Multi-band And Wide-band Antennas For Wireless Communication System

Recent development of modern wireless and mobile communication has evoked increasing demands for novel antennas. Work in this paper includes two aspects:Firstly, a triple-band omni-directional printed WLAN (Wireless local area networks) antenna for WLAN terminal equipment is proposed and studied. The antenna which comprises three pairs of dipoles placed back to back and printed on a dielectric substrate operates in three bands (2.4-2.48GHz, 5.15-5.35GHz and 5.725-5.825GHz). The proposed triple-band omni-directional printed WLAN antenna not only achieves the demands of impedance bandwidths, but also realizes almost omni-directional radiation patterns in the azimuthal plane. On the base of the triple-band WLAN antenna, a dual-band omni-directional printed WLAN antenna comprising two pairs of dipoles placed back to back is designed, which also covers the three bands of WLAN and has advantages of high antenna gain and simple structure. The two proposed antenna are fabricated and measured. The measured results of the antennas are in good agreement with the simulated. Both the two antennas are compact in size and easy to fabricate due to the printed structures applied.We also proposed the design of wide-band biconical antenna and wide-band patch antenna for the indoor Digital Video Broadcasting (DVB) system. By combining the monopole mode and the microstrip patch mode together, the wide-band properties of the two antennas are achieved (cover 470 MHz -860MHz). The heights of the antennas are small and the antennas can be used as buried-on-wall antennas.