Research Of The Circularly Polarized Planar Antenna Arrays In Q-Band

With the rapid development of wireless communication,higher data transmission rate and wider transmission bandwidth of communication channels are required.The wireless communication systems have been developing towards high-frequency and broadband directions.In the face of increasingly complex communication environments,circularly polarized antennas have unique advantages in reducing polarization losses,resisting multipath effects and avoiding Faraday rotation.Circularly polarized antennas have been widely used in radio frequency identification,broadcast television,vehicle-mounted radar,electronic countermeasures,satellite communications and many other fields.This thesis mainly focuses on the circularly polarized planar antenna arrays in Q-band and is organized as follows:Firstly,two kinds of circularly polarized patch antenna arrays fed by substrate integrated waveguide(SIW)are designed.Truncated corner patch antennas using slot-coupling feeding technology are adopted as radiation elements and the center frequency is set as 45 GHz.(a)A parallel-fed 2×2 circularly polarized patch antenna array is simulated,fabricated and measured.According to the different positions of slots,four radiation elements are skillfully arranged to achieve sequential rotation(SR).The measured-10-dB impedance bandwidth is 14.2%,3-dB axial-ratio(AR)bandwidth is 9.3%,peak gain is 12 dBic,and radiation efficiency is 75%.(b)A series-fed 4×4 circularly polarized patch antenna array is simulated,fabricated and measured.In order to expand array scale and avoid transmission loss increasing,the SR technology is applied to series-fed structure and a novel 1×4 series-fed circularly polarized patch linear subarray is proposed.To obtain stable radiation pattern of 4×4 patch antenna array in 43 GHz~47 GHz,four 1×4 linear subarrays are fed in opposite directions and phases.The measured-10-dB impedance bandwidth is 27.6%,3-dB AR bandwidth is 11.6%,peak gain is 17.1 dBic,and radiation efficiency is 76.9%.Next,a circularly polarized 4×4 patch antenna array loading meta-surface is proposed.The antenna array consists of sixteen truncated corner patches loading meta-surface to increase antenna impedance matching,AR and gain characteristics,four microstrip-based compact SR feeding networks to extend AR bandwidth,and a SIW-based power divider to expand array scale.The measured-10-dB impedance bandwidth is 32%,3-dB AR bandwidth is higher than 22.2%,peak gain is 18.2 dBic,and radiation efficiency is 86.1%.