Adaptive 3D ray tracing approach for indoor radio signal prediction at 3.5 GHz

This paper explained an adaptive ray tracing technique in modelling indoor radio wave propagation. As compared with conventional ray tracing approach, the presented ray tracing approach offers an optimized method to trace the travelling radio signal by introducing flexibility and adaptive features in ray launching algorithm in modelling the radio wave for indoor scenarios. The simulation result was compared with measurements data for verification. By analyzing the results, the proposed adaptive technique showed a better improvement in simulation time, power level and coverage in modelling the radio wave propagation for indoor scenario and may benefit in the development of signal propagation simulators for future technologies.

Seasonal Distribution of the Radio Wave Refraction Index over the Territory of Buryatia

The values of the atmospheric refraction index N for ultra-short radio waves for the territory of Buryatia according to the data of meteorological stations were calculated. The monthly average values N contours maps for the central months of the seasons of 2020 were constructed. It is shown the humidity of Lake Baikal and the relief significantly influence N. On average, the values of the refractive index near the lake are 20–30 N-units higher. It is revealed the monthly average N values have maxima in winter and summer with minimums in spring and autumn, with the main maximum occurring in July.

Testing and Diagnostics of Carbon Polymer Composite Materials by Radio Wave Method Used in Aircraft Construction

The article is devoted to the applicability of radio wave methods of testing and diagnostics of aviation composites for newly launched products. The description of the measurement process is also considered by the method of integral equations.

Millimeter-wave band subsurface sounding module

Radio-wave devices are used for many environmental and material research tasks. These devices and the development of relatively simple and affordable quasi-optic radio wave receivers and transmitters of millimeter and terahertz bands are important for numerous applications. Results of the design of a terahertz-band quasioptical transmitter-receiver module are presented. The module is intended for the remote detection of various objects and for measuring the depolarized field components backscattered by various long objects hidden behind obstacles (building materials and/or everyday items that prevent visual contact with the objects). These may be interfaces between materials with different dielectric constants, fiber optic cables, electric cables, and otherobjects. Results of full-scale experimental testing of the module on the detection of electric cables buried under plater in the wall of a building are presented.

Modelling the influence of meteoric smoke particles on artificial heating in the D-region

We investigate if the presence of meteoric smoke particles (MSPs) influences the electron temperature during artificial heating in the D-region. By transferring the energy of powerful high-frequency radio waves into thermal energy of electrons, artificial heating increases the electron temperature. Artificial heating depends on the height variation of electron density. The presence of MSPs can influence the electron density through charging of MSPs by electrons, which can reduce the number of free electrons and even result in height regions with strongly reduced electron density, so-called electron bite-outs. We simulate the influence of the artificial heating by calculating the intensity of the upward-propagating radio wave. The electron temperature at each height is derived from the balance of radio wave absorption and cooling through elastic and inelastic collisions with neutral species. The influence of MSPs is investigated by including results from a one-dimensional height-dependent ionospheric model that includes electrons, positively and negatively charged ions, neutral MSPs, singly positively and singly negatively charged MSPs, and photochemistry such as photoionization and photodetachment. We apply typical ionospheric conditions and find that MSPs can influence both the magnitude and the height profile of the heated electron temperature above 80 km; however, this depends on ionospheric conditions. During night, the presence of MSPs leads to more efficient heating and thus a higher electron temperature above altitudes of 80 km. We found differences of up to 1000 K in electron temperature for calculations with and without MSPs. When MSPs are present, the heated electron temperature decreases more slowly. The presence of MSPs does not much affect the heating below 80 km for night conditions. For day conditions, the difference between the heated electron temperature with MSPs and without MSPs is less than 25 K. We also investigate model runs using MSP number density profiles for autumn, summer and winter. The night-time electron temperature is expected to be 280 K hotter in autumn than during winter conditions, while the sunlit D-region is 8 K cooler for autumn MSP conditions than for the summer case, depending on altitude. Finally, an investigation of the electron attachment efficiency to MSPs shows a significant impact on the amount of chargeable dust and consequently on the electron temperature.

Verification of the Radio Wave Absorption Effect in the Millimeter Wave Band of SWCNTs and Conventional Carbon-Based Materials

Using a sample coated with three types of carbon-based paints, namely single-wall carbon nanotube (SWCNTs), carbon black, and graphite, the amount of radio wave absorption for each was measured. SWCNTs proved to have the superior radio wave absorption effect in the millimeter band. Considering the change in the amount of radio wave absorption depending on the coating amount, three different coating thicknesses were prepared for each test material. The measurement frequency was set to two frequency bands of 28 GHz and 75 GHz, and the measurement method was carried out based on Japanese Industrial Standard (JIS) R1679 “Radio wave absorption characteristic measurement method in the millimeter wave band of the radio wave absorber.” As for the amount of radio wave absorption in the 28 GHz band, a maximum amount of radio wave absorption of about 6 dB was obtained when 35 m of CNT spray paint was applied. It was confirmed that the carbon black paint came to about 60% that of the SWCNT, and the graphite paint did not obtain much radio wave absorption even when the coating thickness was changed. Furthermore, even in the 75 GHz band, the radio wave absorption was about 7 dB when 16 μm of CNT spray paint was applied, showing the maximum value. Within these experimental results, the CNT spray paint has a higher amount of radio wave absorption in the millimeter wave band than paints using general carbon materials. Its effectiveness could be confirmed even with a very thin coating thickness of 35 μm or less. It was also confirmed that even with the same paint, the radio wave absorption effect changes depending on the difference in coating thickness and the condition of the coated surface.

High-frequency radio wave electrocautery in modified Hotz operations for epiblepharon correction

To report the experience and advantageous effects of high-frequency radio wave electrocautery in modified Hotz operations for epiblepharon, We reviewed the records of all pediatric patients who underwent a modified Hotz operation with the use of high-frequency radio wave electrocautery (Ellman Surgitron Dual Frequency RF S5; Ellman International, Inc, Hewlett, NY) for epiblepharon between March 2016 and September 2019 at Korea University Guro Hospital. We evaluated the success rate, complications, recurrence rate and degree of satisfaction of our technique. Information from the medical records was collected, including demographics, ocular symptoms, severity of keratopathy, operation time, success/recurrence rate, and complications. 133 patients (98.52%) showed good correction of epiblepharon without complications or unpleasant cosmetic problems during 3 months of median follow-up period. Two patients (1.48%) showed recurrent corneociliary touch, but the degree was very mild and re-operation was not performed. One patient showed mild ectropion on his left lower eyelid, but the patient recovered well without operation. For complications, suture abscess and granulation were the most common, 3 cases in each, but all of those were temporary and resolved with conservative management. The approach with electrocautery for epiblepharon allows precise and fast incision of the lower eyelid, little bleeding, and minimal scarring. Surgical outcomes associated with the modified Hotz operation with electrocautery were consistent with previous studies.