A beam steering linear antenna array with novel simultaneous frequency agility and polarization reconfigurablity

In this abstract, a beam steering linear (1×4) antenna array with novel simultaneous frequency agility and polarization reconfigurablity is presented. This includes development of a (i) Wideband frequency agile antenna, (ii) Polarization reconfiguration control circuit and (iii) Beam forming network with digital phase shifters and low noise amplifiers (LNAs). The array radiating elements consist of a circular microstrip patch and a concentric annular ring patch around it. Four varactor diodes have been placed between the central patch and the ring patch. By varying the varactor capacitance values, the coupling between the patch and ring is varied. When the varactors are biased such a way to provide low capacitance value, the antenna shows high impedance, and therefore, the patch and the ring become decoupled. In this case, only the central patch radiates in the dominant TM11 mode giving the higher frequency coverage. However, when the varactors are biased such a way that they provide high capacitance value, the antenna shows low impedance, and therefore, the patch and the ring become fully coupled. In this case, both central patch and outer ring patch participate in the radiation mechanism operating in the dominant TM11 mode and provide lower frequency coverage. Therefore, by varying the capacitance of the varactor, the resonant frequency can be varied between 1.5GHz and 2.4GHz. The overall frequency agility range of around 46% has been achieved. This antenna has been fabricated on a Rogers RT/Duroid 5880 (εr = 2.2, tanδ = 0.0009, 3mm thick) and tested for impedance matching and radiation patterns.