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Aperture and Phased Array Antennas
Published in Habibur Rahman, Fundamental Principles of Radar, 2019
The phased array is essentially the special case of an antenna composed of a number of small radiating elements—suitably spaced with respect to one another—acting together to generate a radiation pattern, whose shape and direction are determined by the relative amplitudes and phases of the currents at the individual elements. The radiating elements might be dipoles, open-ended waveguides, slots cut on the conducting surface, or any other type of antenna. The flexibility to control the aperture illumination offered by the phased array antenna in steering the beam is by means of electronic control. The steering of the beam may be controlled by the use of computer, which facilitates to rapidly change the phase and amplitude of signals to or from the individual array elements. This offers the full potential of a phased array antenna to operate in a multifunctional way in performing surveillance and tracking of a variety of targets.
Micromachined Microwave Phase Shifters
Published in Shiban Kishen Koul, Sukomal Dey, Radio Frequency Micromachined Switches, Switching Networks, and Phase Shifters, 2019
Shiban Kishen Koul, Sukomal Dey
One very important application of the phase shifter is in electronically scanned antenna arrays for modern defense radar systems. It also has commercial applications in advanced wireless communication systems requiring beam steering. Phase shifters allow the antenna beam to be steered in the desired direction without physically repositioning the antenna. Two or more radiating elements are present in a phased array antenna and are spatially arranged that emit phase-shifted signals to form a radio beam. A phase shifter is connected to each radiating element that produces the necessary phase shift to steer the antenna beam [8,9]. The phase of each element is adjusted by steering the beam so that individual signals sum up at the desired beam-pointing angle (theta). Many studies and experiments have been performed on the electronic beam-steering principle. The most popular and useful method is to use phase shifters in combination with an antenna array [10,11]. The method of beam steering is broadly classified as time delay, frequency scanning and phase scanning. The amplitude and phase of each antenna element are controlled, and they both can be used to adjust side lobe levels and steer nulls better than that achieved by phase control alone. Figure 5.1a shows a simple phase shift beam forming for a two-antenna system and Figure 5.1b shows a schematic of a beam-steering front end-based phased array antenna. Phase shifters are the general devices used in phased arrays and they account for nearly half of the cost of an entire electronically scanned phased array.
Transmission and Propagation of Electromagnetic Waves
Published in Sibley Martin, Modern Telecommunications, 2018
A phased array consists of a number of transmitting antennae placed a certain distance apart and fed by the same signal but at different phases. Consider the two-element array shown in Figure 5.20. The two elements are spaced d metre apart and are fed with the same signal but with a phase shift of ϕ. At some point P in the far-field, i.e. far enough away that we have a plane wavefront, the two waves will either add constructively or destructively. The wave from Antenna 1 has an additional phase shift associated with it by virtue of the increased path length. With reference to Figure 5.20, this additional path length is d cos θ and this gives rise to an additional phase shift of βd cos θ. If there is an additional electrical phase shift, α, the total phase difference between the two waves at point P is
Design and development of T-Shaped antenna structure for wireless communication
Published in Waves in Random and Complex Media, 2022
A single element is used to start the design of a 1X2 phased array elliptical inverted T-shaped slotted sectored patch antenna, and beam steering is added. The stubs and slots create multiband and wide-bandwidth elements in a single element. An elliptical-shaped aperture beyond the radiating patch, as well as stubs and DGS, increase the antenna bandwidth. The phased array allows the antenna to have high gain and beam-steering capabilities. The antenna array's dimensions are intended to fit inside any current small smartphone. The suggested antenna is built on an FR4 substrate with a dielectric constant of 4.2 and a thickness of 0.0058 mm. The DGS is double bracket-shaped slots etched in the ground to change the current distribution. Antenna design, simulation, optimization, and analytical assessments are performed using the CST Studio Suite. The goal is to disrupt the present distribution on the stubs of a radiating patch linked to the DGS ring slot through an indirect connection. The antenna impedance qualities are controlled by various design factors such as slot width, ring diameter, split ring percentage, and slot placement.
Electromechanical coupling modelling of distributed MEMS phase shifter for phased array antennas
Published in International Journal of Electronics, 2018
Congsi Wang, Kang Ying, Haihua Li, Wei Gao, Lei Yin, Meng Wang, Xuelin Peng, Shaoxi Wang
Active phased array antenna has important applications in radar, communication, navigation, electronic warfare and other fields, and it’s the future direction of space radar development, but also a sign of national competitiveness (Wang et al., 2017). Currently the cost and power consumption of phased array antenna is a major factor, which limits its fast development. With the development of microelectromechanical systems (MEMS) technology and the application of MEMS technology in the microwave field (Aboul-Seoud, Hamed, & Hafez, 2012; Aguilar-Armenta & Porter, 2015; Panduro, Reyna, & Camacho, 2009; Scardelletti, Ponchak, Zaman, & Lee, 2005), it has promoted the further development of phased array antennas. As the core part of the phased array antennas, the phase shifter can be regarded as the ‘steering wheel’ of phased array antenna beam steering. And the choiceness of phase shifter performance directly determines the level of the phased array antenna performance. MEMS phase shifter has become one of the current mainstream phase shifters because of its many advantages including low loss, low cost, high linearity, miniaturisation, easy integration and so on (Rebeiz, Tan, & Hayden, 2002; Ehmke et al., 2000; George, 2003, May 19).
Unequally Spaced Scalable dual-polarized Ultra-wideband Antenna Array with Slot Positioning for Large Scale Array
Published in Electromagnetics, 2022
Yuanjiang Zhu, Xiangxiang Li, Jing Tao, Weixiang Jiang
Ultra-wideband phased array system has the advantages of beam agility, fast beam scanning, multi-target tracking, and multi-function, etc., so it is widely used in radar and communication application(Chen, Li, and Li 2019; Kant et al. 2011; Labate et al. 2021; Li, Xiao, and Guo 2018; Ren et al. 2022). With the increase of the array scale, the scalability has become a new feature of the phased array system. The scalability of the array can realize the rapid splicing of the phased array, shorten the production cycle and reduce the system cost.