Design of an E-band Self-Biased Field-Displacement Isolator using Al-doped Strontium Hexaferrite for SATCOM applications - Equipe Smart Materials and Related Technologies Access content directly
Conference Papers Year : 2023

Design of an E-band Self-Biased Field-Displacement Isolator using Al-doped Strontium Hexaferrite for SATCOM applications


SATCOM systems are used for broadcasting TV or internet around the world. Due to the generalization of video streaming and online gaming, the demand for high-speed satellite communications grows exponentially. Associated with the fast-growing amount of users, space service providers and satellite manufacturers are forced to expand the capacity of their systems, leading to more spectrum usage. Future feeder links will use the 71 - 76 GHz band for downlink and from 81 - 86 GHz for uplink. Because the free-space wavelength is small at these frequency bands, components design is challenging. Moreover, space systems now feature dynamic resource allocation. Using active electronically scanned arrays (AESAs), satellite operators can focus antenna beams on regions of the world that need most of the satellite throughput at a specific time. Huge amount of front-ends closely spaced are needed to build AESAs. Therefore, a strong need for cheap and small components that are completely contained in the cross section of a standard rectangular waveguide rises. Isolators are usually used in space RF chains for amplifier decoupling. Waveguide field-displacement isolators consist of a ferrite slab precisely placed into the waveguide, with a resistive layer deposited on one face. The magnetized ferrite slab changes field distribution in the waveguide, depending on the direction of propagation of the incident wave. When the electromagnetic wave travels in the forward direction, its electrical field is nulled on the resistive layer whereas being maximum when the wave is travelling in the reverse direction. So, the resistive layer dissipates most of the RF energy in the reverse direction while being transparent when the wave is travelling in the forward direction. Traditional ferrite devices need an external field created by permanent magnets. However, it is possible to remove them using hard ferrites, such as pre-oriented barium or strontium hexaferrites. Those devices are called self-biased devices. Self-biased ferrites devices are interesting for space application as they are small, lightweight and robust to external magnetic field. In this work, we demonstrate the ability to create an E-band self-biased field-displacement isolator. In order to use the field-displacement effect at E-band, the hexaferrite should have a high anisotropy field of 25 kOe. Pure barium hexaferrites have an anisotropy field of around 18 kOe and their strontium counterparts are closer to 20 kOe. Thus, a custom hexaferrite is needed for the E-band self-biased isolator. That’s why an aluminum-doped strontium hexaferrite is synthesized and characterized. Aluminum doping is well-known to enhance the anisotropy field [1]. For ease of manufacturing, fused deposition modelling (FDM) 3D-printing technique is used to create the resistive layer with a lossy dielectric material of carbon-loaded polylactic acid (PLA-C), based on previous work at the laboratory [2]. A dielectric spacer is also added, made out of polylactic acid (PLA), to accurately place the ferrite slab in the waveguide. Isolator simulated S-parameters shows good non-reciprocity (S_12 ~ 13 dB,S_21>-1 dB) and good impedance matching (S_11,S_22<-25 dB) over the whole SATCOM downlink band (71-76 GHz). Dimensions of the designed isolator are only 3.1 x 1.55 x 12.7 mm3 which confirms its compactness. References [1] F. K. H. Gellersen, C. Diker, J. Peschel, A. Ochsenfarth, and A. F. Jacob, “Doped Barium Hexaferrite Films for Self-Biased Nonreciprocal Components in the Q-/V-Band,” IEEE Antennas Wirel. Propag. Lett., vol. 17, no. 11, pp. 1938–1942, Nov. 2018, doi: 10.1109/LAWP.2018.2866547. [2] E. Roué et al., “Three-Dimensional Printing of a Waveguide Termination for Millimeter Wave Applications,” in 2021 51st European Microwave Conference (EuMC), Apr. 2022, pp. 555–558. doi: 10.23919/EuMC50147.2022.9784182.
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hal-04158590 , version 1 (11-07-2023)


  • HAL Id : hal-04158590 , version 1


Evan Roué, Vincent Laur, Antoine Hoez, Alexis Chevalier, Jean-Luc Mattei, et al.. Design of an E-band Self-Biased Field-Displacement Isolator using Al-doped Strontium Hexaferrite for SATCOM applications. 1st Space Microwave Week, ESA-ESTEC, May 2023, Noordwijk, Netherlands. ⟨hal-04158590⟩
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