Beampattern Synthesis for Frequency Diverse Array Based on Time-Modulated Double Parameters Approach

Abstract

The basic frequency diverse array (FDA) using linearly increasing frequency increments generates a range-angle dependent beampattern. However, it is coupled in range and angle dimensions and is also periodic in range and time, making its applications limited. In this paper, a novel FDA beampattern synthesis approach is proposed utilizing the time-modulated double parameters based on the chaos sequence. The chirp signal mechanism is used instead of the single-frequency signal mechanism. Meanwhile, the multi-carrier architecture is used for range-angle decoupling. Satisfactory time-invariant range-angle beampattern can be synthesized for both single and multiple targets locations. Simulation results show the effectiveness of the proposed FDA scheme. Furthermore, comparative study with the existing technology indicates that the proposed approach can provide better performance in spatial focusing and side-lobe suppressing.

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

“…The time-invariant FDAs simply calculate the beampattern by assuming the variable t to be a fixed value (t = 0) [9][10][11][12][13][14][15][16][17][18][19][20][21] or defining the variable t in the range from 0 to T as in [35][36][37][38][39][40][41][42]48].…”

“…Similarly, it is also unconvincing to achieve the desired beampattern within the pulse duration that is at t = T, because the desired range is usually taken as r d ≫ T ⋅ c. It is noted that the variable t represents the actual time of the signal traveling in the space. Furthermore, the time-modulated frequency offsets are designed in [36][37][38][39][40][41][42]48] to achieve a time-invariant spatial beampattern. In general, the time-varying frequency offsets are given as…”

“…where Δ f (m) is a non-linear function with respect to the element index m [36][37][38][39][40][41][42]48]. In these FDA schemes, the time-modulated frequency offsets were directly substituted in (5).…”

“…Nevertheless, the beampatterns of these FDAs are range-angle dependent only for a fixed time, neglecting the influence of time. Recently, FDAs with time-dependent or time-modulated frequency offset have been proposed in [36][37][38][39][40][41][42], which achieve a time-invariant and aperiodic beampattern. Among them, a multi-carrier FDA with timemodulated logarithmic frequency offset is proposed in [36].…”

“…It achieves a pencil-shaped time-invariant beampattern to be suitable for target tracking application, which, however, does not consider the time-variance problem. Similarly, a multi-carrier FDA with frequency diverse chirp signal is proposed in [42] to produce a dotshaped range-angle dependent beampattern, wherein timemodulated logistic map based frequency offsets are considered. Though the beampatterns achieved by FDA schemes presented in [36][37][38][39][40][41][42] are time-independent for a given range-angle pair, they remain time-dependent for other values of range and angle.…”