Kyoichi Iigusa

Gain Enhancement of H-Plane Sectoral Post-Wall Horn Antenna by Connecting Tapered Slots for Millimeter-Wave Communication

We propose a millimeter-wave antenna to serve as an element antenna for a multi-sector switched-beam antenna, which can be fed by a post-wall waveguide. Several tapered slot antennas are connected to an aperture of an H-plane sectoral post-wall horn antenna whose radiation pattern is narrowed in the H-plane to further narrow the pattern in the E-plane. Moreover, the aperture of each tapered slot antenna is loaded with a dielectric to increase the gain. We designed an antenna whose gain is over 16 dBi in the frequency band of 57-66 GHz. The wideband property is experimentally examined.

Experimental Proof of Electrically Invisible State of Inductively Loaded Dipole and Proposal of Electrically Invisible Meander-Lines

We examine that an inductively loaded dipole becomes electrical invisible showing that the influence on a nearby antennas input impedance and on its radiation pattern (scattering) are minimized. We also verify that the direction of the current reverses on the electrically invisible dipole so that the integral of the dipole current becomes zero. By making an inductive load with a distributed constant line, we fabricate an electrically invisible dipole without using chip devices and evaluate its performance. Furthermore, we propose electrically invisible conductor lines formed by connecting these electrically invisible dipoles in series using open stubs as connectors, and analytically examine their invisible state

Improving gain of H-plane sectoral post-wall horn antenna for millimeter-wave communication by connecting tapered slots

We propose a millimeter-wave antenna that can be assembled using several printed boards. A post-wall horn antenna structure and tapered slots are responsible for the narrowing of the radiation pattern in the H-plane and the E-plane, respectively. Further, to improve the matching with free space and obtain a better radiation pattern, a dielectric projection that tapers is attached to the antenna tip. Numerical results show that a working gain of ≥17 dBi can be obtained in the frequency range 57- 66 GHz.

A wideband planar monopole antenna set perpendicularly beside a ground plate

We investigate a planar monopole antenna fed from the side of a perpendicular ground plate and show that impedance matching is attainable at a fractional bandwidth of 150% by adjusting the relative position of the ground plate to the monopole.

Bandwidth enhancement of bent monopole antenna by closely locating a slotted plate

We propose locating a slotted conductor plate in close proximity to a bent monopole antenna in order to enhance the bandwidth, and clarify that impedance matching is achieved in a fractional bandwidth of about 50% with the plate at less than 0.3 wavelengths in length. The possibility of further downsizing is also shown.

Radio-wave transparent surface containing lines loaded with impedance at regular intervals

The vector effective length of a half wavelength-dipole becomes almost zero when a reactance of about 500 ohm is loaded to its center. Since the current integral is almost zero when the vector effective length is zero, the electric influence on other antennas and to the radiation field is smaller than an open-circuited dipole. On the other hand, although other antennas affect the amplitude of the current distribution, the shape of the distribution does not change. Therefore, the vector effective length should be kept to zero. Accordingly, not only the influence on other antennas but also the influence by other antennas can be neglected. Dipoles are, therefore, thought to be almost electrically invisible. Lines composed with electrically invisible dipoles joined in series with a connector of open stubs are also thought to be electrically invisible. A surface containing such lines arranged in parallel is thought to be electrically transparent for radio waves at the same frequency at which the dipoles become electrically invisible. In this paper, we examine analytically the transparency of such surfaces.

Bandwidth enhancement of a bent planar monopole antenna by ground plate extension

A method to enhance the impedance matching frequency band of a bent planar monopole antenna by extending the ground plate is proposed. It is shown by a simulation that the fractional band width of 104 % is attainable.

A wideband printed bent monopole antenna with a small ground plate and basic study

A bent monopole antenna whose feeding side is closely located to a small ground plate is proposed. It is shown that a wideband impedance matching is attainable in -10 dB fractional bandwidth of about 71% by adjusting the interval between the monopole and the ground plate.

Efficiency of short-distance wireless transmission considering radiation loss

To evaluate radiation loss and conductor loss which are the cause of deterioration in the wireless electric power transmission, a calculation method of a transmission electric power, a radiated power, and a conductor loss as a ratio to the input electric power is proposed. The dependency of these ratios on the resistance and the reactance of the receiving circuit are clarified for the short distance wireless electric power transmission between small dipoles, and the method to improve the transmitting efficiency is investigated.

Periodically Loaded Straight Wires for Radio Wave Transmission Control

Calculating current distributions along conducting straight wires reveals that the electric influence of the wires is more effectively reduced by loading reactances than it is by disconnecting the loading ports. With the electric influence almost eliminated, a sheet consisting of reactively loaded straight wires can almost perfectly transmit a radio wave of a frequency determined by the interval between the loading ports and the reactance value. The frequency responses of radio wave transmissions for a normal incident plane wave are numerically calculated, and it is shown that by controlling the reactance value, the transmission can be changed more than 30 dB. Thus, a sheet by which radio wave transmission can be electronically controlled is proposed, and its operation is experimentally examined.