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... three quarter wavelength vertical antenna with one radial element, scaled for the 137 MHz band, was built and installed in a convenient place (Fig. 5 left). The Antenna Under Test (AUT) was connected to a computer controlled communication receiver ICOM PCR1000, which sends the Received Signal Strength Indicator (RSSI) signal via the COM port to a PC (Fig. 5 right). The real antenna characteristic in the vertical plane was plotted with the Signal Plotter application available in the ...
Context 2
... quarter wavelength vertical antenna with one radial element, scaled for the 137 MHz band, was built and installed in a convenient place (Fig. 5 left). The Antenna Under Test (AUT) was connected to a computer controlled communication receiver ICOM PCR1000, which sends the Received Signal Strength Indicator (RSSI) signal via the COM port to a PC (Fig. 5 right). The real antenna characteristic in the vertical plane was plotted with the Signal Plotter application available in the APT-Decoder Software [20]. This software is dedicated to the weather satellite picture reception in Automatic Picture Transmission (APT) format and it ensures the receiver control and the Doppler Effect compensation. ...
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The network of the meteor observation inthe radio range consisting of 6 stations located inMykolaiv (3 stations), Rivne, Lviv and Hlukhiv has beencreated. The main goal of the network is to expandinformation about meteor phenomena, including theassessment of the kinematic parameters (velocities,radiants and orbital elements) of meteoroids and their...
Citations
... The three-quarter wavelength (3λ/4) antenna element offers several advantages that will be highlighted in the following paragraphs. Different studies [23][24][25][26] revealed that compared to other antenna configurations, such as half-wavelength (λ/2) and the widely used quarter-wavelength (λ/4), in the case of the 3λ/4 antenna element, in the radiation pattern's vertical plane, the maximum radiation lobe (main lobe) rises towards medium elevation angles, while preserving its omnidirectional characteristic in the horizontal plane. Additionally, even at low elevation angles, the 3λ/4 antenna gain is superior to, or at least equal to, that offered by the widely used conventional λ/4 vertical monopole elements, but also to that provided by the λ/2 configuration. ...
LEO satellite constellations can provide a viable alternative to expand connectivity to remote, isolated geographical areas and complement existing IoT terrestrial communication infrastructures. This paper aims to improve LEO satellite communications by implementing a new phased antenna array system that can significantly improve the radio communication link’s performance. By adjusting the progressive phase shift to each element of the antenna array system, the direction of the main radiation lobe of the phased antenna array system can be controlled with accuracy. As far as we know, it is the first time that a four-element, three-quarter wavelength phased antenna array system has been successfully realized with the intention of being optimized for implementation in LEO IoT satellite reception systems. The proposed system’s high level of performance is confirmed by the measurements, which indicate effective control of the main radiation lobe orientation. The numerical analysis shows a maximum gain close to 12 dBi for about 42° elevation, a Half Power Beamwidth (HPBW) of 32° in the vertical plane, and 80° in the azimuth plane. The experimental measurement results at various main lobe orientation angles revealed an HPBW ranging from 76° to 87° in the azimuth plane and a maximum Front-to-Back ratio (F/B) of 14.5 dB.
... To make better the parameters and to optimize the performances, many antenna configurations have tested and continue to test in cases where it is necessary to follow specific conditions to make receiving from the satellite. [5][6][7][8]. Arrays of antennas are combine of groups of antennas adjusted to get aimed directivity properties. An array can formed with any combination of radiant elements but, in application usually classified equivalent elements in organized geometries are used. ...
... With progressing of satellite, communications, in order to make receiving or transmitting the signals as close as feasible to the space where the signals have needed, via not to disturb other spaces, the radiation model have been more and more precise. So, antenna arrays in phased [5,7] have been highly improved. These antennas can alter the radiation model in array with respect to the phase shift that occurred among the elements supply voltages. ...
