Reconfigurable Antenna With Switchable Broadside and Conical Beams and Switchable Linear Polarized Patterns

A 2 × 2 array with pattern and polarization diversities is presented. The radiating element of the array is a stacked annular-ring microstrip antenna where four p-i-n diodes are symmetrically placed in the inner slot of the lower ring patch. By, respectively, activating these diodes, the element can generate broadside radiations with different polarization directions, including φ = +45°, -45°, +135°, and -135°. When the four polarization reconfigurable radiating elements are fed with a 1 × 4 Wilkinson power divider, the resultant array can give broadside radiations with +45° and -45° linear polarizations as well as conical radiations with vertical and horizontal polarizations. The experimental results show that the operation bandwidth of the array is from 2.25 to 2.58 GHz, and the peak gains of the array operated in the broadside and conical radiation modes are about 12.5 and 6.8 dBi, respectively. Simulation results obtained with HFSS are also provided, and they validate the measured data.