The Dual Polarization Waveguide Slot Array Antenna Feed By Two Port

In order to improve the performances of low probability of intercept(LPI) radar systems and in order to meet the needs of LPI equipment to the transmit antenna, a wide bandwidth, high gain, total diameter dual circularly polarized antenna is designed in this thesis., the polarization agility can be realized by controlling the port feed method. The design antenna can be achieved with a beam scanning by changing frequency. The main research contents of this thesis are mainly including the following several aspects1) T-type compound slot unit is optimized and is analyzed using the electro-magnetic simulation software Ansoft HFSS, the caliber fields of two solts in a unit are calculated using the moment method, and the results coincide with the r esult by HFSS.2) On the basis of the simulation unit can easily find that the structure can realize a circular polarization when feeding from one end of the unit, and can realize another circularly polarization when feeding from the other end of the unit, the result patterns of both forms of feed are symmetrical substantially. Based on these characteristics, the same spacing and the same unit size between the standard waveguide line array is designed in order to relize left-handed and right-handed circular polarization through controlling the feed port. The standard waveguide is filled up with Teflon which dielectric constant is 2.3.3) According to the requirements of the line array antenna feed, waveguide/coaxial feed structure is designed. Waveguide slot array antenna is motivated by coaxial probe in the waveguide broadside and is achieved impedance matching between coaxial and waveguide. Planar is designed which can achive a frequency sweep range, the AR and patterns meet the requirements with the indepedance bandwith with 2.25 GHz.4) This thesis is further studied in order to broaden the operating bandwidth of the dual circular polarization antenna. The nonstandard waveguide is filled up with Teflon which dielectric constant is 2.3, the structure can achieve absolute operational bandwidth increased from 2.25 GHz to 3.75 GHz. VSWR are less than 1.5, 3 dB lobe width are less than 5° in the XY plane and “near XZ plane”, axial ratio are less 3.5) Simulating machining errors are done in order to anslys the effect of antenna parameters on the performance of the waveguide slot antenna which is more concerned in the engineering process. Random errors within a certain range are generated using MATLAB, and main dimension parameters of waveguide antenna are revised in order to simulating error analysis.6) Another X-type waveguide slot array is designed which have the same function on the basis of magnetic field distuibution of the waveguide, the X-type waveguide slot area array is designed on the basis of the line array antennas, the AR and patterns meet the requirements with the indepedance bandwith 2 GHz.