Wideband Rod-Dipole Antenna with a Modified Feedfor DTV Signal Reception

摘要

Digital television (DTV) broadcast services have,been available in many countries for years. The DTV reception is becoming an alluring feature for applications in mobile devices and vehicles. Several standalone DTV antennas have been reported [1-5]. A folded .dipole antenna with stubs to cover the upper-edge frequency- at 710.MHz is studied in [1] as vehicle antennas. In [2], an earpiece cord is utilized as the DTV antenna for mobile phones. Two asymmetricaldipole antennas with a step-shaped [3] and an L-shaped [4] feed gaps for DTV reception in the 470-806 MHz band,are demonstrated. The broadband operation in [3, 4] is obtained by combining the one-wavelength and the half-wavelength resonant modes. These. designs, however, can not ,cover the .entire 470-862-MHz UHF band of broadcast TV ,channels in most regions of the world [5], which are required by specifications in industry. In this Letter, we introduce a. new rod-dipole antenna .capable of wideband operation in the 470-862 MHz band for DTV. reception. By incorporating a modified feed into the conventional rod. dipole, goodimpedance matching over the first higher-order mode excited close to the antennafundamental resonant mode, can be achieved. The two resonance can form a wide band of above 60% bandwidth (3:1 VSWR) centered at 666 MHz. In addition, with the retractable dipole-arm structure, the antenna is able to be stored away when not in use. When the antenna is in use, the retractable rods are very flexible to tilt for better signal reception and polarization.