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Abstract: In this article, the frequency‐response analysis of an H‐shaped slot resonator etched in the ground plane is shown by using transmission‐line analysis and even‐and‐odd mode analysis. Based on a stepped‐impedance structure, we systematically derive a resonance analysis of the slot resonator, addressing resonance conditions, and harmonic responses. The design rule of the slotted‐ground‐plane resonator was successfully derived. The design equations and figures regarding the impedance ratio of the H‐shaped slot resonator have been analytically proven so that the resonant modes can be predicted without electromagnetism simulation software. Aided by the proposed design procedure, we demonstrate a low‐pass filter (LPF) with a unit‐cell topology, which consists of a uniform‐impedance transmission line, an H‐shaped slot resonator, and two C‐like slot resonators which are also designed with the same design rule. By embedding the two C‐like slot resonators inside the H‐shaped slot resonator, several additional transmission zeros are excited in frequency characteristics so that the device achieves wideband rejection performance. Finally, to enhance the frequency characteristics of the LPF, a modified case is also presented by adding a rectangular stub at the transmission line. [ABSTRACT FROM AUTHOR]

The frequency response characteristics, such as resonance condition and spurious harmonic, of a mallet-like slotted-ground-plane resonator have been shown in this work. Unlike the conventional slotted-ground-plane resonator with a half wavelength, the length of this proposed structure is only quarter-wavelength long so that compactness can be achieved. The technique of size reduction for the resonator is furthermore presented by modifying the impedance ratio of the mallet-like slot segments. Owing to the semi-ground plane, decrease of the quality factor causes enhancement of the rejection bandwidth. We analytically derive design equations with respect to the impedance ratio of the mallet-like slot resonator and can predict resonant modes without utilizing EM simulation software. In addition, by utilizing the thru-reflect-line calibration technique and theoretical methods, parameter extraction of the equivalent circuit of the mallet-like open-slot resonator is presented. [ABSTRACT FROM AUTHOR]

ABSTRACT A dual-band monopole antenna for UHF-band applications has been demonstrated in this work. The dual-band characteristics are achieved using several strip monopole radiators. In addition, a small planar inverted-F monopole antenna is connected to the ground plane. The bandwidth improvement for the antenna is obtained mainly by modifying the geometrical configuration of the strip monopoles added at the antenna and the ground plane. The measured results of the impedance-bandwidth are about 44 MHz (458-502 MHz) and 118 MHz (701-819 MHz). © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:896-900, 2014 [ABSTRACT FROM AUTHOR]

Abstract: In this paper, new techniques are proposed to increase the front-to-back ratio of the stepped-impedance (SI) open-slot antenna for operation from 1.67GHz to 4.25GHz, covering the required frequency bands of the wireless communications systems, such as DCS, PCS, IM-2000, and WLAN. By designing a stub-protruded feedline and adding two symmetrical stubs at the edge of a quarter-wavelength slot, additional capacitance is introduced to the resonator. Hence, the impedance-matching condition of the SI open-slot antenna is not only effectively improved, but also the resonance frequency of the slot antenna is significantly shifted down and then an improvement in impedance bandwidth is achieved. In order to decrease the back radiation, two pairs of symmetrical open slots with uniform width are etched at the back of the blocking open slot such that the currents along the longitudinal edges of the ground plane cannot flow to the back direction. In addition, by embedding an array of seven slits beside the radiating slot, the back lobe at the upper frequency bands can be reduced. Two pairs of three-element metal strips are utilized as a power director to increase the forward power and enhance the front-to-back ratio of the SI open-slot antenna. Compared to conventional unidirectional radiation antennas, the proposed antenna demonstrates improved wideband unidirectional radiation characteristics and relatively smaller size. [Copyright &y& Elsevier]

A new design of broadband monopole antenna with circular polarization (CP) is shown.The broadband characteristics are achieved using a microstrip-fed rectangular dual-loop monopole configuration and an asymmetrical feeding structure. The improvement of CP for the antenna is obtained mainly by the separation between the monopole antenna and the ground plane. The measured result of the impedance-bandwidth is about 3.66 GHz from 0.98 to 4.64 GHz; the 3-dB axial ratio bandwidth is about 180 MHz at the lower band (1.5 GHz). The antenna is extremely low cost and does not require any truncation corner, reflector surface, or via connections, all of which increase the fabrication cost. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2556-2560, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26353 [ABSTRACT FROM AUTHOR]

A design procedure for a wideband planar unidirectional antenna is presented based on the monopole slot antenna. Owing to the additional capacitance contributed by a stub-protruded feedline and two symmetrical stubs at the slot edge, the impedance-matching condition is improved; meanwhile, the resonance frequency of the monopole slot antenna is significantly shifted down, and an improvement in impedance bandwidth is achieved. By modifying the width of the ground plane, connecting one metallic finger at the upper right corner, and etching two asymmetrical slits in the ground plane as reflectors, the radiation directivity of the monopole slot antenna can be enhanced. The proposed antenna achieves a measured 97.4% bandwidth for S11 < -10 dB at the center frequency of 2.31 GHz, better than 10 dB front-to-back ratio. [ABSTRACT FROM AUTHOR]