A Compact Series-Fed Two-Element Dipole Antenna

Abstract

A typical two-element endfire dipole antenna has wide impedance and gain bandwidths and can be manufactured inexpensively. However, it has the disadvantage of a large size due to the spacing between dipoles required to satisfy the endfire condition for good antenna radiation characteristics. In this paper, we propose a compact series-fed two-element dipole antenna that satisfies the endfire condition. Meander lines were used to connect the dipoles to reduce the spacing between them and satisfy the endfire condition. Bent dipoles and a corrugated ground plane were used to further reduce the size of the antenna. The proposed antenna size is <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.33\ \lambda_{\mathrm{o}}\times 0.33\ \lambda_{\mathrm{o}}\times 0.014\ \lambda_{\mathrm{o}}$</tex> , where <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\lambda_{\mathrm{o}}$</tex> is the free space wavelength at a center frequency of 5 GHz. The −10-dB impedance bandwidth is 4.43-5.73 GHz, and the 3-dB gain bandwidth is 4.02-6.76 GHz. The gain ranges from 4.8 to 5.9 dBi, and the cross-polarization level is less than −30 dB within the impedance bandwidth.