A Miniaturized Wideband Dual-Polarized Planar Antenna Based on Multiresonance

Abstract

In this letter, a miniaturized wideband dual-polarized antenna with a simple structure is proposed. The proposed antenna includes two stacked square loops, which are positioned around the cross-dipole, these loops are utilized to introduce a new resonant mode at a relatively low frequency band, which essentially widens the impedance bandwidth and realizes the miniaturization design. It also includes metallic plates that are vertically positioned on the reflector. These parasitic vertical metallic plates, operating in coincidence with the coupling energy from the nearby radiators, serve to generate an additional resonant mode outside the original impedance passband of the cross-dipole antenna. This enables further expansion of the impedance bandwidth. A prototype was fabricated and tested, where the measured results demonstrated that the proposed antenna ability to achieve a wide impedance bandwidth, i.e., up to 91% (0.98 to 2.6 GHz) with VSWR <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$ &lt; $</tex-math></inline-formula> 2. Additionally, the isolation between the two linear orthogonal polarizations was greater than 20 dB. The unidirectional radiation patterns are stable over the entire operating frequency band, with an average gain of 7.5 dBi. Furthermore, the overall size of the proposed antenna is very compact, amounting to only approximately <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\ 0.36\;{{\mathrm{\lambda }}_{\mathrm{L}}} \times 0.36\; {{\mathrm{\lambda }}_{\mathrm{L}}} \times 0.13\; {{\mathrm{\lambda }}_{\mathrm{L}}}$</tex-math></inline-formula> , where <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${{\mathrm{\lambda }}_{\mathrm{L}}}$</tex-math></inline-formula> is the longest operating wavelength.