Mobile Base Station Antennas Research Articles

Measurement of the electric field of mobile telephone base station antennas in Riobamba (Ecuador), to determine the specific absorption rate (SAR) in the human body

Exposure to electromagnetic and radio frequency fields generated by communication technologies such as mobile phones has raised concerns about electromagnetic pollution and its possible health effects. The objective of the study was to measure the electric field coming from cell phone base station antennas and determine through simulation in virtual anatomical models the maximum and average SAR in the whole body and in 10 g in different parts of the human body. The measurements were carried out with a selective non-ionizing electromagnetic radiation meter at 10 sites in the city of Riobamba, Ecuador. The highest maximum and average SAR for whole body was 3.045x10−7 and 3.923 x10−8 W/kg, respectively. While, at 10 g, the maximum SAR reached up to 8.52x10−9 W/kg in arms and the average SAR 2.13x10−9 W/kg in legs. All results are well below the limits established by the ICNIRP, suggesting a low risk of exposure. This work provides valuable information on the levels of exposure to electric fields from mobile telephone base stations and the results collected in this research could serve as a reference for future research, since the sampling method used could be reproduced to study the temporal variation of electric field levels in the city and conduct more comprehensive studies of SAR distribution in the human body.

A Millimeter-Wave Fabry–Perot Cavity Antenna With Unidirectional Beam Scanning Capability for 5G Applications

In this article, a millimeter-wave (mmW) leaky-wave antenna (LWA) with unidirectional beam scanning (UBS) capability based on the Fabry–Perot cavity (FPC) structure is proposed for fifth-generation (5G) applications. The proposed antenna consists of a main radiating element, a metallic wall, a ground plane, and a single-layer partially reflective surface (PRS). To improve the UBS performance, a single radiating element is designed such that it provides a tilted beam with good radiation performance over the scanning angles. The metallic wall is used close to the radiating element as a reflector to suppress the propagation in undesired directions. A general design guide is given by a theoretical analysis of the FPC structures using the ray-tracing method to formulate the beam-steering functionality versus frequency over desired predetermined angles. The PRS layer is designed without any tuning elements to provide the beam scanning over the angles of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^\circ &lt; \theta &lt; 45 ^\circ $ </tex-math></inline-formula> and the frequency range of 24–30 GHz. The proposed Fabry–Perot cavity antenna (FPCA) structure is fabricated and the measurement results show a beam steering from 19° to 54° over the frequency band from 24 to 30 GHz, which is in good agreement with the calculated results from the theoretical analysis. A maximum measured gain of 14.5 dBi at 24 GHz is achieved. The proposed antenna can be used in the 5G mobile communication systems and 5G base station antennas (BSAs), where beam steering with high-gain and low fabrication cost features over the mmW spectrum is required.

Very high radiofrequency radiation at Skeppsbron in Stockholm, Sweden from mobile phone base station antennas positioned close to pedestrians’ heads

In urban environment there is a constant increase of public exposure to radiofrequency electromagnetic fields from mobile phone base stations. With the placement of mobile phone base station antennas radiofrequency hotspots emerge. This study investigates an area at Skeppsbron street in Stockholm, Sweden with an aggregation of base station antennas placed at low level close to pedestrians' heads. Detailed spatial distribution measurements were performed with 1) a radiofrequency broadband analyzer and 2) a portable exposimeter. The results display a greatly uneven distribution of the radiofrequency field with hotspots. The highest spatial average across all quadrat cells was 12.1 V m⁻1 (388 mW m⁻2), whereas the maximum recorded reading from the entire area was 31.6 V m⁻1 (2648 mW m⁻2). Exposimeter measurements show that the majority of exposure is due to mobile phone downlink bands. Most dominant are 2600 and 2100 MHz bands used by 4G and 3G mobile phone services, respectively. The average radiofrequency radiation values from the earlier studies show that the level of ambient RF radiation exposure in Stockholm is increasing. This study concluded that mobile phone base station antennas at Skeppsbron, Stockholm are examples of poor radiofrequency infrastructure design which brings upon highly elevated exposure levels to popular seaside promenade and a busy traffic street.

