planer transformer si a kind of hf transformer which has high efficiency ans smaller size. many militry and electronic communication ppwer use it to get high efficiency of about greater than 96% and small size. the winds can be bonze strip type.
1 week ago I found one very good manual design of the planar transformers. In generally the advantages for this type of transformer are very good isolation, small size and excellent repeat ability. My advice is after design of the transformer to check finally isolation parameters with partial discharge device!