Pattern-Reconfigurable Planar Antenna Based on Vivaldi Structure

A pattern-reconfigurable planar antenna based on Vivaldi structures is investigated in this letter. An annular feed line with four branches is employed to uniformly excite four rotationally symmetric Vivaldi structures, which are etched on the ground. Ten different radiation patterns can be obtained by switching the on/off states of the four PIN diodes across the rectangular slots. When only one PIN diode is turned off, a single beam in four directions can be excited. By combining two orthogonal and symmetrical Vivaldi modes, four inclined beams and two dual-beam states can be achieved. The overall size of the antenna is 0.62 lambda(0) x 0.62 lambda(0) x 0.0084 lambda(0) (lambda(0) is the free wavelength at 2.48 GHz). The unique design of shared-aperture Vivaldi structures enables it to obtain an overlapping impedance bandwidth of 2.38 GHz to 2.59 GHz (8.4%) in multiple states. The measured average gains are about (3.2, 2.8, 3.9) dBi, with an efficiency over -1.8 dB (66%). The proposed antenna features an ultralow profile and various and flexible pattern-reconfigurable capacity. It can be used in miniaturized and multifunctional intelligent communication applications.