Ferrites are a series of magnetic crystals with permeability tensor controlled by applied magnetic field. The controllability and nonreciprocity of the ferrites in interaction with electromagnetic signals has led to widespread using in transmitters and receivers of telecommunications and military applications. The most important of these devices are circulators, phase shifters, isolators, filters and limiters. It is also used in telecommunication systems with a capacity of several milliwatts to several megawatts, which caused them to be used in a wide range of electromagnetic signals. Hence, the design of magnetic devices with small dimensional, low insertion loss and high return loss are very favorable at high frequencies. The need to increase bandwidth and sending lots of data in wireless communication systems is one of the most important factors in the emergence of higher frequencies and millimeter waves. These demands have led to the appearance of a family of hexaferrites and Ferromagnetic Nanowires. Also, the desire to send high power signals in communication systems has led to widespread use of high power magnetic devices in a millimeter wave bands. Accordingly, the design and simulation of magnetic devices with commercial software, whose scattering parameters are well matched to the measurement values, are important issues in their economic Manufacturing technology. Most magnetic devices act in the partial magnetization state. For example, due to the small geometric dimensions of the circulators in the millimeter wave bands, self-biased magnetic structures are desirable, which are permanent magnet. As a result, their permeability tensor modeling is a major challenge in their suitable design. In the design of high power magnetic devices, the nonlinear mechanisms, which increase the loss of devices, must be considered. In this thesis, by using a precision modeling of hexaferrite tensors as well as ferromagnetic nanowires, we design, analyze and simulation more accuracy some of the three port y-type waveguide circulators at high frequencies. Also, the mechanism of stimulation of spin wave and control of them, is investigated in a high power phase shifter, and the power of signal transmitted with this device is calculated. Ultimately, the scattering parameters of phase shifter will be simulated. Keywords Millimeter waves, Magnetic devices, Partial magnetized state of ferrites, Hexaferrites, Ferromagnetic Nanowires, High power ferrite devices, Permeability tensor modeling