Dajeong Eom

A Compact Feeding Structure for an Wide-band Array Antenna using a Microstrip Metamatreial UWB Power Divider

In this paper, a new method is suggested to reduce the size of a wide-band array antenna. The power-divider for the feeding structure is made compact as with the help of a novel Metamaterial UWB bandpass filter. This power divider is clearly different from others in that the proposed design uses microstrip structured Composite Right and Left-Handed (CRLH) filters, while others use two dielectric layers or long tapered transmission lines. In order to validate the proposed design method, the circuit and full-wave simulated results of the power divider with the Metamaterial UWB filters are compared to each other, and the Metamaterial properties of the structure are shown with the electric field at the ZOR and dispersion diagram. Furthermore, the antenna performance of the fabricated antenna with the power divider is measured and compared with the prediction. Also, the size reduction effect by the proposed scheme is addressed.

A metamaterial-inspired handset antenna with the SAR reduction

A method to reduce the specific absorption rate(SAR) of the antenna for WiMAX mobile communication is proposed in this paper. The SAR reduction is achieved by miniaturizing the physical size of the antenna for the given resonance frequency by devising a metamaterial-inspired radiator much smaller than the quarter-guided wavelength appearing in the conventional planar inverted F antenna(PIFA) or modified monopole antenna. The proposed antenna is placed near the head-phantom and its SAR is evaluated by the full-wave simulations(SEMCAD X), where the metamaterial-inspired antenna is shown to have the lower value than a modified monopole as the reference in terms of the SAR.

Compact MIMO antenna of the open-loop and meandered-line 1-layer radiators with improved isolation

We propose a compact MIMO antenna with high inter-antenna isolation. It is featured by small radiating elements each of which comprises a meandered line and an open-loop, and a modified T-shaped decoupling structure to lower the interaction between the radiators. For a WiMAX band, the size of the entire MIMO antenna is 0.22λg showing effective miniaturization. And the gain, efficiency and isolation are 3.7dBi, 56% and 17dB, acceptable to the industrial standard.

Wide-band power divider miniaturized by combining CRLH ZOR bandpass filters

In this paper, a new method is suggested to reduce the size of a wide-band power divider. It is made compact with the help of a novel Metamaterial wide-band power divider. The power divider has the Zeroth Order Resonant (ZOR) bandpass filter that is as small as approximately about λg/17. This power divider is clearly different from others in that the proposed design uses simple microstrip structured Composite Right and Left-Handed (CRLH) filters. The power divider is analyzed based on even- and odd- mode approach. The power divider is measured and compared with the prediction. Also, the size reduction effect is addressed.

Design of a Compact Bandstop Filter-combined UHF-band CRLH Bandpass Filter to Suppress the Spurious in L-band

In this paper, we propose a way to improve the quality of L-band wireless communication from unfriendly influential factors lying in the neighboring RF bands. The UHF-band system has resonator components and they generate harmonics as the spurious in the L-band. Therefore, a metamaterial CRLH bandpass filter is designed for the purpose of system miniaturization and smaller insertion loss, and its spurious phenomenon is observed in the frequency domain. And its harmonics in the L-band are suppressed by a compact bandstop filter whose equivalent circuit is newly developed. The design methodology is validated by the equivalent circuit to be compared with commercial full-wave EM software simulations, where the spurious is dropped by 20dB. Also, the advantage of the proposed design is presented by the comparison where our filter is much smaller than the conventional parallel edge coupled filter by over 50%, with excellent harmonic suppression.

Dual-Band Unequal Power-Divider Miniaturized by Metamaterial CRLH Phase-Shift Lines

In this paper, a new compact dual-band unequal power divider is suggested. Instead of the quarter wavelength transmission line(TX-line)s for the branches of the conventional Wilkinson`s power divider, we use composite right- and left-handed(CRLH) phase-shift lines and can reduce the physical length. With the non-linear dispersion of the meta-meterial, each branch in the proposed divider is designed to have and at and respectively. To validate the proposed method, the performances of the circuit and full-wave simulation results are shown with the CRLH dispersion curve. The measurement results are compared with the simulation results. Also, the size reduction effect by the proposed scheme is addressed.

Compact Antenna Design for the UWB Lower Half-Band WVAN Gbps Data-Rate Transceiver

In this paper, a compact antenna is designed for the UWB lower half-band WVAN Gbps data-rate transceiver. The proposed antenna broadens the bandwidth less than -10 dB by placing the ring stubs and an open stub on the rectangular monopole above the partial ground and creating multiple resonant current paths. The designed antenna goes through the electromagnetic simulation and is fabricated and the implemented antenna has the characteristics of the return loss lower than -10 dB, the antenna gain greater than 5 dBi, and the efficiency over 80 % in the UWB lower half-band ranging from 3.197 GHz to 4.732 GHz. Therefore, it is thought that the proposed antenna is suitable for the size-reduced and excellently performing wireless communication transceiver.

Novel common-mode current detector using metamaterial CRLH transmission-line structure

A novel planar common-mode current(Ic) and differential-mode current(Id) detector is designed to provide a quick check of Ic and Id from the differential-mode signalling, size-reduction effect and possibility of lower manufacturing cost. This is made possible by implementing a branch-line balun which has metamaterial Composite Right- and Left-Handed(CRLH) 1-layer microstrip- structure phase shifter as small as approximately λg/14. The proposed balun clearly differs from others who meander the delay line or make slits on the metal ground. When the proposed balun is connected to the output ports of the differential-mode signal lines through its inputs Port U and Port L, Id and Ic are obtained at Port Δ and Port Σ of this compact balun, respectively. The design method is validated by the circuit and full-wave simulations(SEMCAD X) with the dispersion diagram showing metamaterial properties of the structure. Also, the even and odd modes in differential-mode signalling are treated as examples of the Ic and Id Detector. The size-reduction effect is addressed also.

Compact UHF 5th-Order bandpass filter with sharp skirt

We propose a bandpass filter miniaturized by the composite right-handed and left-handed(CRLH) zeroth order resonators(ZORs). A 5th-order bandpass filter form a cascaded triplet(CT) to have a significantly sharp skirt for high frequency selectivity. First, we design an in-line ZOR bandpass filter whose total size is nearly 0.2 of the parallel-edge coupled filter. Second, we create multiple transmission zeros(TZs) by changing the three innermost ZORs of the in-line filter to a CT. As a result, the proposed filter has the insertion loss less than 1.5dB and the return loss less than −15dB. The simulation and measurement validate the proposed design method, and the CRLH ZOR properties are proven by the no-phase variation electric field and dispersion diagram.

Filtered antenna for UWB systems: Band-selective and compact feed by filters/channel-combiners with/without metamaterials

The Ultra-Wide Band(UWB) telecommunication needs to avoid the collision with other service bands and off-limit frequencies. UWB Antennas have been introduced to notches generated by U-slits on the main radiators. To overcome the shortcomings of the narrow bands and not to lose the benefit of a small radiator by filling the limited space with multiple slits, we suggest the efficient method to provide the function of band selectivity for the UWB antenna system instead of forming defects on the main radiators, and complicating the impedance matching adjustment. The feed of the UWB antenna is equipped with compact filters and channel combiners that adopt metamaterials or improved transversal loops, which turns out capability of suppressing the growth in the overall size of the antenna system. We present several design examples of our filtered antenna.