A³PNet: Antijam and Accurate Antenna Parameters Measuring Network for Mobile Communication Base Station Using UAV

Whether the down-tilt angle of the mobile communication base station antenna is reasonable directly affects the coverage effect and communication quality of the whole network. Measurement of traditional antenna parameters mainly relies on engineers climbing the base station for manual measurements, confronting the dilemma of low measurement efficiency and a dangerous working environment. Moreover, due to the interference of the wind field in real unmanned aerial vehicle (UAV) measurement scenes, there is attitude disturbance during observation, which leads to a sharp increase in measurement error. To tackle these problems, we propose an antijam and accurate antenna parameters&#x2019; measurement framework, named A³PNet, which aims to realize fully automatic mobile communication base station antenna parameters&#x2019; measurement through UAV. Above all, for measuring in windy environment, an adaptive feature recovery module (AFRM) is presented to restore the antenna attitude while reducing the measurement error. Also, contour modulation strategy (CMS) is cooperated to smooth the deformation path and decouple the offset movement of the vertex to speed up the learning process. Go one step further, a general antenna down-tilt measurement module is proposed to replace the cumbersome numerical fitting analysis method, and it is embedded in the mainstream model to realize the task of down-tilt angle measurement. Extensive experiments over both the newly established Antenna-disturb dataset and the original Antenna-scapes dataset demonstrate the effectiveness of A³PNet. Specifically, it outperforms the state-of-the-art (SOTA) approaches by 2.40&#x0025; on the Antenna-scapes dataset and 7.23&#x0025; on the Antenna-disturb dataset, and meanwhile has 27.1 frames/s real-time processing speed, improving the measurement method of antenna parameters.

Health Effects of 5G Base Station Exposure: A Systematic Review

The Fifth Generation (5G) communication technology will deliver faster data speeds and support numerous new applications such as virtual and augmented reality. The additional need for a larger number of 5G base stations has sparked widespread public concerns about their possible negative health impacts. This review analyzes the latest research on electromagnetic exposure on humans, with particular attention to its effect on cognitive performance, well-being, physiological parameters, and Electroencephalography (EEG). While most of their results indicated no changes in cognitive function, physiological parameters, or overall well-being, the strength of the EEG alpha wave is noticed to vary depending on various aspects of cognitive functions. However, the available studies have not investigated the health effects resulting from exposure from the 5G mobile phone and base station antennas from 700 MHz to 30 GHz on the cognitive performance, well-being subjective symptoms, human physiological parameters, and EEG of adults. There is a need for such research regarding this current emerging technology. Such studies are significant in determining whether 5G technology is indeed safe for humans.

AntennaNet: Antenna Parameters Measuring Network for Mobile Communication Base Station Using UAV

In the field of measuring parameters of mobile communication base station antenna, most of its methods share some deficiencies to a different extent. The traditional ones suffer from inferior efficiency and low safety coefficient while the state-of-the-art ones reveal problems of unsatisfying operational speed and accuracy. To address these problems, a high-speed and high-precision measuring system has been proposed with AntennaNet to speed up instance segmentation. First, the dual attention mechanism module is designed and adopted in AntennaNet, which can promote the accuracy and efficiency of the detection and segmentation of mobile base station antenna, while the PointRend module with down-tilt fitting is also employed to smooth the edges of masks segmented from antenna images and measure the parameters data. Second, transfer learning is introduced to ameliorate overfitting and training difficulty caused by small samples. Third, threshold, pixel coordinates, and least square are applied to ascertain the number of antennas and measure the relevant parameters. Finally, this high speed and high precision measuring system is complete with the combination of android App and UAV. Experimental results fully attest to the preponderance of the proposed method in its significant improvement of segmentation speed, fitting accuracy speed, and fitting accuracy of the antenna, whose relevant parameters of the fitting also conform to industry standards. Our method not only ensures staff safety but also improves social efficiency, which revolutionized the way of measuring antenna parameters of mobile communication base stations.

A High Isolation Dual-Polarized Microstrip Antenna for Sub-6 GHz Base Station

A dual-polarized microstrip antenna with high isolation for Sub-6 GHz (3.4- 3.6 GHz) base station application is presented in this letter. To increase isolation between two feed ports, the stacked patches are excited by double orthogonal open-ended feed lines. The proposed antenna is simulated by HFSS18.0. The simulation results show that the isolation is better than 50 dB over the whole bandwidth from 3.23 to 3.85 GHz with the cross-polarization levels less than - 30 dB when the gains are higher than 7.64 dBi for dual polarization. It’s valuable for this design method to devise mobile communication system base station antenna used in Sub-6 GHz of China Unicom and China Telecom.

