I am working in a biomedical implant. I have to design an antenna for the wireless power transmission. The frequency that I am using is 13.56 MHz. I used some antennas found in some articles but when I test them (just the antennas) I cannot have a good performance in terms of distance and power transmission.
I used a loop antenna that I need to reduce the size until 5 cm diameter. It has to be a very little antenna (ofc, High frequency) for this communication.
Could you help me with this please! I need to know where to start or what am I doing wrong..