Satellite communications (SatComs) recently, have admitted as a new technological advances that attracted and raised special investment and ventures. Space communication technology has found many application areas from costly, one-of-a-sort structures, to utilize again of technology on sequential tasks, to the progress of canonical protocols accepted by space agencies of lots of countries. Satellite communication has accepted as one of the important technologies for 5G backhauling, particularly on bandwidth request increased in 5G mobile broad band (eMBB) applications. This paper presents the efficiency of the satellite communication system using 16 QAM digital modulation technique for the X band. This digital modulation method presents high data rate in transmission without raising the bandwidth compared with other digital modulation methods. Applications are realized in Matlab environment and obtained conclusions are discussed such as power spectrum diagrams, constellation schemas and BER ratio for several bands such as 4, 8, 12, 16 GHz.
... The array contains two monopole radiant elements in 3λ/4 (three-quarter wavelength) configuration, located on a contiguous metallic ground plane. The advantages of using thus configuration and also of ground plane antennas have been analyzed in several previous theoretical [1] and practical [5], [6] studies. These highlighted the superior gain at medium elevations and the maintenance of a stable impedance close to 50 Ohm, used in most modern equipment. ...
... Numerous antenna configurations have been tested and continue to be tested in order to improve their parameters and to optimize their performances in cases where it is necessary to adapt to special conditions for satellite reception. Previous studies [1] - [4] have shown the advantages of vertical monopole antennas of three-quarter wavelength (3λ/4), fed at the base and placed above a conductive ground plane or, instead, fitted with quarter wavelength radial elements connected to the shield of the coaxial transmission line. The radials are those elements who provide an electrical ground and do not require the contact with the surrounding earth. ...
... The studies and experiments mentioned above have encouraged the extension of research to an antenna array containing elements thus configured. The three-quarter wavelength configuration has been briefly approached in several works, under the practical aspects [1], [2], [4] and of the theoretical considerations [6], [9]. However, the approaches do not include the study and analysis of the behavior of this configuration within an of three-quarter wavelength antenna array, placed on a ground plane. ...
... For the experimental verification of the results obtained by simulation, an omnidirectional antenna with complex conjugate impedance reduced in scale was built. The test antenna was dimensioned for the 137MHz band allocated to NOAA weather satellite communications, with the purpose of determining with their help the radiation pattern under real operating conditions [12]. ...
... The antenna was used as a part of RF front end for software defined radio used for meteorological survey. 16,17 Compact wideband and multiband printed quadrifilar helix have been proposed for small satellites. Variations in radiation patterns, reflection coefficients, and gain were studied for these antennas when placed over different size ground planes. ...
Quadrifilar helix antenna (QHA) has its applications in satellite communications. This paper presents the performance optimisation of input and radiation characteristics of QHA in the presence of infinite and finite metallic ground planes. For the infinite ground plane, it has been observed that input parameters such as impedance and voltage standing wave ratio (VSWR) are stable, and the antenna has broader half power beamwidth (HPBW). Smaller metallic platforms that act as finite ground planes produce better 3‐dB axial ratio beamwidth and boresight axial ratio. Deployment of QHA on smaller metallic platforms such as nanosatellites and CubeSats enhances the circularly polarised beamwidth of the antenna with improved boresight axial ratio. However, on large low earth orbit (LEO) satellites, stable input characteristics and broader HPBW have been achieved at the cost of narrow circularly polarised beamwidth and degraded boresight axial ratio. This paper presents the performance optimisation of input and radiation characteristics of QHA in the presence of infinite and finite metallic ground planes. It has shown that smaller metallic platforms that act as finite ground planes produce better 3‐dB axial ratio beamwidth and boresight axial ratio. Other performance parameters including impedance, voltage standing wave ratio (VSWR), and half power beamwidth (HPBW) have been measured.
... To make better the parameters and to optimize the performances, many antenna configurations have tested and continue to test in cases where it is necessary to follow specific conditions to make receiving from the satellite. [5][6][7][8]. Arrays of antennas are combine of groups of antennas adjusted to get aimed directivity properties. An array can formed with any combination of radiant elements but, in application usually classified equivalent elements in organized geometries are used. ...
... With progressing of satellite, communications, in order to make receiving or transmitting the signals as close as feasible to the space where the signals have needed, via not to disturb other spaces, the radiation model have been more and more precise. So, antenna arrays in phased [5,7] have been highly improved. These antennas can alter the radiation model in array with respect to the phase shift that occurred among the elements supply voltages. ...
