Sakuyoshi Saito

Radiation properties of microstrip array antenna fed by radial line

The authors present an array antenna which excites a singly fed circularly polarized microstrip antenna via a low-loss radial waveguide. In order to check the performance of this antenna, some planar arrays were fabricated and tested at the SHF band. Satisfactory performance was obtained in both radiation pattern and directivity gain. This type of array demonstrated high-efficiency performance (approximately 90% aperture efficiency). It was confirmed that this type of antenna can be a useful model of a circularly polarized planar antenna.<<ETX>>

Radiation properties of shaped beam antenna using radial line microstrip array

In the fabrication of a large-scale multi-element planar array, reduction of the feeding loss is important for realization of high-efficiency performance. An array antenna fed by a radial line has been investigated by many researchers, because it has high-efficiency performance. This paper presents a basic design technique of the shaped beam antenna fed by a low-loss radial waveguide. In order to check the performance of this antenna, some planar arrays were constructed and tested at the SHF-band. As a result of experiments, satisfactory performance was achieved in both radiation pattern and directivity gain.

A frequency-tunable varactor-loaded single-layer ring microstrip antenna with a bias circuit on the backside of the ground plane

This paper presents a frequency-tunable single-layer ring microstrip antenna fed by an L-probe with varactor diodes. In order to develop a frequency-tunable ring microstrip antenna, two varactor diodes are mounted on a square split ring patch antenna. An L-shaped feeding probe arranged in the same layer as the ring patch is used to excite the ring patch. The antenna structure is processed with a single-layer dielectric substrate. Resonant frequencies of the proposed antenna can be controlled by DC bias voltage applied to the varactor diodes. The bias circuit is placed on the backside of the ground plane of the ring patch antenna with another thin dielectric substrate to reduce unwanted radiation from it. In order to demonstrate the basic operation of the proposed antenna, a prototype antenna is designed and measured. Fractional bandwidth of the frequency-tunable range of the test antenna is around 10% under the condition of more than 3 dBi gain and the radiation pattern is stable over the tunable frequency range. The antenna configuration can be extended to multiband operation more than dual-band by arranging more ring patches.

Measurement of a microstrip antenna array fed by transverse slots on a broad wall of the rectangular waveguide with standing-wave excitation for linear polarization parallel to the axis

This paper presents measurement of a microstrip antenna array fed by transverse slots on a broad wall of the rectangular waveguide with standing wave excitation for linear polarization parallel to the axis. A series-fed two-element microstrip antenna array on a dielectric substrate excited by a transverses slot of the waveguide is used as an element of the proposed array for grating lobe suppression due to the transverse slots. In this paper, a prototype array consisting of six microstrip antennas fed by three transverse slots on the broad wall of the rectangular waveguide with standing-wave excitation is designed and fabricated. The measured results are agreed with the simulated ones obtained by HFSS. The measured radiation pattern reveals that grading lobes due to the transverse slots are well reduced by the proposed array. Validity of the design of the proposed array is confirmed by the measurement.

A frequency-tunable dual-band multi-ring microstrip antenna fed by an L-probe with varactor diodes

This paper presents a frequency-tunable multi-ring microstrip antenna (MR-MSA) fed by an L-probe with varactor diodes. In order to realize a frequency-tunable multiband microstrip antenna, multiple ring patches are arranged concentrically and two varactor diodes are mounted on each ring patch. An L-shaped feeding probe is used to excite the ring patches. Resonant frequencies of the proposed antenna can be controlled by the DC bias voltage applied to the varactor diodes. In order to demonstrate the basic operation of the proposed frequency-tunable multiband microstrip antenna, a dual-band MR-MSA composed of two ring patches are designed and tested. The fractional bandwidth of the frequency-tunable range of the test MR-MSA is measured to be around 10% under the condition of 1 dB gain reduction from the maximum and of the reflection less than −10 dB. The antenna configuration can be easily extended to multiband operation more than dual-band by arranging more ring patches.

Design and measurement of a linearly polarized radial line MSA array with U-slot circular MSAs

This paper presents design and measurement of a linearly polarized radial line microstrip antenna array (RL-MSAA) with U-slot circular MSAs (C-MSAs). An circular microstrip antenna with U-shaped slot is used as a radiation element of the RL-MSAA. Radiation phase of the U-slot C-MSA is controlled by tuning a radius of the C-MSA and dimensions of the U-slot on the C-MSA; therefore, the desired phase distribution of the RL-MSAA can be designed. In this paper, a linearly polarized RL-MSAA with three concentric rows of the C-MSAs at a spacing of 0.65 wavelengths is designed and tested at 12 GHz. For uniform phase distribution, U-slot C-MSAs for inner two rows and normal C-MSAs for the termination row are arranged. Validity of the linearly polarized RL-MSAA with the U-slot C-MSAs for radiation phase control is confirmed by simulation and measurement.

Beamtilted SHF planar antenna composed of microstrip paired element.

本研究では, 広帯域な円偏波特性を呈する円偏波ペア素子と, この円偏波ペア素子よりなる新しいタイプのビームチルト型円偏波平面アンテナの提案をなし, その構成法および放射特性等につき検討を加え, この種のアンテナ系を構成する際重要となる設計基礎資料を得た.また, これらの結果を用い, 所望の帯域内 (11.7～12.OGHz) で, チルト角約30。, 主ビーム方向の軸比約0.5dB, 入力定在波比1.5以下の良好な特性を呈する新しいタイプの多素子ビームチルト型円偏波平面アンテナを実現した.さらに, このビームチルト型平面アンテナを用いて, 衛星放送の受信実験を行ったところ, 良好な受信画像が得られ, この種のアンテナ系が簡易型の衛星放送受信用平面アンテナとして有用な一形式となり得ることを明らかにした.