Jungyub Lee

Quad-Band Monopole Antenna Including LTE 700 MHz With Magneto-Dielectric Material

A magneto-dielectric (MD) material, which has allowably low magnetic loss and moderate permeability for the wireless communication band, is presented. A quad-band monopole antenna with the MD material is proposed and compared to an antenna with a dielectric material. It is demonstrated that the MD material is advantageous for an antenna miniaturization and bandwidth expansion for the LTE 700 MHz. Measured results of the total efficiencies and envelope correlation coefficients for the multiple-input-multiple-output (MIMO) antenna with the MD materials are presented. It is demonstrated that the MD antenna has relatively higher efficiencies at the band edges and wider impedance bandwidth than the dielectric antenna for the LTE Band 17, and the developed MD material can be practically applicable to the wireless communication systems.

Design of Small Antennas for Mobile Handsets Using Magneto-Dielectric Material

This communication presents practical implementations of small antennas using magneto-dielectric (MD) materials. We first describe the manufacturing process of MD materials with a low-loss property (tan δm <; 0.1) up to 2 GHz. With this MD material as a substrate, miniaturized handset antennas are developed and the radiation performances are compared with the dielectric substrate antenna. The measured results show that the required volume of MD chip antenna is minimized to 25 mm × 5 mm × 3 mm at cellular frequency and the bandwidth is better compared to dielectric chip antennas. In addition, MD loaded antenna is designed to improve the performance of conventional antennas on the plastic carriers.

Miniaturized Antennas With Reduced Hand Effects in Mobile Phones Using Magneto-Dielectric Material

In this letter, magneto-dielectric (MD) material is proposed to reduce the antenna volume without significant performance degradation and mitigate the efficiency decrease by the human hand. The MD ceramic, which has small magnetic loss tangent around 0.1 or less at 2 GHz, is developed using hexagonal ferrites. This ceramic material is mixed with polymers to form the MD composites, which can be easily applied to the complex-shaped substrates of mobile antennas. Inverted-F antennas (IFAs) on the composites are simulated for studying of the antenna miniaturization and hand effects. Mobile antennas using the composites are manufactured by injection molding and plating processes. Then, the radiation efficiencies are measured with and without the hand phantom. The test results show that the MD composites are useful for miniaturizing antennas and reducing hand effects in the mobile phones.

Designing antenna booster cases for mobile phones using capacitive coupling techniques

Additional antenna elements are designed on the flip cover of the mobile phones to boost the radiation performance of the mobile antennas. We used the capacitive coupling technique and the multi-resonant technique to implement antenna booster cases. The designed prototypes show that the antenna booster can make the internal antennas to have the average radiation efficiencies over 50%, which is difficult to achieve because of interferences with the surrounding metal parts.

Passive repeater for removal of blind spot in NLOS path for 5G fixed wireless access (FWA) system

This paper presents an approach to improve the link budget in a non-line-of-sight (NLOS) path between a base station (BS) and a customer premises equipment (CPE) for 5G fixed wireless access (FWA) system. The oblique incidence of transmitting power into a receiver is one of most challenging scenarios for the 5G mm-wave system with highly directive antennas. In this work, we propose application of an additional antenna structure attached near window such as a passive repeater array which can reflect an incident power into a specific angle. With the passive repeater, the path loss is measured in the real environment assuming a feasible challenging scenario where the incident angle is near 90°. The measurement shows that the passive repeater array enables to improve the link budget by 40 dB, compared to the case without any additional reflector structure.

Low-charged battery compatible harmonic reflector integrated in a mobile device for detection of trapped victims

This paper presents a harmonic reflector integrated in a mobile device for detection of trapped victims. With no power consumption, the module consisting of an antenna and a schottky diode generates a second harmonic tone (2f0) for an incident fundamental tone signal (f0) and reflects it. Therefore, the reflected harmonic signal is a good candidate for an indicator of the location of trapped victims in post-disaster situations. The harmonic based module is successfully integrated in a commercial smart phone to show an application of the harmonic reflector to a mobile device. For effective isotropic radiated power (EIRP) of 30 dBm, the coverage of 30 m is measured in a noise level of -110 dBm with a dc voltage of 0.5 V applied to a schottky diode while the range is 5 m with an unbiased diode. This result implies the feasibility of the detection of victims using a second harmonic signal reradiated from their personal mobile devices even with a low charged battery.

Reducing effects of hand phantom on mobile antennas using magneto-dielectric material

In this paper, a practical application of the magneto-dielectric (MD) materials to the mobile handset antennas is presented. The polymer MD composites with the property of low magnetic loss (tan δm <; 0.1) up to 2 GHz are developed using hexagonal ferrites and polymer matrices. The MD composites are applied to manufacture an actual antenna substrate for a mobile handset. Experimental results show that the MD composite antenna is advantageous for an antenna miniaturization and deterioration of performance by a hand phantom.