna enabled) - the only thing I was varying before and after I enabled the external antenna was the reader power.
The resistance of the multimeter across the external antenna initially shows a number but settles at OL.
I am fairly sure the issue is with the external antenna.
Thanks ,
Luke
Just an update from today - I tested the continuity of the connection to the u.FL connector and and found that there was continuity. One interesting development was that when I moved the tag over top of the pads immediately next to the u.FL connector, the reader actually read the tags. I am still at a loss to explain exactly how or why this is happening. The external antenna has still not read any tags at all. To me, this isolates the problem to either the antenna itself or the cables that connect the reader to the antenna. While regrettable, I have ordered a new antenna and cables. Hopefully this solves the problem.
did it?
I have the same problem and ordered recommended MTI-242043 antenna and it did not work. Then I bought Sargas RFID reader and it works with both antennas fine using the same tags and regions.
Hi Luke,
I was able to reproduce your discovery too.
EXTERNAL antenna jumper ON , INTERNAL antenna jumper OFF, powered by over USB or external power.
External antenna connected and not connected cause the same effect.
Touching u.FL with with a tag - detects the tag
I was listening the ether by SDR receiver around EXTERNAL antenna and scan signal on spectrum 865-965 MHz comparing the same antenna with another working reader is much low. There is something broken in SparkFun reader. Could be output diode.