A Compact Multiband Reconfigurable Quasi-Isotropic Antenna with Planar Structure

Isotropic antennas which can radiate a power into all direction and provide full spatial coverage have drag attention for modern wireless applications such as wireless power transfer, wearable antennas, wireless access point and radio frequency energy harvesting. Since an isotropic antenna which radiate with polarization of all direction is impossible to implement in practice, many researchers have designed quasi-isotropic antenna by implementing electric dipoles and magnetic dipoles [1, 2]. The isotropic antennas, especially for mobile applications, need to be compact and provide multiband operation. However, previous works have rarely suggested multiband operations with isotropic patterns. In addition, the antenna for mobile application needs to be planar to integrate with circuit board and provide reconfigurable operation to be able to cover broader bands.