Hygienic strategy of mobile communication base station antennas radiofrequency electromagnetic field values modern control

Introduction. The urgency of the issue is due to the rapid development of new telecommunications and information technologies, the widespread introduction and distribution of cellular base stations (BS), which changes the conditions of contact of the population with sources of electromagnetic radiation of radio frequencies (EMR RF). The aim of the study is to summarize the results of the analysis of the project documentation for the placement of mobile radiotelephone network BS in terms of comparability of calculated and actually measured levels of electromagnetic radiation (EMR) from transmitting antennas; to determine the prospective tasks of hygienic control of the safety of the BS. Materials and methods. For hygienic control of EMR levels, serial broadband meters PZ-42 and NBM-550 were used; the method according to MUC 4.3.1677-03 "Determination of the levels of the electromagnetic field created by radiating technical means of television, FM radio broadcasting and base stations of land mobile radio communications". 74 BS were examined, whose antennas were a source of EMR at the frequency of 2620-2640 MHz with a power of 24.2-24.4 W. Results. The maximum length of the building restriction zone (BRZ) from the BS antennas ranged from 16 m to 101 m, regardless of the power of the radiating means, in 50% of cases the length of the BRZ was 30-45 m. In 40% of cases, BS antennas are installed on the roofs of low-rise buildings with BRZ at a height that falls to 5-10 meters from ground level. The excess of the calculated EMR values in terms of energy flux density (EFD) was determined for 50% of the BS. Instrumental measurements of EFD in 19.4% of cases showed excess remote, 11.1% - exceeding marked only by considering the expanded uncertainty (EU) measurement EFD. It was found that the values of EFD measured with EU are more closely approximated to the calculated values. Conclusions. Substantiated recommendations on whether the calculation of the era for height and length for the lower lobes in a radiation direction of antenna, recording ratio EU of the measured values of EFD for additional health human in multivariate emitters of EMR RF. The prospective tasks of hygienic control of the safety of the BS operation are defined.

Human Exposure Levels Due to Mobile Base Station Antennas in Sri Lanka

Human Exposure Levels Due to Mobile Base Station Antennas in Sri Lanka

Radiofrequency radiation from nearby mobile phone base stations-a case comparison of one low and one high exposure apartment.

Radiofrequency (RF) radiation in the frequency range of 30–300 GHz has, since 2011, been classified as a ‘possible’ human carcinogen by Group 2B, International Agency for Research on Cancer (IARC) at WHO. This was based on a number of human epidemiology studies on increased risk for glioma and acoustic neuroma. Based on further human epidemiology studies and animal studies, the evidence on RF radiation carcinogenesis has increased since 2011. In previous measurement studies, it has been indicated that high environmental RF radiation levels are present in certain areas of Stockholm Sweden, including in one apartment. Field spatial distribution measurements were performed in the previously measured apartment in Stockholm, which exhibited high RF radiation from nearby base stations. Based on the RF broadband analyzer spot measurements, the maximum indoor E-field topped at 3 V m−1 in the bedroom at the 7th floor. The maximum outdoor exposure level of 6 V m−1 was encountered at the 8th floor balcony, located at the same elevation and only 6.16 m away from the base station antennas. For comparison, a measurement was made in a low exposure apartment in Stockholm. Here, the maximum indoor field 0.52 V m−1 was measured at the corner window, with direct line of sight to the neighboring house with mobile phone base station antennas. The maximum outdoor field of 0.75 V m−1 was measured at the balcony facing the same next-door building with mobile phone base station antennas. The minimum field of 0.10 V m−1 was registered on the apartment area closest to the center of the building, demonstrating the shielding effects of the indoor walls. Good mobile phone reception was achieved in both apartments. Therefore, installation of base stations to risky places cannot be justified using the good reception requirement argument.

Effect of radio frequency electromagnetic field from mobile phones’ base station antennas on maturation of rat erythrocytes

The biological effects of radiation emitted by mobile telephone base station antennas are still controversial. The present study was designed to evaluate the effects of radio frequency electromagnetic field frequency range of 1200–1400 MHz, from a mobile phone base station on erythropoietic cells in the rat bone marrow. Out of a total of 48 rats, 24 were exposed for 2 h each day for 7, 14, 30, and 60 days to electromagnetic radiation at specific absorption rate (SAR) levels 1.165 W/kg. Electromagnetic field–exposed rats were compared with sham-exposed control rats. The animals of the sham-exposed control group and each radio frequency electromagnetic field–exposed group were killed on the final day of exposure. Bone marrow smears were examined. In comparison with the sham-exposed animals, the findings revealed significantly increased polychromatic erythrocytes (P < 0.05) on experimental days 30 and 60. The frequency of micronucleated polychromatic erythrocytes was also significantly increased on experimental day 30 (P < 0.05). Pair-wise comparison of data obtained after 7 and 14 days, electromagnetic field exposure, did not reveal statistically significant differences between sham-exposed and radio frequency electromagnetic field exposure groups. The findings revealed a transient effect on the erythropoietic cells in the rat bone marrow and the sporadic appearance of micronucleated immature bone marrow red cells.

