The size and/or shape of each loop transmission coil in one pair of small loop transmission coils 22 can be different, and the shapes and structures of the pairs of the different small loop transmission coils 22 are the same. As shown in FIG. 5A, one small loop transmission coil 22 of the pair has a smaller dimension (size) than the other one of the pair. However, it is possible that the one small loop transmission coil 22 has a different shape than the other one of the pair, as shown in FIG. 6A. FIGS. 7A and 7B show the structure and fabrication method for producing the primary coil antenna 21 with the pairs of small loop transmission coils 22 of the charging device 20 shown in FIGS. 2A-2C according to an embodiment. The whole antenna unit made up of the primary coil antenna 21 and the pairs of small loop transmission coils 22 can be fabricated by using a printed circuit board (PCB) with four (4) layers. The four layer PCB has four (4) metal layers 29-32 and three (3) dielectric layers 33-35. The layer stackup is shown in FIG. 7B. The primary coil antenna 21 is printed on the first and second metal layers 29, 30. The small loop transmission coils 22 are printed on the third and fourth metal layers 31 and 32. Vias 36 between the metal layers 29-32 provide electrical connection for the primary antenna coil 21 and the pairs of small loop transmission coils 22. The dielectric layers 33-35 between the metal layers 29-32 are dielectric material, such as FR4 and BT, for example. The dielectric layer 34 is a PCB core in the middle of the PCB structure.