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A common method of antenna array synthesis uses least squares approximation to fit the radiation pattern of the array to a set of samples of an ideal desired pattern Fid. However, it has long been known that discontinuities in Fid prevent close approximation, and that sampling a target pattern Ftar that approximates Fid can afford better results. Here we show, for the case of circular planar arrays,...
A planar array composed of 41 parasitic dipoles above a ground plane, fed by an active dipole at 5 GHz was designed to obtain a pencil beam pattern with a moderate gain and bandwidth. Experimental results are in good agreement with the theory and show a pattern with an 18.78 dB gain, a sidelobe level (SLL) of -15 dB, an impedance bandwidth of 16.53% (the frequency range over which the value of S11...
Low-sidelobe radiation patterns with good directivity can be generated by antennas consisting of a linear array of parasitic dipoles in front of a smaller linear array of active dipoles fed uniform voltages, a configuration that facilitates the task of feed network design. The fundamental effect of the parasitic array is to allow the length of the active array to increase by a factor of 2 or more,...
The proposed method allows very rapid synthesis of large antenna arrays, affording footprint patterns of satisfactory quality. It is possible to reduce the number of array elements by reducing the number of filled nulls of the modified Elliott-Stern pattern that is sampled at the expense of reducing of the average slope of the pattern (dropoff rate) and a small reduction in the pattern directivity.
For tracking and search design array antennas is very usually the optimization of the main beam sum pattern to sidelobe level ratio, SLL, while still maintaining high directivity of the main beam. For tracking systems, a difference pattern is needed as an auxiliary pattern with a boresight null coincident with the beam peak of the main (sum) pattern. The tracking drive system moves the antenna positioner...
A simple method for synthesising low-sidelobe sum and difference patterns with a common aperture zone is presented. Such a method is based on the perturbation of the Bayliss roots by means of the simulated annealing technique. The appropriate discretisation of the resulting continuous apertures to a linear array would lead to a simplification of its feeding network, mainly due to the above-mentioned...
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