An Optimizing Method for Parameters of Cavity Filter for Approximate Estimation of Class Curve Fitting

In the design process of cavity filter, optimizing the geometric parameters of the cavity filter is a significant task. The electromagnetic field inside the cavity filter is difficult to calculate because of the complexity of filter structure, so the geometric parameters of the cavity filter cannot be directly calculated by mathematical formulas. In order to obtain the ideal S parameters of the filter, we often need to continuously optimize the geometric parameters in simulation software, which is a tedious task that usually takes a lot of time and is difficult to obtain the ideal S parameters. So it is necessary to adopt certain optimization algorithms. This article investigates a class curve fitting approximation estimation method to optimize the parameters of cavity filters. Due to the inability to obtain a mathematical expression for the mapping relationship between the geometric parameters of the cavity filter and the S parameters,polynomial functions is used to approach the mapping relationship between geometric parameters and S parameters of cavity filters. The algorithm samples values in a certain parameter range, obtaining the coefficients of the polynomial functions by solving matrix equations to obtain the approximation. The optimal solution within that parameter range is solved through the approximate function. A rectangular waveguide filter was designed in HFSS software and applied for parameter optimization. The ideal S parameters were obtained in a relatively short period of time. The advantage of this algorithm is that it can not only be used for parameter optimization alone, but also be combined with other optimization algorithms to improve the speed and efficiency of optimization. This algorithm is flexible to apply in optimization.