Ku-band Conical Radome Complex Permittivity Distribution Measurement Technique

The uniformity of the complex permittivity distribution of a conical radome directly determines its electrical performance,and the distribution test of the complex permittivity of a conical radome can not only quickly know its electrical performance,such as calculating the insertion phase,power transmission coefficient,etc.,but can also know whether there is unevenness in the electrical thickness of the radome,so as to guide the electrical thickness compensation in the manufacturing process of the radome;more importantly,knowing the More importantly,knowing the distribution of the complex dielectric constant of the radome can provide important support for the integrated design of the antenna-radome system and the rapid acquisition of the system orientation map.Therefore,it is very necessary to test the complex permittivity distribution of conical radome.The purpose of this thesis is to conduct a theoretical study of the complex permittivity distribution of a conical radome,design and build a conical radome complex permittivity distribution test system,complete the conical radome complex permittivity distribution test,and obtain the complex permittivity distribution of the entire radome to be tested.In order to achieve the research objective of this thesis,an equivalent model of the conical radome distribution test area is firstly established in this thesis;then the insertion loss calculation formula for the conical radome distribution test area is derived based on the theory of oblique incidence of a uniform plane wave on a single dielectric plate,and the actual dual antenna test is simulated using FEKO software,and the inverse calculation of the dielectric constant and loss tangent of the set material is obtained using this formula.Then,for the test band of this thesis and the requirements of high accuracy,high test stability and wide test range,a Ku-band miniaturised corrugated horn antenna with matching aperture lens,high gain,circular symmetric directional map,low side flap and low cross-polarisation was developed and a near-field electric probe scanning system was built to test the near-field characteristics of the antenna.Finally,a three-dimensional scanning system based on a robotic arm and a precision turntable was built to test the complex permittivity distribution of the conical radome,and its permittivity and loss angle tangent distribution were measured and analysed for some quantifiable error sources.Through the above systematic study,the feasibility of testing the complex permittivity distribution of the free-space conical radome is demonstrated,which makes up for the shortcomings of the existing testing methods,such as the resonance method requires thin thickness,low loss and less bending samples;most of the free-space methods equate the curved surface as a whole to a flat plate,which results in large calculation errors,etc.,and provides a basis for the design and manufacture of the conical radome,the rapid integration design of the antenna-radome system and the rapid calculation of the electrical properties of the radome,It provides technical support for the design and manufacture of conical radomes,the rapid integration of antenna-radome systems,and the rapid calculation of the electrical properties of the radome.