Seong-Ook Park

This letter presents a monopole antenna with a magnetodielectric material and its multiple-inputmultiple-output (MIMO) applications. The proposed antenna fed by a 50-Omega coaxial line occupies a compact volume of 9.5 times 3 times 1.2 mm³ and the parameters of the magnetodielectric material as a supporter are epsiv'= 3.86 -j0.032 and mu'- jmmu' = 1.23-j0.25 at the resonant frequency. The bandwidth is 850 MHz (3.384.23 GHz) at S₁₁< 10 dB, and the measured maximum gain is 5.57 dBi at 3.8 GHz. For evaluations of the MIMO application, the antenna has been measured in both the spherical and reverberation chamber. The microwave studio (MWS) simulation is employed for optimizing the design parameters and the simulated results are well agreed with those of the measured one.

An alternating-direction-implicit finite-difference time-domain (ADI-FDTD) method based on the fast-adaptive-composite grid ADI (FAC-ADI) scheme is introduced to reduce the truncation error generated when ADI-FDTD is derived from the Crank-Nicolson (CN) ADI scheme, and its efficiency is investigated. The relaxation equation and residual equation for FAC-FDTD are constructed by defining the error vector between the traditional ADI and CN FDTD formulas, and the iterative formulas are defined using the iterative schemes. A comparison of the computational efficiency between the FAC-ADI and ADI-FDTD is presented.

A new circular polarization spiral-dipole antenna has been proposed for multilple-input-multiple-output (MIMO) systems. A dipole antenna is loaded with spirals at both of its ends to generate omnidirectional left-hand or right-hand circular polarization. The sense of polarization [left-hand circular polarization (LHCP) or right-hand circular polarization (RHCP)] depends on the orientation of the spirals. The measured bandwidth of the antenna is 8% at the center frequency of 5.2 GHz with 3.6-dBic gain. The isolation ( S ₂₁) between collocated LHCP and RHCP antennas is better than 30 dB that makes them suitable for MIMO.

This paper proposes a T-shaped wide slot harmonic suppression antenna at the frequency of 4 GHz. Harmonic suppression is achieved by using a narrow microstrip-line-fed and a grounded T shaped conductor line. The return losses and radiation patterns of the antenna at fundamental and harmonic frequencies are measured and compared with those of the conventional T-shaped slot antenna.

In this paper, we propose a PIFA based multiband internal antenna that can support seven frequency bands. The antenna is designed to operate at GSM (Global System for Mobile Communications, 880-980 MHz), PCS (Personal Communication Services, 1880-1990 MHz), UMTS (Universal Mobile Telecommunications System, 1.9-2.17 GHz), WiBro (2300-2390 MHz), Bluetooth (2.4-2.48 GHz), S-DMB (Satellite-Digital Multimedia Broadcasting, 2.630 ~ 2.655 GHz) and WLAN (Wireless Local Area Network, 5.16 ~ 5.5 GHz) frequency bands. Multiple frequency bands have been realized by using slots and quarter-wave length resonating strips. A matching stub and multiple short circuiting strips are utilized for improving impedance matching across the targeted frequency bands. A prototype antenna is fabricated and characterized by measuring return loss and radiation patterns. Comparison of the measured and simulated results is given in the paper.

A proposed compact PIFA antenna with small dimension suitable for 4G handsets is presented. Overall volume of this antenna is significantly small with 0.741cm3 that makes it attractive for recent modern slim personal communication handhelds. This proposed antenna is attached with a varactor diode to archive tuning frequency property that makes antenna able to covering most popular frequency bands for wireless communication systems such as DCS, PCS, UMTS, Bluetooth, WiBro, WLAN and ISM band. The measured return loss (Sn) of the antenna is within the acceptable limit at all frequency bands with good radiation performance.

A planar inverted-F antenna type tunable antenna with U-shaped slot is proposed. A varactor diode is integrated between the slot and bias feeding strip line for tuning the operating frequency. This antenna covers from 1.64 GHz to 2.05 GHz refer to the dc bias voltage from 0 V to 20 V The frequency tuning range is about 410 MHz bandwidth which covers several mobile communication bands of DCS (1710~1880 MHz), PCS(1750~1870 MHz) and PCS(USA)(1850~1990 MHz). This antenna occupies a compact volume of 40 times 15 times 8 mm³. The simulation result is based on the Finite Integral Method.

A printed diversity monopole antenna for WLAN operation at the 5 GHz band, such as the 5.2GHz (5150-5350 MHz) and 5.8GHz (5725-5875 MHz) bands is presented. The proposed diversity antenna fed by a coaxial connector consists of two planar monopole antennas which are symmetrical and a ground which has two slots for enhanced isolation characteristic between two antennas. The bandwidth of the diversity antenna (S1K-10 dB) has achieved about 2360 MHz starting from 4520 MHz to 6880 MHz. Details of the antenna design and experimental results are demonstrated.