A Polarization Reconfigurable Antenna for Satellite Communication in Foldable Smartphone

A polarization reconfigurable antenna based on dipoles is proposed for foldable smartphones in this communication. Two dipoles, a driven dipole and a parasitic dipole, are placed on the top of the two parts of the foldable phone. The induced current on the parasitic dipole is similar in amplitude to the current on the driven dipole, with a phase difference of 90°. When the two parts of the phone are at 90°, the two dipoles are L-arranged orthogonally, realizing circularly polarized (CP) radiation. When the phone is in the fully unfolded or fully folded state, the proposed antenna can still work with linearly polarized (LP) radiation. Users can freely choose the folded state for satellite communication. A prototype for three different states was fabricated and tested to validate the concept. The measured bandwidth with
$S_{11} < -10$
dB for the antenna in each state can cover the target band 2.483–2.5 GHz. Besides, the measured 3-dB axial ratio (AR) bandwidth of the antenna in the CP state is 2.464–2.516 GHz. The maximum gains of the three states are 3.9, 5.9, and 4.1 dBi over the operating band. The efficiencies are higher than 70%. The proposed antenna shows great potential in the satellite communication application for foldable smartphone.