Abstract-Desired far-field radiation patterns of 5 × 11 conformal antenna array are synthesized using a hybrid genetic algorithm (HGA), which combines the simplified quadratic interpolation (SQI) method and the real-coded genetic algorithm (RCGA). This hybrid genetic algorithm is shown to outperform standard genetic algorithm (GA) when used to synthesize amplitude weights of the elements to satisfy specified deep notches, nulls and average sidelobe level constraints. The HGA procedure appears to be a high effective means to compensate the mutual coupling effects on the individual element patterns for the conformal antenna array.
Abstract-The optimization and simulated realization of planar 2-D antenna array with a flat-top shaped-beam pattern are proposed in this paper. The shaped-beam planar array can be used as an element of Very Large Array for the Deep Space Detection. A conventional genetic algorithm is chosen for the optimization. However, the synthesis of flat-top shaped-beam using a planar 2-D array is difficult because of the inherently large number of degrees of freedom involved in the algorithm (in generally, the amplitude and phase of each element must be determined). Therefore, a sub-array rotation method, which lies on the flat-top pattern synthesis itself, is proposed in this study to resolve the design problem. Besides, the proposed synthesis has taken the actual element patterns but identical and isotropic ones into account, which can reduce the error between computation and realization. A 8 × 8 (64)-element rectangular array is exampled, and the results of the optimized flat-top patterns are shown to illustrate the validity and high efficiency of the technique.
Abstract-A modified two-element Yagi-Uda antenna with tunable beams in the H-plane (including four significant beams: forward, backward, omni-directional, and bi-directional beams) is presented. These tunable beams are achieved by simply adjusting the short-circuit position of the transmission line connected to the parasitic element. The principle of operation is investigated by examining the current relations between the driven and parasitic elements. Measured results of a fabricated prototype are presented and discussed.
Abstract-In this paper, we propose two swallow-tailed ultrawideband planar monopole antennas that exhibit notch characteristics in the IEEE802.11a frequency band (5.15-5.825 GHz) by inserting various slots into the antennas. The effects of the lengths of the slots on the notched frequency band are analyzed. The radiation patterns of the proposed antennas are also measured and the gains are shown to be flat, except in the notched frequency band.
Abstract-A new reconfigurable microstrip patch antenna allowing switching between two circular polarizations is proposed. It consists of a square radiating patch and a 3 dB hybrid coupler. Using only a single-polar-double-throw (SPDT) switch, the polarization switching can be achieved. This design of the dc-bias network is extremely simple. From experimental results, the proposed antenna avoids the frequency offset phenomena which often happened to antennas with switchable polarization.
Abstract-A novel miniaturized circularly-polarized antenna is presented. By using tapered meander-line structure, the designed antenna has a size reduction rate of 96% compared with a traditional turnstile dipole antenna. The unequal lengths of the two meanderline dipoles are properly adjusted to achieve a circularly polarized radiation. Furthermore, the impedance matching is effectively realized by a lumped matching network. A prototype of the antenna with a size of 64 × 64 mm 2 has been implemented and tested. Good agreement is achieved between the simulated results and the measured results, which shows that the axial ratio is less than 3.0 dB and the VSWR less than 2.0:1 in the frequency range of 450 ± 1.5 MHz.
The simulation was performed in the HFSS. As shown in Figure 5(a), to achieve the good integrated matching performance a slot of 0.15 ϫ 0.5 ϫ 0.01 mm 3 has been added in the radiator feeding part [5]. Furthermore, for the consideration of good mechanical property in LTCC technology a large slot of 2 ϫ 2ϫ0.01 mm 3 has been added [5]. Figure 6(a) shows the connection of the antenna to the carried UWB transceiver die using bond wires, signal traces, and vias. As detailed in [5] the connection dimensions are optimized. The CPW ground trace has the same width with the signal trace, the gap between the signal trace to the ground trace is 0.15 mm and the radius of the shorted via is 0.05 mm. The trace length of the CPW1 and CPW2 are 1.8 mm and 2.3 mm, respectively. The trace width of the CPW1 and CPW2 are optimized as 0.17 mm and 0.35 mm, respectively. The bond wire length, diameter, and neighboring spacing are optimized as 0.9 mm, 0.04 mm, and 0.15 mm, respectively. The aperture radius is optimized as 0.75 mm. The performance of the final connection networks is shown in Figure 6(b). With return loss larger than 10 dB from 5.05 to 11.75 GHz the connection provides an acceptable matching to a 50-⍀ source over this frequency range.Figures 7-9 show the final integration results of the UWB antenna. It is seen that the 10-dB impedance bandwidth is 6.7 GHz from 5.05 to 11.75 GHz, which indicates good matching to a 50-⍀ source in an ultra wide frequency band. In addition, it is found from Figure 8 that the impedance value at a specific resonant frequency exhibits a small peak in the resistance and a gentle swing in the reactance from inductive to capacitive. Note that the multi-resonant characteristic can be clearly observed. This multiresonant characteristic is useful to make the integrated antenna achieve the ultra wide band performance [6]. Furthermore, Figure 9 shows the radiation patterns in both E-and H-planes at 5.05 GHz, 8 GHz, and 11.75 GHz respectively. According to the figures, the H-plane pattern is rather uniform whereas the E-plane pattern exhibits dual-polarized properties. The cross-polarization component is generally lower than the dominant one for the H-plane pattern at all frequencies. While for the E-plane pattern the cross-polarization component become more significant at the higher frequency. The simulated integrated UWB antenna achieves the high radiation efficiency Ͼ96% at 5.05 GHz, 8 GHz, and 11.75 GHz. In addition, the antenna achieves the gain of 2.5 to 4.3 dBi over the simulated UWB frequency range. CONCLUSIONA compact UWB antenna in LTCC technology was designed, fabricated, and tested. It has size 17 ϫ 10 ϫ 1 mm 3 and achieves impedance bandwidth of 6.7 GHz from 3.5 to 10.2 GHz. The measured E-and H-plane antenna radiation patterns at 6.85 GHz have also been presented. The UWB antenna was further studied for a single-package solution of UWB radio transceivers. The antenna was, therefore, integrated into a simplified ceramic ball grid array package. The integration was analyzed with an emphasis on ...
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