Design and Development of Microwave Circulator for Field Emission Based Magnetron Using Fem and Cfdtd Simulations
Kaviya Aranganadin1*, Ling Li1, Hua-Yi Hsu2, Ming-Chieh Lin1
1Multidisciplinary Computational Laboratory, Department of Electrical and Biomedical Engineering, Hanyang University, Seoul 04763, Korea
2Department of Mechanical Engineering, National Taipei University of Technology, Taipei 10608, Taiwan
* Presenter:Kaviya Aranganadin,
A microwave circulator is a passive non-reciprocal 3- or 4- port device, in which a microwave or radio frequency (RF) signal entering any port is transmitted to the next port in rotation. The Y-junction wave guide circulators has been widely used in microwave and millimeter wave transmission and communication system although the planar circulators have been utilized more in microwave devices and circuits, the wave guide circulator have still have their place in large power devices. Ferromagnetic material are non-conducting in nature hence they ensure total penetration of electromagnetic field which is an important criterion in waveguide design. This penetration of high frequency fields is due to the absence of skin effect similar to metals because the ferrimagnetic oxides of iron combine the property of magnetic material with that of electrical insulator. This paper focuses on the design of an H-plane partial height ferrite circulator in S-band region with a metal stage which acts as an impedance transformer to achieve a wider operating bandwidth of minimum 80-200 MHz with the frequency centered at 2.45GHz. The design and development are performed using both the finite element method (FEM) and the conformal finite difference time-domain (CFDTD) simulations. The goal of this research is to design and develop a low cost but high efficiency and wide bandwidth microwave circulator for field emission based magnetrons operating at frequencies 2.48 GHz and 2.43 GHz and at a working power of 3 KW. This paper also gives a detailed derivation about formulation of tensor matrix for a ferrite magnetic material and some novel strategies to modify the resonant structure to achieve the designs.

Keywords: Microwave circulator, magnetron, FEM, CFDTD