COMPARISON OF THE CHARACTERISTICS OF THE CORRELATION-INTERFEROMETRIC BELLOWS WHEN USING DIRECTIONAL AND NON-DIRECTIONAL ANTENNA ELEMENTS

При создании корреляционно-фазовых пеленгаторов, как правило, в качестве антенных элементов используют ненаправленные антенные элементы (АЭ). Для использования измерений направленных АЭ требуется модифицировать алгоритмы пеленгации. Представлены соответствующие модификации алгоритмов и проведено сравнительное исследование точности пеленгования применительно к двухканальным корреляционно-интерферометрическим стандартным пеленгаторам, использующим плоские антенные решетки из направленных и ненаправленных АЭ. Рассмотрена также возможность определения пеленгов лишь по энергетическим измерениям, отсутствующая применительно к пеленгаторам с ненаправленными АЭ. Показано, что применение направленных АЭ позволяет снизить вероятность возникновения аномальных ошибок, повысить точность пеленгования при существенно больших значениях угла места, определяющего направление на источник радиоизлучения, снизить негативное влияние отказа от учета сферичности приходящей волны и, следовательно, уменьшить размеры ближней зоны пеленгатора, для которой характерно появление аномальных ошибок пеленгования. В многосигнальной радиообстановке использование направленных свойств АЭ позволяет также формировать пеленгационную диаграмму, обеспечивающую частичное подавление помеховых сигналов. Вместе с тем эффективное использование направленных свойств антенных АЭ требует максимально точного учета их диаграмм направленности (ДН). Погрешности описания ДН могут приводить к заметным ошибкам при определении пеленга, поэтому повышение качества работы пеленгационной системы за счет использования направленных АЭ сопровождается повышением требований к определению и точности практической реализации ДН АЭ When creating correlation-phase direction finders, as a rule, non-directional antenna elements (AE) are used. To use directional AE measurements, it is necessary to modify the direction finding algorithms. We present the corresponding modifications of the algorithms and we carried out a comparative study of the direction finding accuracy in relation to two-channel correlation-interferometric standard direction finders using flat antenna arrays of directional and non-directional AEs. We also considered the possibility of determining bearings only from energy measurements, which is absent in relation to direction finders with nondirectional AE. We show that the use of directional AEs makes it possible to reduce the probability of occurrence of anomalous errors, to increase the accuracy of direction finding at significantly large values of the elevation angle, which determines the direction to the radio emission source, to reduce the negative effect of refusing to take into account the sphericity of the incoming wave and, consequently, to reduce the size of the near-field zone of a bearer, which is characterized by the appearance of abnormal direction finding errors. In a multi-signal radio environment, the use of the directional properties of the AE also makes it possible to form a direction finding diagram that provides partial suppression of interference signals. At the same time, the effective use of the directional properties of antenna AEs requires the most accurate consideration of their directional patterns (DP). Errors in the description of the pattern can lead to noticeable errors in determining the bearing, therefore, improving the quality of operation of the direction finding system due to the use of directional AEs is accompanied by increased requirements for the determination and accuracy of practical implementation of the pattern of AE

Radiation Profile of 2.45 GHz Bi-Circular Loop Antenna using Parabolic Reflector Made of Frying Pan (Wajanbolic)

This study aims to determine the dimensions of the antenna and reflector which can optimally work at a frequency of 2.45 GHz. A good antenna is an antenna that has high directive capability, high performance, and inexpensive. In this work, the proposed antenna model was a Bi-Circular Loop (BCL) with a reflector using a frying pan (Wajanbolic). The methods were used in this research for instance computational simulation, fabrication, and characterization. Simulations were carried out using the Finite Different Time Domain (FDTD) technique. The simulation results were compared with the measurement process. In the first simulation, four reflectors sizes could qualify as antennas, namely diameters of 309.00 mm, 335.00 mm, 364.00 mm, and 381.00 mm. The four reflectors sizes were optimized by changing the radius parameter of the BCL antenna. The best results were obtained on the reflector with a diameter of 364.00 mm and a BCL radius of 17.38 mm. The simulation results showed a radiation profile consisting of an RL value of -35.69 dB and a gain value of 16.40 dBi. Based on the fabrication and measurement of the antenna, the RL value was -54.75 dB and the directional antenna gain was 16.00 dBi. An antenna with such performance can be used as a point-to-point Wi-Fi transmitter.

Influence of the radiation pattern errors for the correlation interferometer

While designing phase-correlation direction finders, as antenna components, the non-directional ones are usually applied. Mounting the non-directional antenna components provides certain new options but makes the bearing computation procedure more problematic. In the present paper, the feasibility of using the directional antenna components is discussed and confirmed in terms of its positive influence on the stability of the bearing results in the case when the deviations of the implementations of the actual diagrams of the antenna components from their reference model occur.

Deteksi Radar Terhadap Multi-Object Bergerak Dengan Pemrosesan Doppler

In general, Radar or Radio Detection and Ranging is an electromagnetic wave system that is useful to measure distance and answer and make maps of surrounding objects. Radar has an advantage compared to other navigation tools, which is that radar does not require a transmitter station as a transmitter. Radar has an electronic wave emission principle that emits short radio wave pulses emitted in a narrow beam by a directional antenna. In this study, a multi-object radar detection simulation was carried out using Dopler processing both MTI and PDP, which later on the radar will detect related objects. Multi-object here is a condition that is achieved when a navigation radar detects more than one object. The result of this research is a multi-object detection process using the MTI and PDP methods and the matched-filter obtained from the predetermined data. So Doppler processing aims to mitigate the clutter signal to improve the detection performance of moving targets even though there is a dominance of signals originating from stationary clutter.