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A dual-antenna system that consists of a planar meander monopole antenna and a planar inverted-F antenna (PIFA) in the folder-type mobile phone is proposed. By using the planar monopole type radiating element constructed with meander strips, the monopole antenna provides a degree of miniaturization while retaining a wide impedance bandwidth of 740 MHz (440-1180 MHz) and 220 MHz (1710-1930 MHz) that covers DVB-H/GSM/DCS within 3:1 VSWR; while by exciting dual-resonant modes of 1/8 λ at 900 MHz and 1/4 λ at 1800 MHz, the PIFA with coupling feed shows dual impedance bandwidths of 142 MHz (858-1000 MHz) and 410 MHz (1790-2200 MHz) that covers GSM/PCS/3G(UMTS) within 3:1 VSWR. The approximately omnidirectional pattern, good gain, over the operating bands have also been obtained. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:306-310, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25695 [ABSTRACT FROM AUTHOR]

A novel broadband horizontally polarized (HP) omnidirectional antenna is proposed for meteor-burst communication system in VHF. The proposed antenna is composed of three bowtie dipoles, which are concentrically placed to form a loop antenna. The bowtie dipole is shorted at the terminal by folded elements in order to reduce antenna size. The bowtie dipoles are fed by a three-way power divider. A slotted line balun is employed to achieve broadband impedance matching and realize balanced-to-unbalanced transformation. The designed HP omnidirectional antenna exhibits a fractional bandwidth of 24.7% with VSWR < 2 ranging from 39 to 50 MHz. Uniform omnidirectional radiation patterns in the azimuth plane with HP have been obtained. The loop antenna provides a relatively low gain of no more than 1.5 dBi. Therefore, a two-element HP antenna array is developed to enhance its gain. In order to reduce longitudinal dimension of the array, the two loop antenna elements are placed in reverse and employ differential feeding method to realize in-phase current. Both the simulation and measured results are used to verify the design approach. [ABSTRACT FROM PUBLISHER]

The authors present a wideband circularly polarised antenna array consisting of a 10‐element ellipse dipole antenna and a feed network. A metal pillar is vertically loaded at the end of each ellipse dipole arm to extend the current path, thereby reducing the lateral dimension of the antenna element. For uniform coverage over the Earth's surface, antenna with an isoflux pattern is required due to its uniform power density over a wide coverage area. To obtain wideband and isoflux characteristics, the amplitude and phase distributions along the network are optimised by applying the hybrid of the genetic algorithm and particle swarm optimisation. Particularly, the feed network with broadband phase shifting performance is designed to attain a broad bandwidth requirement. The proposed antenna can achieve excellent impedance matching and axial ratio characteristics from 1.1 to 1.6 GHz. In addition, the isoflux radiation pattern is obtained with the beamwidth of ±21° where the gain is higher than 0 dBi in the elevation plane (xoz‐Plane). The realised gain is better than 10.2 dBi and the side lobes are below −14.2dB across the operating frequency. Finally, the antenna array is manufactured and measured, and good agreement is achieved between the simulation and measurement results. [ABSTRACT FROM AUTHOR]

In this paper, an offset reflector antenna with dual-beam and dual-polarization characteristics is developed to provide the angular diversity function for troposcatter communication system. The antenna system consists of a parabolic reflector and a dual-beam feed. For the dual-beam feed, two identical Ku-band feed elements are arranged side by side to generate two beams toward the reflector. The two beams are substantially nonoverlapping. The feed element is composed of a dielectric rod, a square waveguide, and an ortho-mode transducer. The dielectric rod is effective in reducing the beamwidth of the feed and providing more tapered illumination on the reflector in order to increase the antenna gain. Moreover, the developed antenna is able to produce two independent beams with the vertical and horizontal polarizations. The antenna was fabricated and tested with good agreement between the simulation and measurement results. The measured voltage standing wave ratios of the four feed ports are less than 1.5:1, and the beam separation angle is not more than 0.7° or about one time half-power beamwidth, and the antenna gain is higher than 45 dBi over the operating band from 14.5 to 15.35 GHz. [ABSTRACT FROM AUTHOR]

In this article, a novel rectangular ring monopole with triple-band operation for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications is presented.The antenna is composed of a rectangular ring, two different types of strips on the inner edges of the ring and a partial ground plane. With the two strips, the rectangular ring monopole antenna can realize triple impedance bandwidths (VSWR ≤ 2) of 320 MHz (2.29-2.61 GHz), 1170 MHz (3.19-4.36 GHz), and 1360 MHz (4.95-6.31 GHz), which make it easy to cover the required bandwidths for WLAN bands (2.4-2.483, 5.15-5.35, and 5.725-5.825 GHz) and WiMAX bands (2.4-2.6, 3.3-3.8, and 5.25-5.85 GHz) applications. Details of the proposed triple-band antenna design are presented and discussed. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:974-978, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25943 [ABSTRACT FROM AUTHOR]

A novel broadband circularly polarized antenna is proposed, designed, and measured. Basically, the antenna consists of a PIFA and a square ground with an arrow-like branch at its corner, which permit the antenna both broadband and circular polarization characteristics. For ease integration with active devices and design facilitation, the radiating element and ground are etched on the same layer of the substrate. Prototypes of the proposed antenna are fabricated and tested. The obtained −10-dB return loss bandwidth and 2-dB axial ratio (AR) bandwidth reach as large as 39.8 and 41.7%, respectively. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:204-208, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25633 [ABSTRACT FROM AUTHOR]