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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]

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]

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]