V.M. Krekhtunov – Ph.D. (Eng.), Associate Professor at «Radio-electronic systems and devices» chair, Bauman Moscow State Technical University. E-mail: firstname.lastname@example.org
A.A. Budkin – Engineer at RET Research Institute of Bauman Moscow State Technical University
K.V. Lulukin – Student of Bauman Moscow State Technical University
Widely used tunable waveguide ferrite devices, such as ferrite polarization switches, channel switches and breakers, as well as attenuators, power dividers, phase shifters and others are investigated. A common device, combining these devices into a single class, is the rotator of linearly polarized wave polarization plane in a waveguide with longitudinally magnetized ferrite rod. At present, typically performed rotators are based on ferrite rod with lateral surface conductive coating and outer yoke, such as ferrite brackets reducing the demagnetization field and provides the possibility of realizing a magnetic memory device.
One of the drawbacks of such devices are low speed and high switching pulse energy W caused by "effect of closed loop", which performs the role of a waveguide in the form of a lateral surface conductive coating of the ferrite rod. The relations of devices’ switching time and energy W from their parameters are analyzed and the radical way to improve performance what is to perform it on the basis of the ferrite rod without lateral surface conductive coating is offered. Thus it is possible to improve the performance of the device to the limit determined by magnetizing inductance of the magnetic system and reduce the required control power to a minimum, determined by the volume of ferrite rode and ferrite yoke and magnetic parameters of materials. At the same time it increases the phasing structure activity and simplifies the practical realization of the device, so there is no need to apply a conductive coating and solder in or paste in the ends of the ferrite rod in the device’s armature.
The feature of Faraday rotator, built on the basis of non-metallized ferrite rod, is the placement of the magnetization system elements in the field of microwave surface wave, which may lead to increased losses as dissipation and reflection. To eliminate these undesirable effects a complicated geometry of the magnetic circuit is suggested.
For the purpose of devise calculating and optimizing its complex electrodynamic analysis based on the decomposition method and including the calculation and analysis of the forming waveguides self modes and electrodynamic modeling of the whole device and its individual components. As a result of numerical optimization the optimal configuration and sizes of the ferrite block were found.
The effectiveness of the proposed rotator design is illustrated by the example of a Ku-band waveguide ferrite polarization switch, operating in the frequency range 10.9 ... 11.7 GHz, with the insertion loss of not more than 0.3 dB, polarization isolation of at least 25 dB, switching time and energy 5mks and 20 mJ, respectively.
Mikae'lyan A.L. Teoriya i primenenie ferritov na
sverxvy'sokix chastotax. M.: E'nergoizdat. 1963. 663 s.