Design Of Planar Array Antenna Based On Hybrid Feeding Technique

With the rapid development of wireless communication technology,the demand for spectrum resources has increased sharply.The existing resources are no longer sufficient to meet the demand for high transmission rates.People gradually turn their attention to higher frequency bands.Thus,how to achieve a planar array with low profile,high gain and high efficiency operating within the different required bandwidth has become a research hotspot.A variety of microwave transmission lines have been used in the design of array antenna feed networks.Among them,the microstrip transmission line has the characteristics of low profile,compact size and flexible design,but in the millimeter wave band its large transmission loss will reduce the efficiency of the antenna array.Traditional metal waveguides have lower transmission loss,but usually need a large number of screws or welding methods to avoid energy leakage.Gap waveguide is a new type of transmission line proposed in recent years,which has low loss characteristics of waveguide and is convenient for system integration.In this thesis,based on the advantages of the above-mentioned different transmission lines,a variety of planar array antennas with high efficiency and low profile have been realized by adopting the hybrid feeding method.1.A one-dimensional monopulse low side-lobe planar array antenna combining groove gap waveguide with microstrip line has been studied and designed.A side-fed rectangular microstrip patch antenna is designed as the element for the array,and Chebyshev distribution is used to determine the excitation coefficients of the 2×2 subarrays.Then,a low side-lobe microstrip feed network composed of several unequal power dividers is designed.To improve the efficiency of the array antennas,a one-dimensional sum-and-difference network is realized by using groove gap waveguide technology.Finally,the 12×16 one-dimensional monopulse low side-lobe planar array antenna achieves a side-lobe level below-18.7 d B,and a gain greater than 28 d Bi.2.On the basis of the one-dimensional sum-and-difference network,the ridge gap waveguide is used to realize a miniaturized two-dimensional monopulse sum-and-difference network.Then,a two-dimensional monopulse low side-lobe planar array antenna is completed.The sum beam and difference beam realized by the antenna have good symmetry,with the zero depth less than-37 d B.3.A wideband planar array antenna with a new type of hybrid feed topology in the millimeter-wave band is studied and designed.A slot antenna is designed as the element for the array which uses a stepped double-ridge structure in the slot and the radiating layer to widen the antenna bandwidth.The simulation results indicate that a 50%impedance bandwidth is obtained.Then,a double-layer wideband feed network is achieved by combining the ridge waveguide with the E-plane waveguide.Finally,the 8×8 wideband millimeter-wave planar array antenna achieves a low profile height of 1.85₀l,the relative bandwidth of 47.6%from 24 GHz to 39 GHz and a gain greater than 24.5 d Bi,the antenna efficiency is greater than 72%.