i designed a circular array patch antenna around a breast model and i need to make SAR maximum at tumor locations but there is no hot spot neither in model nor at tumor location how i can fix this ?
It is a hard problem. It looks like most of the power is being absorbed in the outer layer, and that there is a strong mismatch or reflection between the outer layer and the inner material. Maybe you have to use a different frequency. Is your model hollow? It looks like it but I don't suppose it really is. Is the outside blood-rich tissue and the inside breast-fat?
@malcolm white no my model not hollow , it composed of three materials skin , fats and gland tissue .. i don't know what is the wrong i did ... What is the mismatch you mention above
By mismatch I mean a mismatch in impedance. This is proportional to the ratio between the complex refractive index of two materials. There is a significant ratio between the impedance of skin and the impedance of fat, which can cause a large reflection. However, it depends on the thickness of the skin layer, and the frequency.
The materials can be treated as if they form a transmission line, and the reflections calculated. It is similar to radome design, and the paper below has some of the equations and concepts detailed.
Article An Accurate Method for Designing, Characterizing, and Testin...