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5G phased arrays (with MATLAB)


For practical 5G phased arrays, the beamforming effect is generated primarily by antenna spacing. 

1. How 5G phased arrays work

  • 5G base stations use multi-element antenna arrays (often 8×8, 16×16, or even more elements for Massive MIMO).
  • Each antenna element transmits the same signal, but the phase of each element is controlled electronically.
  • The physical spacing between antennas—usually ~0.5位 (half-wavelength) to 位—creates inherent phase differences when the signal reaches a user at an angle.

蠁total,n = 蠁steering,n - (2蟺/位) n d sin(胃)

Where:

  • n = antenna index
  • d = antenna spacing
  • 胃 = angle of the target
  • 蠁steering,n = electronic phase shift applied to steer the beam
The steering phase compensates for the inherent phase from spacing to direct the beam toward the desired angle.

2. Why not use a single antenna with time delays?

  • Software time delays can emulate phased arrays in simulations.
  • But in real hardware:
    1. You need separate RF paths for each antenna element.
    2. Phase shifts are applied electronically using phase shifters at GHz frequencies.
    3. Physically shifting time on a single antenna would require ultra-fast RF switches—impractical at mmWave frequencies.

So, antenna spacing + electronic phase shifts is the standard method in 5G hardware.

3. Practical Summary for 5G

Aspect How It’s Done
Beamforming Electronic phase shifts per antenna element
Direction control Steering phases compensate for inherent spacing phase
Physical array Required; spacing usually 0.5位 or 位
Simulation Can use single antenna + time delays, but only for modeling

In real 5G phased arrays, the array spacing is the fundamental cause of phase differences, and beam steering is done by applying phase shifts per element, not by artificially delaying a single signal.

MATLAB Code

 
clc; clear; close all;
%% Parameters
N = 8; % Number of antenna elements
lambda = 1; % Wavelength (normalized)
d = 0.5*lambda; % Antenna spacing (half wavelength)
theta = -90:0.1:90; % Angle range in degrees
%% 1. Inherent Phase Only (No Steering)
theta_rad = deg2rad(theta);
inherent_phase = 2*pi*d/lambda * (0:N-1)' * sin(theta_rad);
AF_inherent = sum(exp(1j*inherent_phase),1); % Array factor
AF_inherent_dB = 20*log10(abs(AF_inherent)/N);
%% 2. Apply Phase Shifts to steer to 30 degrees
theta_s = 30; % Steering angle
steering_phase = -2*pi*d/lambda * (0:N-1)' * sin(deg2rad(theta_s));
AF_steered = sum(exp(1j*(inherent_phase + steering_phase)),1);
AF_steered_dB = 20*log10(abs(AF_steered)/N);
%% Plot
figure('Color','w','Position',[100 100 800 400]);
plot(theta, AF_inherent_dB,'b','LineWidth',2); hold on;
plot(theta, AF_steered_dB,'r','LineWidth',2);
grid on; xlabel('Angle (degrees)'); ylabel('Normalized Array Factor (dB)');
title('Linear Phased Array: Inherent vs Steered Phase');
legend('Inherent Phase (spacing only)','Applied Phase Shift (beam steering)');
ylim([-40 0]);
 

 Output

 

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