A Low-Profile Triple-Band Triple-Polarization Antenna With Two Triangular Rings

In this letter, a low-profile triple-band triple-polarization antenna is proposed. The antenna employs two triangular rings (TRGs) with different sizes. The two triangular rings each works as a dual-frequency dual-polarization radiator. The polarization states at the three bands are horizontal polarization, 45
${^\circ}$
polarization, and vertical polarization, which are achieved by the horizontal mode of the larger TRG, the superposition of the vertical mode of the larger TRG and horizontal mode of the smaller TRG, and the vertical mode of the smaller TRG, respectively. The overall size of the proposed antenna on the substrate with a low dielectric constant of 2.2 is
$0.28{\lambda _0} \times 0.28{\lambda _0} \times 0.04{\lambda _0}$
, where
${\lambda _0}$
denotes the wavelength in free space at 8.38 GHz.