Base Station Antenna Pattern Distortion in Practical Urban Deployment Scenarios

Abstract

In real urban deployments, base station antennas are typically not placed in free space conditions. Therefore, the radiation pattern can be affected by mounting structures and nearby obstacles located in the proximity of the antenna (near-field), which are often not taken into consideration. Also the intrinsic propagation mechanisms of the urban environment (far-field) can contribute to the distortion of the radiation pattern observed in a practical deployment scenario, especially when comparing it to the antenna pattern provided by the manufacturer and typically measured in free space. This paper presents a combination of near-field and far-field simulations aimed to provide an overview of the distortion experienced by the base station antenna pattern in two different urban deployment scenarios: rooftop and telecommunications tower. The study illustrates how, in comparison with the near-field effects, the urban propagation becomes the main contributor to the total distortion experienced. For the considered scenarios, the simulation results show a front-to-back-ratio reduction of approximately 10-15 dB in the effective antenna pattern compared to the free space reference. The near-field distortion has been evaluated by means of finite integration technique (FIT) simulations, while the far-field effects have been analyzed through intelligent ray tracing (IRT).