A Novel 3D Hemispherical Reconfigurable Antenna with Switchable Radiation Patterns Using a Butler Matrix

This paper presents a compact 3D hemispherical reconfigurable antenna for sub-6 GHz 5G applications. The proposed structure integrates a four-element Vivaldi antenna array with a 4×4 Butler matrix and a PIN-diode switching network to enable beam steering toward three primary directions. Measurements confirm a stable gain of 4.7 dBi, radiation efficiency above 85%, and hemispherical coverage of about 67% in both elevation and azimuthal planes. The compact and low-power architecture makes it attractive for dynamic wireless environments.