Kaoru Sudo

A millimeter-wave radial line slot antenna fed by a rectangular waveguide through a ring slot

A radial line slot antenna (RLSA) is a high gain and high efficiency planar antenna proposed for DBS subscribers in the 12 GHz band. In recent years, several radio systems have been developed in the millimeter wave band. In conventional RLS, a radial waveguide has been fed by a coaxial feeder. In the millimeter wave band, fabrication of the feeder is considerably difficult, since the physical size is small. High accuracy in manufacturing is needed to give high antenna efficiency. We have proposed a planar feed circuit with a ring slot and a microstrip line (see Kigure, Y. et al., IEICE Natl. Conv. Rec., B-1-102, 1999). The feed circuit may be easily integrated with an RF planar circuit. In this structure, however, undesired radiation to the back of the antenna is significant and the antenna efficiency is degraded. In terms of efficiency in the millimeter wave band, a rectangular waveguide is more attractive for feeding a radial waveguide. A rectangular-to-radial waveguide transformer through a ring slot is proposed. This transformer is slightly bulky, however there is no leakage. It is suitable for integrating with existing RF modules that have an interface to the rectangular waveguide. The rectangular-to-radial waveguide transformer through a ring slot is designed and fabricated at the 12 GHz band and we integrate a RLSA with this feed circuit at the 38 GHz band.

Two types of exciting modes in a rectangular-to-radial waveguide transformer as a feeder of radial line slot antennas

The authors discuss two types of exciting modes in a rectangular-to-radial waveguide transformer for radial line slot antennas (RLSAs). One is the rotating-mode gene a crossed slot in a radial waveguide. The measured ripple of the amplitude is 3.0 dB in the ¿ -direction at 5.95 GHz and the bandwidth below 6 dB is 7.0% in the 5.8 GHz band. The other is the coaxial mode; which is proposed in this paper. The calculated ripple of the amplitude in the ¿ - direction is about 1.2 dB in the 12 GHz band.

Analysis of a slot pair coupling on a radial line filled with double-layer dielectric

A radial line slot antenna (RLSA) is a high-gain, high-efficiency and low-cost planar antenna. This paper proposes an analysis method of slot coupling on a radial line filled with a double-layer dielectric by using method of moments (MoM) with eigenmode expansions and discusses the design of the RLSA.

Reduction of Azimuthal Amplitude Ripple in the Rotating-Mode Feed to a Radial Waveguide by Using a Crossed Dog-Bone Slot

The use of a crossed dog-bone slot in a rectangular-to-radial waveguide transformer is proposed as a feeder for a radial line slot antenna to reduce the amplitude ripple in the azimuthal direction because the beamwidth of the dog-bone slots is wider than that of straight slots in radiating into a radial waveguide. The transformer is analyzed and designed by using the method of moments with numerical eigenmode basis functions. By the use of the crossed dog-bone slot, the measured amplitude ripple in the azimuthal direction becomes 0.80 dB, which is 1.4 dB lower than that of the conventional crossed straight slot in the 5.8 GHz band.

Full-model analysis of a radial line slot antenna including the feeder and improvement of aperture field uniformity by shift of position of each slot pair in the radial direction

A full model structure of CA-RLSA with feeder has been analyzed by using the MoM. The results of the calculated aperture-field show reasonable agreement with the experimental ones on the outermost round of slot pairs by the full-model analysis. We propose a design method by using this full-model analysis. The /spl rho/-positions of the slot pairs are adjusted respectively to suppress the deviation of the phase in the /spl phi/-direction. As a result of the design, enhancement of the aperture efficiency is 2 %.

Aperture Field and Directivity of a Radial Line Slot Antenna Filled with Double-Layer Dielectric

In this paper, the measured characteristics of RLSAs with double-layered dielectrics, such as directivities and aperture field illumination obtained from near-field measurement are presented and compared with the design. Some future works to improve the efficiency are also discussed

Excitation of a rotating mode in a radial waveguide by a cross slot-coupled rectangular waveguide

A radial line slot antenna (RLSA) is a high gain, high efficiency and low cost planar antenna proposed for DBS subscribers in the 12 GHz band. In the conventional RLSA, a radial waveguide has been fed by a coaxial feeder. In the millimeter wave band, fabrication of the feeder is considerably difficult, since the physical size is small. In this paper, an analysis for excitation of a rotating mode in a radial waveguide by a cross slot-coupled rectangular waveguide is proposed and an excellent transformer is designed. Instead of a ring slot, a cross slot was proposed for the excitation of the rotating mode in a radial waveguide. The lengths of slots are different from each other and the slots are crossed on 90/spl deg/.

Coupling of a circularly polarized slot pair on a corrugated waveguide of finite length

We analyze a circularly-polarized slot pair on a hollow rectangular waveguide of finite length with corrugations on the bottom by the method of moments. The analysis is for designing a radial line slot antenna for high-power or space applications. The reflection from the end of the corrugation array gives ripples in the slot coupling for the relative position of the slot pair but the ripples are so small that averaging of the slot coupling is acceptable for practical design of the antenna.