Miniaturized Wideband Metasurface Antenna With Filtering Performance for 5G Application

A miniaturized wideband filtering metasurface antenna (MSA) is proposed, comprising 3 × 3 square metasurface elements and a driven patch. Symmetrically arranged shorting vias and an open stub induce the first two radiation nulls <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${f_{\mathrm{{n1}}}}$</tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$f_{\mathrm{{n2}}}$</tex-math></inline-formula> in the lower and upper stop-bands, respectively. To move the newly resonant point caused by <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$f_{\mathrm{{n2}}}$</tex-math></inline-formula> forward and expand the impedance bandwidth (IBW) of the filtering MSA, two slots are etched on the driven patch. Meanwhile, introducing the second radiation null <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$f_{\mathrm{{n3}}}$</tex-math></inline-formula> in the upper stop-band. After that, two L-shaped branches will help to enhance the roll-off rate by shifting <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$f_{\mathrm{{n3}}}$</tex-math></inline-formula> from 5.65 GHz to 5.5 GHz. Measurement of the prototype reveals a large 10 dB fractional IBW of 35.8% (from 3.55 GHz to 5.1 GHz) with an average realized gain of 7.1 dBi. What is more, the radiation aperture size is merely 0.41 × 0.41<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\lambda _{0}^{2}}$</tex-math></inline-formula>, while maintaining the radiation suppression level of 16 dB and 25.6 dB at the lower and upper band edges, respectively, rendering this filtering MSA more promising for 5G (sub 6G) application.