Novel ultrawideband monopole antenna with miniaturized size

Abstract

there are four transmission zeros and three resonant frequencies (even-mode frequency f m 1 , odd-mode frequency f m 2 , and the resonant frequency created by the parallel-coupling line). The transmission zeros T z 2 and T z 4 near the lower cutoff frequency and in the upper-stopband are attributed to the ended-coupling between the 50 X input/output feed lines. When compared with the simulated result of the filter without the loaded identical short stubs, two additional transmission zeros T z 1 and T z 3 can be generated near the upper cutoff frequency and in the lower stopband by the loaded identical short stubs, leading to sharp upper skirt and deep stopband. Simultaneity, the transmission zero T z 2 moves toward the lower cutoff frequency. EXPERIMENTAL RESULTSTo validate the above design approach, the dual-mode broadband BPF with the loaded identical short stubs is fabricated on the RT/ Duroid 5880 substrate and its photograph is shown in Figure 5. The filtering performance is measured by Agilent network analyzer N5230A. The measured |S 11 | in dB and |S 21 | in dB as well as group delay are shown in Figure 6 and illustrated good agreement with simulated results. The measured 3 dB passband is in the range of 3.19-5.84 GHz and its measured input return loss (|S 11 | in dB) is less than À14.3 dB. Three transmission zeros T z 1 , T z 2 , and T z 3 are located at 0.93, 2.39, and 6.78 GHz with an attenuation level of less than À42dB, resulting in sharp roll-off and deep lower-stopband. The upper-stopband in experiment is extended up to 9.5 GHz with an insertion loss better than À25 dB. In addition, the measured in-band group delay is varying from 0.34-0.65 ns, which is quite small and flat in all the passband. CONCLUSIONA compact broadband BPF with high selectivity is proposed using the dual-mode folded-T-type resonator and the identical short stub loaded parallel-coupling feed structure. Four transmission zeros are created near the cutoff frequencies and in the stopband by the feed structure, leading to high selectivity. A dual-mode broadband filter with the fractional bandwidth 58.89% is simulated and fabricated. The size for the resonator is only 0.156k g  0.303k g in which k g is the guided wavelength of 50 X microstrip line at 4.5 GHz. The measured results agree well with the electromagnetic (EM) simulations. When the water-drop falls into the water surface, water wave will appears. A structure will be obtained after the dispersion of waves on a water surface. In fluid dynamics, dispersion of water waves generally refers to frequency dispersion, which means that waves of different wavelengths travel at different phase speeds [5]. A photograph of water wave is shown in Figure 1. In this work, a water-wave shape, which is composed of several annuluses with different radius, is proposed. The proposed water-wave shape is convenient to be printed on the substrate [6]. ACKNOWLEDGMENTSIn this article, a novel water-wave monopole antenna is simulated, fabricated, and measured. Its characteristics, including the retu...

Utilizing Symmetry of Planar Ultra-Wideband Antennas for Size Reduction and Enhanced Performance

“…It is noted that the patterns of the current distribution matches the conditions of magnetic mirror symmetry. Some researchers have shown that chopping off half of the symmetrical monopole antenna retains one strong current path and can operate over a wider bandwidth [45][46][47][48][49][50][51]. Degradation in the cross-polarization level is reported as a limitation to this technique [52,53].…”