3.3 Antenna system for a mmWave pico-cell remote station of 5G mobile communication network

From the outcome of Section 1, it follows that using an antenna's installation height of 3 m and a coverage radius of 50 m, the elevation angle of 78°, provided by a half-wave dipole in the E-plane, is sufficient to provide a radius of not more than 0.5 m for the dead zone in the immediate vicinity of the mast (see Figure 6).

As can be seen in Figure 4, the extreme beams generated by the Butler matrix have a significantly greater width and less directivity than the others do. Their use

Figure 5. Block diagram of the 3�8 Blass matrix (bottom) and corresponding BFN beam rosette (top).

Design of Reconfigurable Multiple-Beam Array Feed Network Based on Millimeter-Wave… DOI: http://dx.doi.org/10.5772/intechopen.89076

Figure 6. Calculation of the radiation pattern in the elevation plane for one-dimensional PAA.

should be abandoned in order to avoid creating significant interference outside the service sector. Thus, the 4�4 matrix makes it possible to effectively exploit only two beams, which is not enough for spatial multiplexing of communication channels under the conditions illustrated in Figure 2; it is necessary to use an 8�8 matrix with six active channels. A fan using six beams allows covering a sector of the order of 50° for the �4 dB level (see Figure 4), which provides a full 360° coverage with four PAAs mounted at 90° relative to each other, as shown in Figure 7.

According to [1], the radiation pattern of a PAA Dð Þ θ, φ is determined by the radiation pattern of a single antenna element f (θ, φ) and the array factor F(θ, φ) by the formula

$$D(\theta,\,\rho) = f(\theta,\,\rho) \* F(\theta,\,\rho),\tag{4}$$

where θ is an elevation angle and φ is an azimuth. For a half-wave dipole,

$$\begin{aligned} f(\theta, \varphi) &= f(\theta) \* f(\varphi) \\ f(\varphi) &= \text{const}, \\ f(\theta) &= \frac{1 + \cos(\pi \cos \theta)}{\sin \theta} \end{aligned} \tag{5}$$

For a one-dimensional linear equidistant 8�1 PAA with a distance between elements d = λ0/2

$$\begin{aligned} F(\theta, \varphi) &= F(\theta) \* F(\varphi) \\ F(\theta) &= \text{const}, \\ F(\varphi) &= \sum\_{n=1}^{8} A\_n e^{j\frac{2\pi f}{\epsilon} n \frac{\lambda\_0}{2} \cos \varphi}, \end{aligned} \tag{6}$$

Figure 7. Configuration of the antenna system for the mmWave pico-cell remote station under study.

inputs can also be arbitrary and is determined by the required number of beams to be formed. The block diagram of the Blass matrix for three inputs and eight outputs,

The amplitude-phase distribution at the outputs of the Blass matrix with N inputs is determined by the delays of the transmission lines τmn and the levels of the signals branched off each of the directional couplers amn according to the formula:

> An <sup>¼</sup> <sup>X</sup> N

where m is the input number n is the output number.

the BFN based on the Butler matrix will be studied.

communication network

Figure 5.

116

m¼1

3.3 Antenna system for a mmWave pico-cell remote station of 5G mobile

Block diagram of the 3�8 Blass matrix (bottom) and corresponding BFN beam rosette (top).

From the outcome of Section 1, it follows that using an antenna's installation height of 3 m and a coverage radius of 50 m, the elevation angle of 78°, provided by a half-wave dipole in the E-plane, is sufficient to provide a radius of not more than 0.5 m for the dead zone in the immediate vicinity of the mast (see Figure 6).

As can be seen in Figure 4, the extreme beams generated by the Butler matrix have a significantly greater width and less directivity than the others do. Their use

amne

Due to the fact that the RF signal from the input port sequentially passes through several directional couplers for feeding all the PAA elements, each coupler in the matrix must has the strictly defined value of the branch ratio, which greatly complicates the design. The configuration of the Blass matrix requires a larger number of directional couplers than Butler matrix, which increases its cost and often degrades the C-SWAP characteristics. However, due to the use of delay lines, the beams do not deviate from their position when the wavelength λ varies as it happens using the Butler matrix (see Eq. (2)). For this reason, the Blass matrix is better feasible for ultrawide band systems with a fractional bandwidth of more than 20%, as well as in systems requiring specific beam placement, for example, in satellite broadcasting equipment. Based on this outcome, in the course of further consideration of 5G mmWave MBA beam steering, only

�jωτmn , (3)

as well as the BFN beam rosette is shown in Figure 5.

Advances in Array Optimization
