S. H. Yeung

Design of optimized circular sectors for ultra-wideband patch antenna

An UWB patch antenna design based on optimized circular sectors is presented. The shape modeling of the antenna is based on a number of small circular sectors. In this structure, the shape of the antenna varies with the antenna parameters. This results in a highly tunable structure that is suitable for different design requirements. The optimization objectives are based on the VSWR, antenna size, radiation pattern and gain. The optimized antenna achieved VSWR ≤ 2 with omni-directional pattern, which satisfy the basic requirements of UWB antenna.

Wideband circular polarized antenna with a slot composed of multiple circular sectors

Circular polarized antenna is an important component in satellite communication. There are many designs in the literature for improving the return loss as well as the axial ratio bandwidth of the antenna [1 – 4]. A dual-feed structure can provide a wideband characteristic for circular polarized antenna design [1, 2]. However, the size of the antenna becomes larger with the inclusion of the broadband power divider with quadrature phase distribution. The single feed circular polarized antennas [3, 4] have narrower bandwidths compared with the dual-feed designs but with simpler structures. A recent design of wideband circularly polarized antenna with L-shaped slot [4] can provide 46.5 % bandwidth. In this paper, we are going to extend the bandwidth further by replacing the L-shaped slot with a slot composed of multiple circular sectors. A similar approach for designing an ultra-wideband antenna with multiple circular sectors has already been proposed in [5].

Broadband 3dB hybrid coupler with flat coupling designed by Jumping Genes Evolutionary Algorithm

A compact slot-coupled broad band 3 dB hybrid coupler has been designed and implemented. Compensation sections are added to achieve a flat coupling without significantly enlarging the size of the coupler. Optimization base on Jumping Genes Evolutionary Algorithm is performed to obtain a tight coupling within 1 dB imbalance over the band 1.8 - 5.7 GHz.

Broadband Butler Matrix optimized using Jumping Genes Evolutionary Algorithm

A broadband Butler matrix with simple structure is presented, consisting of broad band rectangular patch hybrid couplers and novel broad band phase shifters using lambda/8 open and short stubs. Jumping genes evolutionary algorithm is employed to obtain the optimum design. It is measured to have a wide bandwidth of 35.6% centered at 3.65 GHz.

Broad band CBCPW phase shifter optimized with Jumping Genes Evolutionary Algorithm

A 45deg microwave phase shifter is optimized for broad band application using jumping genes evolutionary algorithm. The simple structure based on conductor backed coplanar waveguide structure eliminates the air bridges and via holes. The measured insertion loss and phase difference for the two paths are within 0.5 dB and 45degplusmn5deg, respectively, over the frequency band from 3.21 to 4.62 GHz. The measured return loss is found to be better than -10 dB over the operating frequency band.

Jumping genes paradigm for designing dielectric resonator antenna with multiple parasitic strips

The conformal-strip fed hemispherical dielectric resonator antenna (DRA) with multiple parasitic strips has been designed by jumping genes genetic algorithm. The corresponding Pareto-optimal fronts are obtained, showing the relation between impedance bandwidth and radiation pattern. The number of parasitic strips on linearly polarized (LP) and circularly polarized (CP) DRAs is optimized with the hierarchical genetic algorithm. The results showing the designed frequency, impedance bandwidth and radiation pattern are presented

ISM Band Antenna Design Based on Fuzzy MCDM Selection Technique

A design methodology of an ISM band folded patch antenna is presented in this paper. The antenna is designed for covering three ISM band at 2.400-2.480 GHz, 5.150-5.350 GHz, and 5.725-5.825 GHz, which is ideally suitable for short-range wireless applications. Jumping genes evolutionary algorithm is used for optimizing the antenna performance, and the non-dominated solution set of antenna dimensional parameters is obtained. Then, a fuzzy-based multiattribute decision method is designed for selecting the most suitable antenna solution in the non-dominated solution set. Finally, the selection solution is compared with the other solutions for demonstrating the effectiveness of the scheme

A jumping genes paradigm with fuzzy rules for optimizing digital IIR filters

A Jumping Genes Paradigm that combines with fuzzy rules is applied for optimizing the digital IIR filters. The criteria that govern the quality of the optimization procedure are based on two basic measures. A newly formulated performance metric for the digital IIR filter is formed for checking its performance while its system order which usually reflects upon the required computational power is also adopted as another objective function for the optimization. The proposed scheme in this paper was able to obtain frequency-selective filters for lowpass, highpass, bandpass and bandstop with better performance than those previously obtained and the filter system order was also optimized with lower possible number.