How to design implantable antenna 402-405Mhz band

I am new to this forum and also new to cst studio. I am trying to design implantable antenna in the MIC band i.e 402-405 band.Is there anyone who knows to do it.I have looked through some of the IEEE papers but they talk about meander,stacking and using short pins to achieve the desired frequency.I have tried to reproduce some of the antennas in the papers but I am not getting the right result.I need help please.

Your task is quite difficult. I do not expect any model can help you. Human tissue is a complex material with varying impedance and loss. Do not expect someone gives you a reasonable direction.
You will have to experiment to find how to achieve a good antenna function.

Google Alabaster: Ph.D.Thesis on Microwave Tissue Parameters where some results and references can be found. Make experiments with tissue phantoms and salty water to see what happens. Inserting a dipole into a living tissue will result in a poor match as well as in a funny radiation pattern. After a lot of work you might earn a Ph.D. in the field.

Good luck!

Thank you very much for your help.I have checked the reference in your message and it is worth looking into it.My problem is I have managed to design some of the antennas in IEEE papers but none of them is resonating at the required frequency. I may be doing something fundamentally wrong so I am trying to figure that out.Thank you once more.