Best Paper Award 2015

Best Paper Award

Design of mm-Wave RLSAs with Lossy Waveguides by Slot Coupling Control Techniques

Tung NGUYEN，Jiro HIROKAWA，Makoto ANDO，Manuel Sierra-Castaner

[Trans. Commun., Sep. 2015]

Tung NGUYEN

Jiro HIROKAWA

Makoto ANDO

Manuel Sierra-Castaner

In the past few decades, as the demand for ground-satellite communications has grown, many studies focusing on satellite onboard antennas have been conducted. The most common antennas used in satellite communications are parabolic reflectors. However, conventional reflectors have the problem that the antenna system occupies a large volume, which results in heavy weight and difficulties associated with its manufacture and installation on a satellite. A honeycomb structure was introduced as the dielectric spacer in a radial line slot antenna (RLSA) to reduce the weight. As a result, a 900mm-diameter RLSA weighs only about 1kg, which is very attractive in terms of a satellite onboard application. Demands for high-gain and lightweight planar antennas in mm-wave are rapidly increasing. It is inevitable that there will be many studies on how to make use of lightweight, lossy materials, and this has become a particularly urgent task for satellite antenna designers.
This paper discusses how to design an RLSA where the waveguide is filled with high-loss dielectric materials. The authors introduce a new design for the aperture slot coupling synthesis to restrain the dielectric losses and improve the antenna gain. Based on a newly defined slot coupling, a number of RLSAs of different sizes and with different loss factors are analyzed and their performances are predicted. Theoretical calculations suggest that the gain is sensitive to the material losses in the radial lines. The gain improvement attained by using the new coupling formula is especially notable for larger antenna sizes and the higher loss factor of the dielectric material. Three prototype RLSAs have been designed and fabricated at 60GHz following different slot coupling syntheses, and their measured performances validate the theory.
As stated above, in this paper, the key issue on the gain improvement of the RLSA with high-loss dielectric material is clearly identified, a novel design to solve the issue is proposed, and also, the effectiveness of the design is confirmed through measurements. Accordingly, this paper deserves the IEICE Best Paper Award.