Browsing by Subject "DVB-T"

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    ItemOpen Access
    Analysis and design of broadcast tower antenna systems
    (2014) Ali Abdul
    In broadcasting, the coverage and interference requirements of antennas are designated in terms of Effective Radiated Power (ERP), tower location and height, and antenna patterns. When antennas are tailored to satisfy the requirements, transmitter powers, cable losses, and phase adjustments for antenna elements must be taken into account in addition to the parasitic effect of the supporting and nearby towers on characteristics of antenna. Digital video and audio broadcasting requires antennas to be at least 95 % effi- cient, wideband, low weight and high gain with enhanced radiation performance. For this reason many wire and planar antennas have been designed to meet the requirement of Digital Video Broadcasting-Terrestrial (DVB-T) and TerrestrialDigital Audio Broadcasting (T-DAB). We used a tool NEC (Numerical Electromagnetic Code) to model antenna on top of a tower structure. Simulation results for parasitic effect of the tower on characteristics of antenna such as impedance, return loss, gain, front-to-back ratio and radiation patterns are reported. In addition, the effect of nearby tower on antenna characteristics is studied. We designed a broadband antenna in the UHF (470 - 860 MHz) band that works for both digital and analog TV with return loss ≥10 dB, fractional bandwidth of 85% and gain at center frequency 12.5 dB. The ERP is calculated by mounting the antenna at each face of the tower to give a satisfactory coverage to a region around the antenna. Moreover, the design of a transmitter antenna for DVB-T and T-DAB is presented with Stacked Suspended Plate Antenna (SSPA) structure. Considering the similar products in the world, antennas have been designed in (174-254)MHz for DVB-T and (174-230)MHz for T-DAB with horizontal polarization and return loss ≥ 10 dB. The antenna gives an average gain of 8.5 dB and cross polarization isolation is 31 dB. Contrary to conventional dipole structures, we have employed SSPA structure with two plates for wideband matching and design flexibility. Radiating primary plate has been excited by novel wideband modified inverted L-type probe in a capacitively coupled manner. Vertical plate between primary plate and ground plane also provides wideband matching and adjustment of halfpower beam width properly. Parasitic secondary plate has been used for further matching and tuning. Together with the parametric study of designed antenna, simulation and measurement results for the input impedance, S11, gain and radiation patterns are presented.
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    ItemOpen Access
    Parasitic effects of the metallic towers on the characteristics of the broadcast antennas
    (John Wiley and Sons, 2018) Ali, A.; Colantonio, P.; Altintas, A.
    In this article, we use a tool NEC (Numerical Electromagnetic Code) to model antenna on top of a tower structure. Simulation results for the parasitic effect of the tower on characteristics of broadcast DVB-T (Digital Video Broadcasting Terrestrial) antenna such as input impedance, return loss, gain, front-to-back ratio and radiation patterns are reported. In addition, the effect of a nearby tower on antenna characteristics is studied. A 3D tower and broadband antenna in the UHF (470-862) MHz band are constructed. The antenna works for both digital and analog TV with return loss (RL) ≥ 10 dB, fractional bandwidth of 87% and gain of 12.3 dBi at center frequency. The effective radiated power is calculated by mounting the antenna at each face of the tower to give a satisfactory coverage to a region around the antenna.
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    ItemOpen Access
    VHF suspended plate transmitter antenna design for DVB-T and DAB-T
    (John Wiley and Sons, 2018) Ali, A.; Ciydem, M.; Altintas, A.; Koc, S.
    This paper presents the design of stacked suspended plate transmitter antenna for digital video and audio broadcasting. Contrary to conventional dipole structures, we have designed the antenna in VHF band (174-254 MHz) with two plates for wideband matching and design flexibility. Radiating primary plate has been excited by novel wideband modified inverted L-type probe. Parasitic secondary plate, and vertical wall between primary plate, and ground plane have been used for further matching and beamwidth adjustment. A bandwidth of 42% and gain of 8.5 dBi is obtained at center frequency. Together with equivalent lumped element circuit model of designed antenna and experimental results for S11, gain, and radiation pattern are presented. To the best of authors knowledge this is the first stacked suspended plate antenna achieving a record bandwidth of 42% in VHF band.