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Ultrawideband ribbon antenna array with wide-angle scanning

Published: 11/17/2007
Original: Radiotechnica (Moscow), 1995, №7...8, p.p.49...53
© 1995, V. S. Filippov, I. V. Sutyagin
© 2007, EDS–Soft,  http://www.eldys.org,   E-mail: publications@eldys.org

Results of numeric modeling. We shall estimate the effectiveness of the receiving ultrawideband AA with wide-angle scanning by using the reflectivity coefficient of the incident wave. All specified sizes are determined relative to the unit frequency. To determine main properties of multilayer plane antenna arrays, we have conducted a series of numeric experiments, which determined the influence of various parameters of the structure on the frequency and angle dependencies of the reflectivity coefficient modulo. The scanning plane and polarization of the incident wave were selected to ensure that no depolarization of the scattered field takes place in the entire angle sector. It was assumed that the input resistance of the receiving modules does not depend on the frequency.


Fig. 2 shows the relation between the reflectivity coefficient and frequency for three scanning angles: 0°, 30° и 60°°; the number of layers is 1; the width of ribbons is 0.1; the direction to the screen is 0.25; the array period is 0.25; the lumped resistance in this case is 377 Ohm. As we can see in the charts, with these parameters of the structure are assumed with frequency 1.09 for normal incidence, good matching is provided. The width of the operating wideband of the single layer AA with reflectivity coefficient equal to -20 dB is 20%. When the phasing angle is changed, the frequency, on which the reflectivity coefficient module is minimal, is sliding and the matching quality becomes lower.



Fig 3 and 4 display the same dependencies for structures with higher amount of layers(5 for fig.3 and 10 for fig 4.) As we can see that as the number of layers and the frequency band is increased, the reflectivity coefficient becomes less susceptible to changes of the phasing angle. The ribbon AA with 5 layers in the 120% band frequency has the reflectivity coefficient not worse than -18 dB with normal wave incidence. When the number of layers is increased to 10 in the same frequency band, the reflectivity coefficient does not exceed -30 dB and on the level of -20 dB the frequency band is 180% for normal phasing and 120% in the sector of angles ±60°.


Fig 5. shows relation between the maximum and minimum operating frequency (coeffi-cient of bandness) for the level of -20 dB of a multilayer ribbon AA, and the number of layers for various laws of changing the lumped resistances of ribbons from layer to layer. As the charts show, the increase in the number of layers from 5 to 10 does not affect the characteristics of the structure very much and 4…5 layers are enough to provide near-optimum properties. Thus, multilayer scanning receiving antenna arrays provide high values for the bandness coefficient in wide sector of angles.

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1. Filippov V.S. In: Antennas / Edited by D. I. Voskresensky. - M.: Radio i svyaz, 1985, vol. 32, p.17.