Research On Antenna Gain And Polarization Based On AMC

With the rapid development of modern communication technology,the design of antennas for wireless transmission systems is required to achieve higher performance.Electromagnetic band gap(Electronic Band Gap,EBG),artificial magnetic conductor(Artificial Magnetic Conductor,AMC)and frequency selective surface(Frequency Selective Surface,FSS)are representatives of the structure of artificial electromagnetic materials.They are widely used to design high-performance antennas,including high-gain antennas,ultra-wideband antennas,and circularly polarized antennas due to their frequency selectivity and specific reflected phase feature.The applied scenarios include the wearable field and wireless medical field that reduce back radiation,the military field of reducing the radar cross section of radar(Radar Cross Section,RCS),and the aerospace field.In this paper,a high-gain antenna loaded with an AMC reflector is designed for the problem of impedance mismatch of omnidirectional antennas in wireless body area network communication when approaching the human body or metal surfaces.The antenna is a slot antenna with omnidirectional radiation,and a miniaturized AMC structure is loaded underneath.The high impedance and zero reflection phase characteristics of AMC are used to improve the antenna gain.After the AMC reflector is loaded,the resonance frequency of the antenna is 2.44 GHz,the bandwidth is 75 MHz,and the gain reaches 6.8 d Bi whereas the gain of antenna is 3.8 d Bi without AMC.At the same time,the back radiation is also greatly reduced,and the robustness of antenna is improved.In order to meet the needs of high-speed movement of objects that need to receive signals in real time in 2.4G wireless communication,a low-profile circularly polarized antenna was designed using AMC and monopole antenna.The reflection phase of the different polarization directions of the heteromorphic AMC is studied,and the reflection phase of ± 90 ° is achieved in the two orthogonal directions of the AMC structure to change the polarization of the antenna.The right-hand circularly polarized antenna is realized structurally while the size of the AMC reflector is reduced to 2 * 2 units.The measurement results show that the bandwidth of the circularly polarized antenna covers 2.15 GHz-2.52 GHz,the axial ratio bandwidth is 65 MHz,the antenna gain at resonance frequency is 6.9 d Bi.The experiments indicate that the designed circularly polarized antenna can satisfy the application requirements.