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Waveguides and resonators with gyrotropic media. Microwave ferrite devices
Published in A.G. Gurevich, G.A. Melkov, and Waves, 2020
Every waveguide that contains points with circular (or nearly circular) polarization of the magnetic field can be used to design the resonance isolator. In the case of a microstrip or a coaxial waveguide, a dielectric sample should be inserted to obtain such points. Microstrip and coaxial waveguides with dielectric and ferrite samples cannot be analyzed rigorously, and a parallel-plane waveguide is often used as an approximate model. In Figure 5.10, a coaxial isolator and its parallel-plane analog are shown. It is clear from symmetry considerations that, without the dielectric sample, it is impossible to attain different losses at different directions of propagation. The microstrip and coaxial waveguides are wide-band. To get a wide-band isolator it is necessary only to ensure the ferromagnetic-resonance condition in the whole frequency band. This can be achieved, for instance, by the use of a nonuniform steady magnetic field. The frequency band of such isolators can be as large as an octave, the forward losses being 0.2â0.4 dB, and isolation, not less than 50.
RF Combiner and Diplexer Systems
Published in Jerry C. Whitaker, The RF Transmission Systems Handbook, 2017
Isolators are commonly used in microwave transmitters at low power to protect the output stage from reflections. Until recently, however, the insertion loss of the ferrite made use of isolators impractical at high-power levels (25 kW and above). Ferrite isolators are now available that can handle 500 kW or more of forward power with less than 0.1 dB of forward power loss.
2.45 GHz Active Isolator based on asymmetric coupler
Published in Automatika, 2021
Ui-Gyu Choi, Bo-Yoon Yoo, Seong-Tae Han, Jong-Ryul Yang
A microwave isolator is a two-port device with unidirectional transmission characteristics such that signal transmission occurs in only one direction at the matched ports [1]. The isolator is useful for preventing possible damage from reverse transmission in RF/microwave systems and measurement equipment [2]. Ferrite-based isolators are conventionally used in such systems, however, the isolators are bulky, heavy, and expensive, thereby causing them to be poorly suited for use in multiple applications [3]. Magnetic-free isolators based on resonators or varactors have been studied as a substitute to ferrite-based isolators, however, they also have limited applications because of their low isolation and low power handling capability [4].
Microwave power absorption profile of detergent surfactant agglomerates during microwave heating
Published in Drying Technology, 2018
Muhammad Y. Sandhu, Sharjeel Afridi, Qari Khalid, Ian C. Hunter, Nigel S. Roberts
Microwave isolator is a two-port microwave device which allows electromagnetic waves to travel in one direction only. Its purpose is to protect the magnetron from the damaging effects of reverse microwave power due to mismatched load. A 6âkW GA116 microwave isolator from Gerling Applied Engineering (GAE) is connected to the output of the microwave power generator. Microwave power generated from the magnetron travels in the forward direction to the load. The reflected power signal traveling in the opposite direction is dissipated in a water load connected to the isolator.