Paolo Gianola

A Fraunhofer-Based Approach for the Assessment of the Field Radiated in the Fresnel Region of an Antenna

The letter focuses on a simplified and conservative method for the assessment of the electromagnetic exposure in proximity of a radiator. The method allows the use of the Fraunhofer antenna pattern to estimate the electromagnetic field radiated in the Fresnel region of base transceiver station (BTS) antennas. The proposed approach is introduced from a theoretical point of view and validated with simulations and measurements on linear and planar array systems. For its application, a specific description of the boundaries of the Fresnel region for a generic antenna of parallelepipedal shape, which takes into account the dependency from the direction of observation, is introduced. The method provides a rapid and simple solution of assessment issues in relation to the electromagnetic fields exposure limits.

Electromagnetic Field Zones Around an Antenna for Human Exposure Assessment: Evaluation of the human exposure to EMFs.

The regulatory framework on human exposure to electromagnetic fields (EMFs) is a crucial task that the telecommunication operators and the authorities have to face. Some procedures have been introduced in standards, based on both computations and measurements, for the assessment of the compliance of the radio transmitters to the given EMF limits. The procedures could vary depending on the position of the observation point around the transmitting antennas. In this article, the definitions of EMF zones and the zones boundaries around an antenna are revised and tailored for the evaluation of human exposure to the EMFs. The space around the antenna is sectioned into three regions: reactive, radiating near field, and far field. The analytical and numerical results are used to support the proposed regions boundaries. Some examples of region boundaries are given for a few antenna types.

Electromagnetic Shielding of Building Walls: From Roman times to the present age.

We have investigated the electromagnetic (EM) shielding effectiveness (SE) of building walls built in different ages. The measurements were carried out in the city of Rome, analyzing different building typologies from Roman Empire historical ruins up to modern reinforced concrete and steel/glass buildings. The method consisted of a measurement performed by means of a portable two-port vector network analyzer (VNA) connected to a couple of light antennas located in opposite positions with respect to the middle wall. The explored frequencies were in the range of 0.7-5.0 GHz, which many countries have currently adopted for mobile-phone radio access network (RAN) and satellite positioning services. The SE measurements showed values of up to 100 dB, and the analysis of the results showed that ancient Romans building walls and steel/glass building structures have the highest shielding capability. A numerical simulation of the outdoor-to-indoor transition attenuation and a statistical analysis of the signal code power in the live RAN of Telecom Italia integrate the discussion of the results.

Simplified numerical field assessment in the Fresnel region of BTS antennas

Numerical field assessment is a topical point of interest for a preliminary estimation of human exposure to upcoming radio stations. In many practical situations, the electromagnetic field must be calculated far from the antenna, into the Fraunhofer region of the radiator, and analysis techniques can be satisfactory based on far-field simulations. If obstacles and buildings are present, the simulation can be integrated by use of ray-tracing techniques [1]. All these methods do not require the knowledge of geometrical and electrical design data, since in the Fraunhofer region, the electromagnetic field depends only on the radiation pattern that is typically provided by antenna manufacturers or can be alternatively measured directly by the end-user. If the points of interest belong to regions closer to the radiator, the angular representation of the radiation diagram is not unique. Hence, the radiation pattern concept is not valid and the field must be calculated by means of a full-wave solution of the electromagnetic problem. As an alternative to the use of standard full-wave numerical techniques, some authors propose dedicated solutions [2], in some cases adopting simplified approaches [3].

Active antenna system testing and trials in Telecom Italia

Active Antenna Systems embed into one equipment only everything between Base Band processing and signals radiated over the air. It is a new technology for the mobile communications market whose testing requires well-known measurement techniques to be revisited, new ones to be invented and trials are worth being done. Current paper summarizes Telecom Italia experience in that field, after having worked on it for a few years.