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In this paper, sideband radiations which are generally regarded as the undesired effects of time-modulated antenna arrays (TMAAs), are exploited to design multi-beam antenna arrays. Time modulation (TM) is applied into uniformly excited linear array of half wave dipole radiators to generate low side-lobe sum and difference patterns at the center frequency and first sideband respectively while the...
In this work, the effectiveness of a relatively newly developed optimization algorithm, artificial bee colony (ABC) algorithm has been employed to synthesize uniformly excited, non-uniformly spaced, symmetrical linear arrays. ABC is used to reduce the side lobe level (SLL) of uniformly excited linear antenna arrays by taking the element spacing as the optimization parameters. The effectiveness of...
In this paper, a cosecant squared shaped beam pattern is synthesized from a uniformly spaced but nonuniformly excited linear antenna array where the uniform spacing of the array elements is considered as half of the desired signal wavelength. The shaped beam pattern is synthesized for the angular beam width of 32° by reducing the side lobe level (SLL) to −20.06 dB and almost without any ripple in...
In addition to the desired frequency, theoretically the Time Modulated Antenna Array (TMAA) radiates signals at the infinite number of different harmonics of the modulation frequency. But the radiation energy at the first few harmonics (called sidebands) is most significant. In this paper, the maximum radiation at first two harmonics of TMAA has been studied for the different values of the side lobe...
In this work, the Artificial Bee Colony (ABC) algorithm is used to minimize the side lobe level of the main beam and the first two side band radiation of the uniformly excited time modulated linear antenna array. ABC searches the switch on or excitation time duration of each of the element of the antenna array under consideration. This approach gives satisfactory results without changing the amplitude...
A novel technique to achieve reduced side lobe level by sequential modification of Sierpinski carpet patterned array is presented in this paper. A 9 × 9 planar array is reduced to a Sierpinski carpet shaped array and after final modification it exhibits a peak SLL of -21dB and about 40% reduction in the number of elements.
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