Compact Wideband Folded Dipole Antenna With a Parasitic Dipole

A wideband folded dipole antenna with stable radiation patterns and a compact size is proposed. A folded bowtie dipole and a reflector with two vertical metal plates are applied to achieve compact dimensions. By introducing a parasitic dipole orthogonal to the folded bowtie dipole and a cylindrical substrate placed on these two dipoles, the impedance matching is improved over the entire operating bandwidth. A parasitic patch loaded above the two dipoles enhances the directional radiation capability at the high end of the operating bandwidth, and it is also used to improve the impedance matching in the middle of the operating bandwidth. The measured impedance bandwidth (IBW) for VSWR ≤ 2 is 135.8% (0.65–3.4 GHz). Experimental results also indicate that the broadside gain ranges from 4.1 to 7.4dBi, and stable, smooth radiation patterns with wide half‐power beamwidths (HPBWs) are achieved. The design achieves a compact size of 0.29 λ L × 0.22 λ L × 0.11 λ L ( λ L is the free‐space wavelength at the starting frequency).