Linear Antenna Array Sample Clauses

Linear Antenna Array. ‌ Adaptive antenna system (AAS) or smart antennas are collected of at least two an- tennas working in harmony to create a unique radiation pattern which is performed with hardware or is carried out digitally [64]. Arrays of antennas can be in any geometry form such as linear arrays, circular arrays, planar arrays and conformal arrays. The details about these arrays of antennas can be referred in [65, 66]. This section presents a fundamental concept of a linear antenna array [67]. As illustrated in Figure 2.7, a signal wavefront, z(t), impinging on an antenna array comprising M antennas spaced d apart each other at angle θ , and has a band- x sn,i,1 x sn,i,2 + SM ×1 … M sn,i,M x w1 w2 wM CSI DoA Adaptive algorithm .. .. .. . . . . . . RRH Figure 2.6: Beamforming technique. width B can be expressed as z(t) = β (t)e j2πνct . (2.2) In (2.2), β (t) is the complex envelope representation of the signal and νc is the carrier frequency. Furthermore, let denote the traveling time of the wavefront across any two adjacent antennas as Tz. It can be stated that Tz = dsin(θ ), (2.3) c where c is the speed of light. It is assumed that the maximum time of the wavefront traveling along one array is to be much smaller than the reciprocal of the bandwidth z(t) z(t) z(t) z(t) θ (M − 1)d sin(θ ) d sin(θ ) 2d sin(θ ) d d . . . antenna 1 antenna 2 antenna 3 antenna M Figure 2.7: A schematic of a wavefront impinging across an array of antenna. of all transmitted signals, i.e., B 1 . (2.4) (M − 1)Tz By assuming that antenna element patterns are identical, the received signal at the first antenna can be defined as y1(t) = z(t) = β (t)e j2πνct (2.5) and the received signal at the second antenna can be defined as