Varactor-Loaded Pattern Reconfigurable Array for Wide-Angle Scanning With Low Gain Fluctuation

An improved phased array using pattern reconfigurable antenna elements in this communication is proposed to realize wide-angle scanning performance with low gain fluctuation. The pattern reconfigurable element is a microstrip Yagi antenna with its parasitic strips loaded with varactors. The reconfigurability of radiation pattern from the element is enabled by tuning the capacitive reactance of the varactors. Five elements were arranged in an equally spaced linear array, and the effects of several key parameter variations on the radiation characteristics of the array are provided. The proposed array is fabricated and experimentally verified. It is seen from the measured results that the main beam of the array can scan from -70° to 70° in the H-plane with a gain fluctuation less than 2 dB. Meanwhile, the coverage of 3-dB beamwidth of the array is from about -87° to 87°. The agreement between simulated and measured results validates our design exhibiting a good performance of wide-angle scanning.