Analysis of Fabricability of Flexible Waveguide Parts for Satellite Applications

Satellite onboard equipment includes waveguide transmission lines. One of the tasks to be solved is the temperature decoupling of the waveguide path and onboard equipment devices. In order to prevent waveguide path deformation during expansion/contraction due to thermal effects, the waveguide is equipped with a flexible waveguide section capable of changing the length without deteriorating radio technical characteristics. The paper considers the issues of fabrication of flexible waveguide parts, concerning the requirements for structure, properties, heat treatment of raw materials, dimensions of workpieces, equipment, and tooling. Within the study, we optimized and tested in practice operations of the technological process of extracting parts from sheet material, rolling, profiling, and shaping, which make it possible to manufacture parts of waveguide paths of the required quality.

Analyses of Substrate-Dependent Broadband Microwave (1–40 GHz) Dielectric Properties of Pulsed Laser Deposited Ba0.5Sr0.5TiO3 Films

Ba0.5Sr0.5TiO3 (BST-0.5) thin films (600 nm) were deposited on single crystal MgO, SrTiO3 (STO), and LaAlO3 (LAO) substrates by pulsed laser deposition at an oxygen partial pressure of 80 mTorr and temperature of 720 °C. X-ray diffraction and in situ reflection high-energy electron diffraction routinely ascertained the epitaxial quality of the (100)-oriented nanocrystalline films. The broadband microwave (1–40 GHz) dielectric properties were measured using coplanar waveguide transmission line test structures. The out-of-plane relative permittivity exhibited strong substrate-dependent dielectric (relaxation) dispersions with their attendant peaks in loss tangent (tanδ), with the former dropping sharply from tens of thousands to ~1000 by 10 GHz. Although homogeneous in-plane strain , enhances with at lower frequencies, two crossover points at 8.6 GHz and 18 GHz eventually change the trend to: . The dispersions are qualitatively interpreted using (a) theoretically calculated (T)- phase diagram for single crystal and single domain BST-0.5 film, (b) theoretically predicted -dependent, anomaly that does not account for frequency dependence, and (c) literature reports on intrinsic and extrinsic microstructural effects, including defects-induced inhomogeneous strain and strain gradients. From the Vendik and Zubko model, the defect parameter metric, , was estimated to be 0.51 at 40 GHz for BST-0.5 film on STO.

RF Small and large signal characterization of a 3D integrated GaN/RF-SOI SPST switch

This paper presents the radio frequency (RF) measurements of an SPST switch realized in gallium nitride (GaN)/RF-SOI technology compared to its GaN/silicon (Si) equivalent. The samples are built with an innovative 3D heterogeneous integration technique. The RF switch transistors are GaN-based and the substrate is RF-SOI. The insertion loss obtained is below 0.4 dB up to 30 GHz while being 1 dB lower than its GaN/Si equivalent. This difference comes from the vertical capacitive coupling reduction of the transistor to the substrate. This reduction is estimated to 59% based on a RC network model fitted to S-parameters measurements. In large signal, the linearity study of the substrate through coplanar waveguide transmission line characterization shows the reduction of the average power level of H2 and H3 of 30 dB up to 38 dBm of input power. The large signal characterization of the SPST shows no compression up to 38 dBm and the H2 and H3 rejection levels at 38 dBm are respectively, 68 and 75 dBc.

An analytical method with numerical results to be used in the design of optical slab waveguides for optical communication system applications

<p>This study develops an analytical method with numerical results for the design of optical slab waveguides for optical communication system applications. An optical slab waveguide structure made of silicon on silicon dioxide material is designed and analyzed. The effective index of the mode is studied against variations in the waveguide dimensions. Transmission and reflection coefficients are studied and compared to the wavelength and dimensions of the waveguide. Variations are sketched with the x-axis, in addition to the electric field intensity distribution and effective refractive index. Waveguide bending loss is also studied with waveguide thickness and length variations within three waveguide transmission windows of 850 nm, 1300 nm, and 1550 nm.</p>