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A new design of broadband slot antenna with circular polarization is presented. The broadband characteristics are achieved using a coplanar-waveguide (CPW)-fed two-arm spiral slot configuration. The spiral slot antenna and the feeding structure are fabricated on the same plane of the substrate so that the circuit process and the position alignment could be simplified. The improvement of circular polarization for the antenna is obtained mainly by an arc slot surrounding the spiral slots. The turn number of the spiral slots and the geometrical dimensions of the arc slot are varied in order to derive the better performance of the circular polarization. The measured impedance bandwidth of a S11 < -10 dB ranges from 1.25 to 8 GHz and covers most of the commercial wireless communication systems, such as GPS, DCS, PCS, IMT-2000, WLAN, and HiperLAN. The measured 3-dB axial-ratio bandwidth (ARBW) is 10.6% with respect to 1.605 GHz. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1204–1208, 2010; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/mop.25142 [ABSTRACT FROM AUTHOR]

A wideband coplanar waveguide (CPW)-fed two-arm spiral slot antenna without a balun circuit is presented in this article. Phase progressions at arm ports are realized through the coplanar waveguide excitations. A detailed characterization of all antenna components and parameters is provided along with guidelines and recommendations for broad bandwidth and small reflection. Variations of the impedance matching due to the turn numbers, the ground width separated between two neighboring turns and the slot width are tested and studied. The measured impedance bandwidth of a S11 ≤ 10 dB ranges from 1.63 to 8 GHz and covers most of the commercial wireless communication systems, such as DCS, PCS, IMT-2000, WLAN, Bluetooth, and HIPERLAN. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 222–225, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23947 [ABSTRACT FROM AUTHOR]

A new technique is proposed to increase the bandwidth (BW) of a Z-Iike slot antenna for operation at 2.4 GHz and 5GHz, over the industrial-scientific-medical (ISM) bands and the Hiperlan2 bands. By splitting two side slots of the Z-like slot antenna into two or three fingers, several additional resonances can be created. After careful optimization of the geometrical parameters of the antenna, the resonances are merged and thus a wide impedance bandwidth is obtained. [ABSTRACT FROM AUTHOR]

A compact wideband leaky-wave antenna (LWA) with etched slot elements and tapered structure is studied. The proposed antenna is composed of an asymmetric-fed multi-section tapered short leaky-wave antenna with two embedded slots and a ground plane with etched slot elements. Base on the concept of LWA, the asymmetric-fed is utilized to excite the first higher order mode. By etching slot elements on the ground plane, the current distribution of this antenna can be influenced to compact the width of conventional LWA. In order to achieve the impedance matching, this multi-section tapered short leaky-wave antenna is embedded with two rectangular slots. This technique not only improves the impedance matching but also suppresses the back lobe. According to the measured results, the impedance bandwidth achieves about 1.30 GHz for 7-dB return loss, which covers the range from 3.30 to 4.60 GHz, and the scanning angle of the measured main beam is about 36°, which covers the range from 17° to 53°. This short LWA is only about 1.14 λ0 at 3.4 GHz, and the back lobe can be suppressed by 7.5 dB at 4.3 GHz. Due to the etched slot elements on the ground plane, the frequency of the radiation angle is shifted to lower frequency by 750 MHz, which can compact the width of LWA by more than 20%. [ABSTRACT FROM AUTHOR]

Novel broadband monopole antenna designs with dual-band circular polarization (CP) are presented. The proposed antenna comprised of a ground plane embedded with an inverted-L slit, which is capable of generating a resonant mode for broadband impedance-bandwidth, and excites two orthogonal E vectors with equal amplitude and 90 ° phase difference (PD) for radiating left-hand circular polarization (LHCP) at 2.5 GHz and right-hand circular polarization (RHCP) at 3.4 GHz. A bevel is cut in the rectangular radiator to increase the impedance-band- width. The measured result of the impedance-bandwidth is about 4.46 GHz from 2.12 to 6.58 GHz; the 3-dB axial ratio (AR) bandwidths are about 150 MHz at the lower band (2.5 GHz) and 230 MHz at the upper band (3.4 GHz). Furthermore, embedding an I-shaped slit in the rectangular radiator and adding an I-shaped stub in the ground plane, the impedance-bandwidth can be further increased to 6.30 GHz (2.17-8.47 GHz), and the 3-dB AR-bandwidth at the upper band is greatly enhanced from 230 to 900 MHz. [ABSTRACT FROM AUTHOR]