Synthesis procedures of load impedances to reduce EM scattering from a conducting cylinder with arbitrary cross section
✍ Scribed by Hong-Cheng Yin; Zhi-He Xiao
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 152 KB
- Volume
- 23
- Category
- Article
- ISSN
- 0895-2477
No coin nor oath required. For personal study only.
✦ Synopsis
Ž of "5.625Њ using weights for the phase shifters of 11.25Њ, . 22.5Њ, 45Њ, 90Њ, and 180Њ , so the resulting pattern is usually degraded. In fact, if we discretize the calculated amplitudes and phases using these weights without any further optimization, the ripple of the pattern is increased to "0.9 dB and the sidelobe level to y22.5 dB.
In order to recover the desired sidelobe level, it was necessary to use our optimization method, truncating the amplitudes and phases to discrete values in each iteration. This allowed us to obtain a pattern with a sidelobe level of y25 dB and a ripple level of "1.0 dB. Figures and show Ž the corresponding amplitude and phase distributions plotted . by dashed lines . In order to reduce the ripple level of the pattern, it has been found necessary to increase the number of bits of the phase shifters. In this example, the use of 6 bit phase shifters allowed us to synthesize the previous pattern with a ripple level of "0.7 dB.
4. Conclusions
A method for synthesizing patterns of equispaced linear arrays under certain restrictions on their amplitudes andror phases distributions has been described. The method searches for the optimal sidelobe and null-filling topography of the synthesized pattern to obtain the best solution, keeping its sidelobe and ripple level under control. It has been found that the ripple of the pattern can be improved by increasing the number of bits of the phase shifters when a digital network is used. This method is easily applicable to a circular Taylor distribution, and also to its extension that allows us to synthesize shaped patterns with circular and elliptical conw x tours 4 . For the examples shown, the solution was found in about 10 min measured on a Pentium-II running at 350 MHz.