Recently, “Both-Side Retrodirective System” was proposed, as a beam convergence technique, for microwave high power transmission. To demonstrate the effectiveness of the both-side retrodirective system by experiment, the authors propose a 2-dimensional measurement equipment. Propagation in the parallel plate waveguide was analogized based on free-space propagation, and the theory and characteristics were clarified by simulation. The electric field distribution in the waveguide was measured by electric probe with the proposed equipment. Two types of measurement equipment were developed. One is a 4-element experiment system, which is a small-scale device for principle verification. The other is a 16-element measurement equipment, which is intended to evaluate beam convergence of a both-side retrodirective system in the next step. The measured results were compared with simulation results. As a result, it was confirmed that the beam formed in the waveguide was successfully measured. Thus, the effectiveness of 2-dimensional measurement equipment for evaluation of beam convergence was shown.

This study mainly involved examining a high-directivity radiation system with spherical dielectric resonator as pseudo multipole source. The method of spherical wave expansion is focused on wherein the plane wave that is infinitely spread can be radiated from or absorbed by multipoles at the origin. It is not possible to explain this phenomenon by Huygens' principle, which is a basic principle of aperture antenna theory. Thus, in the study, a high-directivity beam design is proposed by synthesizing spherical waves. The directivity of the synthesized spherical wave corresponds with the angular momentum and angle, which is an uncertainty relation different from that of the aperture source. The estimation of the effective aperture of the synthesized spherical wave indicates that the wave intrinsic source is assumed to exist at the surface of the cutoff region. Finally, the results reveal that a radiation system without a singular point can be composed using a spherical dielectric resonator. The study discusses the potential of a high-directivity radiation system constructed by a multi-mode degenerate spherical dielectric resonator as a pseudo multipole source.

In the beam-type microwave power transmission system, it is required to minimize the interference with communication and the influence on the human body. Retrodirective system that re-radiates a beam in the direction of arrival of a signal is well known as a beam control technique for accurate microwave power transmission. In this paper, we newly propose to apply the retrodirective system to both transmitting and receiving antennas. The leakage to the outside of the system is expected to minimize self-convergently while following the atmospheric fluctuation and the antenna movement by repeating the retrodirective between the transmitting and receiving antenna in this system. We considered this phenomenon theoretically using an infinite array antenna model. Finally, it has been shown by the equivalent circuit simulation that stable transmission can be realized by oscillating the system.

A new electromagnetic coupling structure has been proposed for a millimeter wave DR-VCO. The structure consists of a microstrip substrate placed on a planar type dielectric resonator and provides a strongly confined electromagnetic field and a high Q. The resonator used in this structure is a TE010 mode dielectric resonator composed of a dielectric substrate and electrodes on both sides of the substrate. Each electrode has a circular hollow patch. A microstrip circuit substrate with an aperture on the ground electrode is stacked on the resonator. The resonator is magnetically coupled to the transmission line through the aperture. The coupling structure has advantages as follows: (a) The electromagnetic field is strongly confined at the hollow patch, and (b) unloaded Q reduction is only 18% under a strong coupling. When the structure is used as a resonant circuit for a DR-VCO, the circuit can be small because the transmission lines to be isolated from the resonator are able to be placed near the resonator. Both a large loaded Q and a large reflection coefficient of a resonant circuit are obtained with the structure. Fabricated DR-VCO has following performances. The oscillation center frequency is 30. 242 GHz and the frequency tuning range is 91 MHz when the control voltage varies 2 to 10 V. An output power of more than 7.3 dBm and a C/N of 90 dBc/Hz at 100 kHz offset are obtained at the frequency range.