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Multiturn loop antenna design

Guest tandrroman

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Guest tandrroman

Hi all, I need some help on a coil antenna design. I have been tasked to design a small low frequency (24Hz) beacon. The design of the electronics is very simple. I am using a square wave generator that drives a low side MOSFET switch, which in turn used to drive the antenna. The MOSFET driver ON time is 0.025s and OFF time is 0.018s. If I understand correctly the coil antenna can be represented as an inductor connected to my MOSFET switch (please correct me if I am wrong). I am using the following equation to compute the peak current: VL = L di/dt, then L = VL dt/Ipeak. Ipeak current has to be around 0.1A and I am driving the coil with 12V square pulse. So, if I am using the correct equation L = 12V 0.025 / 0.1 = 3H. Next I need to determine all the parameters for the antenna. I have found the following web page which describes a very similar design: http://www.cnktechlabs.com/index_fil...ennaDesign.htm. According to the article presented on the site an antenna radiation depends of the area and the number of turns. I need to know how can I determine the number of turn to maximize the radiation efficiency of my antenna and at the same time to keep the peak current under 100mA (to conserve battery life). Can I trust those equations presented on the webpage? They compute number of turns by the following equation:image12411.gif
Is that equation correct?


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