3-D Pixel-Based Multiport Antennas

We extend the conventional 2-dimensional (2D) versatile pixel antenna concept to 3-dimensional (3D) structures. The idea is to conform a pixel surface onto a 3D object and develop appropriate feeding mechanisms to form a 3D pixel-based multi-port antenna. We focus on a pixel-based antenna cube with four antenna ports for investigation and experimental verification. Different from 2D antennas, the antenna current on the cube surface can flow from one oriented plane (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$xz$</tex-math></inline-formula>-, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$yz$</tex-math></inline-formula>- or <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$xy$</tex-math></inline-formula>-plane) to another when the cube is excited. This allows more flexibility for pixel connections to achieve spatial and polarization diversity, as well as further miniaturization. As the cubic geometry has rotational symmetry, the analysis of mutual coupling among multiple ports can also be simplified so it is more convenient to deal with. Furthermore, decoupling structures can be designed and printed on internal faces of the cube to further enhance multi-port antenna performance. To provide experimental verification an example design with 4-ports operating at 1.77 GHz in a pixel cube with a side length of 24.4 mm (equivalent to only 0.14 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda _{0}$</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">$\lambda _{0}$</tex-math></inline-formula> is the wavelength in free space) is provided.