Custom Antenna Design


#1

I am currently studying Mechanical Engineering in Boston and have had my implant for about 2 years now. I backed the xNT and have been loving it ever since. The biggest issue is readability. I have watched the videos and explanations on orientation to a flat antenna and how to get better reads from your transponder, however, I still have issues with reads. I was wondering if it would make sense to make a custom antenna that was cylindrical instead of flat and rectangular. Is this possible and if so how could this be achieved? Thanks in advance!


#2

Hi there,

Yes you can design a cylindrical antenna that would couple better with our x-series implantable transponders. However, doing so is not as straightforward as you might think. Unlike an electric field emitting antenna like an FRS radio or cell phone or wifi hot spot, a passive RFID antenna is simply a magnetic field inductor, or a loop antenna similar to AM radio. It involves both a wire coil as well as an accompanying parallel and series capacitive elements that help create and maintain resonant tuning at the desired operating frequency. Simply replacing the wire coil part of the “antenna” will require obtaining the capacitive values already designed into the reader and creating a complimentary coil for those values, or somehow replacing the entire antenna including capacitive elements.


#3

Amal,

thank you for your response. I was watching the video from your CES implant and that is what got my brain thinking about my implant again. I am trying to find more ways of using my implant in daily activities. Are there any recommended, smaller sized, readers out there that will work decently well with the xNT?


#4

I don’t have many examples of readers but rather than try to curate a list for people, I created the xLED to allow you to get a good idea of where/how to hold your implant to a specific reader. Check out www.dangerousthings.com/shop/xled for more info.

As an aside, we do have a list being created of devices that read various implants, but performance is not a factor listed… the xLED should be able to address most performance issues.


#5

I will have to purchase one of these. Thank you!


#6

I had some success with a custom antenna. I must admit the hard work picking the inductor and calculating the matching circuit components was done by someone else.

I’m a little disappointed with the number of implantees out there that nobody has found a good PCB antenna design that works better tan the ones tuned for cards. I keep meaning to do it myself, but you know how it is. Too busy with so many other things.


#7

Nice! Love this project!

The Adafruit NFC shield does a pretty decent job with the xNT. They went the extra mile to make a really well tuned antenna.


#8

Hi…i am a new user here. As per my knowledge unlike an electric field emitting antenna like an FRS radio or cell phone or wifi hot spot, a passive RFID antenna is simply a magnetic field inductor, or a loop antenna similar to AM radio. It involves both a wire coil as well as an accompanying parallel and series capacitive elements that help create and maintain resonant tuning at the desired operating frequency.

pcb prototyping


#9

@RickyTerzis that’s correct… passive RFID tags in the LF and HF ranges function more like an air-core transformer, with the reader coil acting as the primary and the tag antenna acting as the secondary. Tuning does require a properly tuned LC circuit which isn’t always easy because when you bring the tag antenna into range of the reader antenna, they can detune each other… so in-application antenna matching is important as well.