Design of Polarization Diversity Patch Antenna Based on a Compact Reconfigurable Feeding Network

A design of stacked square-ring patch antennas with quadri-polarization diversity is proposed. The polarization switching is realized with a 1-to-4 reconfigurable feeding network composed of a quasi-lumped coupler and PIN diodes. The size of the feeding network is less than 0.01λ
₀
²
, where λ
₀
is the free-space wavelength of the operating frequency. In addition, by controlling dc voltages, the operation of the feeding network can be varied among four different modes. The performances of the stacked patch antenna and the reconfigurable feeding network are respectively exhibited. A prototype that integrates the feeding network into the inner slot of the lower square-ring patch of the stacked patch antenna is designed and constructed. The prototype can provide dual orthogonal linear polarizations and dual orthogonal circular polarizations at 1.98 GHz. Details of the experimental results for the prototype are shown.