MODELING THE ANTENNA INPUT IMPEDANCE BY THE METHOD OF MOMENTS

The paper presents a comparison of excitation source models when modeling antennas by the method of moments. By using a set of adjacent edges when specifying the impact, it is possible to obtain correct results when the computational grid of the antenna model is more frequent. This is shown on the example of a symmetric electric vibrator.

In Situ Assessment of 5G NR Massive MIMO Base Station Exposure in a Commercial Network in Bern, Switzerland

This paper describes the assessment of radiofrequency (RF) electromagnetic field (EMF) exposure from fifth generation (5G) new radio (NR) base stations in a commercial NR network in Bern, Switzerland. During the measurement campaign, four base station sites were investigated and the exposure induced by the NR massive multiple-input-multiple-output (MaMIMO) antennas was assessed at 22 positions, at distances from the base station between 30 m and 410 m. The NR base stations operated at 3.6 GHz and used codebook-based beamforming. While the actual field levels without inducing downlink traffic were very low (<0.05 V/m) due to a low traffic load and low antenna input powers of up to 8 W, setting up a maximum downlink traffic stream towards user equipment resulted in a time-averaged exposure level of up to 0.4 V/m, whereas the maximum extrapolated exposure level reached 0.6 V/m. Extrapolated to an antenna input power of 200 W, values of 4.3 V/m and 4.9 V/m, respectively, were obtained, which amount to 0.5–0.6% of the reference level recommended by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). In Bern, it was found that the impact of the NR network on the total environmental RF exposure was very limited; with maximum downlink, it contributed 2% on average. Finally, it was also concluded that extrapolation to the maximum exposure level can be done without prior knowledge of the radiation patterns, directly based on the measurement of the Physical Downlink Shared Channel (PDSCH) resource elements.

Analysis of dual-band matching of an ends-fed dipole-like antenna and a coaxial line

The problem of dual/multi-band radiation of a single-body antenna is of a great topicality today when there is a continuing development of wireless communications both for civil and military purposes. The estimation of dual-band performance of endsfed dipole-like radiator, in particular, its matching with a standard purely active resistance coaxial line is given in the paper. The focus was on stating the necessary conditions and requirements on the geometric sizes of the structure under investigation and the frequency range it have to be analyzed through. It is also considered how to decrease amount of calculations needed at the starting stage of the antenna designing that includes the exact analytical approaches for near field calculations. This decrease is based on the difference in the impact the parameters under consideration have on the antenna input impedance. For the crucial electrodynamics characteristics calculations the induced electromotive forces (EMF) method is used, which has established itself as one of the most convenient in this field.