Research Of Millimeter Wave Circularly Polarized And Broadband Antennas

Nowadays,our lives are inseparable from wireless communication.Antenna is a key component of signal transmission and reception,and its quality and characteristics directly affect the communication quality,therefore it`s very valuable to research antennas.At present,our high requirements for communication quality have made millimeter waves have attracted the attention of many scholars due to their advantages of low signal transmission delay,fast transmission rate,and rich spectrum resources.Among the different types of millimeter wave antennas,circularly polarized antennas have many unique advantages such as anti-polarization mismatch and anti-multipath reflection.Therefore,it is of great significance to carry out research on circularly polarized antennas.In addition,miniaturization is a trend of equipment design in the future,which can be achieved by improving the integration of antennas and improving the utilization of free space in equipment.It is also possible to achieve the goal by reducing the number of antennas through the design of broadband antennas,allowing one antenna to cover multiple frequency bands.Combining the advantages of millimeter wave and circularly polarized antennas,and considering the trend of equipment miniaturization,an endfire antenna and two broadband antenna arrays are designed in this paper.Considering the universality of linearly polarized antennas,a millimeter wave broadband linearly polarized antenna is designed through multi-mode technology.The results of this paper are as follows:1.A millimeter wave end-fire circularly polarized antenna that works at 42.5-50GHz(16.7%)is proposed.The feeding part and the radiating part of the antenna form a non-coplanar T-shaped structure,meanwhile a SIW structure is adopted to feed the antenna to improve the integration of the antenna with the device motherboard.The antenna achieves an impedance bandwidth of 40-50GHz(22.2%)through loading inductance and capacitance in the SIW.At the same time,its end-fire structure is beneficial to reduce the signal blocking of the handheld device by hands.2.A broadband millimeter wave loop circularly polarized antenna array is proposed.The loop circularly polarized antenna element works at 43.46-47.82GHz(9.7%),furthermore through designing a suitable feeding network and using sequential rotation feeding technique,the axial ratio and impedance coincidence bandwidth of the 4×4 broadband array is increased to 37-52GHz(33.3%),covering the frequency band around 45 GHz announced in IEEE802.11aj-2018.3.A broadband millimeter wave circularly polarized stacked antenna array is proposed.The broadband stacked antenna element uses multi-layer parasitic patches and loads L-shaped branches on the driven patches to achieve a working bandwidth of 32-42 GHz(27%).By designing a feeding network with the same amplitude and same phase,the axial ratio and impedance coincidence bandwidth of the 4×4 array is 30-38GHz(23.5%)which covers the frequency band near 35 GHz in the Q-band.4.A broadband millimeter wave(linearly polarized)antenna is designed.The antenna which is feed by coupled energy from the microstrip to slot has a compact structure with a feeding layer and a radiating layer.Through multi-mode technology,the antenna achieves a working bandwidth of 26.7-43.8GHz(48.8%),covering multiple application frequency bands used by many countries in Q band.