## 6 Summary  
In this paper, we presented a new approach to interference analysis. The high complexity level of the analytical description of the real multi-antenna pattern significantly hinders the inter-beam interference evaluation. The simple antenna pattern models provide the opportunity to simplify this analysis. However, these models introduce errors in estimating the SIR. For this reason, we proposed modifying the simple antenna models, which provides a compromise between the SIR assessment accuracy and the complexity  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Comparison of SIR** & **Condition** & **RMSE (dB)** & **ME (dB)** \\ \hline Gaussian vs. 3 GPP & & 21.41 & 19.46 \\ Sinc vs. 3 GPP & & 21.51 & 19.46 \\ Modified Gaussian vs. 3 GPP & & 22.06 & 19.71 \\ Modified Sinc vs. 3 GPP & & 19.63 & 16.50 \\ \hline Gaussian vs. 3 GPP & & 3.95 & 2.07 \\ Sinc vs. 3 GPP & & 3.89 & 1.95 \\ Modified Gaussian vs. 3 GPP & & \(-4.58\) & \(-6.02\) \\ Modified Sinc vs. 3 GPP & & \(-14.95\) & \(-16.82\) \\ \hline \hline \end{tabular}
\end{table}
Table 3: RMSE and ME for SIR.  
of the antenna pattern description. The developed modification considers the change in directivity of the real 3 GPP antenna pattern along with the change in its main lobe direction.  
The simulation studies using the MPM for selected spatial scenarios under LOS and NLOS conditions were performed to check the SIR estimation accuracy. Our tests considered the Gaussian, Cosine, and Sinc models and their modified versions. For the scenario and propagation conditions, we determined \(SIR\) and \(\Delta SIR\) as a function of the separation angle between the serving and interference beams. \(\Delta SIR\), as an accuracy measure, is the SIR ratio between the analyzed modified or non-modified simple and 3 GPP reference pattern models. Then, based on these values, the RMSE and ME were determined. The simulation results show that the proposed modification better reflects the SIR changes for the 3 GPP pattern compared to the non-modified Gaussian and Sinc models. It follows that the modified Sinc provides the smallest approximation error under LOS and NLOS conditions. However, for NLOS conditions, the modified Gaussian, which has the most straightforward analytical formula, can also be used.  
Conceptualization, J.M.K.; methodology, J.W., C.Z. and J.M.K.; software, J.W.; validation, J.W.; formal analysis, J.W. and C.Z.; investigation, J.W.; resources, J.W., [PERSON] and [PERSON]; writing--original draft preparation, [PERSON], [PERSON] and [PERSON]; writing--review and editing, [PERSON], [PERSON] and [PERSON]; visualization, [PERSON]; supervision, [PERSON], [PERSON] and [PERSON]; project administration, [PERSON]; funding acquisition, [PERSON]. All authors have read and agreed to the published version of the manuscript.  
This work was developed within a framework of the research projects: MubaMilWave no. 2021/43/I/ST7/03294 sponsored by the National Science Center (NCN) Poland, under the OPUS call in the Weave programme, and grant no. UGB/22-863/2023/WAT sponsored by the Military University of Technology (WAT).  
Not applicable.  
The data presented in this study are available on request from the corresponding author.  
The authors would like to express their great appreciation to the _Sensors_ Editors and anonymous Reviewers for their valuable suggestions, which have improved the quality of the paper.  
The authors declare no conflict of interest.