Jeongho Ju

A UWB antenna combined with the CRLH metamaterial UWB bandpass filter having the bandstop at the 5 GHz-band WLAN

This paper investigates how a Ultrawide Band(UWB) antenna can get the stopband created by the UWB filter which has a notch at the 5 GHz-band WLAN(Wireless Local Area Network) service. Particularly, we proposed the design of the Composite Right- and Left-Handedness(CRLH) metamaterial UWB notched-bandpass filter to have the smallest component possible connected to the feedline of the UWB antenna. We will see the λ/9-long UWB filter with and without the notch, and the acceptable VSWRs of the UWB antenna before and after being combined with the notched metamaterial UWB filter.

Design of the Miniaturaized UHF Bandpass Filter with the Wide Stopband Using the Inductive-Coupling Inverters and Metamaterials

This paper presents a novel bandpass filter design method for suppressing spurious response in the GSM band and effectively reducing the overall size with the unbalanced-conditioned metamaterials. Compared to the conventional bandpass filters based on half-or quarter-wave resonators, the CRLH(composite right/left-handed) bandpass filter works excellently in harmonic-suppression by 4050 dB and 80 %-miniaturization using the zero-order resonators bridged by Inductive-coupling Inverters suggested first time. The proposed technique, with the equivalent circuit and dispersion diagram, is validated by performance predictions and experiments.

A novel metamaterial CRLH ZOR microstrip patch antenna capacitively coupled to a rectangular ring

In this paper, a novel rectangular patch antenna is proposed to have Zeroth Order Resonance(ZOR) generated based on the Metamaterial Complosite Right- and Left-Handed(CRLH) structure. Making the in-phase electric field over the entire antenna other than a half-wavelength as the fundamental resonance mode of a standard microstrip patch or its positive multiple, the metallic patch is suggested to be capacitively coupled with only one surrounding rectangular ring, different from the previous 1D ZOR antennas commonly having several metal cells in line. The performance of the proposed antenna is simulated by a 3D field solver that inputs the sizes of the physical structure corresponding to the equivalent circuit designed to have ZOR at 2.4 GHz. Consequently, the resonance frequency, the gain and the antenna efficiency are observed 2.4 GHz, 5 dB and 98%, respectively. Besides, the important property of the proposed antenna is addressed as the combination of the low profile as an advantage of microstrip patch antennas, and the omni-directional field pattern typical of monopole antennas.

Realized Metamaterial CRLH Bandpass Filter for UHF-Band WLAN with Harmonics Suppressed

This paper presents the design of a size-reduced Bandpass Filter working in the UHF band. To minimize the overall size of the component, the concept of Left-Handedness is adopted and combined with Right-handed lines for using the resonators as small as around one eighth of a quarter-wavelength as well as suppressing higher ordered harmonics. In addition to the basic metamaterial theory, the inverters are included and implemented for C-coupling. This design method is validated by the physical realization as well as rigorous simulations.

Left-Handedness based Bandpass Filter Design for RFID UHF-Band applications

This paper presents the design of a size-reduced bandpass filter working in the UHF band. To minimize the overall size of the component, the concept of Left-Handedness is adopted and combined with Right-handed lines for using the resonators a lot less than a quarter-wavelength. In addition to the basic metamaterial theory, the inverters are included and implemented. This design method is validated by the physical realization as well as rigorous simulations.

Design of the Miniaturized UWB BandPass Filter Using the 1 Unit of CRLH-TL

This paper presents a new design method of the Ultra-Wide-Band BandPass Filter using the CRLH-TL(Composite Right- and Left-Handed Transmission-line) having the Metamaterials` properties. Instead of the periodic type or many cells of the CRLH-TL, only the unit cell is used to miniaturize the target component, which can not be realized by the conventional quarter guided-wavelength resonator-based filters. Particularly, the strong coupling essential to the Ultra Wide Band is enabled by the interdigital coupled lines between the grounded stubs. The proposed design scheme is validated by the electromagnetic simulation and measurement of the fabricated filter which shows the total size of `the guided-wavelength/9.4`, the 100 % fractional bandwidth for the UWB, the insertion loss of less than 1 dB and the flat group-delay.

The Design of a Dielectric Rod Antenna Using Genetic Algorithm Optimization for Vessel's Collision Avoidance Applications

In this paper, we present the development of an antenna specialized for the maritime collision avoidance system. This antenna is configured as the dielectric rod partially embedded in the metal cavity to reduce the overall size, simultaneously assuring the mechanical sturdiness against the challenging oceanic weather conditions. More importantly, the design has been carefully done to meet the requirements on the radiation pattern(with the slope＜5 dB/deg in the elevation(E-plane), circular in the azimuth) suitable to receiving the reflected signals from the other objects on the sea. To find the optimal design parameters, the genetic algorithm has been used to meet the goals of the desired return loss and pattern. This design methodology is validated by the good agreement between the calculation and measurement.

Real-coefficient AFS derived for the equivalent circuit modelling of RF passives

In this paper, the Adaptive Frequency Sampling(AFS) technique is modified to macromodel the RF components. The conventional AFS can just express the frequency response as a rational function, but ends up with inefficiency in macromodelling So the proposed scheme here enables the AFS to macromodel the problem by finding the equivalent circuit of the frequency response, since the coefficients of the rational function are made real-valued and easily arranged to the well-known configurations of resistors, capacitors and inductors. The validity of the proposed technique is watched by showing the accuracy of the equivalent circuit compared to the original data and vector fit curve of an RF DGS filter as an instance‥

Improving the stopband of the UWB bandpass filter with a novel compact 1-cell CRLHTL geometry with additional nulls

Previously, we suggested the unprecedented design of a very compact UWB bandpass filter, which is based on the 1-cell microstrip Composite Right- and Left-Handed Transmission-line(CRLH-TL)[1]. Though the design result turned out satisfactory in terms of Bandwidth, Insertion Loss, Return Loss, Group Delay variation and so on, it had a narrow stopband beyond the upper passband edge. Therefore, we present the improved design to widen the stopband from ‘10.6 GHz∼12.6 GHz’ to ‘10.6 GHz∼14.6 GHz’ by modifying the original structure to create additional nulls(or poles), and the resultant structure is still as small as ‘guided wavelength( λg )/9.4’.

Design of the Novel Compact UWB Bandpass Filters Using the SIR-Type Transversal Structure

A new compact UWB bandpass filter with sharp-rejection, low insertion-loss and flat group-delay is developed In this paper, using the transversal filtering combined with SIR(stepped impedance resonator) concept. To form the required passband, multiple out-of-band transmission zeros are created around band-edges, securing very low insertion loss in the very wide frequency range. Also it is found to be beneficial to realize a sharp rejection of higher order with a relatively small overall size and simultaneously have very smoothly varying group-delay which is proper for the UWB applications. The validity of the proposed technique is proven theoretically and experimentally.