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I am new to the forum, after doing a bunch of research, thought someone here might be able to help.
I am working on a project to replicate the actions of an RFID tag when it is scanned. In the sense that when it is scanned it performs an action ( creates small voltage to do XXXX ).
The frequency of the scanner antenna is 134khz and is 1.5 inch diameter. The power out is unknown at the moment to me and will have some degree of range. The scan reach is approximately an inch.
Currently I have reproduced another handmade antenna that does exactly what I want. But it is 1.5 inch diameter and I would like to shrink this antenna to .5 inches. I don’t have any real test equipment other than a multi-meter but the antenna will light an LED ( 1ma and 1.6v ) which is really all I need. Just want to trigger a solid-state relay. Overall goal is to have the most volts and amps that can be gained.
The current antenna is 1.5 inches using 39 awg wire with 70 turns which from an online calculator gives around 290uH. I have no idea how proficient this antenna is compared to a properly tuned one.
So to the help needed…
1) Can this program help me make and tune an equivalent .5 inch antenna?
2) How much better if any would it be ( power out) ?
3) Can you tell me approximately what wire size I would need to make this into a .5 inch antenna so I can go ahead and get it ordered or is it just a matter of using the same wire size with a different number of wraps.
If there are any questions or more information is needed I will try to answer them best I can.
Brian
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Hi LockTech,
I am not an expert, but maybe I can help a little.
Normally the inductance of a coil is proportional to N^2*A, where N is the number of turns and A is the area. Making the antenna smaller means you have to increase your number of turns to get the same inductance.
The wire thickness is mostly irrelevant, except if it leads to a very different antenna geometry compared to zero thickness. Other than that, if you have a lot of turns at some point it will also affect the resistance of the coil.
What do you have the coil connected to?
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Buy a cheap inductance meter from Ebay. They are not far from a proper 1000$ inductance meter. It will be of great help.
Also, have a look here: Antenna Circuit Design for RFID Applications
GL and keep up posted on your progress.
Last edited by app_o1 (2017-03-04 13:21:28)
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Tiberius
All the coil is going to do, and connected too, is a solid state relay, to open it and close it. when the coil is receiving a signal and generates a voltage to open relay which will then turn on and off another circuit that is battery supplied to run n LED and a noise maker.
app_o1
I would get one of the cheap inductance meters if i new what inductance i really needed. All my googling says inductance between 500uH - 1000uH, thats quite a wide range. The problem is i am just not sure what inductance i need. All the antenna math is just a little bit over my head.
any simpler ways to figure out ?
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