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A Compact Antenna for IoT Applications Operable even in Close Proximity to a Metal

A compact antenna for IoT applications is presented, which can operate 2.4 GHz band. The proposed antenna is comprised of a Double Folded Loop (DFL) antenna. A DFL antenna has connection points at the quarter wavelength from the feed point. These connection points connect between the inner and outer loop antenna. To realize the compact antenna, we use a dielectric substrate and via holes to bend the DFL antenna. It has a total size of 37 × 20 × 1 mm3, The radiation efficiency of a DFL antenna is higher than 6 dB as compared with the half wavelength dipole antenna in close proximity to a metal. The simulated and measured results of the proposed antenna prove that the realized gain is more than −1 dBi independent of the metal distance. Moreover, the proposed antenna can operate even if the metal is close to the front side or the back side.