Antenna arrays benefit from spatial diversity, which enables the control of the pattern specifications in space. Adding frequency diversity to arrays provides an opportunity to control the beams in the Space-Time domain. Contrary to the conventional arrays, the added frequency diversity in the Frequency Diverse Arrays (FDA) leads to time-variant and range-dependent patterns. The time variation of the pattern affects both steering and auto-scanning applications. The array factor depends coherently on the frequency and spatial distributions of elements, in the same way, the spatial and time behavior of the FDA’s pattern is correlated. Due to this space-frequency coherency, an adjoint spatial-frequency design algorithm is the best approach for controlling the array's spatial and time behaviors. Although Due to the complexity of the array factor formulations in the FDA, the frequency and spatial distribution of the elements has been separately designed. This study proposes an algorithm to concurrently, allocate the location and frequency of the elements for a desired pattern. First, using some symmetry, a straightforward formulation for the array factor is obtained and used to design a symmetrical FDA for a stable and periodic scanning beam. Second, by analyzing the formulations, two important design parameters and some crucial design criteria of the FDA pattern for scanning applications are suggested, and using these parameters a designing algorithm is extracted. The novelty of the proposed approach is the simultaneous design of the location and frequency of the elements in the space-frequency plane, which results in meeting the time and spatial requirement of the pattern. Using this approach, two different planar arrays are designed, and their results are compared with those of other planar configurations. This study paves the way for a new approach to designing FDAs.
Coupled microwave oscillators could be potentially considered a good replacement for the feed network of frequency‐diverse arrays. However, previous studies showed that the stability region for a mutually weak‐coupled oscillator array in the Mode Lock State (MLS) is too small to be practical. Besides, by increasing the coupling strength or reducing the initial natural frequency of the oscillators, the current analytical methods lose their accuracy. The final steady‐state and dynamic of a non‐linear Van‐der‐Pol medium‐coupled oscillator array in the MLS is investigated. By using the Kuramoto Model results in analysing the biological cells, an alternative approach is suggested and investigated in the entrainment region for the mode‐locked microwave oscillator array. This approach is accurate even for medium‐coupled oscillator arrays, where the locking range to the beat frequency ratio is greater than 0.1. The stability of the oscillator in this region is investigated by imposing some perturbations in the form of phase noise on the initial signals. Also, the optimum initial condition to design large arrays is investigated using the analysis results. In the described initial conditions for small beat frequencies, the simulation results show that the stability region is much greater than the large beat frequency region. This capability initiates a new practical approach for implementing Frequency Diverse Arrays.
Antenna arrays benefit from spatial diversity, which allows controlling the pattern specifications in space. Adding frequency diversity to the arrays initiates opportunity to control the beams in the Space-Time domain. Frequency Diverse Array (FDA) has a Range-Angle dependent pattern; therefore, the array's spatial and time behavior should be designed simultaneously for optimum performance. Due to the lack of simple array factor formulations for non-regular configurations, array geometry design has not been the primary concern in many current studies. Due to coherency between frequency and spatial distribution in FDAs, the spatial and time behavior of the pattern is correlated. Frequency diversity of the FDA leads to time-variant beam in steering and auto-scanning beam in CW applications. The present study in addition of SLL discusses two important scanning array parameters; the pattern periodicity and stability in each scan round. In this study using some symmetry rules, a straightforward formulation for the array factor is obtained and used to achieve a stable and periodic scanning beam, suggesting a novel joint space-frequency allocation scheme for the FDA. The approach allows the location and frequency of elements to be designed in the frequency-space plane that minimizes the error function, which is defined based on the time and spatial behavior of the array. Using these concepts, two arrays are designed, and their results are compared with other planar configurations. This study paves the way for a new approach to design FDAs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.