Low capacity wide‐band mobile base station antenna

In most of the crowded cities and with the vast increase of capacity-hungry applications, operators tend to use capacity enhancement techniques such as MIMO, OFDMA etc. Authors’ problem is completely different. In several rural areas, the needed capacity is very low and the single base station has a standard capacitance which is considered over sufficient with respect to the required spectrum in these rural areas. The solution to make the best use of such resources is to design a two-sector antenna with a single feed. The proposed antenna covers two areas simultaneously. Thus, the spectrum capability is distributed over two sectors that share the available frequency resources. If the total area is small enough, then the base station power will be saved to the half as well as the number of antennas also reduced to the half. Otherwise, the concept of frequency reuse can be applied with minimum base stations. Authors’ antenna is designed over FR-4 substrate with a noticeable reduction in the cost. A very good agreement between the simulated and measured results is noticed .

OTA Test Method for Receiver Sensitivity of Mobile Communication Base Station Based on the Conduction Method

The paper carries out test towards the mobile communication base station antenna radiation port over the air (OTA), analyzes the interference generated by antenna, and tests the single input and single output OTA with conduction method. The conduction-based test firstly checks the reversed interference generated at the base station radio frequency port as well as the antenna interface parameters, then uses channel simulator to replace the empty port wireless environment to simulate the wireless circumstance of base station communication, including reversed interference and multi-path signal, next measures the receiving sensitivity of the base station radio frequency port, and finally figures out the antenna radiation port sensitivity level. The results reveal when compared with normally used far-field test method, the conduction-based test has low uncertainty but accurate outcome.

Path-Loss Estimation for Wireless Cellular Networks Using Okumura/Hata Model

In cellular networks, accurate path-loss estimation is highly desirable not only to improve the performance but also to realize precise estimation of financial feasibility. In other words, while accurate path-loss estimation helps to achieve an acceptable performance and reasonable cost, inaccurate path-loss estimation would either lead to degrade the performance, or increase the cost. Different models were introduced in the literature for achieving accurate path-loss estimation. One of theses models is the Okumura/Hata model which is recommended for being used to estimate the path-loss in the cellular systems that employing micro-cells. It is characterized by its suitability for being used in a variety of environments. The main objective in this paper is to provide a guide line for path-loss estimation analysis using Okumura/Hata model. Matlab software was used to perform this analysis. Compared with free space model in which frequency and separation distance are the only contributors for path-loss, more accurate estimation can be achieved when Okumura/Hata model is used as it includes further correction factors, such as mobile station antenna height and base station antenna height.

AERATED CONCRETE MICROWAVE REFLECTION AND TRANSMISSION PROPERTIES IN A WET ENVIRONMENT

Excess water content within the building material could greatly alter the interaction of the microwave with the material. In this study aerated concrete (AEROC) block walls (60x60cm) were investigated for their microwave (2.4 GHz) properties under wetting conditions. The spray wetting of the wall was conducted to simulate the environmental processes such as raining or water damage. 50ml/m² water dosage was applied on the surface of the concrete 21 times in 1 min intervals. The results show a noticeable decrease in microwave penetration power through the material after the sample gets enriched with water. As the water content on the surface of the material rises, so does the transmission loss. During the different water content of the aerated concrete, the reflection loss varied from -15.04 dB (dry wall) to -5.03 dB (wet wall’s surface). The transmission loss continues to rise during the entire length of the experiment, from -4.5 dB as a dry sample to -8.3 dB after 441 ml (1035 ml/m² during 23 min) of sprayed water. The variation of reflected microwave power was approximately ten times, which is quite a significant indicator of alteration of microwave propagation. The results demonstrate wetting process as an considerable factor in assessing microwave propagation in near the sources, such as mobile phone base station antennas, industrial microwave heaters and ovens etc.

