Takaomi Matsuzaki

Study of material loss in mm-wave RLSA with honeycomb structure

Analysis of the electrical properties of dielectric materials, which were used to fill an oversized radial waveguide of the RLSA, was carried out at 32 GHz. The use of multiple layers is indispensable to meet the requirements for space-use RLSA, and the electrical properties (permittivity, loss factor) need to be specified accurately in order to design the slot array and optimize the antenna performances. Simulation results of the waveguide filled with NOMEX® honeycomb structure suggested a significant material loss at 32 GHz. The measurement results of fabricated antennas supported this anticipation.dielectric materials,oversized radial waveguide

Estimation and measurement of cylindrical wave propagation in parallel plate with honeycomb spacer for the use in mm-wave RLSA

Analysis of non-metallic honeycomb structures to be used as the waveguide at 32 GHz in a satellite on-board Radial Line Slot Antenna (RLSA) was carried out. Incorporating honeycomb structure for the waveguide is indispensable to meet the requirements for space-use while maintaining the electrical characteristics. At 8.4 GHz this was successfully done using Quartz honeycomb structure, where the cell size was much smaller than the guided wavelength. At 32 GHz, with the design frequency 4 times larger, estimation of propagation characteristics in the millimeter wave region was a necessity. Simulation results anticipated anisotropic propagation around 32 GHz for larger cell sizes and significant material loss for smaller cell sizes. These results were partly confirmed by measurements of honeycomb structure and antenna measurements supported significant material loss.

A concise design of large mm-Wave Radial Line Slot Antenna with honeycomb structures for space application

This paper reviews the state of the art concise design of a large aperture Radial Line Slot Antenna (RLSA) in millimeter waves to be used as a satellite on-board antenna. Honeycomb structures are employed as core of the dielectric spacer to reduce the antennas weight. We derived an equivalent model for the design and analysis of large size RLSA, where four layers honeycomb radial line is replaced by a two layers dielectrics sheets. A constant slot correction length is introduced to utilize the Moment method for neglect of higher order modes. Several prototypical RLSAs are manufactured based on this concise design; a 90cm RLSA with a gain of 44.6dB at 32GHz, and the weight of only 1kg, is currently the best and promising for satellite on-board antennas.

An equivalent two-layer model for a fast design of a high gain multi-layer Radial Line Slot Antenna using MoM

A simple but reliable two-layer model of the waveguide structure was introduced to replace a real, complex four-layer model in the design of Radial Line Slot Antenna (RLSA) for satellite on board antenna in 32GHz band. Fidelity of this equivalent model was examined experimentally by several test antennas. A fast analysis method using the Method of Moment (MoM) was also applied on the equivalent model to estimate the antenna performance. Finally, an RLSA having φ = 900mm diameter was fabricated and characterized by the near field measurement. A directivity of 48.3dBi correspond to 73% aperture efficiency was obtained at 31.9GHz.

Material choices of honeycomb structures and their effects in mm-wave RLSAs

This paper investigates the material choices to create the honeycomb structures to be used as the dielectric spacers inside the Radial Line Slot Antennas (RLSAs). Nomex® and Quartz fibers are studied and compared in many aspects such as electromagnetic properties, physical behaviors, or market availabilities. Each material has its own advantages and disadvantages. 90cm RLSAs fabricated using the same slot design, with different material choices; and the peak gain of the RLSA with Quartz honeycomb structure is 46.2dB, which improves 1.5dB from a 44.6dB peak gain of the RLSA with Nomex® honeycomb structure.