Figure 6-7. Taper Effect on Pattern and Efficiency The total area must be obtained in a single antenna of continuous elements, and not made up of a set of spaced antennas whose total area equals . Widely spaced segments result in very low efficiency because power is diverted into grating lobes that are not directed at the ground antenna. This is true even if the space between active elements is filled with passive elements tuned to the proper frequency. Figure 6-8 shows the reduction in first sidelobe level as taper is increased with more power placed in the main beam. Figure 6-9 shows that higher beam efficiencies call for higher tapers and that there will be near optimum combinations of taper and efficiency to limit receiving antenna size. The large size of the transmitting antenna dictates that it be sectored into many subarrays, or sections, so that errors due to mechanical distortion can be corrected. (This phase front control problem is covered in the next section. ) An example of this sectored arrangement is given in Figure 6-10 for a circular
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