榎原 晃

In the paper, improvement of the efficiency for the Rectenna (Rectifier + Antenna) is described. The rectifier circuit in this research promotes further improvement in efficiency and expansion of the power range by using the passive path switching method that can be shifted according to the frequency band. In the previous research, the circuit was configured by using the conventional branch-line coupler as a power divider, however the conversion efficiency on the low power region was not so good. Therefore, in this research, the circuit is configured by using the doubly asymmetrical branch-line coupler to widen the impedance difference at the output ports. As a result, it was confirmed by using an electromagnetic simulation (AWR AXIEM) that the conversion efficiency at low power region was improved up to 65.8%, which was about twice that of the conventional one. In addition, it is verified experimentally as well as analyzed.

This paper treats a power divider with three-frequency matching characteristics consisting of 15 elements. A wide relative bandwidth is considered for each band by placing the matching frequencies on the low frequency side close together for dual-band dividers. In order to confirm the practicality in IoT and 5G (sub6 band), the design frequency is set to UHF/SHF band, and actual measurement is carried out after circuit pattern design and analysis.

In this paper, a 180-degree rat-race hybrid which consists of short transmission lines less than quarter wavelength with shunt capacitors at both ends and an ideal phase inverter is described. We show the possibility of realizing a compact and wideband 180-degree rat-race hybrid that is about 1/10 smaller than the conventional rat-race hybrid and has twice the operating band by an electromagnetic simulation with a uniplanar structure at 28 GHz band used for 5G applications.

Optical couplers based on Multi-mode interference (MMI) were considered using Ti-diffused LiNbO3 (Ti:LN) waveguides. Properties of MMI waveguides of Ti:LN were analyzed using the beam propagation method. An optical 90-degree hybrid of the MMI structure was designed and fabricated with the Ti:LN waveguides. We experimentally confirmed that the MMI coupler could operate as a 90-degree hybrid using the MMI waveguide part of 50 μm width and 2.13 mm length.

We designed and fabricated an electro-optic modulator for optically compensating the nonlinear distortion. The single-chip structure and the single-input operation were realized by integrating a microwave 180-degree hybrid on the DPMZM substrate.

© 2019 IMA - Institut fur Mikrowellen- und Antennentechnik e.V. Screen printing technology using silver nanoparticle ink with high conductivity attracts attention as a technology for fabricating low-loss transmission lines in high frequency band such as millimeter-wave band. Its effectiveness has been confirmed in millimeter-wave band exceeding 100 GHz [1]. This paper describes a 180-degree rat-race circuit (RRC) utilizing composite a right-/left-handed transmission line (CRLH-TL) composed of lumped elements at 76 GHz band in order to confirm the reliability of circuit components by utilizing the screen printing technology. The proposed RRC consists of three right-handed transmission lines (RH-TLs) and a CRLH-TL. Conventionally, it has also been the mainstream to use chip elements for these lumped elements, however the proposed circuit consists of only transmission lines without them. For 76 GHz band, the designed -10 dB RRC with the CRLH-TL can realize compact size and practical characteristics. Effectiveness of the design method was confirmed by using a commercially electromagnetic field simulator (ANSYS HFSS).

© 2018 IEEE This paper describes design of a substrate integrated waveguide (SIW) slot antenna for microwave liquid heating. It is well known that the SIW characteristics are similar to dielectric-filled waveguides. A proposed microwave heating system heats liquid by radiation microwave from slots that are arranged on upper surface of the SIW. From result of designing the SIW slot antenna using a commercial electromagnetic simulator (ANSYS HFSS), a reflection characteristic of -20dB or less at a center frequency of 2.45GHz is realized. Measurement result of a fabricated SIW slot antenna is good agreement with the simulation result.

© 2018 IEEE. This paper describes wideband three-way Wilkinson power dividers using LC-ladder circuits. The proposed dividers consist of multi-section LC-ladder circuits between input and output ports, and their output ports are connected each other through external circuits composed of series RL circuits. By connecting the appropriate external circuits in accordance with the number of LC-ladder circuits, the proposed dividers can be realized extremely wideband operation. In order to verify the design procedure, wideband three-way Wilkinson power dividers are simulated and fabricated at VHF-band. As results of simulation and experiment, we can obtain broadband characteristics with a relative bandwidth of over 60%, which are near agreement with the theoretical results.