The Application Of The Ebg Structure Antenna

EBG structure has been attracted much attention after EBG structure is proposed. The characteristics of EBG structure, such as electromagnetic band gap characteristics and the in-phase reflective properties, determine a wide applications. The miniaturization of the EBG structure and the bandwidth widening of the band gap are difficulties and hot spots in this field. In this paper, the EBG structure theory and research methods are introduced briefly. The high-impedance surface properties, the suppression of surface wave characteristics and in-phase reflection characteristics are analyzed and the reflection phase characteristics of a variety of EBG structure are compared. The electromagnetic properties of EBG structure are respectively used in the stop-band antenna, surface wave suppression antenna and low profile antenna. This work includes the following aspects:(1) The equivalent circuit model for mushroom-like high-impedance surface structure has been analyzed and the reflection phase of the structure, suppression of surface wave characteristics, band-notch bandwidth characteristics have been studied systematically. Numerical simulation of the reflection phase and the measurement method of EBG band gap width are also introduced. In addition, phase characteristics of several typical EBG structure have been analyzed and the EBG reflection phase characteristics of different EBG structure of the same size have been compared.(2) The ultra-wideband planar printed monopole antenna fed by the microstrip and cop lanar waveguide have been designed and analyzed respectively. The structure size is relatively compact with only40mm×40mm×1mm. Various parameters affecting the antenna performance have been simulated and analyzed. The optimized antenna has good radiation characteristics. The bandwidth of the microstrip-fed monopole antenna is2.4GHz-11.7GHz (S11<-10dB), with the relative bandwidth of132%; coplanar waveguide-fed monopole antenna has a bandwidth range of2.4GHz-11.2GHz (S11<-10dB) with the relative bandwidth of129%. The gain of the two antennas is all greater than2dB in the range of the bandwidth, with omnidirectional H-field radiation pattern below8GH while splitted above9GHz.(3) The ultra-wideband monopole antenna has been loaded with EBG, and a band-notch is formed. Two structures are proposed:one is loading EBG on both sides of the feeder, another one is loading EBG between the ground structure and the feeder. The former structure has a relatively narrow relative bandwidth of only11.8%, compared with the latter structure, which has a relative bandwidth of only58.2%.(4) Based on the ultra-wideband monopole antenna, a surface wave suppressed antenna and low profile antenna have been designed by adding EBG structure. Adding the EBG structure, the antenna radiation performance has been greatly improved. The gain of surface wave suppressed antenna improves approximately3dB, suppressing the lateral radiation. The gain of low-profile antenna has also been improved. The profile size of the designed antenna is only2.5mm, which is far less than PEC reflector antenna.