Wideband printed dipole antenna for DTV signal reception

Abstract

A novel printed dipole antenna capable of generating a wide operating band for digital television (DTV) signal reception in the 470 ~ 806 MHz band is presented. The antenna is of a rectangular shape and has a size of 20 times 227 mm2, and the antenna comprises two asymmetric radiating portions of arm 1 and arm 2 separated by a step-shaped feed gap with its one open end at the center of antenna's one long side edge and the other open end at about L/4 away from the center of the opposite long side edge. By the use of the step-shaped feed gap, the proposed antenna can generate two adjacent resonant modes to form a wide operating band of larger than 50% in 2.5:1 VSWR bandwidth, which is much wider than that of the corresponding conventional center-fed dipole antenna with a straight feed gap. The antenna's first resonant mode is operated as a 0.5-wavelength mode controlled by the antenna length L, while the second resonant mode is a 1.0-wavelength mode controlled by the total effective length of arms 1 and 2, which is about 1.25L in the proposed design. Detailed design considerations and radiation characteristics of the two excited resonant modes for broadband operation of the proposed dipole antenna are discussed in the paper.