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Technical Issues in Ultra-Wideband Radar Systems
Published in James D. Taylor, Introduction to Ultra-Wideband Radar Systems, 2020
For frequencies above the design frequency the radiation pattern will exhibit grating lobes. For polycycle waveforms the existence and location of grating lobes is dependent on the period of the carrier (as is the case for narrowband systems), rather than the duration of the pulse, thus it would appear that in any application of an array antenna for a polycycle UWB signal, one would want to put the upper edge of the signal spectrum at the design frequency of the antenna. The signal frequencies below the design frequency will have an effect on the sidelobe structure, but they will not produce grating lobes.
Array Theory – Linear Arrays
Published in Lawrence J. Ziomek, An Introduction to Sonar Systems Engineering, 2023
Since the far-field beam pattern given by (6.5-1) or, equivalently, (6.5-7) is periodic [see (6.5-9)] because the elements are equally spaced, there is a potential problem with grating lobes. Grating lobes are extraneous, unwanted mainlobes that exist within the visible region. One way to avoid grating lobes is to use unevenly spaced elements. However, since the elements in our linear array are equally spaced, in order to guarantee only one mainlobe within the visible region, steered in the desired direction, the interelement spacing d must be chosen properly.
Array Theory – Linear Arrays
Published in Lawrence J. Ziomek, An Introduction to Sonar Systems Engineering, 2017
Since the far-field beam pattern given by (6.5-1) or, equivalently, (6.5-7) is periodic [see (6.5-9)] because the elements are equally spaced, there is a potential problem with grating lobes. Grating lobes are extraneous, unwanted mainlobes that exist within the visible region. One way to avoid grating lobes is to use unevenly spaced elements. However, since the elements in our linear array are equally spaced, in order to guarantee only one mainlobe within the visible region, steered in the desired direction, the interelement spacing d must be chosen properly.
A Wideband Dual-Polarized Tightly Coupled Array with Compact Size for 5G Millimeter-wave Mobile Devices
Published in Electromagnetics, 2023
Chan Bai, Shuai Zhang, Qi Gong, Zixuan Song, Yuguo Liu
Various types of mmW antennas include lens antennas, Vivaldi antennas, slot antennas, patch antennas, magneto-electric (ME) dipole antennas, and so on. Lens antennas have been widely applied in 5 G mmW applications due to their low cost, light weight, enhanced gain, and multibeam function (Basavarajappa et al. 2019; Wang, Pan, and Dong 2022). Vivaldi antennas can support dual polarization, wideband, high efficiency, and large beam steering range (Ikram, Nguyen-Trong, and Abbosh 2020; Kähkönen et al. 2022). Slot antennas have advantages of wideband, high gain, low cost, and ease of fabrication (Guo and Hao 2021; Radenamad, Aoyagi, and Hirose 2011). However, these studied antennas are not small. The size of these antennas is unrealistic to be integrated into mobile phones. Meanwhile, the miniaturized antennas have been widely researched. Patch antennas can support low profile, low cost, lightweight, simple structure, and be easy to be fabricated (Yang, Hong, and Zhang 2014; Yin et al. 2019a). However, these antennas have narrow bandwidth and so they cannot cover dominant 5 G mmW communication bands simultaneously. Magneto-electric (ME) dipole antennas are well known because of their wideband (Hao and Li 2017; Yin et al. 2019b). However, these antennas cannot support large-angle scanning without grating lobes and consequently reduce the connectivity distance and signal coverage. To avoid grating lobes, the element spacing for a phase array should be calculated as d ≤ λ/2 (Robert 2005).
Design of Beam Steering-Switching Array for 5G S-Band Adaptive Antenna Applications – Part-I and Part-II
Published in IETE Journal of Research, 2022
Vidya P. Kodgirwar, Shankar B. Deosarkar, Kalyani R. Joshi
A blind area exists between adjacent beams where gain drops dramatically from the peak region, thus, the users may suffer from signal fading or even call drops when moving across this region [3]. Also, the variation in these blind areas increases the complexity in link budget estimation, which is undesirable in system design [3]. In this paper, a novel planar four element beam switching array with a feed network is proposed for 5G S-Band applications [6,7]. For the feed network, two schemes are proposed. The first scheme feed network is designed with 90° Hybrid Directional Coupler (HDC), Wilkinson Power Dividers (WPD) and delay line as shown in Figure 1. Grating lobes due to element spacing are used to reduce the sidelobe level and to increase the overall gain of the array. The second scheme is proposed with PIN diode based Switched Line Phase Shifters (SLPS) and WPD to generate multiple beams in different directions and it is presented in Figure 2.
A hybrid algorithm of orthogonal perturbation method and convex optimization for beamforming of sparse antenna array
Published in Electromagnetics, 2020
Lei Liang, Can Jin, Hailin Li, Jialing Liu, Yachao Jiang, Jianjiang Zhou
In the field of array signal processing, in order to suppress the grating lobes, the array layout with the element spacing not greater than half wavelength is usually adopted. However, under the constraints of the array aperture and the number of elements, the performance of the array is difficult to guarantee. In this case, sparse arrays with spacing greater than half wavelength are often adopted, and the excitation of the array elements is optimized at the same time. To describe the difference of excitation, the excitation amplitude ratio (EAR) of the array is defined as: