University of Tabriz Tabriz Journal of Electrical Engineering 2008-7799 55 3 2025 12 22 "Introducing a novel method for reducing coupling between range and angles in SIAR based on frequency coding in a circular array." "Introducing a novel method for reducing coupling between range and angles in SIAR based on frequency coding in a circular array." 561 569 17960 10.22034/tjee.2024.55812.4603 FA Reza Fatemi Mofrad Department of Electrical Engineering, Malek-Ashtar University of Technology, Tehran, Iran. Ghasem Asadi Department of Electrical Engineering, Malek-Ashtar University of Technology, Tehran, Iran. Journal Article 2023 04 16 The Synthetic Impulse and Aperture Radar (SIAR) are radars that have characteristics such as the ability to detect low RCS targets, Low Probability Of Intercept , resistance to anti-radiation missiles, and simultaneous detection and tracking of multiple targets. In these radars, one of the most important challenges is coupling between range and angle. This means that range error causes angle error and vice versa. To address this issue, radar designers typically design transmitting waveforms based on carrier frequency coding techniques In the past, sequential carrier frequency coding, positive and the negative sequential carrier frequency coding and random carrier frequency coding have been proposed to reduce the coupling between range and angle for a linear array(2D). In this article, geometrical and mathematical equations of coupling are presented for a circular array(3D) and a new method called as positive and negative random carrier frequency coding is proposed. It will be shown that proposed method reduces coupling and side lobe level by about 40% more than the previous frequency coding methods. Moreover, we provide evidence that the coupling between azimuth and elevation angles remains consistent across different frequency coding techniques. Furthermore, the random change of carrier frequency coding from one transmit period to the next allows us to leverage pulse-to-pulse frequency agility, adding an additional advantage to this method The Synthetic Impulse and Aperture Radar (SIAR) are radars that have characteristics such as the ability to detect low RCS targets, Low Probability Of Intercept , resistance to anti-radiation missiles, and simultaneous detection and tracking of multiple targets. In these radars, one of the most important challenges is coupling between range and angle. This means that range error causes angle error and vice versa. To address this issue, radar designers typically design transmitting waveforms based on carrier frequency coding techniques In the past, sequential carrier frequency coding, positive and the negative sequential carrier frequency coding and random carrier frequency coding have been proposed to reduce the coupling between range and angle for a linear array(2D). In this article, geometrical and mathematical equations of coupling are presented for a circular array(3D) and a new method called as positive and negative random carrier frequency coding is proposed. It will be shown that proposed method reduces coupling and side lobe level by about 40% more than the previous frequency coding methods. Moreover, we provide evidence that the coupling between azimuth and elevation angles remains consistent across different frequency coding techniques. Furthermore, the random change of carrier frequency coding from one transmit period to the next allows us to leverage pulse-to-pulse frequency agility, adding an additional advantage to this method https://tjee.tabrizu.ac.ir/article_17960_f8ee918e3f669f92f8f6264e88ac970f.pdf