Radiation Pattern Performance of Unequally Linear Arrays with Parasitic Element

&lt;p&gt;For next generation of 5G mobile base station antennas, multibeam, multifrequency and low sidelobe characteristics requested. Simplify the feeding network will contribute a low feeder loss and frequency dependent. From the previous research by the author, low sidelobe level reported by density tapered array configuration from -13 dB to -16 dB and the result maintained for wideband operation frequency at 28 GHz, 42 GHz, and 56 GHz. However, the grating lobe has occurred due to element spacing larger than a wavelength of higher frequency (56 GHz). In this paper, an investigation was made of the performance of radiation pattern for unequally microstrip linear array antenna in frequency 42 GHz and 56 GHz by loading parasitic elements. The effect of parasitic element to the impedance, gain, and sidelobe level of unequally microstrip linear spaced tapered array also examined. The design has been simulated using Ansoft High Frequency Structural Simulator (HFSS) ver 16.0.&lt;/p&gt;

LOW SIDELOBE AND WIDEBAND CHARACTERISTICS OF DENSITY TAPERED ARRAYS FOR 5G MOBILE SYSTEMS

Conventional mobile base station antennas are composed of equally spaced linear array antennas. In order to achieve low side lobe characteristics, excitation coefficients for array elements are determined by a feeding network. Because of complexity of the feeding network, applicable frequency range is limited. In 5G mobile system, multi frequency band operation is requested. For achieving low sidelobe and wide frequency characteristics, a density tapered array configuration is promising. Because of uniform excitation coefficients, feed network has no frequency dependence and wide frequency range application is expected. In this paper, abilities and design method of low sidelobe characteristics are investigated. By density tapering, sidelobe levels are reduced from -13dB to -16dB. As for wide band characteristics, low sidelobe characteristics are maintained during 28GHz to 56GHz operations. Usefulness of a density tapered array is numerically clarified.

SAR compliance assessment of PMR 446 and FRS walkie‐talkies

The vast amount of studies on radiofrequency dosimetry deal with exposure due to mobile devices and base station antennas for cellular communication systems. This study investigates compliance of walkie-talkies to exposure guidelines established by the International Commission on Non-Ionizing Radiation Protection and the Federal Communications Committee. The generic walkie-talkie consisted of a helical antenna and a ground plane and was derived by reverse engineering of a commercial walkie-talkie. Measured and simulated values of antenna characteristics and electromagnetic near fields of the generic walkie-talkie were within 2% and 8%, respectively. We also validated normalized electromagnetic near fields of the generic walkie-talkie against a commercial device and observed a very good agreement (deviation <6%). We showed that peak localized specific absorption rate (SAR) induced in the oval flat phantom by the generic walkie-talkie is in agreement with four commercial devices if input power of the generic walkie-talkie is rescaled based on magnetic near field. Finally, we found that SAR of commercial devices is within current SAR limits for general public exposure for a worst-case duty cycle of 100%, that is, about 3 times and 6 times lower than the limit on the 1 g SAR (1.6 W/kg) and 10 g SAR (2 W/kg), respectively. But, an effective radiated power as specified by the Private Mobile Radio at 446 MHz (PMR 446) radio standard can cause localized SAR exceeding SAR limits for 1 g of tissue.

Environmental Impact of Radiofrequency Fields from Mobile Phone Base Stations

This review examines the potential environmental impact of radiofrequency (RF) fields emitted by mobile phone base station antennas and other sources of RF radiation. Overall, many alarming investigations were found but most are characterised by severe methodological shortcomings. For this reason these studies do not provide any evidence that observed biological effects are associated with exposure to the electromagnetic fields. So far, the studies do not prove that environmental exposures to mobile phone base station radiation (and other environmental RF exposures) are harmful to wildlife.

Radio frequency electromagnetic field compliance assessment of multi‐band and MIMO equipped radio base stations

In this paper, different methods for practical numerical radio frequency exposure compliance assessments of radio base station products were investigated. Both multi-band base station antennas and antennas designed for multiple input multiple output (MIMO) transmission schemes were considered. For the multi-band case, various standardized assessment methods were evaluated in terms of resulting compliance distance with respect to the reference levels and basic restrictions of the International Commission on Non-Ionizing Radiation Protection. Both single frequency and multiple frequency (cumulative) compliance distances were determined using numerical simulations for a mobile communication base station antenna transmitting in four frequency bands between 800 and 2600 MHz. The assessments were conducted in terms of root-mean-squared electromagnetic fields, whole-body averaged specific absorption rate (SAR) and peak 10 g averaged SAR. In general, assessments based on peak field strengths were found to be less computationally intensive, but lead to larger compliance distances than spatial averaging of electromagnetic fields used in combination with localized SAR assessments. For adult exposure, the results indicated that even shorter compliance distances were obtained by using assessments based on localized and whole-body SAR. Numerical simulations, using base station products employing MIMO transmission schemes, were performed as well and were in agreement with reference measurements. The applicability of various field combination methods for correlated exposure was investigated, and best estimate methods were proposed. Our results showed that field combining methods generally considered as conservative could be used to efficiently assess compliance boundary dimensions of single- and dual-polarized multicolumn base station antennas with only minor increases in compliance distances.