Modelling of miniaturised multiband 3D slot loop antennas

A novel miniaturised multiband 3D slot loop antenna is proposed as a built-in terminal antenna with multiple bands of individual broad bandwidth. The antenna is constructed three-dimensionally by printing a rectangular slot loop antenna with a narrow outer conductor on the surface of a substrate box. The chip-formed antenna is then mounted on the top edge of the ground plane of the PCB. Simulation results of the proposed antenna with dimensions of 20 mm × 24 mm × 1.12 mm on a substrate box of dielectric constant ε_r = 6 show the -6 dB bandwidths of 1.78 GHz (1.37 - 3.15 GHz) in the first band and 0.82 GHz (3.74 - 4.56 GHz) in the second band. Compared with the corresponding flat slot loop antenna, the 3D slot loop antenna not only reduces the size by a factor of 2, but also provides wider bandwidth in both bands. Furthermore, the proposed 3D slot loop has a balanced structure which is insensitive to the perturbation of the ground plane. The antenna can be designed for specific applications with the adjustment of appropriate dimensions.