Author: 02CamaroSS
Subject: 641
Posted: 22 November 2009 at 12:21pm
It seems that we destroyed the communication ports on the M1-mini by connecting it directly to the computer's serial port. The converter I built was working fine. Se we ordered a new M1-mini and it is working great with no issues as of right now. But as you requested here is a link I found that has been very helpful regarding the m1-mini, it includes both top and bottom view pictures.
We are having issues with an external antenna though. When using the internal antenna we are able to read tags correctly with no issues but the read range is very limited. So we decided to build an external antenna. See below for picture. Using an analyzer I measured the inductance of the antenna and it is 310nH and has a resistance of 25mΩ. So according to my calculations I used a value of 444pF for Cp and 220pF for Cs as to get the 50Ω impedence to match the m1-mini. I followed the design guide of chapter 6 and also found several other design guides and according to them I should be on track. I have also have access to an O-scope and function generator so I used the function generator to create a 13.56MHz signal and used the O-scope to look at the waveforms to tune the antenna even greater using some variable capacitors. Yet when we connect the antenna to the reader we are not getting any Tag ID's. Am I missing somthing fundamental here or what?
Thanks,
-Dave
Antenna Info:
Copper Tape - Corry's Slug and Snail Copper Tape Barrier
Mounting Surface - 12"x12" sheet of plexiglass
Inner diameter of antenna is 6-3/8"x6-3/8"
Wire - 50Ω Coax cable
![]()
Subject: 641
Posted: 22 November 2009 at 12:21pm
It seems that we destroyed the communication ports on the M1-mini by connecting it directly to the computer's serial port. The converter I built was working fine. Se we ordered a new M1-mini and it is working great with no issues as of right now. But as you requested here is a link I found that has been very helpful regarding the m1-mini, it includes both top and bottom view pictures.
We are having issues with an external antenna though. When using the internal antenna we are able to read tags correctly with no issues but the read range is very limited. So we decided to build an external antenna. See below for picture. Using an analyzer I measured the inductance of the antenna and it is 310nH and has a resistance of 25mΩ. So according to my calculations I used a value of 444pF for Cp and 220pF for Cs as to get the 50Ω impedence to match the m1-mini. I followed the design guide of chapter 6 and also found several other design guides and according to them I should be on track. I have also have access to an O-scope and function generator so I used the function generator to create a 13.56MHz signal and used the O-scope to look at the waveforms to tune the antenna even greater using some variable capacitors. Yet when we connect the antenna to the reader we are not getting any Tag ID's. Am I missing somthing fundamental here or what?
Thanks,
-Dave
Antenna Info:
Copper Tape - Corry's Slug and Snail Copper Tape Barrier
Mounting Surface - 12"x12" sheet of plexiglass
Inner diameter of antenna is 6-3/8"x6-3/8"
Wire - 50Ω Coax cable
