Research On Novel Wideband Unidirectional Magneto-electric Dipole

The tremendous growth of wireless communication services, such as the third generation (3G) mobile phone, Wi-Fi and Wi-Max, has led to increasing demand for wide-band unidirectional antennas that can accommodate several wireless communication systems with excellent electrical characteristics such as wide impedance bandwidth, low cross-polarization, low back-lobe radiation, symmetric radiation pattern, stable gain over the operating band and cost effectiveness. Recently, a wideband complementary antenna element, designated as the magneto-electric dipole, was proposed by Luk and Wong. The antenna has wide impedance bandwidth of43.8%(SWR≤1.5). Stable radiation pattern with low cross-polarization, low back-lobe radiation, nearly identical E-and H-plane patterns and a stable antenna gain is found across the entire operating bandwidth.On the basis of the research above, firstly, we increase the bandwidth of the magneto-electric dipole micro-strip antenna, propose the E-shaped magneto-electric dipole antenna, and then design very wideband magneto-electric dipole antenna, wideband dualband magneto-electric antenna and dualband dual-polarized antenna continually.The innovation points of the paper are listed below:(1) A novel E-shaped wideband magneto-electric dipole antenna with a staircase-shaped feeding strip is presented. By modifying the patch and feeding strip, this antenna has realized wide impedance bandwidth of60%(SWR≤1.5). Stable unidirectional radiation patterns, low cross-polarization level and high average gain are achieved over the passband.(2) A novel wideband magneto-electric dipole antenna is presented. This antenna achieves an impedance bandwidth of107%(SWR^2) from2.3GHz to7.56GHz. Due to the two complementary configuration of the antenna and the incorporation of a modified ground plane, the antenna has a stable broadside radiation pattern with low cross polarization and low back-lobe radiation over the operating band.(3) A novel dual-band wideband unidirectional magneto-electric dipole antenna is presented. The proposed antenna has wide dualband impedance bandwidths of34%and49.5%(SWR≤2) in the lower and the upper bands, ranged from0.78GHz to1.1GHz and from1.58GHz to2.62GHz respectively. More importantly, the antenna has stable gains across each band, demonstrating the high stability of the radiation characteristic for the two radiation modes. The radiation patterns are symmetric, low back-lobe radiation and low cross-polarization. Because of these excellent features, the antenna should find wide applications in the modern2G、3G、LTE、Wifi、and Wimax wireless communication systems.(4) A novel dual-band dual-polarized wideband magneto-electric dipole antenna excited by two F-shaped strips is presented. The F-shape feeding strip is designed to excite the two-layer antenna. The proposed antenna achieves a common impedance bandwidth of25.5%and39.5%(SWR≤2) in the lower and the upper bands at both input ports, ranged from0.75GHz to0.97GHz and from1.73GHz to2.59GHz respectively. The antenna has good performance in isolation, which is more than-32dB between the two input ports. The antenna has stable gain of average4.3dBi and7.8dBi in the lower and upper bands. It also has a stable broadside radiation pattern with low cross polarization and low back-lobe radiation over the operating band. Because of these excellent features, the antenna should find wide applications in the modern2G and3G wireless communication systems.