Il-Young Oh

Integration of Antenna and Feeding Network for Compact UWB Transceiver Package

This paper presents a low-temperature co-fired ceramic (LTCC) package incorporating an integrated ultra-wide-band (UWB) antenna, antenna-feeding network, and internal space for integration of a compact UWB transceiver chip. The area underneath a planar monopole antenna ground plane is utilized for integration of transceiver components. The LTCC package has overall dimensions of 20 × 20 × 1.2 mm3. The measured bandwidth of the integrated UWB antenna is 6.4 GHz starting from 4.75 to 11.15 GHz and the radiation patterns are suitable for indoor wireless communication environment. The fabricated package reveals reasonable time-domain characteristics. In addition, the practical application of the proposed package geometry is discussed.

Effects of a Metal Plane on a Meandered Slot Antenna for UHF RFID Applications

In this paper, the effects of a metal plane on the performance of a meandered slot RFID antenna are evaluated in a real environment, and 3 metal plane cases are considered (the most likely scenarios in which metal conductive materials are placed near the tag antenna). The metal plane effects can be categorized as matching degradation and antenna gain variation. First, matching degradation due to the antenna’s induced mutual impedance is experimentally investigated. In addition, the gain variation is investigated to figure out the change in the radiation characteristics. With the derived antenna parameters, the read range is calculated with the Friis transmission equation and measured to analyze the effects of a metal plane on RFID system performance. The calculated and measured read range varies from 9.3 m to 19.1 m as the distance between the RFID antenna and the metal plane changes.

Electromagnetic Modeling of High Altitude Electromagnetic Pulse Coupling into Large-Scale Underground Multilayer Structures

This paper gives a electromagnetic coupling mechanism of the high altitude electromagnetic pulse (HEMP) into large- scale underground multilayer structures using analytic and numerical methods. The modeling methods are firstly addressed to the HEMP source which can be generated by intentional nuclear explosion. The instantaneous and intense electromagnetic pulse of the HEMP source is concerned from DC to 100 MHz band, because the power spectrum of the HEMP is rapidly decreased under -30 dB over the 100 MHz band. Through this range, a penetrated electric field distribution is computed within the large-scale underground multilayer structures. As a result, the penetrated electric field intensities at 0.1 and 1 MHz are about 10 and 5 kV/m, respectively. Therefore, additional shielding techniques are introduced to protect buried structures within the large-scale underground structures such as high-lossy material and filtering structures (wire screen).

Multi-Radiating-Element Printed Inverted-F Antenna With Independent Resonant Frequencies for Bandwidth Enhancement

This letter demonstrates a simple yet very effective method of bandwidth enhancement for popular printed inverted-F antennas (PIFAs). An additional radiating element is printed on the other side of the substrate, on the same side as the partially modified ground plane. Together with the primary radiating element, these provide different three electrical paths. The bandwidth of the antenna can be enhanced substantially by optimally locating the corresponding resonant frequencies. Most of all, each of the three radiators has negligible effect on the performance of the other two radiators, implying that they can be designed independently. While maintaining the far-field radiation patterns, as much as 12.6% increase in the relative bandwidth over the 7.0% bandwidth of a conventional PIFA is demonstrated.

Extremely Low Numerical Dispersion FDTD Method Based on H(2, 4) Scheme for Lossy Material

This paper expands a previously proposed optimized higher order (2, 4) finite-difference time-domain scheme (H(2, 4) scheme) for use with lossy material. A low dispersion error is obtained by introducing a weighting factor and two scaling factors. The weighting factor creates isotropic dispersion, and the two scaling factors dramatically reduce the numerical dispersion error at an operating frequency. In addition, the results confirm that the proposed scheme performs better than the H(2, 4) scheme for wideband analysis. Lastly, the validity of the proposed scheme is verified by calculating a scattering problem of a lossy circular dielectric cylinder.

RF performance of CPW transmission line fabricated with inkjet printing technology

While inkjet printing technology shows a great potential for fabricating RF microwave circuitry and interconnects, the additional work is needed. Here we have studied the copper metal nanoparticle ink as a metal for printing coplanar waveguides transmission lines on BT substrates. Although the RF efficiency of the printed CPW lines exhibits an overall some lower characteristics than that of the CCL CPW lines, the improvements in printing techniques and the surface preparation will provide for lower conductor losses and then the printed line will be almost a match for CCL in RF performance. We confirm that the inkjet printing shows a very promising future for ultra-low-cost printing of passive microwave circuitry and interconnects. Low cost RF MEMS and CNT sensor device are also envisioned in the future of inkjet printing.

Bandwidth property of folded planar inverted-F antennas

The bandwidth property of a folded planar inverted F antenna (PIFA) is investigated. In a folded PIFA, a part of the radiating element of the antenna is patterned on the backside of the substrate, resulting in both bandwidth enhancement and size reduction. Between the radiating elements on the top and bottom of the substrate, an electrical connection is maintained by two via holes. When these two via holes are positioned at different locations, a secondary electrical path is provided and a bandwidth enhancement is achieved. Experimental results show that the relative bandwidth of the proposed PIFA is more than 2% larger than that of a conventional PIFA on the same size substrate, while maintaining nearly the same radiation patterns. Both the simulated and experimental results for the proposed PIFA are provided along with a comparison with a conventional PIFA.

Extremely Low Dispersion Higher Order (2,4) 2-D-FDTD Scheme for Maxwell-Boltzmann System

An extremely low dispersive algorithm based on two-dimensional higher-order (2,4) (H(2,4)) finite-difference time-domain method is developed for calculating a Maxwell-Boltzmann system. To minimize large numerical errors near the plasma frequency, a two-step process is proposed. In the first step, the weighted sum of the H(2,4) and Yee schemes is obtained, and correction of the electron density and collision frequency of weakly ionized plasma is implemented in the second step. With this process, the proposed scheme accurately estimates the electron density and collision frequency of weakly ionized plasma. Lastly, two plasma problems are solved to verify the validity of the proposed scheme.

Design of a meandered slot antenna for UHF RFID applications

A meandered slot antenna is proposed without matching network. For size reduction, the meander-line configuration combined with slot dipole antenna was applied in tag antenna. Also, effects of the conductor area on the performance of the antenna are investigated for tag impedance matching. The proposed design is verified by simulation and measurement which show good agreement. The measured bandwidth and simulated gain of the proposed antenna are 80 MHz and 2.17 dBi at 910 MHz, respectively.

Optimization of Extremely Low Numerical-Dispersion FDTD Method Based on H(2,4) Scheme for Wideband Analysis of Lossy Dielectric

This paper proposed the optimization method of the extremely low numerical-dispersion finite-difference time-domain (ELND-FDTD) method based on the H(2,4) scheme for wideband and extremely accurate electromagnetic properties of lossy material, which has a constant conductivity and relative permittivity. The optimized values of three variables are calculated for the minimum numerical dispersion errors of the proposed FDTD method. The excellent accuracy of the proposed method is verified by comparing the calculated results of three different FDTD methods and the analytical results of the two-dimensional dielectric cylinder scattering problem.