Range-azimuth decouple beamforming for frequency diverse array with Costas-sequence modulated frequency offsets

The frequency diverse array (FDA) radar has been extensively studied due to its unique range-angle dependent beampattern. Time-invariant spatial patterns have been reported for FDAs proposed so far. However, some recent studies indicate that the patterns obtained by using these methodologies neglect the time-range or frequency-phase relationship, and the definition of time in some equations are misinterpreted which results in erroneous conclusions. Taking the time-variant property of FDA beampatterns into consideration, in this study, the authors propose a short range FDA radar to generate a timevariant focused range-angle dependent transmit beampattern, where chirp waveform with multi-carrier FDA architecture is used. Both the fixed and time-modulated frequency offsets are considered to analyse the proposed FDA radar. The frequency offset employed across each element is generated by chaos sequence and sine function. By compensating the propagation delays of signals, the transmitted signals sum up constructively to focus on the desired range-angle sector only at a specific instant of time. Numerical results are implemented to verify the validity of the proposed schemes.

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“…In the transmit beampattern derived in (5) and 9, the maximum field can be obtained when the phase term satisfies the condition [37,49,50] 2π…”

Section: Time-invariant Fda Beampattern Synthesismentioning

confidence: 99%

Time‐variant focused range‐angle dependent beampattern synthesis by frequency diverse array radar

Ahmad¹,

Shi

Zhou³

et al. 2020

IET signal process.

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“…Suppose that there are M interference sources located at (r i , u i ) and only one target located in the transmit mainlobe. In this case, the signal model given in (14) is rewritten as…”

Section: Sinr Analysismentioning

confidence: 99%

“…On this basis, many approaches have been proposed which can be divided into two categories. One category is to design the frequency increment or transmit weight, such as logarithmical frequency increment [10][11][12], window-based frequency increment [13], coding modulated frequency increment [14], optimized frequency increment by Genetic algorithm [15] and optimized transmit weight by compression sensing [16,17]. However, the beampatterns of such approaches are subject to quantization error.…”

Section: Introductionmentioning

confidence: 99%

A Novel Transmit–Receive System of Frequency Diverse Array Radar for Multitarget Localization

Wang

Liu

et al. 2018

Electronics

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The frequency diverse array (FDA) has drawn substantial attention because it provides a new degree of freedom. However, the multitarget localization is fundamentally limited by the range-angle-coupled and range-periodic beampattern of the basic FDA. It has been suggested to design a special FDA configuration to localize targets, but seldom of the existing works consider the design both in transmitting and receiving. In this paper, a transmit–receive system of FDA radar is proposed for the multitarget localization. In order to decouple the beampattern in the range and angle domains, the configurations of subarray-based FDA (SB-FDA) and full-band FDA (FB-FDA) are chosen as transmitter and receiver, respectively. In such a system framework, the receive beamwidth in range domain is only a quarter of the transmission. Then, two typical multitarget scenarios, sparse targets and unresolved targets, are both considered in the multitarget localization. For sparse targets, a proper frequency increment is selected to control the range-periodic transmit and receive mainlobes to focus on a single target, besides being staggered with others. In this way, multitarget localization is achieved in different pulses with monopulse processing. For unresolved targets, a method of intra-pulse beam scanning is proposed to localize each target with little interference from others. We also analyze the system performance in Cramér-Rao lower bound (CRLB) of localization and output signal to interference-plus-noise ratio (SINR). Several simulation results demonstrate the effectiveness of the proposed transmit–receive system in multitarget localization.

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“…In past years, remarkable functions have been introduced to generate non-linear frequency offsets, such as square increasing and cubic increasing frequency offsets [16], Hamming windowbased non-uniform frequency offsets [17], Costas sequence modulated frequency offsets [18], piecewise trigonometric frequency offsets [19] and non-uniform logarithmic frequency offsets [20]. Although the range-angle periodicity in FDA beampatterns has been eliminated by the methods proposed in [9][10][11][12][13][14][15][16][17][18][19][20], the time periodicity still prevails. Since the beampatterns generated by the above-mentioned methods are actually timevariant, it will cause difficulties in controlling the main beam direction and improving the target detectability.…”

Section: Introductionmentioning

confidence: 99%

Time‐variant focusing range‐angle dependent beampattern synthesis by uniform circular frequency diverse array radar

Ahmad

Shi

Zhou

2020

IET Radar Sonar & Navi

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The beam steering of phased array (PA) radar is fixed in one direction for all the ranges, thus the resulting beampattern is angle‐dependent but range‐independent. Compared with the PA radar, the frequency diverse array (FDA) radar can achieve range‐angle dependent beampattern by employing a small frequency increment across the array elements. Numerous studies have been conducted using linear FDAs, while other array configurations are seldom studied. On the other hand, the range‐angle dependent beampattern generated by the FDA is also time‐variant. However, previous studies on time‐invariant spatial‐focusing FDA beampatterns neglected the propagation process of the transmitted signals, leading the focused beampattern difficult to achieve when the transmit delay caused by wave propagation is considered. Taking the time‐variant property of the FDA beampatterns into consideration, in this study, we propose a novel uniform circular FDA (UC‐FDA) radar for short‐range beampattern synthesis. The UC‐FDA radar has the ability to scan azimuthally through 360°, which is a potential solution for applications requiring three‐dimensional beam steering. Furthermore, the proposed UC‐FDA radar adopts a pulse‐dependent non‐linear frequency offsets based on logistic map, together with multi‐carrier technique to achieve a dot‐shaped time‐variant focusing beampattern with minimum sidelobe levels and high‐resolution. The effectiveness of the proposed UC‐FDA radar is validated with simulated experiments.

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Range-azimuth decouple beamforming for frequency diverse array with Costas-sequence modulated frequency offsets

Cited by 22 publications

References 29 publications

Time‐variant focused range‐angle dependent beampattern synthesis by frequency diverse array radar

Time‐variant focused range‐angle dependent beampattern synthesis by frequency diverse array radar

A Novel Transmit–Receive System of Frequency Diverse Array Radar for Multitarget Localization

Time‐variant focusing range‐angle dependent beampattern synthesis by uniform circular frequency diverse array radar

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