Showing papers by "Roslan Umar published in 2021"

Study of Solar Radiation Effect on Radio Signal Using Plasma Antenna

Abstract: Plasma antenna can be formed by energizing glass tubes which are filled with neutral gases. It works similarly as metal antenna where it can transmit and receive wireless signal. This study aims to investigate the effect of weather focused on solar radiation towards the performance of plasma antenna represented by signal strength. Fluorescent lamp was set as plasma because it used ionized gas as its conducting element instead of metal. Execution of electrical properties measurements need to be done first, in order to obtain discharge current and voltage values, that need to be used into Glomac programming for the generation of electron temperature and electron density. Next, calculations of the plasma properties was performed to derive the value of plasma and collision frequencies. The plasma properties are important parameters to design and simulate plasma antenna using Computer Simulation Technology (CST). Antenna parameters in terms of return loss, gain, directivity and radiation pattern can be simulated using CST. Signal strength experiment was conducted to evaluate plasma antenna performance in terms of its capability to capture the signals and analyse the effect of solar radiation on that particular moment through the rate of power level over time versus solar radiation data. It was observed at the highest solar radiation rate which is 920 V/m, the power level recorded is the lowest value at-172.93 dBm. Therefore, the signal strength received by the plasma antenna shows remarkable changes under the influence of solar radiation.

Effects of solar flares and coronal mass ejections on Earth's horizontal magnetic field and solar wind parameters during the minimum solar cycle 24

Abstract: Previous studies have reported that coronal mass ejections (CMEs) and solar flares lead to the development of huge storms and high-speed streams. Our aim in this paper is to investigate the response of the geomagnetic index SYM/H to the solar wind parameters, such as solar wind speed V, dynamic pressure P, input energy IE and the interplanetary magnetic field (IMF) Bz component, associated with solar flares and CME events. The response of the ground geomagnetic field (H-component) to the solar wind parameters and the IMF Bz component at three low-latitude stations has also been analysed. Our findings show that the delay of the solar wind changes in the Earth’s magnetosphere in response to the weak geomagnetic storm (SYM/H = −30 nT) at the beginning of 2014 December 21. A weak storm of SYM/H = −30 nT in the middle of 2014 November 5 is suggested by a low magnetic reconnection process in the magnetosphere. In addition, the strong southward IMF Bz component and high solar wind changes in the magnetosphere system, which were a result of the X2.0 solar flare event and the CMEs on 2014 October 27, responded to the moderate storm (SYM/H = −60 nT) at the beginning of 2014 October 28. This dynamic physical process in the magnetosphere caused by solar wind variation is seen to excite the Earth’s H-component through ultra low frequency at the ground-based magnetometers at the BCL (Vietnam), TIR (India) and SCN (Indonesia) stations during the geomagnetic storm. This study relates to seismic investigations and geomagnetic-induced current on the ground.

Behaviour of Geomagnetic storm, horizontal geomagnetic field and solar wind parameters during solar flare and CMEs event.

Abstract: Space weather is driven by solar activities by pulling out the variety of phenomenon such as solar flare and coronal mass ejection (CMEs). It been discovered the CMEs and solar flares have causes disturbance at near-Earth space. This paper is to examined the behaviour of geomagnetic storm, horizontal geomagnetic field and several solar wind parameters during solar flare and CMEs event at minimum of solar cycle of 24. Observational result found that association of strongest solar flare and CMEs have declined the geomagnetic storm until -150nt at 8th September 2017. Following to this, the H component reading also slightly decreased at three magnetometer location respectively. Solar flare and CMEs released the energetic particles that could disturbed the radio communications at the Earth and electronic equipment. Therefore, it was required to study and understanding the solar flare and CMEs event.

The study on the effect of population density on radio frequency interference (RFI) analysis on dynamic spectrum at selected CALLISTO stations

Abstract: Radio Frequency Interference (RFI) has become a critical issue in radio astronomy observation in recentyears. Compact Astronomical Low-Cost Instrument for Spectroscopy in Transportable Observatories(CALLISTO) is a worldwide network of spectrometer system for solar activity monitoring. The detection ofsolar radio bursts is being interrupted due to RFI as these stations are held on the ground. Since RFI signalsare being detected from surrounding, this gives inaccurate data for ground base station observations. RFIsources are mostly from man-made devices. This paper study analysis of RFI level at selected CALLISTOstations by using Kurtosis Analysis. Data from Banting, Malaysia, Sumedang, Indonesia, Ooty, India andDaejeon, South Korea stations for two months (45–870 MHz) that contain solar burst and no solar bursthad been selected. The kurtosis value is then compared with the population density to get the relationshipbetween the population density and the RFI level. The highest average of kurtosis value indicates thelowest of radio frequency interference at these sites. MATLAB software was used for the data analysis andMicrosoft Excel for the RFI profiling graphing. The results show that the high population density is not amain factor that contributes the interference towards the surrounding. Key words: Radio Frequency Interference (RFI), radio astronomy, kurtosis analysis, e-CALLISTO.