Dual-band Patch Antenna with Double Torsion Coil Feeding Structure

In this paper, a dual-band patch antenna fed by double torsion coil structure has been proposed. This feeding structure can excite the $\mathbf{TM}_{\mathbf{01}}$ mode of the patch antenna, and generate an equivalent magnetic dipole at an adjacent frequency at the same time. As a result, the proposed antenna works in two bands $\mathbf{6.23}\sim\mathbf{7.10}$ GHz and $\mathbf{7.57}\sim \mathbf{8.26}$ GHz for terminal applications with S 11 $< -\mathbf{6}\ \mathbf{dB}$ . In the meantime, a dielectric substrate is used to ensure low profile of the patch antenna. The overall size of the patch antenna is $\mathbf{0.26}\boldsymbol{\lambda}_{\mathbf{0}}\times\mathbf{0.26}\boldsymbol{\lambda}_{\mathbf{0}}\times\mathbf{0.08}\boldsymbol{\lambda}_{\mathbf{0}}$ , where $\boldsymbol{\lambda}_{\mathbf{0}}$ is the free-space wavelength at the center frequency of the lower band (i.e., 6.5 GHz).