In recent years increasingly in a variety of radio systems the microwave devices (transmission lines, resonators, filters, etc., that are) performed with using of the phenomenon of high temperature superconductivity (HTS) are used. From the point of view of the nonlinear properties of HTS conductors, these devices are nonlinear devices that are characterized by various nonlinear effects that often degrade the properties of the whole system. Therefore, the prediction of the nonlinear characteristics of devices with HTS is a very important task still at the design stage.

In this paper we consider nonlinear effects in HTS microstrip resonators. A mathematical model based on the method of nonlinear integral equations (NIE) with respect to the distribution of spectral components of current density on the surface of the HTS conductor. A procedure of numerical solution of NIE for a periodic or intermittent mode device is offered.

The results of studies of resonators with resistive and inductive nature of the nonlinearity of the surface impedance are introduced. It is shown that in resonators with inductive impedance with an increase in the level of the input there is a shift of the resonance frequency device and the response becomes asymmetric, which in turn leads to different levels of intermodulation distortion at different boundaries of bandwidth. The level of intermodulation products and the higher harmonics in the cavities of various types is analyzed.