Research And Design Of Novel Radar Microstrip Array Antenna In X-band

As an important component of the radar,the antenna affects the performance of marine radar directly.With the advantages of low cost,small size and easy processing,the microstrip ship radar antenna is widely used in ship radar system.Ship radar antennas are mostly linearly polarized for its better anti-wave clutter capability,The circular polarization antenna has strong rain-fog resistance capability,and receives further attention and application.Aimed at the design and optimization of ship radar microstrip array antenna,two X-band array antennas with new structure are designed based on the Project.The main completed works are as follows:(1)An germanium structure impedance transformer is proposed for X-band microstrip array antenna.The proposed germanium structure impedance transformer reduces the longitudinal dimension of the array antenna and simultaneously reduces the side lobe level in the vertical direction.(2)Then a X-band ship radar microstrip array antenna structure is proposed,interlaced by radiating element patches placed on both sides of a stepped feed network.By changing the distance between each unit patch to 1/2 waveguide wavelength,the horizontal dimension is half that of the conventional linear array antenna,this method reduced the loss of feed network,narrowed the vertical beamwidth,and also increased the gain of the antenna.(3)An X-band and linearly polarized array antenna and circularly polarized microstrip array antenna are proposed with this structure.The radiation patterns of the antenna adopts chebyshev polynomials,while the array adopts series feed mode.And angle feed technology was adopted to realize circular polarization.The simulalion results show that linearly polarized antenna has a good impedance bandwith of 200MHz,the circularly polarized antenna has a good impedance bandwith of 400MHz,and the circularly polarized antenna has a 3dB axis ratio of 200MHz.The horizontal beamwith of both antenna are about 6°,the vetical beamwith are less than 30°;the horizontal side lobe level of both antenna are less than-18dB,and the vertical side lobe level are less than-12.5dB.Both antennas have a gain greater than 19.5dBi.All the simulalion results meet the design requirements.(4)Two types of antennas were processed and then tested in microwave unreflected chamber.Simulalion results are compared with the measurements,and a good agreement is obtained.Therefore,with the advantages of low cost,easy processing,compact structure,the proposed antenna can be a good candidate for the needs of.ship radar.