M. Takahashi

A slot design for uniform aperture field distribution in single-layered radial line slot antennas

The slot design for aperture field synthesis in a single-layered RLSA (radial line slot antenna) is summarized. In order to realize a desired slot coupling, the slot length and the spacing are varied on the basis of a full-wave analysis. An example is presented concerning the design of the uniform aperture field distribution.<<ETX>>

Dual circular polarized radial line slot antennas

A possible design of a dual circular polarized radial line slot antenna is proposed, and its basic characteristics are shown. An efficiency of about 50% is observed for a 0.5m/spl phi/ model prototype antenna.<<ETX>>

Characteristics of radial line slot antennas for DBS reception

The measured performance of single-layered radial line slot antennas (SL-RLSAs) is presented to confirm a recently established method for the slot design. An efficiency of 70%-80% is observed for SL-RLSAs with diameters of 0.25-0.45 m. The high potential of the SL-RLSA and the validity of its slot design is fully demonstrated. The antennas are now commercialized for 12 GHz-band DBS (direct broadcast satellite) reception.<<ETX>>

High Efficiency Flat Array Antennas for DBS Reception

A radial line slot antenna (RLSA) is a high efficiency planar array. A uniform aperture illumination for single-layred one is realized by varying slot lengths and spacings over the aperture. This paper presents the measured performance of the high efficiency SL-RLSAs. The efficiency of 70%~84% is observed for SL-RLSAs with the diameters of 0.25m~0.60m. Two novel techniques are also proposed for further improvement.

Measured performances of a wide band radial line slot antenna

A radial line slot antenna (RLSA) is a planar antenna for DBS reception. It is a kind of slotted waveguide array. The conductor losses are so small that high efficiency is expected irrespective of the aperture diameter. On the other hand, since the RLSA utilizes a travelling wave, particularly for a larger antennas, the frequency bandwith is limited by the long line effect. Therefore, for the application of the RLSA to wideband communication, a new structure of a radial waveguide is required. To solve this problem, the authors proposed a wideband radial line slot antenna (WB-RLSA). The paper presents the measured performance of a WB-RLSA.

Efficiency enhancement of radial line slot antennas by reducing termination loss

The efficiency of single-layered radial line slot antennas has been enhanced by adopting nonuniform aperture illumination, which reduces the termination loss. An efficiency enhancement of 5-10% is observed. A measured gain of 36.7 dBi (87%) and 32.9 dBi (81%) and an axial ratio around 1 dB for 0.6-m phi and 0.4-m phi antennas, respectively, verify this technique.<<ETX>>

Characteristics of dual circularly polarized radial line slot antennas

The possible design of a dual circularly polarized radial line slot antenna is proposed. The slot design comprising the single- and double-layered RLSA is presented which are simultaneously fed by a double coaxial adapter. Theoretical efficiency is no less than 70%. Experiments confirm these results. The peak efficiency of about 600% is observed in dual polarization for a 0.55m/spl phi/ model prototype antenna. The cross polarization level is about 20dB and DBS band is covered by more than 33.5dBi.<<ETX>>

A Single-Layered Radial Line Slot Antenna for DBS Reception

A radial line slot antenna(RLSA) is a commercial high efficiency planar array. Double-layered lines have contributed to realize uniform aperture illumination and to reduce terminated loss power. This paper newly proposes a single-layered RLSA which is much simpler in structure. Two novel techniques are applied; firstly, slot lengths are varied to synthesize aperture Illumination and secondly, a matching spiral reduces reflection and radiates the residual power in circular polarization. The gain of 35.4dBi, efficiency of 65% are measured for a prototype RLSA.