Design Of S-Band High Power1-32Power Divider Network

With the development of the high-power microwave technology, the demand to radiation becomes more and more greater, scholars from both home and abroad are trying to find new type of high power microwave radiation antenna to meet this requirement. High-power radial line helical array antenna, a new type of high power microwave antenna proposed in recent years, has the advantages of high power capacity, high efficiency and miniaturization. In order to obtain a higher antenna gain, multiple high power square radial line helical array antenna (hereinafter referred to as the sub-array) can be close together, through high-power multi-channel power distribution network feed to more than one sub-array, to form a larger square array. In a practical application,it needs to combine32-array into a large square array, it needs to form a32way power distribution network. In this background, this paper studies a kind of32way power distribution network in S band of high power field, achieving feed to the4×8high power square32-sub-array.Through the analysis of a variety of1-32way power distribution network topology the paper selected overmoded circular waveguide/coaxial waveguide to2-way rectangular waveguide power divider, the H-T branch of high-power and high-power waveguide coaxial converter cascade constitute a form of power distribution network, it has the characteristics of the same phase、equal amplitude, and equal length of output path, and the feed can be completed in a single-layer structure. Overmoded circular waveguide/coaxial waveguide to2-way rectangular waveguide power divider is a key element of the power distribution network topology, this paper first proposed and designed three different types of2-way power divider.The first power divider is overmoded coaxial waveguide to the2-way rectangular waveguide power divider. In this power divider, due to the asymmetry of the conversion structure and limited by the size of the coaxial waveguide, TE21mode can produce and disseminate in them, influence power allocation effect. Two cross-support rod are used to suppress high-order mode in coaxial waveguide to ensure single-mode transmission in the power divide. In addition, due to the high power microwave source used circular waveguide output, through the converter can realize the transformation of the overmoded circular waveguide to overmoded coaxial waveguide. Simulation results show that:the power divider has a VSWR of1.06, a conversion efficiency of98.2%, a power-handling capacity of2.38GW under2.88GHz, a VSWR below1.22under the frequency range of2.85-2.93GHz, a reflection coefficient of high-order mode is almost zeroThe second power divider is coaxial waveguide to4-way rectangular waveguide and then to2-way rectangular waveguide power dividers. In this power divider, coaxial waveguide is first converted into4-way rectangular waveguide, it can generate the lowest high order mode is TE41mode which is the cut-off mode in the coaxial waveguide, thus ensuring the single-mode transmission. Through the bend rectangular waveguide and H-T branch cascade to realize4-way rectangular waveguide to2-way rectangular waveguide transition. Also use the converter to realize the transformation of the overmoded circular waveguide to overmoded coaxial waveguide..Simulation results show that:the power divider has a VSWR of1.06, a conversion efficiency of98.8%, a power-handling capacity of3.61GW under2.88GHz, a VSWR below1.22under the frequency range of2.8-2.96GHz, a reflection coefficient of high-order mode is almost zero.The third power divider is circular waveguide direct to the two-way rectangular waveguide power divider.Mode matching method is used in the paper for analysis of the model feature in the power divider. Single-mode transmission can be ensure under the design size. Simulation results show that:the power divider has a VSWR of1.04, a conversion efficiency of99.9%, a power-handling capacity of2.83GW under2.88GHz, a VSWR below1.22under the frequency range of2.82-2.94GHz, a reflection coefficient of high-order mode is almost zero.On the based of the study of the1-2-way power divider, according to1-32power distribution network topological structure, the high power H-T branch and high power waveguide coaxial transformer optimization design was carried out respectively.We maked the second and the third types of1-2way power dividers cascaded respectively with H-T branch and waveguide coaxial converter, designed two types of32way power distribution network. Simulation results show that:the first power divider network has a VSWR of1.14, a conversion efficiency of99.1%, a power-handling capacity of2.99GW under2.88GHz, a VSWR below1.22under the frequency range of2.85-2.92GHz; The second power divider network has a VSWR of1.1, a conversion efficiency of99.8%, a power-handling capacity of2.82GW under2.88GHz, a VSWR below1.22under the frequency range of2.84-2.92GHz. The first kind of power distribution network has certain advantage in power capacity, the second power distribution network in the engineering field has certain advantages. With the second kind of power distribution network as an example, the power distribution network performance are calculated by the method of microwave network considering the reflection characteristics of sub-array, illustrates the feasibility of the feed to the4×8high power square32-sub-array.At last, on the basis of theoretical analysis about transmission properties of electromagnetic waves in the rectangular waveguide, studied the adverse factors’s influence on the insertion loss such as roughness, the insertion loss of the1-32power distribution network were calculated respectively By semi-empirical formula and simulation software.