Dajung Han

A small-sized automobile LTE multi-band MIMO antenna

This paper deals with an effective method to maximize the characteristics of a MIMO antenna system for cars. This stems from the improvement of isolation between the two radiators. A metamaterial kind of decoupling device which is a modified SRR curbs the unwanted interaction between the MIMO elements. New flat dual-band monopoles with the interference-reduction device for the MIMO system are suggested and the numerically experimented results of the cases without and with the proposed structure are compared. These show how good isolation level is obtained. It is certain that the entire structure is adoptable to the placement on the car surface.

A planar 8-way radial power-splitter combined flat ap-antenna with increased h-plane gain

A method to make the access-point(AP) antenna flat and create multiple beams with good gains in the horizontal plane is proposed to overcome the drawbacks of the monopole antenna. The monopole antenna has a relatively high profile and low H-plane gain due to the imbalance in elevation. Considering 8 beams around the circle, the input power is divided by a thin 8-way radial power-splitter which requires technical treatment on very high impedance as large as 400 Ω. This is connected to 8 quasi-Yagi antennas. The experiment shows the desired power-splitting and the improvement of the horizontal-plane gain as a flat antenna structure.

A low profile, wideband and high gain beam-steering antenna for 5G mobile communication

A low profile, wideband and high gain Substrate Integrated Waveguide (SIW) Transmission Line (TL) Butler Matrix (BM) beamforming network (BFN) for beamforming and beam-steering applications at 28 GHz (5G) is presented in this paper. Four distinct beams steering between −50° to 50° with sidelobe and return-loss level below −10 dB are generated by connecting the proposed BFN to microstrip antennas forming a phased array antenna. The simulated and measured results are shown and discussed.

Investigating electromagnetic power transfer ratio of circular polarizing planar metasurface lens

We designed an antenna structure with the circular polarization metamaterial superstrate which increases the directivity of the primary antenna as a lens. The metamaterial superstrate removes the necessity of the array antenna and complicated feed. Plus, it provides the Fabry-perot cavity with the circular polarization. With regard to the primary antenna, a CRLH antenna is adopted to have the size-reduction from the conventional half-wavelength patch antenna.

Electromagnetics computational modelling of magnetic metamaterials for wireless power transfe

We design a compact metamaterial structure enabling the wireless power transfer(WPT) system to enhance its function and model it for electromagnetic characterization. To couple the transmitting and receiving loops of the system compliant with the A4WP requirements, the metamaterial should resonate at a very low frequency as an effectively magnetic device. Additionally, they must be substantially small for the low frequency far below 10 MHz, taking into account the integration to practical handheld devices. The miniaturized structure is simulated through a full-wave method, and its magnetic properties are investigated through the so-called retrieval algorithm to extract its effective permeability. The analysis results present the relationship between the WPT coupling device and metamaterial constitutive parameters.

Low-SAR metasurface-based dipole and its beamforming array

This paper suggests a new planar metamaterial-based dipole with a low SAR. The artificial magnetic conductor(AMC) lies below the dipole through a thin AMC to prevent a high SAR as well as secure a good impedance match, which will become poor near the human tissue by the conventional techniques. The design is conducted for 2.4 GHz WBAN frequency, and shows the strengths at volume miniaturization, return loss and SAR. Also, this method is extended to the beamforming characteristics in an array configuration aiming to build adaptive wearable equipment

Flat Rotman lens for 5G beamforming antenna

In this paper, a planar Rotman lens featured as beamforming and multiple beams is presented, aimed at the potential use for 5G communication. The feeding network and the radiating patches are made as a single layer Taconic-microstrip structure for a 24-GHz area operation for low cost and practicality. The beamforming characteristics are verified by the full-wave simulation which is validated by the fabrication and measurement.