Environmental Sensitivity of Large Stealth Longwave Antenna Systems

This article presents an analysis of measurements collected during a six-month-long experimental deployment of a surface-placed horizontal magnetic loop antenna. The changes in the measured parameters of the loop are investigated in relation to the surrounding environment’s composition, temperature and water content. Basic functions describing these changes are formulated. The results are confronted with outcomes from similar experiments from previous years and different locations, showing good compliance. The developed functions and antenna system can be used for environmental monitoring of soil composition and humidity over large areas and volumes, helpful in, for example, flood awareness.

Video Based Vehicle Detection and Counting Using Digital Image Processing

Vehicle detection and counting is very much important for the purpose of upgrading and widening the road. The information obtained from the traffic monitoring can be used in planning the budget for road maintenance. The traffic monitoring can be done automatically or by detecting and counting the vehicles manually using human labors. In manual method of traffic monitoring the person records the data using tally sheet which may leads to the human errors and most of the automatic traffic census system used nowadays focuses on detecting and counting the vehicles by using devices called magnetic loop detectors. These devices are costly and once installed, cannot be removed. So, it is necessary to build the system that is capable of detecting and counting vehicles without involving persons for traffic monitoring and costlier devices to detect and count the vehicles. For that purpose in this work simple cameras are used for detection and counting of vehicles. Keywords: Detection, Counting, Background subtraction, Canny edge detection, Kalman filter.

Strayfield calculation for micromagnetic simulations using true periodic boundary conditions

We present methods for calculating the strayfield in finite element and finite difference micromagnetic simulations using true periodic boundary conditions. In contrast to pseudo periodic boundary conditions, which are widely used in micromagnetic codes, the presented methods eliminate the shape anisotropy originating from the outer boundary. This is a crucial feature when studying the influence of the microstructure on the performance of composite materials, which is demonstrated by hysteresis calculations of soft magnetic structures that are operated in a closed magnetic loop configuration. The applied differential formulation is perfectly suited for the application of true periodic boundary conditions. The finite difference equations can be solved by a highly efficient Fast Fourier Transform method.

Design and Fabrication of Magnetic Loop Antenna for 5MHz

In the short-wave range, size of the antenna become large and therefore is a major constraint. Magnetic Loop Antenna provides an advantage over other antennas in terms of a smaller size, higher quality factor and better signal to noise ratio. It works on the principle of resonance with the inductor provided by loop and external tuning capacitor operating like a tank circuit. The tunable magnetic loop antenna is designed to work in the high frequency range. The antenna consists of a circular hollow copper pipe, an inductive loop feed and a variable tuning capacitor. The antenna is tuned using variable 9-140pF capacitor paralleled with 150pF capacitor. The designed antenna is simulated using 4NEC2 software. The simulated antenna has high efficiency and quality factor of more than 1000. The real time testing show great result at 5.45MHz with bandwidth of 8KHz.

The Analysis of Experimental Deployment of IGLUNA 2019 Trans-Ice Longwave System

An experimental longwave system operating in the broadcasting spectrum with horizontal magnetic loop transmitting antennas is presented as an element of simulated lunar astronaut mission of the IGLUNA program of Swiss Space Center (ESA_Lab demonstrator) in June 2019 on the Klein Matterhorn glacier in Switzerland. The parameters of the antennas, the environment, the transmitter design, and propagation tests are presented. The best-suited propagation model is developed. As the system, using low powers, provided coverage of maximal distance of 2077.06 km, a single radio station of this type would cover about 36% of the Moon’s surface and allow in situ ground-penetrating research.

FREQUENCY MODULATION APPROACH BASED ON SPLIT-RING RESONATOR LOADED BY VARACTOR DIODE

In the paper, an approach to frequency modulation is presented using a split-ring resonator (SRR) loaded by a varactor diode. The modulation occurs due to the continuous time variation of capacitance of the varactor diode via changing of its bias voltage by the signal which is necessary to modulate. The modulation signal is used for bias voltage. As a source of a carrier signal, one more extra magnetic loop antenna is utilized which is coupled with the SRR via near-field interaction. Investigation of two types of signals (harmonic and chaotic) was performed for modulation in the paper. It is shown that it is possibile to provide the frequency modulation with deviation Δfd = ±80 MHz which covers the frequency range 0.95…1.11 GHz for a 1 GHz carrier signal when a SMV1231 varactor diode is used. The major advantages of the suggested approach are the very simple design and ability to easily define the required values of frequency deviation through tuning of the bias voltage magnitude range of the varactor diode. Therefore, the presented investigation and results can be useful in the manufacturing of low-cost radio components.

The flare cumulative frequencies of UV Ceti stars from different spectral types

ABSTRACT In this study, as a result of the photometric observations continued on nine UV Ceti type stars, examining the parameters obtained from the models of distributions of the flare equivalent durations in the logarithmic scale versus flare total durations, it is found that the highest flare equivalent durations occurring on the stars (Plateau values) are varying with the B − V colour indexes of those stars in agreement with the variations of both the magnetic field strength (B) of the magnetic loop and especially the electron density of its plasma (ne). The distributions of flare cumulative frequencies were derived by using the flare equivalent durations, instead of the flare energy. The main result of this study is a secondary variation, which can be just modelled with the damping sine waves, behind the main exponential variation of the flare cumulative frequency. The models indicate that this secondary variation in the flare cumulative frequency distributions is in the same shape with the periodic or quasi-periodic oscillations detected in the light curves of the stellar and solar flares. This caused to ask new questions about the flare mechanism working on stellar atmospheres.